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Sample records for fiber taper waveguides

  1. Single-mode fiber linearly tapered planar waveguide tunable coupler

    NASA Astrophysics Data System (ADS)

    Das, Alok K.; Hussain, Anwar

    1997-09-01

    We developed a simple system of tunable fiber film coupler using a linearly tapered thin-film planar waveguide (PWG) evanescently coupled by a single-mode distributed fiber half-coupler. We investigate the characteristics of the coupler theoretically and experimentally taking into consideration the refractive index ( n f ) of nonuniform films, the magnitude of nonuniformity ( m ) of the films, and the source wavelength ( ). The thickness variation of the nonuniform film is along the direction of propagation of optical power. Tapered and plano concave thin films of a mix of oils as well as a plano concave poly(methyl methacrylate) film were fabricated to serve as nonuniform PWG s. Similar to single-mode fiber with a uniform thickness PWG coupler, such a coupler also provides light modulation with a change of n f . However, position shifting of a half-coupler in a tapered PWG structure along the direction of propagation exhibits the variation of fiber throughput power. This action serves as a simple system for a tunable fiber film coupler. Wavelength-dependent throughput fiber power for such a coupler also behaves as a filter. The center wavelength can be controlled by shifting the position of the half-coupler. A coupling fiber as a half-coupler can be used for efficient coupling. We performed a theoretical analysis of the structure using Marcuse s model and observed good agreement with the experimental results.

  2. Mode-locked fiber/waveguide lasers based on a fiber taper embedded in carbon nanotubes/polymer composite

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Khanh, Kieu; Honkanen, Seppo; Kueppers, Franko

    2008-04-01

    We generated 2 nJ, ~690 fs pulses with 10 MHz repetition rate from a linear cavity mode-locked Er 3+-doped fiber laser with a fiber taper embedded in carbon nanotubes (CNTs)/polymer composite. Evanescent field out of the taper section can interact with CNTs to see saturation of absorption. With the fiber based saturable absorber this laser has simple and robust all-fiber configuration comparing to traditional linear cavity mode-locked lasers with semiconductor saturable absorbers. In addition, we have demonstrated a mode-locked ring laser, with a similar saturable absorber, by using an ion-exchanged Er 3+-Yb 3+-codoped planar waveguide as the gain medium.

  3. Cross two photon absorption in a silicon photonic crystal waveguide fiber taper coupler with a physical junction

    SciTech Connect

    Sarkissian, Raymond O'Brien, John

    2015-01-21

    Cross two photon absorption in silicon is characterized using a tapered fiber photonic crystal silicon waveguide coupler. There is a physical junction between the tapered fiber and the waveguide constituting a stand-alone device. This device is used to obtain the spectrum for cross two photon absorption coefficient per unit volume of interaction between photons of nondegenerate energy. The corresponding Kerr coefficient per unit volume of interaction is also experimentally extracted. The thermal resistance of the device is also experimentally determined and the response time of the device is estimated for on-chip all-optical signal processing and data transfer between optical signals of different photon energies.

  4. Coupling Single-Mode Fiber to Uniform and Symmetrically Tapered Thin-Film Waveguide Structures Using Gadolinium Gallium Garnet

    NASA Technical Reports Server (NTRS)

    Gadi, Jagannath; Yalamanchili, Raj; Shahid, Mohammad

    1995-01-01

    The need for high efficiency components has grown significantly due to the expanding role of fiber optic communications for various applications. Integrated optics is in a state of metamorphosis and there are many problems awaiting solutions. One of the main problems being the lack of a simple and efficient method of coupling single-mode fibers to thin-film devices for integrated optics. In this paper, optical coupling between a single-mode fiber and a uniform and tapered thin-film waveguide is theoretically modeled and analyzed. A novel tapered structure presented in this paper is shown to produce perfect match for power transfer.

  5. Parabolic tapers for overmoded waveguides

    DOEpatents

    Doane, J.L.

    1983-11-25

    A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.

  6. Acrylic and metal based Y-branch plastic optical fiber splitter with optical NOA63 polymer waveguide taper region

    NASA Astrophysics Data System (ADS)

    Ehsan, Abang Annuar; Shaari, Sahbudin; Rahman, Mohd Kamil Abd.

    2011-01-01

    We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively.

  7. Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

    PubMed

    Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

    2014-10-15

    We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated. PMID:25361125

  8. Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

    PubMed

    Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

    2014-10-15

    We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

  9. Eigenvalue equation and core-mode cutoff of weakly guiding tapered fiber as three layer optical waveguide and used as biochemical sensor.

    PubMed

    Linslal, C L; Mohan, P M S; Halder, A; Gangopadhyay, T K

    2012-06-01

    The core-mode cutoff plays a major role in evanescent field absorption based sensors. A method has been proposed to calculate the core-mode cutoff by solving the eigenvalue equations of a weakly guiding three layer optical waveguide graphically. The variation of normalized waveguide parameter (V) is also calculated with different wavelengths at core-mode cutoff. At the first step, theoretical analysis of tapered fiber parameters has been performed for core-mode cutoff. The taper angle of an adiabatic tapered fiber is also analyzed using the length-scale criterion. Secondly, single-mode tapered fiber has been developed to make a precision sensor element suitable for chemical detection. Finally, the sensor element has been used to detect absorption peak of ethylenediamine. Results are presented in which an absorption peak at 1540 nm is observed.

  10. Tapered GRIN fiber microsensor.

    PubMed

    Beltrán-Mejía, Felipe; Biazoli, Claudecir R; Cordeiro, Cristiano M B

    2014-12-15

    The sensitivity of an optical fiber microsensor based on inter-modal interference can be considerably improved by tapering a short extension of the multimode fiber. In the case of Graded Index fibers with a parabolic refractive index profile, a meridional ray exhibits a sinusoidal path. When these fibers are tapered, the period of the propagated beam decrease down-taper and increase up-taper. We take advantage of this modulation -along with the enhanced overlap between the evanescent field and the external medium- to substantially increase the sensitivity of these devices by tuning the sensor's maximum sensitivity wavelength. Moreover, the extension of this device is reduced by one order of magnitude, making it more propitious for reduced space applications. Numerical and experimental results demonstrate the success and feasibility of this approach. PMID:25606989

  11. Optical coupling and splitting with two parallel waveguide tapers.

    PubMed

    Tao, S H

    2011-01-17

    A coupling and splitting device comprising a width taper and a spatial-modulated subwavelength grating waveguide (SSGW) is proposed. The width taper is a waveguide with increasing width and the SSGW is a waveguide grating whose width and thickness are constant but the filling factor increases along the light propagation. Thus, the effective index of the subwavelength grating increases according to the effective medium theory. Light of orthogonal polarizations from a single-mode fiber can be coupled efficiently with the two parallel tapers. Furthermore, the coupled lights of orthogonal polarizations in the two tapers can be further split with connecting bent waveguides. Fabrication of the device is fully compatible with current complementary metal oxide semiconductor technology.

  12. Fabrication of polymer waveguide tapers to minimize insertion loss

    NASA Astrophysics Data System (ADS)

    Yacoubian, Araz; Lin, Weiping; Bechtel, James H.

    2001-12-01

    Polymer based electro-optic (EO) modulators and other integrated optic devices have the potential to provide low cost and lightweight alternative for high-speed digital as well as analog RF links. To be truly competitive with existing technologies such as LiNbO3, EO polymer modulators must also meet the criteria of low loss. There are two major causes of loss in EO modulators: waveguide loss (including material loss, scattering, etc.), and fiber- to-waveguide coupling (butting) loss. Various techniques can be utilized to minimize these coupling losses, however, to maintain low cost of component, we resort to the simplest possible approach which is easy to manufacture. Pigtails using standard single mode fiber produce coupling loss on the order of 3 to 5 dB/connection. In order to improve mode size matching yet maintain low drive voltage we incorporate waveguide and fibers tapers. Waveguide tapers resulted to butting losses as low as 1.5 dB/connection, whereas fiber tapers resulted to 2.5 dB/connection butting losses. Combining both techniques together, it was possible to produce 1.3 dB/connection butting loss, however, tapered waveguide devices were less sensitive to alignment tolerance than tapered fiber devices, and therefore less sensitive to environmental conditions.

  13. Polymer taper bridge for silicon waveguide to single mode waveguide coupling

    NASA Astrophysics Data System (ADS)

    Kruse, Kevin; Middlebrook, Christopher T.

    2016-03-01

    Coupling of optical power from high-density silicon waveguides to silica optical fibers for signal routing can incur high losses and often requires complex end-face preparation/processing. Novel coupling device taper structures are proposed for low coupling loss between silicon photonic waveguides and single mode fibers are proposed and devices are fabricated and measured in terms of performance. Theoretical mode conversion models for waveguide tapers are derived for optimal device structure design and performance. Commercially viable vertical and multi-layer taper designs using polymer waveguide materials are proposed as innovative, cost-efficient, and mass-manufacturable optical coupling devices. The coupling efficiency for both designs is determined to evaluate optimal device dimensions and alignment tolerances with both silicon rib waveguides and silicon nanowire waveguides. Propagation loss as a function of waveguide roughness and metallic loss are determined and correlated to waveguide dimensions to obtain total insertion loss for the proposed taper designs. Multi-layer tapers on gold-sputtered substrates are fabricated through photolithography as proof-of-concept devices and evaluated for device loss optimization. Tapered waveguide coupling loss with Si WGs (2.74 dB) was experimentally measured with high correlation to theoretical results.

  14. Spot-size converter with a SiO(2) spacer layer between tapered Si and SiON waveguides for fiber-to-chip coupling.

    PubMed

    Maegami, Yuriko; Takei, Ryohei; Omoda, Emiko; Amano, Takeru; Okano, Makoto; Mori, Masahiko; Kamei, Toshihiro; Sakakibara, Youichi

    2015-08-10

    We experimentally demonstrate low-loss and polarization-insensitive fiber-to-chip coupling spot-size converters (SSCs) comprised of a three dimensionally tapered Si wire waveguide, a SiON secondary waveguide, and a SiO(2) spacer inserted between them. Fabricated SSCs with the SiO(2) spacer exhibit fiber-to-chip coupling loss of 1.5 dB/facet for both the quasi-TE and TM modes and a small wavelength dependence in the C- and L-band regions. The SiON secondary waveguide is present only around the SSC region, which significantly suppresses the influence of the well-known N-H absorption of plasma-deposited SiON at around 1510 nm.

  15. Tapered polysilicon core fibers for nonlinear photonics.

    PubMed

    Suhailin, Fariza H; Shen, Li; Healy, Noel; Xiao, Limin; Jones, Maxwell; Hawkins, Thomas; Ballato, John; Gibson, Ursula J; Peacock, Anna C

    2016-04-01

    We propose and demonstrate a novel approach to obtaining small-core polysilicon waveguides from the silicon fiber platform. The fibers were fabricated via a conventional drawing tower method and, subsequently, tapered down to achieve silicon core diameters of ∼1  μm, the smallest optical cores for this class of fiber to date. Characterization of the material properties have shown that the taper process helps to improve the local crystallinity of the silicon core, resulting in a significant reduction in the material loss. By exploiting the combination of small cores and low losses, these tapered fibers have enabled the first observation of nonlinear transmission within a polycrystalline silicon waveguide of any type. As the fiber drawing method is highly scalable, it opens a route for the development of low-cost and flexible nonlinear silicon photonic systems. PMID:27192236

  16. Radiation characteristics of tapered slab waveguides

    NASA Astrophysics Data System (ADS)

    Scheggi, A. M.; Falciai, R.; Brenci, M.

    1983-01-01

    The application of ray optics to the evaluation of near- and far-field radiation patterns of a slab waveguide taper is discussed, noting the importance of calculating the power that can be extracted from the core at the end of the waveguide related to the near-field configurations. A multimode, tapered slab waveguide with a homogeneous core and unlimited cladding is considered. It is pointed out that as the ray proceeds on its zigzag path down the taper, its propagation angle increases from reflection to reflection and eventually surpasses the limit angle of total reflection. To obtain an overall idea of the range of ray angles accepted at the smaller end of the taper, the Williamson (1952) method is used; this makes it possible, through a simple geometrical construction, to trace the ray in a linear cone. It is found that the ray-tracing technique can constitute an adequate tool in the analysis and design of tapered multimode waveguides.

  17. Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids.

    PubMed

    Miao, Yinping; Ma, Xixi; Wu, Jixuan; Song, Binbin; Zhang, Hao; Zhang, Kailiang; Liu, Bo; Yao, Jianquan

    2015-08-15

    A compact fiber-optic magnetic-field sensor based on tapered all-solid waveguide-array fiber (WAF) and magnetic fluid (MF) has been proposed and experimentally demonstrated. The tapered all-solid WAF is fabricated by using a fusion splicer, and the sensor is formed by immersing the tapered all-solid WAF into the MF. The transmission spectra have been measured and analyzed under different magnetic-field intensities. Experimental results show that the acquired magnetic-field sensitivity is 44.57 pm/Oe for a linear magnetic-field intensity range from 50 to 200 Oe. All-solid WAF has very similar thermal expansion coefficient for high- and low-refractive-index glasses, so mode profile is not affected by thermal drifts. Also, magnetically induced refractive-index changes into the ferrofluid are of the order of ∼5×10(-2), while the corresponding thermally induced refractive-index changes into the ferrofluid are expected to be lower. The temperature response has also been detected, and the temperature-induced wavelength shift perturbation is less than 0.3 nm from temperature of 26.9°C-44°C. The proposed magnetic-field sensor has such advantages as low temperature sensitivity, simple structure, and ease of fabrication. It also indicates that the magnetic-field sensor based on tapered all-solid WAF and MF is helpful to reduce temperature cross-sensitivity for the measurement of magnetic field.

  18. Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids.

    PubMed

    Miao, Yinping; Ma, Xixi; Wu, Jixuan; Song, Binbin; Zhang, Hao; Zhang, Kailiang; Liu, Bo; Yao, Jianquan

    2015-08-15

    A compact fiber-optic magnetic-field sensor based on tapered all-solid waveguide-array fiber (WAF) and magnetic fluid (MF) has been proposed and experimentally demonstrated. The tapered all-solid WAF is fabricated by using a fusion splicer, and the sensor is formed by immersing the tapered all-solid WAF into the MF. The transmission spectra have been measured and analyzed under different magnetic-field intensities. Experimental results show that the acquired magnetic-field sensitivity is 44.57 pm/Oe for a linear magnetic-field intensity range from 50 to 200 Oe. All-solid WAF has very similar thermal expansion coefficient for high- and low-refractive-index glasses, so mode profile is not affected by thermal drifts. Also, magnetically induced refractive-index changes into the ferrofluid are of the order of ∼5×10(-2), while the corresponding thermally induced refractive-index changes into the ferrofluid are expected to be lower. The temperature response has also been detected, and the temperature-induced wavelength shift perturbation is less than 0.3 nm from temperature of 26.9°C-44°C. The proposed magnetic-field sensor has such advantages as low temperature sensitivity, simple structure, and ease of fabrication. It also indicates that the magnetic-field sensor based on tapered all-solid WAF and MF is helpful to reduce temperature cross-sensitivity for the measurement of magnetic field. PMID:26274690

  19. Expanded-mode semiconductor laser with tapered-rib adiabatic-following fiber coupler

    SciTech Connect

    Vawter, G.A.; Smith, R.E.; Hou, H.; Wendt, J.R.

    1997-02-01

    A new diode laser using a Tapered-Rib Adiabatic-Following Fiber Coupler to achieve 2D mode expansion and narrow, symmetric far-field emission without epitaxial regrowth or sharply-defined tips on tapered waveguides is presented.

  20. Radiation losses of step-tapered channel waveguides.

    PubMed

    Marcuse, D

    1980-11-01

    We compute the radiation losses of a rectangular dielectric waveguide (integrated optics channel waveguide) that is tapered so that its wider cross-sectional dimension increases by roughly a factor of three while its narrow dimension remains constant. As the waveguide widens its refractive index decreases to ensure that the waveguide supports only one guided mode. The taper is approximated by a discontinuous staircase curve. A rectangular waveguide taper of 2-microm thickness, tapering from 3- to 10-microm width through fourteen steps of 0.25-microm height, has a minimum loss (at 0.6328-microm wavelength) of 0.13 dB for a 200-microm taper length.

  1. Vertically-tapered optical waveguide and optical spot transformer formed therefrom

    DOEpatents

    Bakke, Thor; Sullivan, Charles T.

    2004-07-27

    An optical waveguide is disclosed in which a section of the waveguide core is vertically tapered during formation by spin coating by controlling the width of an underlying mesa structure. The optical waveguide can be formed from spin-coatable materials such as polymers, sol-gels and spin-on glasses. The vertically-tapered waveguide section can be used to provide a vertical expansion of an optical mode of light within the optical waveguide. A laterally-tapered section can be added adjacent to the vertically-tapered section to provide for a lateral expansion of the optical mode, thereby forming an optical spot-size transformer for efficient coupling of light between the optical waveguide and a single-mode optical fiber. Such a spot-size transformer can also be added to a III-V semiconductor device by post processing.

  2. Tapered rib fiber coupler for semiconductor optical devices

    DOEpatents

    Vawter, Gregory A.; Smith, Robert Edward

    2001-01-01

    A monolithic tapered rib waveguide for transformation of the spot size of light between a semiconductor optical device and an optical fiber or from the fiber into the optical device. The tapered rib waveguide is integrated into the guiding rib atop a cutoff mesa type semiconductor device such as an expanded mode optical modulator or and expanded mode laser. The tapered rib acts to force the guided light down into the mesa structure of the semiconductor optical device instead of being bound to the interface between the bottom of the guiding rib and the top of the cutoff mesa. The single mode light leaving or entering the output face of the mesa structure then can couple to the optical fiber at coupling losses of 1.0 dB or less.

  3. Low-crosstalk Si arrayed waveguide grating with parabolic tapers.

    PubMed

    Ye, Tong; Fu, Yunfei; Qiao, Lei; Chu, Tao

    2014-12-29

    A silicon arrayed waveguide grating (AWG) with low channel crosstalk was demonstrated by using ultra-short parabolic tapers to connect the AWG's free propagation regions and single-mode waveguides. The tapers satisfied the requirements of low-loss mode conversion and lower channel crosstalk from the coupling of neighboring waveguides in the AWGs. In this work, three different tapers, including parabolic tapers, linear tapers, and exponential tapers, were theoretically analyzed and experimentally investigated for a comparison of their effects when implemented in AWGs. The experimental results showed that the AWG with parabolic tapers had a crosstalk improvement up to 7.1 dB compared with the others. Based on the advantages of parabolic tapers, a 400-GHz 8 × 8 cyclic AWG with 2.4 dB on-chip loss and -17.6~-25.1 dB crosstalk was fabricated using a simple one-step etching process. Its performance was comparable with that of existing AWGs with bi-level tapers, which require complicated two-step etching fabrication processes.

  4. Waveguide tapering for beam-width control in a waveguide transducer.

    PubMed

    Kwon, Young Eui; Jeon, Hyun Joong; Kim, Hoe Woong; Kim, Yoon Young

    2014-03-01

    In a waveguide transducer that transmits an ultrasonic wave through a waveguide unit to a test structure, it is most preferred to send a non-dispersive ultrasonic wave of a narrow beam width. However, there is an unresolved conflict between the generation of the non- or less-dispersive wave and the transmission of a narrow-beam wave into a test structure. Among others, the thickness of the waveguide unit in a waveguide transducer is the key variable determining these two conflicting criteria, but the use of a uniformly-thick waveguide of any thickness cannot fulfill the two conflicting criteria simultaneously. In this study, we propose a specially-engineered tapered waveguide unit for the simultaneous satisfaction. An excitation unit is installed at the end of the thin region of the tapered waveguide and generates only the lowest non-dispersive shear-horizontal wave. Then the generated wave propagates through the tapered region of the waveguide unit and reaches the thick region of the waveguide with insignificant mode conversion to higher modes. If the tapered waveguide is used, the surviving lowest mode in the thick region of the waveguide is shown to carry most of the transmitted power and is finally propagated into a test structure. Because the beam size of the propagated wave and the thickness of the contacting waveguide region are inversely related, the thick contacting region of the tapered waveguide ensures narrow beam width. Numerical and experimental investigations were performed to check the effectiveness of the proposed waveguide-tapering approach.

  5. Supercontinuum generation in dispersion-managed tapered-rib waveguide.

    PubMed

    Hu, Hongyu; Li, Wenbo; Dutta, Niloy K

    2013-10-20

    We have designed a tapered-rib waveguide and numerically studied the generation of supercontinuum using such waveguides. The Air-SF57 glass-SiO(2) waveguide is 3 cm long, with a varying etched depth to manage the total dispersion. Numerical simulations are conducted for input pulses at a wavelength of 1.55 μm with a width of 150 fs and peak power of 5 kW. The proposed waveguide geometry greatly broadens the output spectrum, extending from ∼1 to ∼6  μm, caused by the continuous modification of the phase-matching condition for the generated waves.

  6. Supercontinuum generation in dispersion-managed tapered-rib waveguide.

    PubMed

    Hu, Hongyu; Li, Wenbo; Dutta, Niloy K

    2013-10-20

    We have designed a tapered-rib waveguide and numerically studied the generation of supercontinuum using such waveguides. The Air-SF57 glass-SiO(2) waveguide is 3 cm long, with a varying etched depth to manage the total dispersion. Numerical simulations are conducted for input pulses at a wavelength of 1.55 μm with a width of 150 fs and peak power of 5 kW. The proposed waveguide geometry greatly broadens the output spectrum, extending from ∼1 to ∼6  μm, caused by the continuous modification of the phase-matching condition for the generated waves. PMID:24216588

  7. Nanofocusing of terahertz wave in a tapered hyperbolic metal waveguide.

    PubMed

    Gao, Hua; Cao, Qing; Zhu, Minning; Teng, Da; Shen, Siyi

    2014-12-29

    An tapered hyperbolic metal waveguide is suggested for the nanofocusing of terahertz waves. We numerically show that, at the frequency of 1 THz, the focal spot can be as small as only 5 nm, which is smaller than that of a plate waveguide by 2 orders of magnitude. Correspondingly, the longitudinal component of the energy flow density is stronger than that of a plate waveguide by 3 orders of magnitude for the same input. It is shown that these significant improvements come from the small imaginary part of the effective index of the hyperbolic metal waveguide.

  8. Optical trapping of microparticles using silicon nitride waveguide junctions and tapered-waveguide junctions on an optofluidic chip.

    PubMed

    Cai, Hong; Poon, Andrew W

    2012-10-01

    We study optical trapping of microparticles on an optofluidic chip using silicon nitride waveguide junctions and tapered-waveguide junctions. We demonstrate the trapping of single 1 μm-sized polystyrene particles using the evanescent field of waveguide junctions connecting a submicrometer-sized input-waveguide and a micrometer-sized output-waveguide. Particle trapping is localized in the vicinity of the junction. We also demonstrate trapping of one and two 1μm-sized polystyrene particles using tapered-waveguide junctions connecting a submicrometer-sized singlemode input-waveguide and a micrometer-sized multimode output-waveguide. Particle trapping occurs near the taper output end, the taper center and the taper input end, depending on the taper aspect ratio.

  9. Workplace for manufacturing devices based on optical fiber tapers

    NASA Astrophysics Data System (ADS)

    Martan, Tomáš; Honzátko, Pavel; Kaňka, Jiři; Novotný, Karel

    2007-04-01

    Many important optical fiber components are based on tapered optical fibers. A taper made from a single-mode optical fiber can be used, e.g., as a chemical sensor, bio-chemical sensor, or beam expander. A fused pair of tapers can be used as a fiber directional coupler. Fiber tapers can be fabricated in several simple ways. However, a tapering apparatus is required for more sophisticated fabrication of fiber tapers. The paper deals with fabrication and characterization of fiber tapers made from a single-mode optical fiber. A tapering apparatus was built for producing devices based on fiber tapers. The apparatus is universal and enables one to taper optical fibers of different types by a method utilizing stretching a flame-heated section of a silica fiber. Fiber tapers with constant waist length and different waist diameters were fabricated. The transition region of each fiber taper monotonically decreased in diameter along its length from the untapered fiber to the taper waist. The fiber tapers were fabricated with a constant drawing velocity, while the central zone of the original single-mode fiber was heated along a constant length. The spectral transmissions of the manufactured fiber tapers with different parameters were measured by the cut-back method.

  10. Tapered fiber based high power random laser.

    PubMed

    Zhang, Hanwei; Du, Xueyuan; Zhou, Pu; Wang, Xiaolin; Xu, Xiaojun

    2016-04-18

    We propose a novel high power random fiber laser (RFL) based on tapered fiber. It can overcome the power scaling limitation of RFL while maintaining good beam quality to a certain extent. An output power of 26.5 W has been achieved in a half-open cavity with one kilometer long tapered fiber whose core diameter gradually changes from 8 μm to 20 μm. The steady-state light propagation equations have been modified by taking into account the effective core area to demonstrate the tapered RFL through numerical calculations. The numerical model effectively describes the power characteristics of the tapered fiber based RFL, and both the calculating and experimental results show higher power exporting potential compared with the conventional single mode RFL. PMID:27137338

  11. Completely CMOS compatible SiN-waveguide-based fiber coupling structure for Si wire waveguides.

    PubMed

    Maegami, Yuriko; Okano, Makoto; Cong, Guangwei; Ohno, Morifumi; Yamada, Koji

    2016-07-25

    For Si wire waveguides, we designed a highly efficient fiber coupling structure consisting of a Si inverted taper waveguide and a CMOS-compatible thin SiN waveguide with an SiO2 spacer inserted between them. By using a small SiN waveguide with a 310 nm-square core, the optical field can be expanded to correspond to a fiber with a 4.0-μm mode field diameter. A coupled waveguide system with the SiN waveguide and Si taper waveguide can provide low-loss and low-polarization-dependent mode conversion. Both losses in fiber-SiN waveguide coupling and SiN-Si waveguide mode conversion are no more than 1 dB in a wide wavelength bandwidth from 1.36 μm to 1.65 μm. Through a detailed analysis of the effective refractive indices in the coupled waveguide system, we can understand mode conversion accurately and also derive guidelines for reducing the polarization dependence and for shortening device length. PMID:27464137

  12. Completely CMOS compatible SiN-waveguide-based fiber coupling structure for Si wire waveguides.

    PubMed

    Maegami, Yuriko; Okano, Makoto; Cong, Guangwei; Ohno, Morifumi; Yamada, Koji

    2016-07-25

    For Si wire waveguides, we designed a highly efficient fiber coupling structure consisting of a Si inverted taper waveguide and a CMOS-compatible thin SiN waveguide with an SiO2 spacer inserted between them. By using a small SiN waveguide with a 310 nm-square core, the optical field can be expanded to correspond to a fiber with a 4.0-μm mode field diameter. A coupled waveguide system with the SiN waveguide and Si taper waveguide can provide low-loss and low-polarization-dependent mode conversion. Both losses in fiber-SiN waveguide coupling and SiN-Si waveguide mode conversion are no more than 1 dB in a wide wavelength bandwidth from 1.36 μm to 1.65 μm. Through a detailed analysis of the effective refractive indices in the coupled waveguide system, we can understand mode conversion accurately and also derive guidelines for reducing the polarization dependence and for shortening device length.

  13. Acrylic-based 1×2 Y-Branch POF coupler with high index contrast waveguide taper

    NASA Astrophysics Data System (ADS)

    Ehsan, A. A.; Abd Rahman, M. K.

    2010-12-01

    An acrylic-based 1x2 Y-Branch POF coupler consists of input POF waveguide, a middle high index contrast waveguide taper and output POF waveguides has been developed. The optical device is based on a 1x2 Y-branch coupler design with a middle high index contrast waveguide taper. Device modeling has been performed using non-sequential ray tracing with an insertion loss of 4.68 dB and coupling ratio of 50:50. Low cost acrylic material has been used for the device substrate. This middle waveguide taper region is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block using high speed CNC machining tool. Input and output POF fibers are inserted in to this device structure in such a way that they are passively aligned to the middle waveguide taper structure. The measured insertion loss is 7.5 dB and with a splitting ratio of 50:50.

  14. Acrylic-based 1×2 Y-Branch POF coupler with high index contrast waveguide taper

    NASA Astrophysics Data System (ADS)

    Ehsan, A. A.; Abd Rahman, M. K.

    2011-01-01

    An acrylic-based 1x2 Y-Branch POF coupler consists of input POF waveguide, a middle high index contrast waveguide taper and output POF waveguides has been developed. The optical device is based on a 1x2 Y-branch coupler design with a middle high index contrast waveguide taper. Device modeling has been performed using non-sequential ray tracing with an insertion loss of 4.68 dB and coupling ratio of 50:50. Low cost acrylic material has been used for the device substrate. This middle waveguide taper region is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block using high speed CNC machining tool. Input and output POF fibers are inserted in to this device structure in such a way that they are passively aligned to the middle waveguide taper structure. The measured insertion loss is 7.5 dB and with a splitting ratio of 50:50.

  15. Dispersion-engineered tapered planar waveguide for coherent supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Hu, Hongyu; Li, Wenbo; Dutta, Niloy K.

    We have designed a tapered planar rib waveguide and numerically studied supercontinuum generation by the propagation of input pulses at 1.55 μm. The Air-SF57 glass-SiO2 waveguide is 2 cm long, with a varying etch depth to manage the total dispersion. This proposed waveguide geometry significantly broadens the output spectrum caused by continuous modification of the phase matching condition for dispersive wave emission. The coherence property has also been investigated, demonstrating that fully coherent supercontinuum extending from ~1 μm to ~4.6 μm can be obtained with proper pumping conditions.

  16. Discontinuous Tapered Surface Plasmon Polariton Waveguides with Gap.

    PubMed

    Lee, Dong Hun; Lee, Myung-Hyun

    2016-06-01

    We investigate characteristics of discontinuous tapered surface plasmon polariton waveguides with a gap (DTG-SPPWs) to control a guided surface plasmon polariton (SPP) at a telecommunication wavelength of 1.55 μm. The DTG-SPPWs are composed of an input 2 μm-wide and 10 μm-long reverse tapered IMI-W (RT-IMI-W) and a 10 μm-long tapered and output 2 μm-wide IMI-W (T-IMI-W) with the 8 μm-long gap. The width and length of the tapered regions in the RT-IMI-W and the T-IMI-W were varied from 2 to 10 μm and 1 to 8 μm, respectively. Gold is used as the metal in the insulator-metal-insulator waveguides (IMI-Ws). The thickness of the gold strips is fixed with 20 nm. A low-loss polymer is used for the 30 μm-thick upper and lower cladding layers. The coupling losses of the DTG-SPPWs are less than 0.055 dB with an 8 μm-long gap and various taper widths up to 10 μm. The normalized transmissions (NTs) of the DTG-SPPWs are less than about -0.060 dB with various taper widths up to 10 μm. The NTs of the DTG-SPPWs are less than about -0.069 dB with various taper lengths up to 8 μm. The maximum NT of about -0.042 dB was obtained using the 6 μm-wide taper width and the 3 μm-long taper length in the DTG-SPPW. The DTG-SPPWs have potential as a new plasmonic modulation device via control of the guided SPP through interaction with an applied force in the gap. PMID:27427702

  17. Long-period cascaded fiber taper filters.

    PubMed

    Martinez-Rios, A; Salceda-Delgado, G; Guerrero-Viramontes, J A

    2014-02-10

    Fiber filters based on periodic cascaded tapered fiber sections are demonstrated. The filters consist of up to seven tapered sections separated periodically by more than 3 mm from center to center, with nominal tapered sections of 1  mm×1  mm×1  mm longitudinal dimensions. The transmission spectrum consists of discrete notches, resembling those observed in long-period fiber gratings, which differs from the observed spectrum in Mach-Zender interferometers based on cascaded tapers. Its sensitivity to external perturbations, such as refractive index or mechanical stress, made the device potentially very useful as a sensor or tunable filter. PMID:24663276

  18. Thin-ribbon tapered coupler for dielectric waveguides

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Otoshi, T. Y.; Shimabukuro, F. I.

    1994-01-01

    A recent discovery shows that a high-dielectric constant, low-loss, solid material can be made into a ribbon-like waveguide structure to yield an attenuation constant of less than 0.02 dB/m for single-mode guidance of millimeter/submillimeter waves. One of the crucial components that must be invented in order to guarantee the low-loss utilization of this dielectric-waveguide guiding system is the excitation coupler. The traditional tapered-to-a-point coupler for a dielectric rod waveguide fails when the dielectric constant of the dielectric waveguide is large. This article presents a new way to design a low-loss coupler for a high- or low-dielectric constant dielectric waveguide for millimeter or submillimeter waves.

  19. Integrated polarizers based on tapered highly birefringent photonic crystal fibers.

    PubMed

    Romagnoli, Priscila; Biazoli, Claudecir R; Franco, Marcos A R; Cordeiro, Cristiano M B; de Matos, Christiano J S

    2014-07-28

    This paper proposes and demonstrates the creation of sections with a high polarization dependent loss (PDL) in a commercial highly birefringent (polarization maintaining) photonic crystal fiber (PCF), via tapering with pressure applied to the holes. The tapers had a 1-cm-long uniform section with a 66% scale reduction, in which the original microstructure aspect ratio was kept by the pressure application. The resulting waveguides show polarizing action across the entire tested wavelength range, 1510-1600 nm, with a peak PDL of 35.3 dB/cm (c.f. ~1 dB/cm for a typical commercial polarizing fiber). The resulting structure, as well as its production, is extremely simple, and enable a small section with a high PDL to be obtained in a polarization maintaining PCF, meaning that the polarization axes in the polarizing and polarization maintaining sections are automatically aligned. PMID:25089397

  20. Complex coupled-mode theory for tapered optical waveguides.

    PubMed

    Mu, Jianwei; Huang, Wei-Ping

    2011-03-15

    A coupled-mode formulation based on complex local modes is developed for tapered and longitudinally varying optical waveguides. Different from the conventional coupled-mode theory that requires integration over the entire spectrum of radiation modes, the new formulation treats the radiation fields via discrete complex modes similarly to the guided modes. Accuracy, convergence, and scope of validity for the solutions of the complex coupled-mode equations are investigated in detail for a typical single-mode waveguide taper. It is demonstrated that the complex coupled-mode theory has overcome the difficulties of the conventional theory in simulation of radiation field effects while preserving the simplicity and intuitiveness of this popular method.

  1. Nanostructured tapered optical fibers for paticle trapping

    NASA Astrophysics Data System (ADS)

    Daly, Mark; Truong, Viet Giang; Nic Chormaic, Síle

    2015-05-01

    Optical micro- and nanofibers have recently gained popularity as tools in quantum engineering using laser-cooled, neutral atoms. In particular, atoms can be trapped around such optical fibers, and photons coupled into the fibers from the surrounding atoms could be used to transfer quantum state information within the system. It has also been demonstrated that such fibers can be used to manipulate and trap silica and polystyrene particles in the 1-3 μm range. We recently proposed using a focused ion beam nanostructured tapered optical fiber for improved atom trapping geometries1. Here, we present details on the design and fabrication of these nanostructured optical fibers and their integration into particle trapping platforms for the demonstration of submicron particle trapping. The optical fibers are tapered to approximately 1-2 μm waist diameters, using a custom-built, heat-and-pull fiber rig, prior to processing using a focused ion beam. Slots of about 300 nm in width and 10-20 μm in length are milled right though the waist regions of the tapered optical fibers. Details on the fabrication steeps necessary to ensure high optical transmission though the fiber post processing are included. Fiber transmissions of over 80% over a broad range of wavelengths, in the 700-11100 nm range, are attainable. We also present simulation results on the impact of varying the slot parameters on the trap depths achievable and milling multiple traps within a single tapered fiber. This work demonstrates even further the functionality of optical micro- and nanofibers as trapping devices across a range of regimes.

  2. Mode-expanded semiconductor laser with tapered-rib adiabatic-following fiber coupler

    SciTech Connect

    Vawter, G.A.; Smith, R.E.; Hou, H.; Wendt, J.R.

    1996-12-01

    Expanded-mode semiconductor lasers are of great interest due to the benefits of reduced far-field divergence and improved coupling efficiency to optical fiber. The authors present a new diode laser using a Tapered-Rib Adiabatic-Following Fiber Coupler (TRAFFiC) to achieve 2D mode expansion without epitaxial regrowth or sharply-defined tips on tapered waveguides. The expanded mode size would allow 0.25 to 1 dB coupling loss to standard telecommunications fiber making smaller-core specialty fibers unnecessary, increasing misalignment tolerance, and eliminating the need for coupling optics.

  3. Silicone polymer waveguide bridge for Si to glass optical fibers

    NASA Astrophysics Data System (ADS)

    Kruse, Kevin L.; Riegel, Nicholas J.; Middlebrook, Christopher T.

    2015-03-01

    Multimode step index polymer waveguides achieve high-speed, (<10 Gb/s) low bit-error-rates for onboard and embedded circuit applications. Using several multimode waveguides in parallel enables overall capacity to reach beyond 100 Gb/s, but the intrinsic bandwidth limitations due to intermodal dispersion limit the data transmission rates within multimode waveguides. Single mode waveguides, where intermodal dispersion is not present, have the potential to further improve data transmission rates. Single mode waveguide size is significantly less than their multimode counterparts allowing for greater density of channels leading to higher bandwidth capacity per layer. Challenges in implementation of embedded single mode waveguides within printed circuit boards involves mass production fabrication techniques to create precision dimensional waveguides, precision alignment tolerances necessary to launch a mode, and effective coupling between adjoining waveguides and devices. An emerging need in which single mode waveguides can be utilized is providing low loss fan out techniques and coupling between on-chip transceiver devices containing Si waveguide structures to traditional single mode optical fiber. A polymer waveguide bridge for Si to glass optical fibers can be implemented using silicone polymers at 1310 nm. Fabricated and measured prototype devices with modeling and simulation analysis are reported for a 12 member 1-D tapered PWG. Recommendations and designs are generated with performance factors such as numerical aperture and alignment tolerances.

  4. Tapered fiber bundle couplers for high-power fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Sliwinska, Dorota; Kaczmarek, Pawel; Abramski, Krzysztof M.

    2014-12-01

    In this work, we would like to demonstrate our results on performing (6+1)x1 tapered fiber bundle combiners using a trielectrode fiber splicing system. In our combiners we have used 9/80 μm (core/clad) diameter fibers as single-mode signal input ports. Using this fiber, instead of a conventional 9/125 μm single-mode fiber allowed us to reduce the taper ratio and therefore significantly increase the signal transmission. We have also performed power combiner which is based on the LMA fibers: input signal fiber 20/125μm and passive double clad fiber 25/300 μm at the output.

  5. Monitoring techniques for the manufacture of tapered optical fibers.

    PubMed

    Mullaney, Kevin; Correia, Ricardo; Staines, Stephen E; James, Stephen W; Tatam, Ralph P

    2015-10-01

    The use of a range of optical techniques to monitor the process of fabricating optical fiber tapers is investigated. Thermal imaging was used to optimize the alignment of the optical system; the transmission spectrum of the fiber was monitored to confirm that the tapers had the required optical properties and the strain induced in the fiber during tapering was monitored using in-line optical fiber Bragg gratings. Tapers were fabricated with diameters down to 5 μm and with waist lengths of 20 mm using single-mode SMF-28 fiber. PMID:26479631

  6. Trapping light into high orbital momentum modes of fiber tapers.

    PubMed

    Strekalov, Dmitry V; Savchenkov, Anatoliy A; Savchenkova, Ekaterina A; Matsko, Andrey B

    2015-08-15

    A tapered cylindrical dielectric optical waveguide acts as a high quality factor white-light cavity providing high field concentration as well as long optical group delay. It is possible to optimize shape of a lossless taper to suppress reflection of the input light and to achieve infinitely high field concentration. These tapers can be used in sensing and optoelectronics applications instead of conventional microcavities. PMID:26274659

  7. Sensitive acoustic vibration sensor using single-mode fiber tapers.

    PubMed

    Li, Yi; Wang, Xiaozhen; Bao, Xiaoyi

    2011-05-01

    Optical fiber sensors are a good alternative to piezoelectric devices in electromagnetic sensitive environments. In this study, we reported a fiber acoustic sensor based on single-mode fiber (SMF) tapers. The fiber taper is used as the sensing arm in a Mach-Zehnder interferometer. Benefiting from their micrometer dimensions, fiber tapers have shown higher sensitivities to the acoustic vibrations than SMFs. Under the same conditions, the thinnest fiber taper in this report, with a diameter of 1.7 µm, shows a 20 dB improvement in the signal to noise ratio as compared to that of an SMF. This acoustic vibration sensor can detect the acoustic waves over the frequencies of 30 Hz-40 kHz, which is limited by the acoustic wave generator in experiments. We also discussed the phase changes of fiber tapers with different diameters under acoustic vibrations.

  8. Analysis of tapered front-coupling X-ray waveguides.

    PubMed

    Bukreeva, Inna; Pelliccia, Daniele; Cedola, Alessia; Scarinci, Fernando; Ilie, Mihaela; Giannini, Cinzia; De Caro, Liberato; Lagomarsino, Stefano

    2010-01-01

    The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

  9. Welding-fume-induced transmission loss in tapered optical fibers

    NASA Astrophysics Data System (ADS)

    Yi, Ji-Haeng

    2015-09-01

    This paper presents a method for sensing welding fumes in real time. This method is based on the results of nanoparticle-induced optical-fiber loss experiments that show that the losses are determined by the nanoparticle density and the taper waist. The tapered fiber is obtained by applying heat radiated from hot quartz, and monitoring is done in real time. First, the durability of the tapered fiber during the welding process is proven. Then, the loss is categorized by using the sizes of welding fume particles. The sensitivity to welding fumes increases with increasing size of the particles; consequently, the dimension of the taper waist decreases.

  10. An acoustic vibration sensor based on tapered triple cladding fiber

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Pang, Fufei; Zhao, Shiqi; Chen, Zhenyi; Wang, Tingyun

    2014-05-01

    An acoustic vibration sensor is investigated and demonstrated by using a tapered triple cladding fiber (TCF). It is fabricated by tapering a length of 2 cm TCF which is spliced between two single mode fibers (SMF). The TCF consists of core, inner cladding, middle cladding and outer cladding. After the tapering process, this structure becomes a tapered coaxial fiber coupler which presents a periodic filtering transmission spectrum. The surrounding vibration perturbation can be directly demodulated by intensity detection of the transmission power at a particular wavelength. The experimental result shows that the maximum frequency response of 700 kHz is achieved.

  11. WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics

    NASA Technical Reports Server (NTRS)

    Stekalov, Dmitry; Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Iltchenko, Vladimir

    2007-01-01

    Theoretical and experimental investigations have demonstrated the feasibility of compact white-light sensor optics consisting of unitary combinations of (1) low-profile whispering-gallery-mode (WGM) resonators and (2) tapered rod optical waveguides. These sensors are highly wavelength-dispersive and are expected to be especially useful in biochemical applications for measuring absorption spectra of liquids. These sensor optics exploit the properties of a special class of non-diffracting light beams that are denoted Bessel beams because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have large values of angular momentum. In a sensor optic of this type, a low-profile WGM resonator that supports modes having large angular momenta is used to generate high-order Bessel beams. As used here, "low-profile" signifies that the WGM resonator is an integral part of the rod optical waveguide but has a radius slightly different from that of the adjacent part(s).

  12. Group delay and dispersion tailoring in nonadiabatic tapered fibers

    NASA Astrophysics Data System (ADS)

    Mas, Sara; Palací, Jesús; Martí, Javier

    2016-09-01

    The dispersion profile of a nonadiabatic tapered singlemode fiber is characterized and dynamically tuned. Its group delay and dispersion parameters are measured and compared to those of a standard singlemode fiber. The dispersion profile can be tuned by introducing a phase shift through mechanical stretching. Coarse tuning is also obtained by varying the surrounding medium of the tapered fiber. Dispersion values up to 700 ps/nm·km in nonadiabatic tapered fibers are obtained for the first time. Dynamic tuning exposed here can be very useful in applications such as nonlinearities or soliton generation.

  13. Numerical simulations of nanodiamond nitrogen-vacancy centers coupled with tapered optical fibers as hybrid quantum nanophotonic devices.

    PubMed

    Almokhtar, Mohamed; Fujiwara, Masazumi; Takashima, Hideaki; Takeuchi, Shigeki

    2014-08-25

    Tapered optical fibers are promising one-dimensional nanophotonic waveguides that can provide efficient coupling between their fundamental mode and quantum nanoemitters placed inside them. Here, we present numerical studies on the coupling of single nitrogen-vacancy (NV) centers (single point dipoles) in nanodiamonds with tapered fibers. Our results lead to two important conclusions: (1) A maximum coupling efficiency of 53.4% can be realized for the two fiber ends when the NV bare dipole is located at the center of the tapered fiber. (2) NV centers even in 100-nm-sized nanodiamonds where bulk-like optical properties were reported show a coupling efficiency of 22% at the taper surface, with the coupling efficiency monotonically decreasing as the nanodiamond size increases. These results will be helpful in guiding the development of hybrid quantum devices for applications in quantum information science. PMID:25321215

  14. Phase sensitive signal analysis for bi-tapered optical fibers

    NASA Astrophysics Data System (ADS)

    Ben Harush Negari, Amit; Jauregui, Daniel; Sierra Hernandez, Juan M.; Garcia Mina, Diego; King, Branden J.; Idehenre, Ighodalo; Powers, Peter E.; Hansen, Karolyn M.; Haus, Joseph W.

    2016-03-01

    Our study examines the transmission characteristics of bi-tapered optical fibers, i.e. fibers that have a tapered down and up span with a waist length separating them. The applications to aqueous and vapor phase biomolecular sensing demand high sensitivity. A bi-tapered optical fiber platform is suited for label-free biomolecular detection and can be optimized by modification of the length, diameter and surface properties of the tapered region. We have developed a phase sensitive method based on interference of two or more modes of the fiber and we demonstrate that our fiber sensitivity is of order 10-4 refractive index units. Higher sensitivity can be achieved, as needed, by enhancing the fiber design characteristics.

  15. Wavelength-dependent femtosecond pulse amplification in wideband tapered-waveguide quantum well semiconductor optical amplifiers.

    PubMed

    Xia, Mingjun; Ghafouri-Shiraz, H

    2015-12-10

    In this paper, we study the wavelength-dependent amplification in three different wideband quantum well semiconductor optical amplifiers (QWAs) having conventional, exponentially tapered, and linearly tapered active region waveguide structures. A new theoretical model for tapered-waveguide QWAs considering the effect of lateral carrier density distribution and the strain effect in the quantum well is established based on a quantum well transmission line modeling method. The temporal and spectral characteristics of amplified femtosecond pulse are analyzed for each structure. It was found that, for the amplification of a single femtosecond pulse, the tapered-waveguide QWA provides higher saturation gain, and the output spectra of the amplified pulse in all three structures exhibit an apparent redshift and bandwidth narrowing due to the reduction of carrier density; however, the output spectrum in the tapered-waveguide amplifier is less distorted and exhibits smaller bandwidth narrowing. For the simultaneous amplification of two femtosecond pulses with different central frequencies, in all the three structures, two peaks appear in the output spectra while the peak at the frequency closer to the peak frequency of the QWA gain spectrum receives higher amplification due to the frequency (wavelength) dependence of the QWA gain. At a low peak power level of the input pulse, the bandwidth of each window in the tapered structure is larger than that of the conventional waveguide structure, which aggravates the spectrum alias in the amplification of femtosecond pulses with different central frequencies. As the peak powers of the two pulses increase, the spectrum alias in the conventional waveguide becomes more serious while there are small changes in the tapered structures. Also, we have found that in the amplification of a femtosecond pulse train, the linear-tapered QWAs exhibit the fastest gain recovery as compared with the conventional and exponentially tapered QWAs.

  16. Wavelength-dependent femtosecond pulse amplification in wideband tapered-waveguide quantum well semiconductor optical amplifiers.

    PubMed

    Xia, Mingjun; Ghafouri-Shiraz, H

    2015-12-10

    In this paper, we study the wavelength-dependent amplification in three different wideband quantum well semiconductor optical amplifiers (QWAs) having conventional, exponentially tapered, and linearly tapered active region waveguide structures. A new theoretical model for tapered-waveguide QWAs considering the effect of lateral carrier density distribution and the strain effect in the quantum well is established based on a quantum well transmission line modeling method. The temporal and spectral characteristics of amplified femtosecond pulse are analyzed for each structure. It was found that, for the amplification of a single femtosecond pulse, the tapered-waveguide QWA provides higher saturation gain, and the output spectra of the amplified pulse in all three structures exhibit an apparent redshift and bandwidth narrowing due to the reduction of carrier density; however, the output spectrum in the tapered-waveguide amplifier is less distorted and exhibits smaller bandwidth narrowing. For the simultaneous amplification of two femtosecond pulses with different central frequencies, in all the three structures, two peaks appear in the output spectra while the peak at the frequency closer to the peak frequency of the QWA gain spectrum receives higher amplification due to the frequency (wavelength) dependence of the QWA gain. At a low peak power level of the input pulse, the bandwidth of each window in the tapered structure is larger than that of the conventional waveguide structure, which aggravates the spectrum alias in the amplification of femtosecond pulses with different central frequencies. As the peak powers of the two pulses increase, the spectrum alias in the conventional waveguide becomes more serious while there are small changes in the tapered structures. Also, we have found that in the amplification of a femtosecond pulse train, the linear-tapered QWAs exhibit the fastest gain recovery as compared with the conventional and exponentially tapered QWAs. PMID

  17. Nonlinear transmission through a tapered fiber in rubidium vapor

    SciTech Connect

    Hendrickson, S. M.; Pittman, T. B.; Franson, J. D.

    2009-02-15

    Subwavelength-diameter tapered optical fibers surrounded by rubidium vapor can undergo a substantial decrease in transmission at high atomic densities due to the accumulation of rubidium atoms on the surface of the fiber. Here we demonstrate the ability to control these changes in transmission using light guided within the taper. We observe transmission through a tapered fiber that is a nonlinear function of the incident power. This effect can also allow a strong control beam to change the transmission of a weak probe beam.

  18. Fabrication Of Fiber-Optic Waveguide Coupler

    NASA Technical Reports Server (NTRS)

    Goss, Willis; Nelson, Mark D.; Mclauchlan, John M.

    1989-01-01

    Technique for making four-port, single-mode fiber-optic waveguide couplers requires no critically-precise fabrication operations or open-loop processes. Waveguide couplers analogous to beam-splitter prisms. Essential in many applications that require coherent separation or combination of two waves; for example, for interferometric purposes. Components of optical waveguide coupler held by paraffin on microscope slide while remaining cladding of two optical fibers fused together by arc welding.

  19. Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

    PubMed Central

    Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

    2016-01-01

    Simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a1 < a2, the optimal length of the taper is 3.198a1a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE11 mode in an optimized taper is 0.0293(a2−a1)4∕a12a22. These formulae are accurate when a2 ≲ 2a1. Slightly more complex formulae, accurate for a2 ≤ 4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2 ≤ 2.12a1 and less than 0.1 % when a2 ≤ 1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication. PMID:27053963

  20. Optical fiber taper coupling and high-resolution wavelength tuning of microdisk resonators at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Srinivasan, Kartik; Painter, Oskar

    2007-01-01

    A system for studying microcavity resonators at cryogenic temperatures (˜10K) through evanescent coupling via optical fiber taper waveguides is reported, and efficient fiber coupling to AlGaAs microdisk cavities with embedded quantum dots is demonstrated. As an immediate application of this tool, the authors study high-resolution tuning of microdisk cavities through nitrogen gas adsorption, as first discussed by Mosor et al. [Appl. Phys. Lett. 87, 141105 (2005)]. By proper regulation of the nitrogen gas flow and delivery of the gas to the sample surface, continuous tuning can be achieved with modest gas flows, and overall wavelength shifts as large as 4nm are achieved.

  1. Tapered fiber optic sensor for potassium detection in distilled water

    NASA Astrophysics Data System (ADS)

    Yasin, M.; Pujiyanto, .; Apsari, R.; Tanjung, M.

    2015-01-01

    A simple sensor is proposed and demonstrated using a silica tapered fiber for sensing different concentration of potassium in de-ionized water. The tapered fiber is fabricated using a flame brushing technique to achieve a waist diameter and length of 10 μm and 80 mm, respectively. For a concentration change from 0 to 50 %, the ouput signal of the sensor decreases exponentially from -10.04 dBm to -11.11 dBm with linearity of more than 92%. The increment of potassium concentration increases the refractive index of the solution, which in turn reduces the index difference between core and cladding of the tapered fiber and thus allows more light to be leaked out from the fiber. This new potassium monitoring system provides numerous advantages such as simplicity of design and low cost of production.

  2. Riccati parameterized self-similar waves in tapered graded-index waveguides

    NASA Astrophysics Data System (ADS)

    Goyal, Amit; Gupta, Rama; Loomba, Shally; Kumar, C. N.

    2012-10-01

    We present a large family of self-similar waves by tailoring the tapering function, through Riccati parameter, in a tapered graded-index nonlinear waveguide amplifier. We show the existence of bright similaritons, self-similar Akhmediev breathers and self-similar rogue waves for generalized nonlinear Schrödinger equation with constant dispersion and nonlinearity, and a distributed gain. We illustrate the procedure to amplify the intensity of self-similar waves using isospectral Hamiltonian approach. This approach provides a handle to find analytically a wide class of tapering function and thus enabling one to control the self-similar wave structure and dynamical behavior.

  3. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    PubMed

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region. PMID:26907442

  4. Single muscle fiber gene expression with run taper.

    PubMed

    Murach, Kevin; Raue, Ulrika; Wilkerson, Brittany; Minchev, Kiril; Jemiolo, Bozena; Bagley, James; Luden, Nicholas; Trappe, Scott

    2014-01-01

    This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I) and fast-twitch (MHC IIa) muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO₂max = 70±1 ml•kg-1•min-1) during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax) while in heavy training (∼72 km/wk) and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14), Myostatin (MSTN), Heat shock protein 72 (HSP72), Muscle ring-finger protein-1 (MURF1), Myogenic factor 6 (MRF4), and Insulin-like growth factor 1 (IGF1) via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (P<0.05). MSTN was suppressed with exercise in both fiber types and training states (P<0.05) while MURF1 and HSP72 responded to running in MHC IIa and I fibers, respectively, regardless of training state (P<0.05). Robust induction of FN14 (previously shown to strongly correlate with hypertrophy) and greater overall transcriptional flexibility with exercise in the tapered state provides an initial molecular basis for fast-twitch muscle fiber performance gains previously observed after taper in competitive endurance athletes. PMID:25268477

  5. Three-dimensional modeling of CPA to the multimillijoule level in tapered Yb-doped fibers for coherent combining systems.

    PubMed

    Andrianov, Alexey; Anashkina, Elena; Kim, Arkady; Meyerov, Iosif; Lebedev, Sergey; Sergeev, Alexander; Mourou, Gerard

    2014-11-17

    We developed a three-dimensional numerical model of Large-Mode-Area chirped pulse fiber amplifiers which includes nonlinear beam propagation in nonuniform multimode waveguides as well as gain spectrum dynamics in quasi-three-level active ions. We used our model in tapered Yb-doped fiber amplifiers and showed that single-mode propagation is maintained along the taper even in the presence of strong Kerr nonlinearity and saturated gain, allowing extraction of up to 3 mJ of output energy in 1 ns pulse. Energy scaling and its limitation as well as the influence of fiber taper bending and core irregularities on the amplifier performance were studied. We also investigated numerically the capabilities for compression and coherent combining of up to 36 perturbed amplifying channels and showed more than 70% combining efficiency, even with up to 11% of high-order modes in individual channels. PMID:25402067

  6. Three-dimensional modeling of CPA to the multimillijoule level in tapered Yb-doped fibers for coherent combining systems.

    PubMed

    Andrianov, Alexey; Anashkina, Elena; Kim, Arkady; Meyerov, Iosif; Lebedev, Sergey; Sergeev, Alexander; Mourou, Gerard

    2014-11-17

    We developed a three-dimensional numerical model of Large-Mode-Area chirped pulse fiber amplifiers which includes nonlinear beam propagation in nonuniform multimode waveguides as well as gain spectrum dynamics in quasi-three-level active ions. We used our model in tapered Yb-doped fiber amplifiers and showed that single-mode propagation is maintained along the taper even in the presence of strong Kerr nonlinearity and saturated gain, allowing extraction of up to 3 mJ of output energy in 1 ns pulse. Energy scaling and its limitation as well as the influence of fiber taper bending and core irregularities on the amplifier performance were studied. We also investigated numerically the capabilities for compression and coherent combining of up to 36 perturbed amplifying channels and showed more than 70% combining efficiency, even with up to 11% of high-order modes in individual channels.

  7. Acoustic vibration sensor based on nonadiabatic tapered fibers.

    PubMed

    Xu, Ben; Li, Yi; Sun, Miao; Zhang, Zhen-Wei; Dong, Xin-Yong; Zhang, Zai-Xuan; Jin, Shang-Zhong

    2012-11-15

    A simple and low-cost vibration sensor based on single-mode nonadiabatic fiber tapers is proposed and demonstrated. The environmental vibrations can be detected by demodulating the transmission loss of the nonadiabatic fiber taper. Theoretical simulations show that the transmission loss is related to the microbending of the fiber taper induced by vibrations. Unlike interferometric sensors, this vibration sensor does not need any feedback loop to control the quadrature point to obtain a stable performance. In addition, it has no requirement for the coherence of the light source and is insensitive to temperature changes. Experimental results show that this sensing system has a wide frequency response range from a few hertz to tens of kilohertz with the maximal signal to noise ratio up to 73 dB.

  8. New Techniques for Exciting Linearly Tapered Slot Antennas with Coplanar Waveguide

    NASA Technical Reports Server (NTRS)

    Simons, R. N.; Lee, R. Q.; Perl, T. D.

    1992-01-01

    Two new techniques for exciting a linearly tapered slot antenna (LTSA) with coplanar waveguide (CPW) are introduced. In the first approach, an air bridge is used to couple power from a CPW to an LTSA. In the second approach, power is electromagnetically coupled from a finite CPW (FCPW) to an LTSA. Measured results at 18 GHz show excellent return loss and radiation patterns.

  9. Ray invariants, plane wave spectra, and adiabatic modes for tapered dielectric waveguides

    NASA Astrophysics Data System (ADS)

    Arnold, J. M.; Felsen, L. B.

    1984-10-01

    In nonseparable problems resulting from the analysis of wave propagation in longitudinally varying waveguides, such as a wedge-shaped taper, singularities appear in both ray and coupled mode treatments at the local normal mode cutoff transition. A uniformization of the local normal (adiabatic) mode is proposed, using plane wave spectra, which effectively resolves this difficulty.

  10. Submicron particle manipulation using slotted tapered optical fibers

    NASA Astrophysics Data System (ADS)

    Daly, M.; Truong, V. G.; Nic Chormaic, S.

    2015-08-01

    The use of optical micro- and nanofibers has become commonplace in the areas of atom trapping using neutral atoms and, perhaps more relevantly, the optical trapping and propulsion of micro- and nanoscale particles. It has been shown that such fibers can be used to manipulate and trap silica and polystyrene particles in the 1-3 µm range using either the fundamental or higher order modes of the fibers, with the propulsion of smaller particle sizes also possible through the use of metallic and/or high index materials. We previously proposed using a focused ion beam nanostructured tapered optical fiber for improved atom trapping geometries; here, we present the details of how these nanostructured optical fibers can be used as a platform for submicron particle trapping. The optical fibers are tapered to approximately 1.2 µm waist diameters, using a custom-built, heat-and-pull fiber rig prior to processing using a focused ion beam. Slots of approximately 300 nm in width and 10-20 µm in length are milled clean though the waist regions of the tapered optical fibers. High fiber transmissions (> 80%) over a broad range of wavelengths (700-1100 nm) are observed. We present simulation results for the trapping of submicron particles and experimental results on the trapping of 200 nm particles. This work demonstrates even further the functionality of optical micro- and nanofibers as trapping devices across a range of regimes.

  11. Image magnification in transformation optics devices based on tapered waveguides

    NASA Astrophysics Data System (ADS)

    Zimmerman, William; Jensen, Christopher; Smolyaninova, Vera; Smolyaninov, Igor

    Recent progress in metamaterial and transformation optics (TO) research gave rise to such fascinating devices as perfect lenses, invisibility cloaks, and numerous other unusual electromagnetic devices. However, the metamaterials have problems with low-loss broadband performance and complexity of fabrication, especially in the visible frequency range. Our TO devices allow us to circumvent these difficulties by using lithographically defined metal/dielectric waveguides to emulate metamaterial properties. Adiabatic variations of the waveguide shape enable control of the effective refractive index experienced by light propagating inside the waveguide. The achieved image magnification is consistent with numerical simulations. We have studied wavelength and polarization dependent performance of the waveguides. Our experimental designs appear to be broadband, which has been verified in the 480-633 nm range. These novel optical devices considerably extend our ability to control light on sub-micrometer scales. This research was supported by the NSF Grant DMR-1104676.

  12. Experimental analysis and prediction of antisymmetric wave motion in a tapered anisotropic waveguide.

    PubMed

    Moll, Jochen; Wandowski, Tomasz; Malinowski, Pawel; Radzienski, Maciej; Opoka, Szymon; Ostachowicz, Wieslaw

    2015-07-01

    This paper presents experimental results for wave propagation in an anisotropic multilayered structure with linearly varying cross section. Knowing the dispersion and wave propagation properties in such a structure is of great importance for non-destructive material testing and structural health monitoring applications for accurate damage detection and localization. In the proposed study, the wavefield is generated by a circular piezoelectric wafer active sensor and measured by a scanning laser-Doppler-vibrometer. The measurements are compared with a theoretical group delay estimation and a signal prediction for the antisymmetric wave motion along the non-uniform propagation path. The required dispersion curves are derived from the well-known global matrix method for segments of constant thickness. A multidimensional frequency-wavenumber analysis of linescan data and the full wavefield provides further insight of the adiabatic wave motion because the wavenumber changes along the tapered geometry of the waveguide. In addition, it is demonstrated that a terahertz time-domain system can be used in glass-fiber reinforced plastic structures as a tool to estimate the thickness profile of thin structures by means of time-of-flight measurements. This information is particularly important for guided wave-based diagnostics of structures with unknown thickness. PMID:26233030

  13. Fiber waveguide sensors for intelligent materials

    NASA Technical Reports Server (NTRS)

    Flax, A. R.; Claus, R. O.

    1988-01-01

    This report, an addendum to the six month report submitted to NASA Langley Research Center in December 1987, covers research performed by the Fiber and Electro-Optics Research Center (FEORC) at Virginia Tech for the NASA Langley Research Center, Grant NAG1-780, for the period from December 1987 to June 1988. This final report discusses the research performed in the following four areas as described in the proposal: Fabrication of Sensor Fibers Optimized for Embedding in Advanced Composites; Fabrication of Sensor Fiber with In-Line Splices and Evaluation via OTR methods; Modal Domain Optical Fiber Sensor Analysis; and Acoustic Fiber Waveguide Implementation.

  14. Fiber Volume Fraction Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

    NASA Astrophysics Data System (ADS)

    Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

    2016-06-01

    Liquid resin is injected into the tapered injection chamber through the injection slots to completely wetout the fiber reinforcements in a resin injection pultrusion process. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the centerline causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to effectively penetrate through the fibers and achieve complete wetout. Fiber volume fraction in the final pultruded composite is a key to decide the mechanical and/or chemical properties of the composite. If the fiber volume fraction is too high, more fibers are squeezed together creating a fiber lean region near the wall and fiber rich region away from the wall. Also, the design of the injection chamber significantly affects the minimum injection pressure required to completely wet the fibers. A tapered injection chamber is considered such that wetout occurs at lower injection pressures due to the taper angle of the injection chamber. In this study, the effect of fiber volume fraction on the fiber reinforcement compaction and complete fiber wetout for a tapered injection chamber is investigated.

  15. Photosensitivity in optical fiber and silica-on-substrate waveguides

    NASA Astrophysics Data System (ADS)

    Malo, Bernard; Bilodeau, Francois; Albert, Jacques; Johnson, Derwyn C.; Hill, Kenneth O.; Hibino, Yoshinori; Abe, Makoto

    1993-12-01

    Ultraviolet light irradiation of optical fibers or silica-on-silica channel optical waveguides photoinduces a permanent refractive index change in the core of the optical waveguide. The effect called `photosensitivity' provides a versatile photolithographic means for processing glass in the form of optical fiber or planar optical waveguides in order to fabricate optical waveguide devices that have applications in optical fiber communications and optical sensor systems. This paper reports on some recent experimental results on photosensitivity in optical fibers and planar optical waveguides and its use in the fabrication of optical waveguide devices.

  16. Mechanically induced long period fiber gratings on single mode tapered optical fiber for structure sensing applications

    NASA Astrophysics Data System (ADS)

    Pulido-Navarro, María. G.; Marrujo-García, Sigifredo; Álvarez-Chávez, José A.; Velázquez-González, Jesús S.; Martínez-Piñón, Fernando; Escamilla-Ambrosio, Ponciano J.

    2015-08-01

    The modal characteristics of tapered single mode optical fibers and its strain sensing characteristics by using mechanically induced long period fiber gratings are presented in this work. Both Long Period Fiber Gratings (LPFG) and fiber tapers are fiber devices that couple light from the core fiber into the fiber cladding modes. The mechanical LPFG is made up of two plates, one flat and the other grooved. For this experiment the grooved plate was done on an acrylic slab with the help of a computer numerical control machine. The manufacturing of the tapered fiber is accomplished by applying heat using an oxygen-propane flame burner and stretching the fiber, which protective coating has been removed. Then, a polymer-tube-package is added in order to make the sensor sufficiently stiff for the tests. The mechanical induced LPFG is accomplished by putting the tapered fiber in between the two plates, so the taper acquires the form of the grooved plate slots. Using a laser beam the transmission spectrum showed a large peak transmission attenuation of around -20 dB. The resultant attenuation peak wavelength in the transmission spectrum shifts with changes in tension showing a strain sensitivity of 2pm/μɛ. This reveals an improvement on the sensitivity for structure monitoring applications compared with the use of a standard optical fiber. In addition to the experimental work, the supporting theory and numerical simulation analysis are also included.

  17. Effects of tapering structures on the characteristics of a coaxial-waveguide gyrotron backward-wave oscillator

    SciTech Connect

    Hung, C. L.; Chang, T. H.; Yeh, Y. S.

    2011-10-15

    This study analyzes the characteristics of a gyrotron backward-wave oscillator (gyro-BWO) with a longitudinally tapered coaxial-waveguide by using a single-mode, self-consistent nonlinear code. Simulation results indicate that although tapering the inner wall or the outer wall can significantly raise the start-oscillation current, the former is more suitable for mode selection than the latter because an increase of the start-oscillation current by a tapered inner wall heavily depends on the chosen C value (i.e., the average ratio of the outer radius to the inner radius over the axial waveguide length). Selective suppression of the competing mode by tapering the inner wall is numerically demonstrated. Moreover, efficiency of the coaxial gyro-BWO is increased by tapering the outer wall. Properly down-tapering the outer wall ensures that the coaxial gyro-BWO can reach a maximum efficiency over twice that with a uniform one.

  18. Double clad tapered fiber for high power applications.

    PubMed

    Filippov, V; Chamorovskii, Yu; Kerttula, J; Golant, K; Pessa, M; Okhotnikov, O G

    2008-02-01

    We report a novel type of active fiber - tapered double clad fiber suitable for pumping by low brightness sources with large beam parameter product of 50/300 mm x mrad. Ytterbium double clad all-silica fiber (core/1(st) clad/2(nd) clad diameters 27/834/890 mum, NA(core)=0.11, NA(clad)=0.21), tapered down by a factor 4.8 for a length of 10.5 m was drawn from a preform fabricated by plasma chemical technologies. At a moderate Yb-ion concentration and 1:31 core/cladding ratio, the tapered double clad fiber demonstrates 0.9 dB/m pump absorption at 976 nm and excellent lasing slope efficiency. An ytterbium fiber laser with 84 W of output power and 92% slope efficiency, a 74 W superfluorescent source with 85% slope efficiency and amplifiers operating both in CW and pulsed regimes have been realized. All devices demonstrated robust single mode operation with a beam quality factor of M(2)=1.07. PMID:18542272

  19. Linearly tapered discharge capillary waveguides as a medium for a laser plasma wakefield accelerator

    SciTech Connect

    Abuazoum, S.; Wiggins, S. M.; Ersfeld, B.; Hart, K.; Vieux, G.; Yang, X.; Welsh, G. H.; Issac, R. C.; Reijnders, M. P.; Jones, D. R.; Jaroszynski, D. A.

    2012-01-02

    Gas-filled capillary discharge waveguides are commonly used as media for plasma wakefield accelerators. We show that effective waveguides can be manufactured using a femtosecond laser micromachining technique to produce a linearly tapered plasma density, which enables the energy of the accelerator to be enhanced significantly. A laser guiding efficiency in excess of 82% at sub-relativistic intensities has been demonstrated in a 40 mm long capillary with a diameter tapering from 320 {mu}m to 270 {mu}m, which gives rise to an on-axis, time-averaged plasma density that varies from 1.0 x 10{sup 18} cm{sup -3} to 1.6 x 10{sup 18} cm{sup -3}.

  20. Novel spot size converter for coupling standard single mode fibers to SOI waveguides

    NASA Astrophysics Data System (ADS)

    Sisto, Marco Michele; Fisette, Bruno; Paultre, Jacques-Edmond; Paquet, Alex; Desroches, Yan

    2016-03-01

    We have designed and numerically simulated a novel spot size converter for coupling standard single mode fibers with 10.4μm mode field diameter to 500nm × 220nm SOI waveguides. Simulations based on the eigenmode expansion method show a coupling loss of 0.4dB at 1550nm for the TE mode at perfect alignment. The alignment tolerance on the plane normal to the fiber axis is evaluated at +/-2.2μm for <=1dB excess loss, which is comparable to the alignment tolerance between two butt-coupled standard single mode fibers. The converter is based on a cross-like arrangement of SiOxNy waveguides immersed in a 12μm-thick SiO2 cladding region deposited on top of the SOI chip. The waveguides are designed to collectively support a single degenerate mode for TE and TM polarizations. This guided mode features a large overlap to the LP01 mode of standard telecom fibers. Along the spot size converter length (450μm), the mode is first gradually confined in a single SiOxNy waveguide by tapering its width. Then, the mode is adiabatically coupled to a SOI waveguide underneath the structure through a SOI inverted taper. The shapes of SiOxNy and SOI tapers are optimized to minimize coupling loss and structure length, and to ensure adiabatic mode evolution along the structure, thus improving the design robustness to fabrication process errors. A tolerance analysis based on conservative microfabrication capabilities suggests that coupling loss penalty from fabrication errors can be maintained below 0.3dB. The proposed spot size converter is fully compliant to industry standard microfabrication processes available at INO.

  1. Plasmonic sensors based on doubly-deposited tapered optical fibers.

    PubMed

    González-Cano, Agustín; Navarrete, María-Cruz; Esteban, Óscar; Díaz-Herrera, Natalia

    2014-03-10

    A review of the surface plasmon resonance (SPR) transducers based on tapered fibers that have been developed in the last years is presented. The devices have proved their good performance (specifically, in terms of sensitivity) and their versatility and they are a very good option to be considered as basis for any kind of chemical and biological sensor. The technology has now reached its maturity and here we summarize some of the characteristics of the devices produced.

  2. Plasmonic Sensors Based on Doubly-Deposited Tapered Optical Fibers

    PubMed Central

    González-Cano, Agustín; Navarrete, María-Cruz; Esteban, Óscar; Díaz-Herrera, Natalia

    2014-01-01

    A review of the surface plasmon resonance (SPR) transducers based on tapered fibers that have been developed in the last years is presented. The devices have proved their good performance (specifically, in terms of sensitivity) and their versatility and they are a very good option to be considered as basis for any kind of chemical and biological sensor. The technology has now reached its maturity and here we summarize some of the characteristics of the devices produced. PMID:24618726

  3. Mid-infrared supercontinuum generation in tapered As2S3 chalcogenide planar waveguide

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Hu, Hongyu; Li, Wenbo; Dutta, Niloy K.

    2016-10-01

    We numerically demonstrate mid-infrared supercontinuum generation in a non-uniformly tapered chalcogenide planar waveguide. This planar rib waveguide of As2S3 glass on MgF2 is 2 cm long with increasing etch depth longitudinally to manage the total dispersion. This waveguide has zero dispersion at two wavelengths. The dispersion profile varies along the propagation distance, leading to continuous modification of the phase-matching condition for dispersive wave emission and enhancement of energy transfer efficiency between solitons and dispersive waves. Numerical simulations are conducted for secant input pulses at a wavelength of 1.55 μm with a width of 50 fs and peak power of 2 kW. Results show this proposed scheme significantly broadens the generated continuum, extending from ~1 to ~7 μm.

  4. Temperature sensing on tapered single mode fiber using mechanically induced long period fiber gratings

    NASA Astrophysics Data System (ADS)

    Marrujo-García, Sigifredo; Velázquez-González, Jesús Salvador; Pulido-Navarro, María. Guadalupe; González-Ocaña, Ernesto; Mújica-Ascencio, Saúl; Martínez-Piñón, Fernando

    2015-09-01

    The modeling of a temperature optical fiber sensor is proposed and experimentally demonstrated in this work. The suggested structure to obtain the sensing temperature characteristics is by the use of a mechanically induced Long Period Fiber Grating (LPFG) on a tapered single mode optical fiber. A biconical fiber optic taper is made by applying heat using an oxygen-propane flame burner while stretching the single mode fiber (SMF) whose coating has been removed. The resulting geometry of the device is important to analyze the coupling between the core mode to the cladding modes, and this will determine whether the optical taper is adiabatic or non-adiabatic. On the other hand, the mechanical LPFG is made up of two plates, one grooved and other flat, the grooved plate was done on an acrylic slab with the help of a computerized numerical control machine (CNC). In addition to the experimental work, the supporting theory is also included.

  5. Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Fujiwara, Masazumi; Zhao, Hong-Quan; Noda, Tetsuya; Ikeda, Kazuhiro; Sumiya, Hitoshi; Takeuchi, Shigeki

    2016-03-01

    We demonstrate successful cooling of ultrathin fiber tapers and their coupling with nitrogen vacancy (NV) centers in nanodiamonds at cryogenic temperatures. Nanodiamonds containing multiple NV centers are deposited on ultrathin fiber tapers with diameters ranging from 450-500 nm. The fiber tapers were successfully cooled down to 9 K with our special fiber mount and an optimization of cooling speed. The fluorescence coupled with the fiber tapers showed characteristic sharp zero-phonon lines of neutral and negatively charged NV centers. The present demonstration is important for the future NV-based quantum information devices and sensitive nanoscale cryogenic magnetometry.

  6. In-situ Tapering of Chalcogenide Fiber for Mid-infrared Supercontinuum Generation

    PubMed Central

    Rudy, Charles W.; Marandi, Alireza; Vodopyanov, Konstantin L.; Byer, Robert L.

    2013-01-01

    Supercontinuum generation (SCG) in a tapered chalcogenide fiber is desirable for broadening mid-infrared (or mid-IR, roughly the 2-20 μm wavelength range) frequency combs1, 2 for applications such as molecular fingerprinting, 3 trace gas detection, 4 laser-driven particle acceleration, 5 and x-ray production via high harmonic generation. 6 Achieving efficient SCG in a tapered optical fiber requires precise control of the group velocity dispersion (GVD) and the temporal properties of the optical pulses at the beginning of the fiber, 7 which depend strongly on the geometry of the taper. 8 Due to variations in the tapering setup and procedure for successive SCG experiments-such as fiber length, tapering environment temperature, or power coupled into the fiber, in-situ spectral monitoring of the SCG is necessary to optimize the output spectrum for a single experiment. In-situ fiber tapering for SCG consists of coupling the pump source through the fiber to be tapered to a spectral measurement device. The fiber is then tapered while the spectral measurement signal is observed in real-time. When the signal reaches its peak, the tapering is stopped. The in-situ tapering procedure allows for generation of a stable, octave-spanning, mid-IR frequency comb from the sub harmonic of a commercially available near-IR frequency comb. 9 This method lowers cost due to the reduction in time and materials required to fabricate an optimal taper with a waist length of only 2 mm. The in-situ tapering technique can be extended to optimizing microstructured optical fiber (MOF) for SCG10 or tuning of the passband of MOFs, 11 optimizing tapered fiber pairs for fused fiber couplers12 and wavelength division multiplexers (WDMs), 13 or modifying dispersion compensation for compression or stretching of optical pulses.14-16 PMID:23748947

  7. Optimization of tapered fiber sample for laser cooling of solids

    NASA Astrophysics Data System (ADS)

    Nemova, Galina; Kashyap, Raman

    2009-02-01

    The physical mechanism of radiation cooling by anti-Stokes fluorescence was originally proposed in 1929 and experimentally observed in solid materials in 1995 by Epstein's research team in ytterbium-doped ZBLANP glass. Some specific combinations of the ions, host materials, and the wavelength of the incident radiation can provide anti-Stokes interaction resulting in phonon absorption accompanied by the cooling of the host material. Although the optical cooling of the Yb3+-doped ZBLANP sample was already observed there are broad possibilities for its improvement to increase the temperature-drop of the sample by optimization of the geometrical parameters of the cooling sample. We propose a theoretical model for an optimized tapered fiber structure for use as a sample in anti-Stokes laser cooling of solids. This tapered fiber has a fluorozirconate glass ZBLANP with a core doped with Yb3+ or Tm3+ ions. As evident from the results of our work, the appropriate choice of the fiber core and the fiber cladding radii can significantly increase the temperature-drop of the sample for any fixed pump power. The value of the maximum of the temperature-drop of the sample increases with an increase in the pump power. The depletion of the pump power causes a temperature gradient along the length of the cooled sample.

  8. Multimode Brillouin spectrum in a long tapered birefringent photonic crystal fiber.

    PubMed

    Tchahame, Joël Cabrel; Beugnot, Jean-Charles; Kudlinski, Alexandre; Sylvestre, Thibaut

    2015-09-15

    We investigate the stimulated Brillouin scattering (SBS) in a long tapered birefringent solid-core photonic crystal fiber (PCF) and compare our results with a similar but untapered PCF. It is shown that the taper generates a broadband and multipeaked Brillouin spectrum, while significantly increasing the threshold power. Furthermore, we observe that the strong fiber birefringence gives rise to a frequency shift of the Brillouin spectrum which increases along the fiber. Numerical simulations are also presented to account for the taper effect and the birefringence. Our findings open a new means to control or inhibit the SBS by tapering photonic crystal fibers. PMID:26371916

  9. Multicolor upconversion emissions in Tm 3+/Er3+ codoped tellurite photonic microwire between silica fiber tapers.

    PubMed

    Chen, Nan-Kuang; Kuan, Pei-Wen; Zhang, Junjie; Zhang, Liyan; Hu, Lili; Lin, Chinlon; Tong, Limin

    2010-12-01

    We report multicolor upconversion emissions including the blue-violet, green, and red lights in a Tm 3+/Er3+codoped tellurite glass photonic microwire between two silica fiber tapers. A silica fiber is tapered until its evanescent field is exposed and then angled-cleaved at the tapered center to divide the tapered fibers into two parts. A tellurite glass is melted by a gas flame to cluster into a sphere at the tip of one tapered fiber. The other angled-cleaved tapered fiber is blended into the melted tellurite glass. When the tellurite glass is melted, the two silica fiber tapers are simultaneously moving outwards to draw the tellurite glass into a microwire in between. The advantage of angled-cleaving on fiber tapers is to avoid cavity resonances in high index photonic microwire. Thus, the broadband white light can be transmitted between silica fibers and a special optical property like high intensity upconversion emission can be achieved. A cw 1064 nm Nd:YAG laser light is launched into the Tm 3+/Er3+ codoped tellurite microwire through a silica fiber taper to generate the multicolor upconversion emissions, including the blue-violet, green, and red lights, simultaneously. PMID:21164907

  10. Refractive index sensors based on the fused tapered special multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  11. Tunable ring laser using a tapered single mode fiber tip.

    PubMed

    Wang, Xiaozhen; Li, Yi; Bao, Xiaoyi

    2009-12-10

    A tunable ring laser using a tapered single mode fiber tip as a bandpass filter has been proposed and demonstrated for the first time to our knowledge. This is a simple and cost-effective tunable source. It is found that the tuning range and bandwidth of the laser are related to the relaxation time of the optical amplifier, the current of the amplifier, and the steepness of the tip shape. The calculations and experimental results show that the laser has a tuning range of 9 nm in the L-band and the spectral linewidth can be varied from 0.06 nm to 0.17 nm. PMID:20011024

  12. Propagation properties and dispersion characteristics of the tapered gap plasmonic waveguides

    NASA Astrophysics Data System (ADS)

    Sheikhi, Kamran; Granpayeh, Nosrat; Ahmadi, Vahid

    2016-08-01

    In this study, we numerically analyse the propagation properties and dispersion characteristics of the tapered gap plasmonic waveguides (TGPWs). Using the finite element method, the waveguide parameters such as modal field distribution and complex propagation constant are calculated for different geometrical parameters over a wide spectral range. Moreover, using a kind of active medium with appropriate gain, the required gains for lossless propagation are obtained. Results show that the propagation properties and dispersion characteristics of the waveguide along with the value of required gain for achieving lossless propagation can be well controlled by adjusting the geometrical parameters of the waveguide. The simulation results indicate that the calculated gain values are obtainable using the existing semiconductor technology such as InGaAsP-InGaAlAs multi-quantum well and InAs/GaAs quantum dot active medium at the wavelength of 1550 nm. The strong mode confinement of the TGPWs can be used for achieving strong nonlinear effects. Furthermore, due to optical energy confinement in nanoscale, optical nanofocusing devices based on TGPWs are attainable. TGPWs can be utilized in the field of nanotechnology to fulfil the photonic devices integration.

  13. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy

    PubMed Central

    Mett, R. R.; Sidabras, J. W.; Anderson, J. R.; Hyde, J. S.

    2011-01-01

    The two-way insertion loss of a 1 m length of waveguide was reduced by nearly 5 dB over a 4% bandwidth at W-band (94 GHz) for an electron paramagnetic resonance (EPR) spectrometer relative to WR10 waveguide. The waveguide has an oversize section of commercially available rectangular WR28 and a novel pair of tapers that vary in cross section with axial position according to a hyperbolic-cosine (HC) function. The tapers connect conventional rectangular WR10 waveguide to the WR28. For minimum loss, the main mode electric field is parallel to the long side of the WR28. Using mode coupling theory, the position of maximum flare (inflection point) in the taper was optimized with respect to the coupling to higher order modes and the reflection of the main mode. The optimum inflection point position is about one-tenth of the taper length from the small end of the taper. Reflection and coupling were reduced by about 20 dB relative to a pyramidal (linear) taper of the same length. Comb-like dips in the transmission coefficient produced by resonances of the higher order modes in the oversize section were about 0.03 dB. Specially designed high-precision, adjustable WR28 flanges with alignment to about 5 μm were required to keep higher order mode amplitudes arising from the flanges comparable to those from the HC tapers. Minimum return loss was about 30 dB. This paper provides a foundation for further optimization, if needed. Methods are not specific to EPR or the microwave frequency band. PMID:21806211

  14. Tunable tapered waveguide for efficient compression of light to graphene surface plasmons

    NASA Astrophysics Data System (ADS)

    Cheng, Bo Han; Chen, Hong Wen; Jen, Yi-Jun; Lan, Yung-Chiang; Tsai, Din Ping

    2016-06-01

    Dielectric-graphene-dielectric (DGD) structure has been widely used to construct optical devices at infrared region with features of small footprint and low-energy dissipation. The optical properties of graphene can be manipulated by changing its chemical potential by applying a biased voltage onto graphene. However, the excitation efficiency of surface wave on graphene by end-fire method is very low because of large wavevector mismatch between infrared light and surface wave. In this paper, a dielectric-semiconductor-dielectric (DSD) tapered waveguide with magnetic tunability for efficient excitation of surface waves on DGD at infrared region is proposed and analyzed. Efficient excitation of surface waves on DGD with various chemical potentials in graphene layer and incident frequencies can be attained by merely changing the external magnetic field applied onto the DSD tapered waveguide. The electromagnetic simulations verify the design of the proposed structure. More importantly, the constituent materials used in the proposed structure are available in nature. This work opens the door toward various applications in the field of using surface waves.

  15. Tunable tapered waveguide for efficient compression of light to graphene surface plasmons.

    PubMed

    Cheng, Bo Han; Chen, Hong Wen; Jen, Yi-Jun; Lan, Yung-Chiang; Tsai, Din Ping

    2016-06-29

    Dielectric-graphene-dielectric (DGD) structure has been widely used to construct optical devices at infrared region with features of small footprint and low-energy dissipation. The optical properties of graphene can be manipulated by changing its chemical potential by applying a biased voltage onto graphene. However, the excitation efficiency of surface wave on graphene by end-fire method is very low because of large wavevector mismatch between infrared light and surface wave. In this paper, a dielectric-semiconductor-dielectric (DSD) tapered waveguide with magnetic tunability for efficient excitation of surface waves on DGD at infrared region is proposed and analyzed. Efficient excitation of surface waves on DGD with various chemical potentials in graphene layer and incident frequencies can be attained by merely changing the external magnetic field applied onto the DSD tapered waveguide. The electromagnetic simulations verify the design of the proposed structure. More importantly, the constituent materials used in the proposed structure are available in nature. This work opens the door toward various applications in the field of using surface waves.

  16. Tunable tapered waveguide for efficient compression of light to graphene surface plasmons.

    PubMed

    Cheng, Bo Han; Chen, Hong Wen; Jen, Yi-Jun; Lan, Yung-Chiang; Tsai, Din Ping

    2016-01-01

    Dielectric-graphene-dielectric (DGD) structure has been widely used to construct optical devices at infrared region with features of small footprint and low-energy dissipation. The optical properties of graphene can be manipulated by changing its chemical potential by applying a biased voltage onto graphene. However, the excitation efficiency of surface wave on graphene by end-fire method is very low because of large wavevector mismatch between infrared light and surface wave. In this paper, a dielectric-semiconductor-dielectric (DSD) tapered waveguide with magnetic tunability for efficient excitation of surface waves on DGD at infrared region is proposed and analyzed. Efficient excitation of surface waves on DGD with various chemical potentials in graphene layer and incident frequencies can be attained by merely changing the external magnetic field applied onto the DSD tapered waveguide. The electromagnetic simulations verify the design of the proposed structure. More importantly, the constituent materials used in the proposed structure are available in nature. This work opens the door toward various applications in the field of using surface waves. PMID:27353171

  17. Tunable tapered waveguide for efficient compression of light to graphene surface plasmons

    PubMed Central

    Cheng, Bo Han; Chen, Hong Wen; Jen, Yi-Jun; Lan, Yung-Chiang; Tsai, Din Ping

    2016-01-01

    Dielectric-graphene-dielectric (DGD) structure has been widely used to construct optical devices at infrared region with features of small footprint and low-energy dissipation. The optical properties of graphene can be manipulated by changing its chemical potential by applying a biased voltage onto graphene. However, the excitation efficiency of surface wave on graphene by end-fire method is very low because of large wavevector mismatch between infrared light and surface wave. In this paper, a dielectric-semiconductor-dielectric (DSD) tapered waveguide with magnetic tunability for efficient excitation of surface waves on DGD at infrared region is proposed and analyzed. Efficient excitation of surface waves on DGD with various chemical potentials in graphene layer and incident frequencies can be attained by merely changing the external magnetic field applied onto the DSD tapered waveguide. The electromagnetic simulations verify the design of the proposed structure. More importantly, the constituent materials used in the proposed structure are available in nature. This work opens the door toward various applications in the field of using surface waves. PMID:27353171

  18. Fiber torsion sensor based on a twist taper in polarization-maintaining fiber.

    PubMed

    Zhou, Quan; Zhang, Weigang; Chen, Lei; Yan, Tieyi; Zhang, Liyu; Wang, Li; Wang, Biao

    2015-09-01

    A novel optical fiber torsion sensor head is proposed. A section of polarization-maintaining fiber (PMF) is spliced between single mode fiber (SMF), and a twist taper is fabricated by a commercial electric-arc fusion splicer in the middle of the PMF. The asymmetric characteristics are obtained by the twist taper so that a fiber torsion sensor with directional discrimination is fabricated. Due to the characteristics of the asymmetric structure, the torsion sensitivity for the twist rate from 0 rad/m to -8 rad/m reaches 2.392 nm/rad·m-1, and for the twist rate from 0 rad/m to 8 rad/m reaches 1.071 nm/rad·m-1 respectively. PMID:26368481

  19. Tunable Brillouin-erbium fiber laser incorporating a low-cost biconic tapered fiber

    NASA Astrophysics Data System (ADS)

    Lin, H. S.; Mansoor, A.; Phua, Y. N.; Mokhtar, M. R.; Abdul-Rashid, H. A.; Yusoff, Z.

    2014-02-01

    A new method of tuning a multi-wavelength Brillouin-erbium fiber laser (BEFL) within a Fabry-Perot cavity by incorporating a low-cost biconic tapered fiber is reported. The biconic tapered fiber was fabricated using a flame elongation technique and it was incorporated into the BEFL system to position the self-lasing cavity modes over a tuning range of 5.5 nm within the erbium-doped fiber gain profile. By injecting the Brillouin pump near to the tunable self-lasing cavity modes, it suppresses the modes and generates stable cascaded Brillouin-Stokes lines with more than 20 dB signal-to-noise ratio.

  20. Localized waveguide formation in germanosilicate fiber transmitting femtosecond IR pulses

    PubMed Central

    Tu, Haohua; Koh, Yee Lin; Marks, Daniel L.; Boppart, Stephen A.

    2010-01-01

    Transmission of intense femtosecond 825 nm pulses progressively produces a waveguide at the entrance of a heavily Ge-doped silicate fiber. The waveguide behaves as a multimillimeter long-fiber bandpass filter that scatters away light with wavelengths shorter or longer than 850 nm. This phenomenon has been correlated with the ~800 nm photosensitivity producing type I-IR fiber Bragg gratings in side-written lightly Ge-doped silicate fibers and low-loss waveguides in pure silica bulk glass. A model incorporating color center formation is proposed to understand the underlying mechanism. PMID:20548798

  1. Design of novel dual-port tapered waveguide plasma apparatus by numerical analysis

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Zhou, R.; Yang, X. Q.; Wu, S. Y.

    2016-07-01

    Microwave plasma apparatus is often of particular interest due to their superiority of low cost, electrode contamination free, and suitability for industrial production. However, there exist problems of unstable plasma and low electron density in conventional waveguide apparatus based on single port, due to low strength and non-uniformity of microwave field. This study proposes a novel dual-port tapered waveguide plasma apparatus based on power-combining technique, to improve the strength and uniformity of microwave field for the applications of plasma. A 3D model of microwave-induced plasma (field frequency 2.45 GHz) in argon at atmospheric pressure is presented. On the condition that the total input power is 500 W, simulations indicate that coherent power-combining will maximize the electric-field strength to 3.32 × 105 V/m and improve the uniformity of distributed microwave field, which raised 36.7% and 47.2%, respectively, compared to conventional waveguide apparatus of single port. To study the optimum conditions for industrial application, a 2D argon fluid model based on above structure is presented. It demonstrates that relatively uniform and high-density plasma is obtained at an argon flow rate of 200 ml/min. The contrastive result of electric-field distribution, electron density, and gas temperature is also valid and clearly proves the superiority of coherent power-combining to conventional technique in flow field.

  2. Fusion splice between tapered inhibited coupling hypocycloid-core Kagome fiber and SMF.

    PubMed

    Zheng, Ximeng; Debord, Benoît; Vincetti, Luca; Beaudou, Benoît; Gérôme, Frédéric; Benabid, Fetah

    2016-06-27

    We report for the first time on tapering inhibited coupling (IC) hypocycloid-core shape Kagome hollow-core photonic crystal fibers whilst maintaining their delicate core-contour negative curvature with a down-ratio as large as 2.4. The transmission loss of down-tapered sections reaches a figure as low as 0.07 dB at 1550 nm. The tapered IC fibers are also spliced to standard SMF with a total insertion loss of 0.48 dB. These results show that all-fiber photonic microcells with the ultra-low loss hypocycloid core-contour Kagome fibers is now possible.

  3. Acousto-optic interaction in biconical tapered fibers: shaping of the stopbands

    NASA Astrophysics Data System (ADS)

    Ramírez-Meléndez, Gustavo; Bello-Jiménez, Miguel Ángel; Cuadrado-Laborde, Christian; Díez, Antonio; Cruz, José Luis; Rodríguez-Cobos, Amparo; Balderas-Navarro, Raúl; Andrés Bou, Miguel Vicente

    2016-03-01

    The effect of a gradual reduction of the fiber diameter on the acousto-optic (AO) interaction is reported. The experimental and theoretical study of the intermodal coupling induced by a flexural acoustic wave in a biconical tapered fiber shows that it is possible to shape the transmission spectrum, for example, substantially broadening the bandwidth of the resonant couplings. The geometry of the taper transitions can be regarded as an extra degree of freedom to design the AO devices. Optical bandwidths above 45 nm are reported in a tapered fiber with a gradual reduction of the fiber down to 70 μm diameter. The effect of including long taper transition is also reported in a double-tapered structure. A flat attenuation response is reported with 3-dB stopband bandwidth of 34 nm.

  4. Temperature-independent gas refractometer based on an S-taper fiber tailored fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Shao, Zhihua; Qiao, Xueguang; Bao, Weijia; Rong, Qiangzhou

    2016-09-01

    A fiber Bragg grating (FBG)-based gas refractometer is proposed and demonstrated experimentally. The configuration consists of a short section of S-type taper incorporated in the upstream of a FBG. The S-taper is capable to couple the core mode to cladding modes into the downstream single mode fiber (SMF), and the low-order cladding modes can be reflected back to the fiber core via the FBG. Because of the recoupling efficiency depending on surrounding refractive index (SRI), the reflection power of the device presents high response to gas RI change with the sensitivity of 172.7 dB/RIU. This power-referenced RI measurement and wavelength-referenced temperature measurement have been achieved via selective cladding modes monitoring.

  5. Controllable pulse width of bright similaritons in a tapered graded index diffraction decreasing waveguide.

    PubMed

    Prakash, S Arun; Malathi, V; Mani Rajan, M S; Loomba, Shally

    2016-03-01

    We obtain the bright similariton solutions for generalized inhomogeneous nonlinear Schrödinger equation (GINLSE) which governs the pulse propagation in a tapered graded index diffraction decreasing waveguide (DDW). The exact solutions have been worked out by employing similarity transformations which involve the mapping of the GINLSE to standard NLSE for the certain conditions of the parameters. By making use of the exact analytical solutions, we have investigated the dynamical behavior of optical similariton pairs and have suggested the methods to control them as they propagate through DDW. Moreover, pulse width of similariton is controlled through various profiles. These results are helpful to understand the similaritons in DDW and can be potentially useful for future experiments in optical communications which involve optical amplifiers and long-haul telecommunication networks. PMID:27036193

  6. Controllable pulse width of bright similaritons in a tapered graded index diffraction decreasing waveguide

    NASA Astrophysics Data System (ADS)

    Prakash, S. Arun; Malathi, V.; Mani Rajan, M. S.; Loomba, Shally

    2016-03-01

    We obtain the bright similariton solutions for generalized inhomogeneous nonlinear Schrödinger equation (GINLSE) which governs the pulse propagation in a tapered graded index diffraction decreasing waveguide (DDW). The exact solutions have been worked out by employing similarity transformations which involve the mapping of the GINLSE to standard NLSE for the certain conditions of the parameters. By making use of the exact analytical solutions, we have investigated the dynamical behavior of optical similariton pairs and have suggested the methods to control them as they propagate through DDW. Moreover, pulse width of similariton is controlled through various profiles. These results are helpful to understand the similaritons in DDW and can be potentially useful for future experiments in optical communications which involve optical amplifiers and long-haul telecommunication networks.

  7. Experiments on a Ku-band gyrotron traveling-wave-tube amplifier with a tapered waveguide

    NASA Astrophysics Data System (ADS)

    Jung, Sang Wook; Lee, Han Seul; Jang, Kwang Ho; Choi, Jin Joo; So, Joon Ho

    2015-09-01

    A Ku-band gyrotron traveling-wave-tube (gyro-TWT) amplifier was investigated. To obtain a wide operating bandwidth, we used a two-stage tapered rectangular waveguide interaction circuit. An electron beam of 27 keV and 3.56 A was produced from a double-anode magnetron-injection-gun (MIG). The measured frequency bandwidth over 10 dB gain in the linear operation region was found to be 18%. The gyro-TWT's saturated output power was 14.9 kW at 14.4 GHz, corresponding to a saturated output power gain of 27.4 dB and an efficiency of 15.5%. The measured experimental results were in agreement with those of non-linear numerical simulations.

  8. Gain characteristics of quantum dot fiber amplifier based on asymmetric tapered fiber coupler

    NASA Astrophysics Data System (ADS)

    Guo, Hairun; Pang, Fufei; Zeng, Xianglong; Wang, Tingyun

    2013-03-01

    We theoretically analyzed the gain characteristics of an integrated semiconductor quantum dot (QD) fiber amplifier (SQDFA) by using a 2 × 2 tapered fiber coupler with a PbS QD-coated layer. The asymmetric structure of the fiber coupler is designed to have a maximum working bandwidth around 1550-nm band and provide a desired optical power ratio of the output signals. By using 600 mW of 980-nm pump, 10 dB gain of a 1550-nm signal is estimated with the gain efficiency of 4.5 dB/cm.

  9. An efficient method for supercontinuum generation in dispersion-tailored Lead-silicate fiber taper

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Ma, S.; Dutta, N. K.

    2010-08-01

    In this paper we theoretically study the broadband mid-IR supercontinuum generation (SCG) in a lead-silicate microstructured fiber (the glass for simulation is SF57). The total dispersion of the fiber can be tailored by changing the core diameter of the fiber so that dispersion profiles with two zero dispersion wavelengths (ZDWs) can be obtained. Numerical simulations of the SCG process in a 4 cm long SF57 fiber/fiber taper seeded by femto-second pulses at telecommunications wavelength of 1.55 µm are presented. The results show that a fiber taper features a continuous shift of the longer zero dispersion wavelength. This extends the generated continuum to a longer wavelength region compared to fibers with fixed ZDWs. The phase-matching condition (PMC) is continuously modified in the fiber taper and the bandwidth of the generated dispersive waves (DWs) is significantly broadened.

  10. Strain sensitivity control of fiber Bragg grating structures with fused tapers.

    PubMed

    Frazão, Orlando; Silva, Susana F O; Guerreiro, Ariel; Santos, José L; Ferreira, Luis A; Araújo, Francisco M

    2007-12-20

    We report on the analysis and experimental validation of the strain sensitivity dependences of a fiber Bragg grating written in standard optical fiber when combined with fused tapers. By controlling the difference between the cross sections of the fused taper and the Bragg grating, the strain sensitivity of the Bragg wavelength can be changed by acting on the gauge length. The strain sensing characteristics of an interferometric structure formed by fabricating a fused taper in the middle of a fiber Bragg grating are also reported. PMID:18091967

  11. Characteristics and Applications of Tapered Fiber Optical Sensors for 1310 nm Wavelength

    NASA Astrophysics Data System (ADS)

    Hwang, Thunter; Cheng, Wood-Hi; Su, Yan-Kuin

    2013-06-01

    Optical sensors for displacement measurement and fluorescence probes were designed and experimentally studied. This is the first time we used photonic sensors for displacement measurement and fluorescence probes at the same time using a long-wavelength (1310 nm) photon beam in the reflective mode. A tapered fiber sensor was chosen to increase the dynamic range for fluorescence probes. The results showed that the tapered fiber sensor exhibited a high resolution of 12 nm and a better dynamic range of 2 mm in our system. The relationship between resolution and dynamic range was experimentally found to vary with tapered fiber tilt angle. The precise diameter of the fiber microlens was measured. These were the characteristics considered in the manufacturing of our chosen device. Moreover, these novel 1310-nm-wavelength tapered fiber sensors with high resolution, good dynamic range, better reliability, and low cost may provide multipurpose applications, such as those in telecommunication systems, commercial measurements, and military inspection.

  12. Characterization of arbitrary fiber taper profiles with optical microscopy and image processing algorithms

    NASA Astrophysics Data System (ADS)

    Farias, Heric D.; Sebem, Renan; Paterno, Aleksander S.

    2014-08-01

    This work reports results from the development of a software to process the parameters involved in the characterization of fiber taper profiles, while using optical microscopy, a high-definition camera and a high- precision translation stage as the moveable base on which the taper is positioned. In addition to this procedure, image processing algorithms were customized to process the acquired images. With edge detection algorithms in the stitched image, one would be able to characterize the given taper radius curve that represents the taper profile when the camera has a sufficient resolution. As a consequence, the proposed fiber taper characterization procedure is a first step towards a high-resolution characterization of fiber taper diameters with arbitrary profiles, specially this case, in which tapers are fabricated with the stepwise technique that allows the production of non- biconical profiles. The parameters of the stitched images depends on the used microscope objective and the length of the characterized tapers. A non-biconical arbitrary taper is measured as an example for the illustration of the developed software and procedure.

  13. Multiplex and simultaneous measurement of displacement and temperature using tapered fiber and fiber Bragg grating

    SciTech Connect

    Ji Chongke; Zhao Chunliu; Kang Juan; Dong Xinyong; Jin Shangzhong

    2012-05-15

    A simple method to work out the multiplexing of tapered fiber based sensors is proposed and demonstrated. By cascading a tapered fiber with a fiber Bragg grating (FBG), the sensor head is provided with a wavelength identification, different FBGs provide the sensor heads with different reflective peaks and they can be distinguished in optical spectrum. By compositing several such sensor heads with a multi-channel beam splitter, a star-style topological structure sensor for multipoint sensing is achieved. At the same time, the output intensity at the peak wavelength is sensitive to one external physical parameter applied on the related FBG-cascaded tapered fiber and the central wavelength of the peak is only sensitive to temperature, so that that parameter and temperature can be measured simultaneously. A sensor for dual-point measurement of the displacement and temperature simultaneously is experimentally demonstrated by using a 2 x 2 coupler in this paper. Experiment results show that the sensor works well and the largest sensitivities reach to 0.11 dB/{mu}m for displacement in the range of 0-400 {mu}m, and {approx}0.0097 nm/ deg. C for temperature between 20 deg. C and 70 deg. C.

  14. Nonlinear evolution equations for surface plasmons for nano-focusing at a Kerr/metallic interface and tapered waveguide

    NASA Astrophysics Data System (ADS)

    Crutcher, Sihon H.; Osei, Albert; Biswas, Anjan

    2012-06-01

    Maxwell's equations for a metallic and nonlinear Kerr interface waveguide at the nanoscale can be approximated to a (1+1) D Nonlinear Schrodinger type model equation (NLSE) with appropriate assumptions and approximations. Theoretically, without losses or perturbations spatial plasmon solitons profiles are easily produced. However, with losses, the amplitude or beam profile is no longer stationary and adiabatic parameters have to be considered to understand propagation. For this model, adiabatic parameters are calculated considering losses resulting in linear differential coupled integral equations with constant definite integral coefficients not dependent on the transverse and longitudinal coordinates. Furthermore, by considering another configuration, a waveguide that is an M-NL-M (metal-nonlinear Kerr-metal) that tapers, the tapering can balance the loss experienced at a non-tapered metal/nonlinear Kerr interface causing attenuation of the beam profile, so these spatial plasmon solitons can be produced. In this paper taking into consideration the (1+1)D NLSE model for a tapered waveguide, we derive a one soliton solution based on He's Semi-Inverse Variational Principle (HPV).

  15. Mass-productive fabrication of a metal-insulator-metal plasmon waveguide with a linear taper for nanofocusing

    NASA Astrophysics Data System (ADS)

    Wongpanya, Kruawan; Kasaya, Takeshi; Miyazaki, Hideki T.; Oosato, Hirotaka; Sugimoto, Yoshimasa; Pijitrojana, Wanchai

    2016-09-01

    The fabrication of a metal-insulator-metal plasmon waveguide with a linear taper is reported. Highly efficient nanofocusing of light with a Au-SiO2-Au waveguide with a three-dimensional taper had been demonstrated. However, conventional vertical taper structures were fabricated with a low-throughput process based on electron beam scanning. We propose an efficient, mass-productive fabrication process using a standard dry etching technique. A key improvement is the employment of a mixed gas of CHF3 and O2. By optimizing the gas composition and the cooling process of the substrate, a SiO2 vertical taper with an angle of 19°, which is very close to the optimum 20°, was successfully produced. At the tip section, an ultra-thin waveguide as thin as 5.6 nm, only one-third of the conventional demonstration, is reproducibly realized by the employment of an atomic layer deposition of Al2O3. Coupling efficiency as high as 72 % numerically demonstrated.

  16. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II. Broadband characterization.

    PubMed

    Sidabras, Jason W; Strangeway, Robert A; Mett, Richard R; Anderson, James R; Mainali, Laxman; Hyde, James S

    2016-03-01

    Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in

  17. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II. Broadband characterization.

    PubMed

    Sidabras, Jason W; Strangeway, Robert A; Mett, Richard R; Anderson, James R; Mainali, Laxman; Hyde, James S

    2016-03-01

    Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in

  18. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II. Broadband characterization

    NASA Astrophysics Data System (ADS)

    Sidabras, Jason W.; Strangeway, Robert A.; Mett, Richard R.; Anderson, James R.; Mainali, Laxman; Hyde, James S.

    2016-03-01

    Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in

  19. Gas refractometer based on an S-taper fiber tailored fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Shao, Zhihua; Bao, Weijia; Qiao, Xueguang; Rong, Qiangzhou

    2015-09-01

    A fiber Bragg grating (FBG)-based gas refractometer is proposed and demonstrated experimentally. The configuration consists of a short section of S-type taper followed with a FBG. The S-taper is capable to couple the core mode to cladding modes into the downstream SMF, and the low-order cladding modes can be reflected back to the fiber core via the FBG, in which the recoupling efficiency is highly dependent on surrounding refractive index (RI) of liquid and gas. Experimental results show that some recoupled cladding modes show high sensitivities to surround RI. This power-referenced RI measurement and wavelength-referenced temperature measurement have been achieved via selective cladding modes monitoring.

  20. Tapered optical fibers as tools for probing magneto-optical trap characteristics

    SciTech Connect

    Morrissey, Michael J.; Deasy, Kieran; Wu Yuqiang; Nic Chormaic, Sile; Chakrabarti, Shrabana

    2009-05-15

    We present a novel technique for measuring the characteristics of a magneto-optical trap (MOT) for cold atoms by monitoring the spontaneous emission from trapped atoms coupled into the guided mode of a tapered optical nanofiber. We show that the nanofiber is highly sensitive to very small numbers of atoms close to its surface. The size and shape of the MOT, determined by translating the cold atom cloud across the tapered fiber, is in excellent agreement with measurements obtained using the conventional method of fluorescence imaging using a charge coupled device camera. The coupling of atomic fluorescence into the tapered fiber also allows us to monitor the loading and lifetime of the trap. The results are compared to those achieved by focusing the MOT fluorescence onto a photodiode and it was seen that the tapered fiber gives slightly longer loading and lifetime measurements due to the sensitivity of the fiber, even when very few atoms are present.

  1. Direct fiber-coupled single photon source based on a photonic crystal waveguide

    SciTech Connect

    Ahn, Byeong-Hyeon Lee, Chang-Min; Lim, Hee-Jin; Schlereth, Thomas W.; Kamp, Martin; Höfling, Sven; Lee, Yong-Hee

    2015-08-24

    A single photon source plays a key role in quantum applications such as quantum computers and quantum communications. Epitaxially grown quantum dots are one of the promising platforms to implement a good single photon source. However, it is challenging to realize an efficient single photon source based on semiconductor materials due to their high refractive index. Here we demonstrate a direct fiber coupled single photon source with high collection efficiency by employing a photonic crystal (PhC) waveguide and a tapered micro-fiber. To confirm the single photon nature, the second-order correlation function g{sup (2)}(τ) is measured with a Hanbury Brown-Twiss setup. The measured g{sup (2)}(0) value is 0.15, and we can estimate 24% direct collection efficiency from a quantum dot to the fiber.

  2. Experimental stress–strain analysis of tapered silica optical fibers with nanofiber waist

    SciTech Connect

    Holleis, S.; Hoinkes, T.; Wuttke, C.; Schneeweiss, P.; Rauschenbeutel, A.

    2014-04-21

    We experimentally determine tensile force–elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force–elongation data and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress–strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius.

  3. Optical similaritons in a tapered graded-index nonlinear-fiber amplifier with an external source

    SciTech Connect

    Raju, Thokala Soloman; Panigrahi, Prasanta K.

    2011-09-15

    We analytically explore a wide class of optical similariton solutions to the nonlinear Schroedinger equation appropriately modified to model beam propagation in a tapered, graded-index nonlinear-fiber amplifier with an external source. Under certain physical conditions, we reduce the coupled nonlinear Schroedinger equations to a single-wave equation that aptly describes similariton propagation through asymmetric twin-core fiber amplifiers. The asymmetric twin-core fiber is composed of two adjoining, closely spaced, single-mode fibers in which the active one is a tapered, graded-index nonlinear-fiber and the passive one is a step-index fiber. We obtain these self-similar waves for different choices of tapered index profile, using a Moebius transformation. Our procedure is applicable for both self-focusing and self-defocusing nonlinearities.

  4. Direct inscription of intrinsic Fabry-Perot interferometers in optical fiber tapers with a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Li, Jinlong; Zhang, Xiaobei; Wang, Wenyuan; Pang, Fufei; Liu, Yunqi; Wang, Tingyun

    2011-12-01

    In this work, we report a sensing configuration of the fiber taper intrinsic Fabry-Perot interferometer directly inscribed in single-mode optical fiber tapers with different waist diameters from 14 to 80 μm using a femtosecond laser micromachining system. By controlling the inscribing depth and intensity of the fs laser pulse, the fringe visibility can exceed 9.0 dB when the fiber taper waist diameter is around 15 μm, which is sufficient for most sensing applications. The sensor sensitivity depends on the fiber taper waist diameter, while a smaller diameter corresponds to a large sensitivity. Different free spectral ranges can be achieved for various cavity lengths. Such a structure can combine the high sensitivity properties of fiber taper sensors with the high resolution features of Fabry-Perot interferometer sensors. Meanwhile, this structure can have a number of outstanding advantages, such as its small size, unique geometry, easy fabrication, low cost and capability for mass production. These fiber taper intrinsic Fabry-Perot interferometer sensors have high potential in fast detection and high precision measurement while maintaining superior reliability for chemical and biological sensing.

  5. Vector rectangular-shape laser based on reduced graphene oxide interacting with a long fiber taper.

    PubMed

    Gao, Lei; Zhu, Tao; Huang, Wei; Zeng, Jing

    2014-10-01

    A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber taper deposited with reduced graphene oxide is proposed, where nonlinearity is enhanced due to a large evanescent-field-interacting length and strong field confinement of an 8 mm fiber taper with a waist diameter of 4 μm. Graphene flakes are deposited uniformly on the taper waist with light pressure effect, so this structure guarantees both excellent saturable absorption and high nonlinearity. The RSL with a repetition rate of 7.9 MHz shows fast polarization switching in two orthogonal polarization directions, and temporal and spectral characteristics are investigated. PMID:25322232

  6. Fabrication and characterization of multimaterial chalcogenide glass fiber tapers with high numerical apertures.

    PubMed

    Sun, Ya'nan; Dai, Shixun; Zhang, Peiqing; Wang, Xunsi; Xu, Yinsheng; Liu, Zijun; Chen, Feifei; Wu, Yuehao; Zhang, Yuji; Wang, Rongping; Tao, Guangming

    2015-09-01

    This paper reports on the fabrication and characterization of multimaterial chalcogenide fiber tapers that have high numerical apertures (NAs). We first fabricated multimaterial As(2)Se(3)-As(2)S(3) chalcogenide fiber preforms via a modified one-step coextrusion process. The preforms were drawn into multi- and single-mode fibers with high NAs (≈1.45), whose core/cladding diameters were 103/207 and 11/246 μm, respectively. The outer diameter of the fiber was tapered from a few hundred microns to approximately two microns through a self-developed automatic tapering process. Simulation results showed that the zero-dispersion wavelengths (ZDWs) of the tapers were shorter than 2 μm, indicating that the tapers can be conveniently pumped by commercial short wavelength infrared lasers. We also experimentally demonstrated the supercontinuum generation (SCG) in a 15-cm-long multimaterial As(2)Se(3)-As(2)S(3) chalcogenide taper with 1.9 μm core diameter and the ZDW was shifted to 3.3 μm. When pumping the taper with 100 fs short pulses at 3.4 µm, a 20 dB spectral of the generated supercontinuum spans from 1.5 μm to longer than 4.8 μm. PMID:26368447

  7. SU8 3D prisms with ultra small inclined angle for low-insertion-loss fiber/waveguide interconnection.

    PubMed

    Nguyen, Minh-Hang; Chang, Chia-Jung; Lee, Ming-Chang; Tseng, Fan-Gang

    2011-09-26

    This paper presents a simple method for fabricating SU8 three dimensional (3D) prisms with very small inclined-angles for optical-fiber/planar-waveguide interconnection with low insertion-loss by combining self-filling, molding and nano-lithography processes on plane surface. The prisms possess ultra low 3D inclined angle of 0.6° and a small surface roughness of 3.5 nm. It is demonstrated that the transmission efficiency of SOI waveguides improved about 4.6 times at the presence of SU8 prisms with a coupling loss of 11 dB per taper and radiation loss of 2.4 dB per taper.

  8. Tapered inner-cladding fiber design for uniform heat deposition in Ytterbium-doped fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Huang, Zhihua; Zhang, Yongliang; Deng, Ying; Lin, Honghuan; Li, Qi; Zhao, Lei; Wang, Jianjun

    2015-04-01

    A method for designing double-clad fiber with tapered inner cladding and uniform core is proposed for linear pump power profile, i.e. uniform heat deposition, in the ytterbium-doped fiber amplifier. The analytical formula for the inner-cladding diameter profile along the fiber is given. The inner-cladding diameter near the pump injection port is determined purely by the diameter of the doped region, the number density of the doped ions, the absorption cross section at the pump wavelength and the length of the fiber. The simplified linearly varying inner-cladding diameter is proven to have a smoother heat deposition profile with lower maximum thermal load in both the co-pumping scheme and the counter-pumping scheme.

  9. Interference phenomena in fraunhofer holograms and in their reconstructions of tapered glass fibers.

    PubMed

    Lomas, G M

    1969-10-01

    Fraunhofer holograms and their reconstructions show interference fringes when applied to tapered glass fibers, which do not occur with opaque fibers. The fringes are shown to be quantitatively related to fiber profile. The phase lag of fiber transmitted light is recorded as identifiable hologram fringes by interference with fiber-diffracted light. This also results in fringes in the reconstructed image. One fringe of both types, for a fiber refractive index n, represents a diameter change lambda/(n-1). Shape changes along a fiber not directly resolved by the optics are measurable. Profile measurement of attenuating glass fibers in the continuous filament process is described.

  10. Optical fiber having wave-guiding rings

    DOEpatents

    Messerly, Michael J.; Dawson, Jay W.; Beach, Raymond J.; Barty, Christopher P. J.

    2011-03-15

    A waveguide includes a cladding region that has a refractive index that is substantially uniform and surrounds a wave-guiding region that has an average index that is close to the index of the cladding. The wave-guiding region also contains a thin ring or series of rings that have an index or indices that differ significantly from the index of the cladding. The ring or rings enable the structure to guide light.

  11. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    NASA Astrophysics Data System (ADS)

    Leich, M.; Jäger, M.; Grimm, S.; Hoh, D.; Jetschke, S.; Becker, M.; Hartung, A.; Bartelt, H.

    2014-04-01

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power.

  12. Tapered cladding diameter profile design for high-power tandem-pumped fiber lasers

    NASA Astrophysics Data System (ADS)

    Huang, Zhihua; Tang, Xuan; Lin, Honghuan; Wang, Jianjun

    2016-05-01

    The thermal effect has become the biggest limiting factor regarding the further power scaling of single mode fiber lasers, and it can lead to coating failure and transverse mode instability. A tapered cladding diameter profile design is proposed for the tandem-pumped fiber laser in this work, as it can smooth the temperature profile and reduce the maximum temperature rise within the fiber tremendously. The improvement in performance of the fiber design is verified by analytical and numerical results.

  13. All fiber magnetic field sensor with Ferrofluid-filled tapered microstructured optical fiber interferometer.

    PubMed

    Deng, Ming; Huang, Can; Liu, Danhui; Jin, Wei; Zhu, Tao

    2015-08-10

    An ultra-compact optical fiber magnetic field sensor based on a microstructured optical fiber (MOF) modal interference and ferrofluid (FF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing a tapered germanium-doped index guided MOF with six big holes injected with FF to two conventional single-mode fibers. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. Due to an efficient interaction between the magnetic nanoparticles in FF and the excited cladding mode, the magnetic field sensitivity reaches up to117.9pm/mT with a linear range from 0mT to 30mT. Moreover, the fabrication process of the proposed sensor is simple, easy and cost-effective. Therefore, it will be a promising candidate for military, aviation industry, and biomedical applications, especially, for the applications where the space is limited.

  14. Frequency-stabilized Yb:fiber comb with a tapered single-mode fiber

    NASA Astrophysics Data System (ADS)

    Yang, Xie; Hai-Nian, Han; Long, Zhang; Zi-Jiao, Yu; Zheng, Zhu; Lei, Hou; Li-Hui, Pang; Zhi-Yi, Wei

    2016-04-01

    We demonstrate a stable Yb:fiber frequency comb with supercontinuum generation by using a specially designed tapered single-mode fiber, in which a spectrum spanning from 500 nm to 1500 nm is produced. The carrier-envelope offset signal of the Yb:fiber comb is measured with a signal-to-noise ratio of more than 40 dB and a linewidth narrower than 120 kHz. The repetition rate and carrier-envelope offset signals are simultaneously phase locked to a microwave reference frequency. Project supported by the National Basic Research Program of China (973 Program) (Grant No. 2012CB821304) and the National Natural Science Foundation of China (Grant No. 61378040).

  15. All fiber magnetic field sensor with Ferrofluid-filled tapered microstructured optical fiber interferometer.

    PubMed

    Deng, Ming; Huang, Can; Liu, Danhui; Jin, Wei; Zhu, Tao

    2015-08-10

    An ultra-compact optical fiber magnetic field sensor based on a microstructured optical fiber (MOF) modal interference and ferrofluid (FF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing a tapered germanium-doped index guided MOF with six big holes injected with FF to two conventional single-mode fibers. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. Due to an efficient interaction between the magnetic nanoparticles in FF and the excited cladding mode, the magnetic field sensitivity reaches up to117.9pm/mT with a linear range from 0mT to 30mT. Moreover, the fabrication process of the proposed sensor is simple, easy and cost-effective. Therefore, it will be a promising candidate for military, aviation industry, and biomedical applications, especially, for the applications where the space is limited. PMID:26367919

  16. Design and performance analysis of InP/InGaAsP-MMI based 1310/1550-nm wavelength division demultiplexer with tapered waveguide geometry

    NASA Astrophysics Data System (ADS)

    Chack, D.; Kumar, V.; Raghuwanshi, S. K.

    2015-12-01

    The design and performance analysis of a 1310/1550-nm wavelength division demultiplexer with tapered geometry based on InP/InGaAsP multimode interference (MMI) coupler has been carried out. Wavelength response of demultiplexer of conventional MMI and tapered input and tapered output (tapered I/O) waveguides geometry of the MMI have been discussed. The demultiplexing function has been first performed by choosing a suitable refractive index of the guiding region and geometrical parameters such as the width and length of MMI structure have been achieved. Access width of tapered I/O waveguides have been adjusted to give a low insertion loss (IL) and high extinction ratio (ER) for the considered wavelengths of 1310 nm and 1550 nm. The total size of the demultiplexer has been significantly reduced over the existing MMI devices. Numerical simulations with finite difference beam propagation method are applied to design and optimize the operation of the proposed demultiplexer.

  17. Room temperature ammonia sensing using tapered multimode fiber coated with polyaniline nanofibers.

    PubMed

    Ibrahim, S A; Rahman, N A; Abu Bakar, M H; Girei, S H; Yaacob, M H; Ahmad, H; Mahdi, M A

    2015-02-01

    We demonstrate an ammonia sensor composed of a tapered multimode fiber coated with polyaniline nanofibers that operates at room temperature (26°C). The optical properties of the polyaniline layer changes when it is exposed to ammonia, leading to a change in the absorption of evanescent field. The fiber sensor was tested by exposing it to ammonia at different concentrations and the absorbance is measured using a spectrophotometer system. Measured response and recovery times are about 2.27 minutes and 9.73 minutes, respectively. The sensor sensitivity can be controlled by adjusting the tapered fiber diameter and the highest sensitivity is achieved when the diameter is reduced to 20 µm.

  18. 600 W power scalable single transverse mode tapered double-clad fiber laser.

    PubMed

    Filippov, V; Chamorovskii, Y; Kerttula, J; Kholodkov, A; Okhotnikov, O G

    2009-02-01

    Pump propagation and absorption in active tapered double-clad fiber has been analyzed based on a ray optics approach. Optimization of the longitudinal shape, absorption and angular distribution of the pump beam allowed for power scaling of a ytterbium fiber laser up to 600 W with high beam quality (M2tapered fiber can be avoided, resulting in high overall efficiency, in good agreement with the presented model. PMID:19188947

  19. Optical microscope and tapered fiber coupling apparatus for a dilution refrigerator.

    PubMed

    MacDonald, A J R; Popowich, G G; Hauer, B D; Kim, P H; Fredrick, A; Rojas, X; Doolin, P; Davis, J P

    2015-01-01

    We have developed a system for tapered fiber measurements of optomechanical resonators inside a dilution refrigerator, which is compatible with both on- and off-chip devices. Our apparatus features full three-dimensional control of the taper-resonator coupling conditions enabling critical coupling, with an overall fiber transmission efficiency of up to 70%. Notably, our design incorporates an optical microscope system consisting of a coherent bundle of 37,000 optical fibers for real-time imaging of the experiment at a resolution of ∼1 μm. We present cryogenic optical and optomechanical measurements of resonators coupled to tapered fibers at temperatures as low as 9 mK. PMID:25638072

  20. Coupled fiber taper extraction of 1.53 microm photoluminescence from erbium doped silicon nitride photonic crystal cavities.

    PubMed

    Shambat, Gary; Gong, Yiyang; Lu, Jesse; Yerci, Selçuk; Li, Rui; Dal Negro, Luca; Vucković, Jelena

    2010-03-15

    Optical fiber tapers are used to collect photoluminescence emission at approximately 1.5 microm from photonic crystal cavities fabricated in erbium doped silicon nitride on silicon. In the experiment, photoluminescence collection via one arm of the fiber taper is enhanced 2.5 times relative to free space collection, corresponding to a net collection efficiency of 4%. Theoretically, the collection efficiency into one arm of the fiber-taper with this material system and cavity design can be as high as 12.5%, but the degradation of the experimental coupling efficiency relative to this value mainly comes from scattering loss within the short taper transition regions. By varying the fiber taper offset from the cavity, a broad tuning range of coupling strength and collection efficiency is obtained. This material system combined with fiber taper collection is promising for building on-chip optical amplifiers.

  1. High-sensitivity refractive index sensors based on fused tapered photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xing-hu; Xie, Hai-yang; Yang, Chuan-qing; Qu, Yu-wei; Zhang, Shun-yang; Fu, Guang-wei; Guo, Xuan; Bi, Wei-hong

    2016-05-01

    In this paper, a novel liquid refractive index (RI) sensor based on fused tapered photonic crystal fiber (PCF) is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single-mode fibers (SMFs). Due to the fused biconical taper method, the sensor becomes longer and thinner, to make the change of the outside RI has more direct effects on the internal optical field of the PCF, which finally enhances the sensitivity of this sensor. Experimental results show that the transmission spectra of the sensor are red-shifted obviously with the increase of RI. The longer the tapered region of the sensor, the higher the sensitivity is. This sensor has the advantages of simple structure, easy fabrication, high performance and so on, so it has potential applications in RI measurement.

  2. Characteristics of a tapered capillary plasma waveguide for laser wakefield acceleration

    SciTech Connect

    Kim, M. S.; Jang, D. G.; Lee, T. H.; Nam, I. H.; Lee, I. W.; Suk, H.

    2013-05-20

    We developed a gas-filled capillary with a tapered density for laser wakefield acceleration, of which the tapering was realized by employing gas feed-lines with different cross-sections. Plasma diagnostics show that the capillary plasma has a significant longitudinal density tapering and a transverse parabolic profile. By using the tapered capillary plasma, high transmission (over 90%) of laser beams, meaning good optical guiding, was observed. These results demonstrate the potential of the tapered plasma source for high-energy laser wakefield acceleration, where the dephasing problem is minimized.

  3. A high-energy cladding-pumped 80 nanosecond Q-switched fiber laser using a tapered fiber saturable absorber

    NASA Astrophysics Data System (ADS)

    Moore, Sean W.; Soh, Daniel B. S.; Bisson, Scott E.; Patterson, Brian D.; Hsu, Wen L.

    2013-02-01

    We report a passively Q-switched all-fiber laser using a large mode area (LMA) Yb3+-doped fiber cladding-pumped at 915 nm and an unpumped single-mode Yb3+-doped fiber as the saturable absorber (SA). The saturable absorber and gain fibers were first coupled with a free-space telescope to better study the composite system, and then fusion spliced with fiber tapers to match the mode field diameters. ASE generated in the LMA gain fiber preferentially bleaches the SA fiber before depleting the gain, thereby causing the SA fiber to act as a passive saturable absorber. Using this scheme we first demonstrate a Q-switched oscillator with 40 μJ 79 ns pulses at 1026 nm using a free-space taper, and show that pulses can be generated from 1020 nm to 1040 nm. We scale the pulse energy to 0.40 mJ using an Yb3+-doped cladding pumped fiber amplifier. Experimental studies in which the saturable absorber length, pump times, and wavelengths are independently varied reveal the impact of these parameters on laser performance. Finally, we demonstrate 60 μJ 81 ns pulses at 1030 nm in an all fiber architecture using tapered mode field adaptors to match the mode filed diameters of the gain and SA fibers.

  4. Large-aperture, tapered fiber-coupled, 10-kHz particle-image velocimetry.

    PubMed

    Hsu, Paul S; Roy, Sukesh; Jiang, Naibo; Gord, James R

    2013-02-11

    We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed particle-image velocimetry (PIV) in turbulent combustion flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of 5.3 mJ and 2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally (bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. Proof-of-concept measurements show significant promise for the performance of fiber-coupled, high-speed PIV using a tapered optical fiber in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine. PMID:23481818

  5. Large-aperture, tapered fiber-coupled, 10-kHz particle-image velocimetry.

    PubMed

    Hsu, Paul S; Roy, Sukesh; Jiang, Naibo; Gord, James R

    2013-02-11

    We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed particle-image velocimetry (PIV) in turbulent combustion flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of 5.3 mJ and 2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally (bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. Proof-of-concept measurements show significant promise for the performance of fiber-coupled, high-speed PIV using a tapered optical fiber in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine.

  6. Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds at cryogenic temperatures.

    PubMed

    Fujiwara, Masazumi; Zhao, Hong-Quan; Noda, Tetsuya; Ikeda, Kazuhiro; Sumiya, Hitoshi; Takeuchi, Shigeki

    2015-12-15

    We demonstrate cooling of ultrathin fiber tapers coupled with nitrogen vacancy (NV) centers in nanodiamonds to cryogenic temperatures. Nanodiamonds containing multiple NV centers are deposited on the subwavelength 480-nm-diameter nanofiber region of fiber tapers. The fiber tapers are successfully cooled to 9 K using our home-built mounting holder and an optimized cooling speed. The fluorescence from the nanodiamond NV centers is efficiently channeled into a single guided mode and shows characteristic sharp zero-phonon lines (ZPLs) of both neutral and negatively charged NV centers. The present nanofiber/nanodiamond hybrid systems at cryogenic temperatures can be used as NV-based quantum information devices and for highly sensitive nanoscale magnetometry in a cryogenic environment. PMID:26670490

  7. Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds at cryogenic temperatures.

    PubMed

    Fujiwara, Masazumi; Zhao, Hong-Quan; Noda, Tetsuya; Ikeda, Kazuhiro; Sumiya, Hitoshi; Takeuchi, Shigeki

    2015-12-15

    We demonstrate cooling of ultrathin fiber tapers coupled with nitrogen vacancy (NV) centers in nanodiamonds to cryogenic temperatures. Nanodiamonds containing multiple NV centers are deposited on the subwavelength 480-nm-diameter nanofiber region of fiber tapers. The fiber tapers are successfully cooled to 9 K using our home-built mounting holder and an optimized cooling speed. The fluorescence from the nanodiamond NV centers is efficiently channeled into a single guided mode and shows characteristic sharp zero-phonon lines (ZPLs) of both neutral and negatively charged NV centers. The present nanofiber/nanodiamond hybrid systems at cryogenic temperatures can be used as NV-based quantum information devices and for highly sensitive nanoscale magnetometry in a cryogenic environment.

  8. A novel graphene-based tapered optical fiber sensor for glucose detection

    NASA Astrophysics Data System (ADS)

    Qiu, H. W.; Xu, S. C.; Jiang, S. Z.; Li, Z.; Chen, P. X.; Gao, S. S.; Zhang, C.; Feng, D. J.

    2015-02-01

    In this study, a novel tapered plastic optical fiber sensor based on the single-layer graphene film is demonstrated. A single-layer graphene film was grown on copper foil by chemical vapor deposition (CVD) and transferred to the cone area of the optical fiber by wetting transfer technology. The tapered plastic optical fiber was fabricated with waist diameters of 1 mm and total lengths of 5 cm. In order to increase the stability of the sensor, the taper regions were coated with a single-layer graphene with length of 1.5 cm. By using this platform, the glucose solution as the analyte was measured. The output light intensity and glucose concentration shows a reasonable linear relationship in the range of 1%∼40%

  9. Investigation on single taper-based all-solid photonic bandgap fiber modal interferometers.

    PubMed

    Li, Jie; Geng, Mengmei; Sun, Li-Peng; Fan, Pengcheng; Liu, Bo; Guan, Bai-Ou

    2016-04-18

    We demonstrate a single taper-based all-solid photonic bandgap (AS-PBG) fiber modal interferometer that consists of a central tapered fiber region connected to the untapered via two abrupt transitions. Modal interference is given by superimposing the bandgap-guided fundamental core mode with a lower effective index and a specific index-guided cladding supermode with a higher effective index. A series of interferometers with taper diameter of 50μm ~60μm and device length of ~3mm are fabricated and studied in contrast to the conventional counterparts. The temperature coefficient of the interferometer is closely determined by the fraction of the cladding supermode energy localized within the index-raised regions of the fiber. The refractive index (RI) responsivities associated to fiber taper sizes are investigated. The measured maximal RI sensitivity is ~3512.36nm/RIU at the taper diameter of 50μm around RI = 1.423. This research gives a deep understanding to the modal-interferometric AS-PBG structure, which we believe to be valuable for the future application of the related device. PMID:27137292

  10. Bent optical fiber tapers for refractometery and biosensing

    NASA Astrophysics Data System (ADS)

    Penchev, Emil; Eftimov, Tinko; Bock, Wojtek

    2015-01-01

    We report the results of our study of the spectral shifts caused by surrounding refractive index changes (SRI) in bent fibre tapers. Fused and etched fibre tapers were fabricated using a gas burner and HF acid. Spectral shifts as high as 200 nm have been observed for SRI variations from 1.33 to 1.44 and sensitivity as high as 830 nm/r.i.u. around water RI values. We present results for refractometric measurements of cow milk of varying fat content and compare results with those obtained with conventional Abbe refractometers and high sensitivity double resonance LPGs.

  11. Octave-spanning spectrum generation in tapered silica photonic crystal fiber by Yb:fiber ring laser above 500 MHz.

    PubMed

    Jiang, Tongxiao; Wang, Guizhong; Zhang, Wei; Li, Chen; Wang, Aimin; Zhang, Zhigang

    2013-02-15

    We report octave-spanning spectrum generated in a tapered silica photonic crystal fiber by a mode-locked Yb:fiber ring laser at a repetition rate as high as 528 MHz. The output pulses from this laser were compressed to 62 fs. By controlling the hole expansion and core diameter, a silica PCF was tapered to 20 cm with an optimal d/Λ ratio of 0.6. Pulses with the energy of 280 pJ and the peak power of 4.5 kW were injected into the tapered fiber and the pulse spectrum was expanded from 500 to 1600 nm at the level of -30 dB.

  12. Manipulating multiparticles simultaneously with tapered-tip single fiber optical tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Wu, Zhongfu; Liu, Zhihai; Yang, Jun; Yuan, Libo

    2008-12-01

    We present a single-core tapered-tip single fiber optical tweezers, which can trap multi-particle simultaneously. In order to test and verify its new function, finite difference time domain (FDTD) method is used to calculate and simulate. The relationship between the trapping force and the particle-parameters, such as the size, refractive index and others of particle are studied. By experimental validation, the tapered-tip single optic fiber tweezers can trap Particle 2nd after the Particle 1st trapped firmly, but can not trap Particle 3rd, which just verifies the theoretical simulation results to be right.

  13. Theoretical study of mode evolution in active long tapered multimode fiber.

    PubMed

    Shi, Chen; Wang, Xiaolin; Zhou, Pu; Xu, Xiaojun; Lu, Qisheng

    2016-08-22

    A concise and effective model based on coupled mode theory to describe mode evolution in long tapered active fiber is presented in this manuscript. The mode coupling due to variation of core radius and slight perturbation have been analyzed and local gain with transverse spatial hole burning (TSHB) effect, loss and curvature have been taken into consideration in our model. On the base of this model, the mode evolution behaviors under different factors have been numerically investigated. Our model and results can provide instructive suggestions when designing long tapered fiber based laser and amplifiers. PMID:27557225

  14. Nonlinear Optics with Tapered Fibers and Magneto-Optically Trapped Rubidium

    NASA Astrophysics Data System (ADS)

    Little, Bethany; Mullarkey, Chris; Howell, John; Vamivakas, Nick; Lin, Qiang

    2016-05-01

    Tapered optical fibers of sub-wavelength diameter present a promising means of integrating the light-atom interaction into larger scale devices. We present work on a tapered fiber system loaded by a magneto optical trap of Rubidium atoms, in which a combination of red and blue detuned beams create a one-dimensional lattice trap along the fiber. The same fiber is used for interacting with the atoms in the trap via the evanescent fields of light propagating along the fiber. Light storage has been demonstrated in a similar system with Cesium, and we believe that much nonlinear optics remains to be explored in this regime. We also plan to see how these nonlinear effects can be enhanced with the addition of a micro-resonator such as the ones in.

  15. All-fiber-integrated single frequency tapered fiber amplifier with near diffraction limited output

    NASA Astrophysics Data System (ADS)

    Zhou, Zichao; Zhang, Hanwei; Wang, Xiaolin; Pan, Zhiyong; Su, Rongtao; Yang, Baolai; Zhou, Pu; Xu, Xiaojun

    2016-06-01

    We present an all-fiber single frequency high-power amplifier using tapered ytterbium-doped fiber (T-YDF) based on a master oscillator power amplification (MOPA) scheme. Different from previous laser amplifiers, the monolithic system is all-fiber-integrated, employing a large mode area (LMA) T-YDF and co-pump scheme. The LMA T-YDF is 7 m long and its core/inner cladding diameters are 20.4/237.1 μm and 46.9/579.9 μm in the input port and output port, respectively. In experiment, the laser amplifier is shown to generate up to 53 W of single frequency laser with slope efficiency of 57.7%, which indicates more than a two times increase of the stimulated Brillouin scattering (SBS) threshold than common LMA fibers with core/inner cladding diameters of 20/400 μm. At the highest output power, the M 2 factor is measured to be 1.25 and 1.20 in the X and Y directions. Results show that this T-YDF can be scaled up to even higher power when other SBS suppression methods are employed simultaneously.

  16. Evaluation of the tapered PMMA fiber sensor response due to the ionic interaction within electrolytic solutions

    NASA Astrophysics Data System (ADS)

    Batumalay, M.; Rahman, H. A.; Kam, W.; Ong, Y. S.; Ahmad, F.; Zakaria, R.; Harun, S. W.; Ahmad, H.

    2014-01-01

    A tapered plastic multimode fiber (PMMA) optical sensor is proposed and demonstrated for continuous monitoring of solutions based on different concentration of sodium chloride and glucose in deionized water The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 mm and 10 mm, respectively, and was used to investigate the effect of straight, U-shape, and knot shape against concentration for both sodium chloride and glucose. The results show that there is a strong dependence of the electrolytic and non-electrolytic nature of the chemical solutions on the sensor output. It is found that the sensitivity of the sodium chloride concentration sensor with the straight tapered fiber probe was 0.0023 mV/%, which was better than the other probe arrangements of U-shape and knot. Meanwhile, the glucose sensor performs with the highest sensitivity of 0.0026 mV/wt % with the knot-shaped tapered fiber probe. In addition, a tapered PMMA probe which was coated by silver film was fabricated and demonstrated using calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observed increment in the transmission of the sensor that is immersed in solutions of higher concentration. As the concentration varies from 0 ppm to 6 ppm, the output voltage of the sensor increases linearly from 3.61 mV to 4.28 mV with a sensitivity of 0.1154 mV/ppm and a linearity of more than 99.47%. The silver film coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber.

  17. Trench-embedding fiber taper sensor fabricated by a femtosecond laser for gas refractive index sensing.

    PubMed

    Cao, Zhitao; Jiang, Lan; Wang, Sumei; Wang, Peng; Zhang, Fei; Lu, Yongfeng

    2014-02-20

    A fiber in-line, multimode coupling interferometer with a trench-embedding, fiber taper probe is proposed and fabricated by femtosecond-laser-induced water breakdown. The reflection-type taper probe is used for gas refractive index (RI) detection from 1.0001143 to 1.0002187 and temperature sensing from 50°C to 500°C. The largest RI sensitivity of the taper probe embedded with a trench at a width of 18.4 μm is 669.502  nm/RIU for hybrid nitrogen and helium. Temperature sensitivity is 9.97  pm/°C and it shows good linearity through the whole testing range. The new-type multimode interferometer is appropriate for high-accuracy gas RI detection of micrometer-scale spaces and wide-range temperature compensation can be realized. PMID:24663297

  18. Optofluidic tunable manipulation of microparticles by integrating graded-index fiber taper with a microcavity.

    PubMed

    Gong, Yuan; Zhang, Chenlin; Liu, Qun-Feng; Wu, Yu; Wu, Huijuan; Rao, Yunjiang; Peng, Gang-Ding

    2015-02-01

    We propose and demonstrate optofluidic tunable manipulation of polystyrene microparticles based on the combination of a graded-index fiber (GIF) taper and a microcavity. The tunability on the manipulation length is experimentally explored by changing the balance between the optical force and the microfluidic flow force, as well as by tuning the focus of light emitting from the GIF taper via adjusting the length of an air microcavity. By optimizing the geometric shape of the GIF taper, as well as the flow rate and laser power, a manipulation length of 177 μm is achieved, more than 4 times longer than the state-of-the-art optical fiber tweezers. This method has advantages of high flexibility, ease of fabrication and use, integration with microfluidics and has the potential for optofluidic sensing applications. PMID:25836228

  19. Dynamic response of tapered optical multimode fiber coated with carbon nanotubes for ethanol sensing application.

    PubMed

    Shabaneh, Arafat; Girei, Saad; Arasu, Punitha; Mahdi, Mohd; Rashid, Suraya; Paiman, Suriati; Yaacob, Mohd

    2015-05-04

    Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol.

  20. Dynamic Response of Tapered Optical Multimode Fiber Coated with Carbon Nanotubes for Ethanol Sensing Application

    PubMed Central

    Shabaneh, Arafat; Girei, Saad; Arasu, Punitha; Mahdi, Mohd; Rashid, Suraya; Paiman, Suriati; Yaacob, Mohd

    2015-01-01

    Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol. PMID:25946634

  1. Diaphragm-free fiber-optic Fabry-Perot interferometer based on tapered hollow silica tube

    NASA Astrophysics Data System (ADS)

    Fang, Guocheng; Jia, Pinggang; Liang, Ting; Tan, Qiulin; Hong, Yingping; Liu, Wenyi; Xiong, Jijun

    2016-07-01

    A miniature fiber-optic Fabry-Perot interferometer fabricated by splicing a diaphragm-free hollow silica tube to a single-mode fiber and fusing the inner core to a taper is presented. The tapered zone forces lights to propagate from the fiber core into the silica tube, and the lights is reflected from the end faces of the optical fiber and the hollow silica tube. The contrast ratio of the interference fringe is determined by the minimum inner diameter of hollow silica tube. The responses of the proposed interferometer to high-temperature, gas refractive index, liquid refractive index and pressure were measured and were found to be linear with sensitivities of 16.26 pm/°C, 610.47 nm/RIU, -122.36 dB/RIU and 1.56 pm/kPa, respectively.

  2. High Sensitivity Refractometer Based on TiO₂-Coated Adiabatic Tapered Optical Fiber via ALD Technology.

    PubMed

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun

    2016-08-15

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO₂) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO₂ nanofilm compared to that of silica, an asymmetric Fabry-Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO₂ nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO₂ on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373-1.3500. Due to TiO₂'s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field.

  3. High Sensitivity Refractometer Based on TiO₂-Coated Adiabatic Tapered Optical Fiber via ALD Technology.

    PubMed

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun

    2016-01-01

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO₂) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO₂ nanofilm compared to that of silica, an asymmetric Fabry-Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO₂ nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO₂ on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373-1.3500. Due to TiO₂'s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field. PMID:27537885

  4. Tunable and switchable dual-wavelength erbium-doped fiber laser based on in-line tapered fiber filters

    NASA Astrophysics Data System (ADS)

    Tong, Zheng-rong; Yang, He; Cao, Ye

    2016-07-01

    A tunable and switchable dual-wavelength erbium-doped fiber laser (EDFL) based on all-fiber single-mode tapered fiber structure has been demonstrated. By adjusting the variable optical attenuator (VOA), the laser can be switched between the single-wavelength mode and the dual-wavelength mode. When the temperature applied on the tapered fiber structure varies, the pass-band varies and the wavelength of the output laser shifts correspondingly. When the temperature changes from 30 °C to 180 °C, the central wavelength of the EDFL generated by branch A shifts from 1 550.7 nm to 1 560.3 nm, while that of branch B shifts from 1 530.8 nm to 1 540.4 nm, indicating the wavelength interval is tunable. These advantages enable this laser to be a potential candidate for high-capacity wavelength division multiplexing systems and mechanical sensors.

  5. Tapered TeX glass optical fibers for remote IR spectroscopic analysis

    NASA Astrophysics Data System (ADS)

    Le Foulgoc, Karine; Le Neindre, Lydia; Zhang, Xhang H.; Lucas, Jacques

    1996-12-01

    Infrared TeX fibers operating in a wide wavelength region have various potential uses in the short distance area such as laser power delivery, remote temperature monitoring and chemical analysis. TeX glass fibers with a minimum attenuation of 0.5 dB/m in the 7 - 10 micrometer range have been obtained. A plastic coating protects these fibers from external environment and improves their mechanical properties. Remote spectroscopy using mono-index fiber is one of the most promising applications. This new technology allows the identification and in situ analysis of many substances such as oils and fertilizers, which have their fingerprint in the 2 - 13 micrometer domain. The detection efficiency using evanescent wave absorption has been studied as a function of the fiber's diameter. It is found that the sensitivity increases very rapidly when the fibers' diameter decreases. The possibility of detecting very low concentrations has been tested by using TeX tapered fibers.

  6. Evanescent wave absorption sensor based on tapered multimode fiber coated with monolayer graphene film

    NASA Astrophysics Data System (ADS)

    Qiu, Hengwei; Gao, Saisai; Chen, Peixi; Li, Zhen; Liu, Xiaoyun; Zhang, Chao; Xu, Yuanyuan; Jiang, Shouzhen; Yang, Cheng; Huo, Yanyan; Yue, Weiwei

    2016-05-01

    An evanescent wave absorption (EWA) sensor based on tapered multimode fiber (TMMF) coated with monolayer graphene film for the detection of double-stranded DNA (DS-DNA) is investigated in this work. The TMMF is a silica multimode fiber (nominally at 62.5 μm), which was tapered to symmetric taper with waist diameters of ~30 μm and total length of ~3 mm. Monolayer graphene film was grown on a copper foil via chemical vapor deposition (CVD) technology and transferred onto skinless tapered fiber core via dry transfer technology. All the components of the sensor are coupled together by fusion splicer in order to eliminate the external disturbance. DS-DNA is created by the assembly of two relatively complemented oligonucleotides. The measurements are obtained by using a spectrometer in the optical wavelength range of 400-900 nm. With the increase of DS-DNA concentration, the output light intensity (OPLI) arisen an obvious attenuation. Importantly, the absorbance (A) and the DS-DNA concentrations shown a reasonable linear variation in a wide range of 5-400 μM. Through a series of comparison, the accuracy of TMMF sensor with graphene (G-TMMF) is much better than that without graphene (TMMF), which can be attributed to the molecular enrichment of graphene by π-π stacking.

  7. Graphene-clad tapered fiber: effective nonlinearity and propagation losses.

    PubMed

    Gorbach, A V; Marini, A; Skryabin, D V

    2013-12-15

    We derive a pulse propagation equation for a graphene-clad optical fiber, treating the optical response of the graphene and nonlinearity of the dielectric fiber core as perturbations in asymptotic expansion of Maxwell equations. We analyze the effective nonlinear and attenuation coefficients due to the graphene layer. Based on the recent experimental measurements of the nonlinear graphene conductivity, we predict considerable enhancement of the effective nonlinearity for subwavelength fiber core diameters. PMID:24322228

  8. Performance evaluation of four-wave mixing in a graphene-covered tapered fiber

    NASA Astrophysics Data System (ADS)

    Jin, Qiang; Lu, Jiamei; Li, Xibin; Yan, Qiang; Gao, Qianyu; Gao, Shiming

    2016-07-01

    Four-wave mixing in a monolayer graphene-covered tapered fiber is theoretically analyzed by taking into account the influence of the graphene layer on the light-field distribution. A figure-of-merit (FOM) coefficient, considering both the high nonlinearity and the heavy absorption, is redefined to evaluate nonlinear performance. The fiber diameter and length are optimized to acquire a higher FOM. Using such a graphene-covered tapered fiber with an optimal diameter of 0.736 μm, a maximum conversion efficiency of -38.07 dB is numerically obtained for the 1.55 μm pump when the graphene length is 34.4 μm and the peak pump power is 10 W. Moreover, a 3 dB bandwidth as broad as 430 nm can be realized in the 1.55 μm telecommunication band.

  9. Theoretical study of power amplification in tapered fiber with multi-seed parallel injection

    NASA Astrophysics Data System (ADS)

    Xiao, Qi-Rong; Ren, Hai-Cui; Li, Dan; Gong, Ma-Li; Yan, Ping

    2013-11-01

    We proposed the concept of parallel injection power amplification. A tapered fiber amplifier with multi-seed sources by the way of parallel injection was studied. The lower-order modes are excited and more than 90% of the input signal power remains in the fiber core if optimal injection and taper design are set. The power in the doped-core is amplified with high optical-optical efficiency. When light is propagating along the fiber, the higher-order modes are filtered which results in the high output beam quality. Incoherent combination of multi-seed lights launched through the wide end gives rise to the output power of several kW.

  10. Investigation on spectral response of micro-cavity structure by symmetrical tapered fiber tips

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Li, Yang; Yan, Xiaojun; Li, Weidong

    2016-06-01

    We proposed and experimentally demonstrated a micro-cavity structure made of symmetrical tapered fiber tips. The waist of a conventional fiber taper fabricated from heating and stretching technique is symmetrically cleaved, and the aligned fiber tips with air gap constitute a Fabry-Perot micro-cavity due to the reflection at the tip facet. The spectral responses of such micro-cavity structure have been investigated both in beam propagation models and experiments. The multibeam interference in the micro-cavity and the impact of the waist diameter and cavity length on the spectral response has been successfully demonstrated. And a micro-cavity structure with 45 μm waist diameter was experimentally achieved, the measured spectra agree well with the simulation ones, indicating that the spectral response of the micro-cavity structure is contributed by both the multibeam interference and the Fabry-Perot micro-cavity.

  11. Tapered and linearly chirped fiber Bragg gratings with co-directional and counter-directional resultant chirps

    NASA Astrophysics Data System (ADS)

    Osuch, Tomasz

    2016-05-01

    A method of spectral width tailoring of tapered fiber Bragg gratings is theoretically analyzed and experimentally verified. This concept is based on inscription grating structures in which synthesis of chirps comes from both taper profile and a linearly chirped phase mask used for grating inscription. It is shown that under UV exposure and depending on the orientation of the optical fiber taper relative to the variable-pitch phase mask, tapered and linearly chirped fiber Bragg gratings (TCFBG) with resultant co-directional or counter-directional chirps are achieved. Thus, both effects, those of reduction and enhancement of the grating chirp, as well as their influence on the grating spectral response, are presented. In particular, using the above approach TCFBG with significantly narrowed spectral width are shown. Moreover, fused tapered chirped FBG with relatively large waist diameter are shown having broad spectrum, something that prior to now was not attainable using previously developed techniques.

  12. Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

    PubMed

    Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

    2015-08-12

    Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples.

  13. Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

    PubMed

    Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

    2015-08-12

    Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples. PMID:26186260

  14. Photonic crystal fiber half-taper probe based refractometer.

    PubMed

    Wang, Pengfei; Ding, Ming; Bo, Lin; Guan, Chunying; Semenova, Yuliya; Sun, Weimin; Yuan, Libo; Brambilla, Gilberto; Farrell, Gerald

    2014-04-01

    A compact single-mode photonic crystal fiber single-mode fiber tip (SPST) refractive index sensor is demonstrated in this Letter. A CO2 laser cleaving technique is utilized to provide a clean-cut fiber tip, which is then coated by a layer of gold to increase reflection. An average sensitivity of 39.1 nm/RIU and a resolvable index change of 2.56×10(-4) are obtained experimentally with a ∼3.2 μm diameter SPST. The temperature dependence of this fiber-optic sensor probe is presented. The proposed SPST refractometer is also significantly less sensitive to temperature and an experimental demonstration of this reduced sensitivity is presented in the Letter. Because of its compactness, ease of fabrication, linear response, low temperature dependency, easy connectivity to other fiberized optical components and low cost, this refractometer could find various applications in chemical and biological sensing. PMID:24686678

  15. Vibration sensing using a tapered bend-insensitive fiber based Mach-Zehnder interferometer.

    PubMed

    Xu, Yanping; Lu, Ping; Qin, Zengguang; Harris, Jeremie; Baset, Farhana; Lu, Ping; Bhardwaj, Vedula Ravi; Bao, Xiaoyi

    2013-02-11

    In this study, a novel fiber-optic sensor consisting of a tapered bend-insensitive fiber based Mach-Zehnder interferometer is presented to realize damped and continuous vibration measurement. The double cladding structure and the central coating region of the in-fiber interferometer ensure an enhanced mechanical strength, reduced external disturbance, and a more uniform spectrum. A damped vibration frequency range of 29-60 Hz as well as continuous vibration disturbances ranging from 1 Hz up to 500 kHz are successfully demonstrated.

  16. Photo-actuating waveguiding fibers based on light responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Hauser, Adam; Rasmussen, Nathan; Kuzyk, Mark; Hayward, Ryan

    2015-03-01

    The combination of light-absorbing nanoparticles with thermally sensitive hydrogels has been widely explored as a strategy for photo-thermal actuation. Here, we employ a system of photo-crosslinkable copolymers containing pendent benzophenone units to prepare planar waveguiding polymethylmethacrylate(PMMA) fibers patterned with poly(N-isopropyl acrylamide) (PNIPAM) copolymer hydrogels containing Au nanoparticles. These structures show both thermally- and photo-actuated bending behavior due to swelling stresses developed in the PNIPAM gel layer. Further, we establish that light can be successfully guided into micro-patterned fibers, yielding a route to remotely controlled micro-actuators.

  17. Tapered Optical Fiber Sensor for Label-Free Detection of Biomolecules

    PubMed Central

    Tian, Ye; Wang, Wenhui; Wu, Nan; Zou, Xiaotian; Wang, Xingwei

    2011-01-01

    This paper presents a fast, highly sensitive and low-cost tapered optical fiber biosensor that enables the label-free detection of biomolecules. The sensor takes advantage of the interference effect between the fiber’s first two propagation modes along the taper waist region. The biomolecules bonded on the taper surface were determined by demodulating the transmission spectrum phase shift. Because of the sharp spectrum fringe signals, as well as a relatively long biomolecule testing region, the sensor displayed a fast response and was highly sensitive. To better understand the influence of various biomolecules on the sensor, a numerical simulation that varied biolayer parameters such as thickness and refractive index was performed. The results showed that the spectrum fringe shift was obvious to be measured even when the biolayer was only nanometers thick. A microchannel chip was designed and fabricated for the protection of the sensor and biotesting. Microelectromechanical systems (MEMS) fabrication techniques were used to precisely control the profile and depth of the microchannel on the silicon chip with an accuracy of 2 μm. A tapered optical fiber biosensor was fabricated and evaluated with an Immune globulin G (IgG) antibody-antigen pair. PMID:22163821

  18. Large-core acetylene-filled photonic microcells made by tapering a hollow-core photonic crystal fiber.

    PubMed

    Wheeler, Natalie V; Grogan, Michael D W; Light, Philip S; Couny, Francois; Birks, Timothy A; Benabid, Fetah

    2010-06-01

    We report on kagomé-lattice photonic microcells with low losses, large outer diameters, and large cores. The large (40-70microm) cores are accommodated by tapering the fibers and splicing the reduced ends to a single-mode fiber. We demonstrate the repeatability of this process and obtain splice losses of 0.6dB by optimizing the taper transition length. Narrow electromagnetically induced transparencies and saturable absorption are demonstrated in an acetylene-filled photonic microcell.

  19. Mode size converter between high-index-contrast waveguide and cleaved single mode fiber using SiON as intermediate material.

    PubMed

    Jia, Lianxi; Song, Junfeng; Liow, Tsung-Yang; Luo, Xianshu; Tu, Xiaoguang; Fang, Qing; Koh, Sing-Chee; Yu, Mingbin; Lo, Guoqiang

    2014-09-22

    High-index-contrast (HIC) waveguide such as Si and Si3N4 has small mode size enabling compact integration. However, the coupling loss with single mode fiber is also remarkable owning to the mode mismatching. Therefore, mode size converter, as the interface between HIC waveguide and optical fiber, takes an important role in the field of integrated optics. The material with refractive index (RI) between HIC waveguide and optical fiber can be used as a bridge to reduce the mode mismatching loss. In this letter, we employ silicon oxynitride (SiON) with RI about 1.50 as the intermediate material and optimize the structure of the SiON waveguide to match with cleaved single mode fiber and HIC waveguide separately. Combined with inverse taper and suspended structure, the mismatching loss is reduced and the dependence to the dimension of the structure is also released. The coupling loss is 1.2 and 1.4 dB/facet for TE and TM mode, respectively, with 3 dB alignment tolerance of ± 3.5 μm for Si(3)N(4) waveguide with just 200 nm-wide tip. While for Si waveguide, a critical dimension of 150 nm is applied due to the higher index contrast than Si(3)N(4) waveguide. Similar alignment tolerance is realized with coupling loss about 1.8 and 2.1 dB/facet for TE and TM mode. The polarization dependence loss (PDL) for both platforms is within 0.5 dB. PMID:25321831

  20. Mode size converter between high-index-contrast waveguide and cleaved single mode fiber using SiON as intermediate material.

    PubMed

    Jia, Lianxi; Song, Junfeng; Liow, Tsung-Yang; Luo, Xianshu; Tu, Xiaoguang; Fang, Qing; Koh, Sing-Chee; Yu, Mingbin; Lo, Guoqiang

    2014-09-22

    High-index-contrast (HIC) waveguide such as Si and Si3N4 has small mode size enabling compact integration. However, the coupling loss with single mode fiber is also remarkable owning to the mode mismatching. Therefore, mode size converter, as the interface between HIC waveguide and optical fiber, takes an important role in the field of integrated optics. The material with refractive index (RI) between HIC waveguide and optical fiber can be used as a bridge to reduce the mode mismatching loss. In this letter, we employ silicon oxynitride (SiON) with RI about 1.50 as the intermediate material and optimize the structure of the SiON waveguide to match with cleaved single mode fiber and HIC waveguide separately. Combined with inverse taper and suspended structure, the mismatching loss is reduced and the dependence to the dimension of the structure is also released. The coupling loss is 1.2 and 1.4 dB/facet for TE and TM mode, respectively, with 3 dB alignment tolerance of ± 3.5 μm for Si(3)N(4) waveguide with just 200 nm-wide tip. While for Si waveguide, a critical dimension of 150 nm is applied due to the higher index contrast than Si(3)N(4) waveguide. Similar alignment tolerance is realized with coupling loss about 1.8 and 2.1 dB/facet for TE and TM mode. The polarization dependence loss (PDL) for both platforms is within 0.5 dB.

  1. Compact bending sensor based on a fiber Bragg grating in an abrupt biconical taper.

    PubMed

    Cui, Wei; Si, Jinhai; Chen, Tao; Hou, Xun

    2015-05-01

    We propose and experimentally demonstrate a compact bending sensor. The head of the sensor is only 0.8 mm in length, and consists of an abrupt biconical fiber taper formed using a conventional fusion splicer, in which a fiber Bragg grating (FBG) is inscribed using a femtosecond laser. The biconical taper incorporating the FBG can couple light from the cladding to the backward-propagating core mode, which realizes an interferometer in reflection-mode. Bending of the structure can be detected from the contrast change of interference fringes. A configuration to measure curvature is investigated to demonstrate the sensing characteristics. The temperature cross-sensitivity of the sensor is studied, and the results demonstrate that it is insensitive to temperature. PMID:25969198

  2. Coherence Properties of Supercontinuum Generated in Dispersion-Tailored Lead-Silicate Microstructured Fiber Taper

    NASA Astrophysics Data System (ADS)

    Hu, Hongyu; Li, Wenbo; Ma, Shaozhen; Dutta, Niloy K.

    2013-05-01

    This article details the numerically studied coherence properties of the supercontinuum generated in a lead-silicate microstructured fiber taper, with an increasing core radius along the propagation distance that tailors the dispersion property. Simulations are conducted by adding quantum noise into the input pulse at 1.55 μm, and the complex degree of first-order coherence function and the overall spectral coherence degree are both calculated. Although the spectral broadening is comparable, the coherence degree is shown to vary with different pumping conditions. It decreases with higher peak power and longer duration due to the significant competition between the soliton-fission process and the noise-seeded modulation instability. By controlling the input pulse parameters, it is possible to generate a perfectly coherent supercontinuum with a flat broadened spectrum extending from ~1 μm to ~5μm in this fiber taper.

  3. Supercontinuum generation in dispersion-tailored lead-silicate fiber taper

    NASA Astrophysics Data System (ADS)

    Hu, Hongyu; Li, Wenbo; Ma, Shaozhen; Dutta, Niloy K.

    2013-01-01

    In this paper we numerically study the coherence properties of the supercontinuum generated in a lead-silicate microstructured fiber taper, with an increasing core radius along the propagation distance which tailors the dispersion property. Simulations are conducted by adding quantum noise into the input pulse at 1.55 μm, and the complex degree of first-order coherence function and the overall spectral coherence degree are both calculated. Although the spectral broadening is comparable, the coherence degree is shown to vary with different pumping conditions. It decreases with higher peak power and longer duration due to the significant competition between the soliton-fission process and the noise-seeded modulation instability. By controlling the input pulse parameters, it is possible to generate perfectly coherent supercontinuum with a flat broadened spectrum extending to ~5μm in this fiber taper.

  4. Single-mode tapered optical fiber loop immunosensor II: assay of anti-cholera toxin immunoglobulins

    NASA Astrophysics Data System (ADS)

    Marks, Robert S.; Hale, Zoe M.; Levine, Myron M.; Lowe, C. R.; Payne, Frank P.

    1994-07-01

    An evanescent wave immunoassay for cholera antitoxin immunoglobulins was performed using a single mode tapered optical fiber loop sensor. The transducer was silanized with 3- glycidoxypropyltrimethoxysilane and chemically modified to link covalently either cholera toxin B subunit or a synthetic peptide derived from it, CTP3. The sensor was exposed to seral fluids, obtained from human volunteers having been exposed to live virulent Vibrio cholerae 01 and shown to produce rice-water stools. Other toxins of interest, such as Clostridium botulinum toxin A, have been tested on similar systems. The bound unlabelled immunoglobulins were then exposed to a mixture of FITC-anti-IgG and TRITC-anti-IgA, without requirement for a separation step. The emanating fluorescent emissions of fluorescein and rhodamine, excited by the input laser light, were coupled back into the guided mode of the tapered fiber, and used to determine the concentrations of the complementary antigens.

  5. Silver iodide phosphate glass microsphere resonator integrated on an optical fiber taper.

    PubMed

    Milenko, Karolina; Konidakis, Ioannis; Pissadakis, Stavros

    2016-05-15

    In this Letter, we demonstrate the fabrication and characterization of a robust and functional whispering gallery mode (WGM) resonating system based on a silver iodide phosphate glass microsphere melted on an optical fiber taper. The fabrication process is presented, together with spectral characterization of the device. The effect of the thermal annealing of the soft glass resonator on the whispering gallery modes' excitation and Q-factor is shown and discussed. PMID:27176958

  6. High energy supercontinuum sources using tapered photonic crystal fibers for multispectral photoacoustic microscopy.

    PubMed

    Bondu, Magalie; Brooks, Christopher; Jakobsen, Christian; Oakes, Keith; Moselund, Peter Morten; Leick, Lasse; Bang, Ole; Podoleanu, Adrian

    2016-06-01

    We demonstrate a record bandwidth high energy supercontinuum source suitable for multispectral photoacoustic microscopy. The source has more than 150  nJ/10  nm bandwidth over a spectral range of 500 to 1600 nm. This performance is achieved using a carefully designed fiber taper with large-core input for improved power handling and small-core output that provides the desired spectral range of the supercontinuum source. PMID:26836298

  7. High energy supercontinuum sources using tapered photonic crystal fibers for multispectral photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Bondu, Magalie; Brooks, Christopher; Jakobsen, Christian; Oakes, Keith; Moselund, Peter Morten; Leick, Lasse; Bang, Ole; Podoleanu, Adrian

    2016-06-01

    We demonstrate a record bandwidth high energy supercontinuum source suitable for multispectral photoacoustic microscopy. The source has more than 150 nJ/10 nm bandwidth over a spectral range of 500 to 1600 nm. This performance is achieved using a carefully designed fiber taper with large-core input for improved power handling and small-core output that provides the desired spectral range of the supercontinuum source.

  8. Optofluidic manipulation of Escherichia coli in a microfluidic channel using an abruptly tapered optical fiber

    NASA Astrophysics Data System (ADS)

    Xin, Hongbao; Li, Yayi; Li, Lingshan; Xu, Rui; Li, Baojun

    2013-07-01

    We report stable optical trapping and controlled manipulation of Escherichia coli cells in a microfluidic channel using an abruptly tapered optical fiber with 980-nm wavelength laser light launched. Stability of the trapping at different optical powers (10-70 mW) was demonstrated in fluids under different flow directions and velocities. The experimental results were supported by finite-element simulations and analytic calculations.

  9. High energy supercontinuum sources using tapered photonic crystal fibers for multispectral photoacoustic microscopy.

    PubMed

    Bondu, Magalie; Brooks, Christopher; Jakobsen, Christian; Oakes, Keith; Moselund, Peter Morten; Leick, Lasse; Bang, Ole; Podoleanu, Adrian

    2016-06-01

    We demonstrate a record bandwidth high energy supercontinuum source suitable for multispectral photoacoustic microscopy. The source has more than 150  nJ/10  nm bandwidth over a spectral range of 500 to 1600 nm. This performance is achieved using a carefully designed fiber taper with large-core input for improved power handling and small-core output that provides the desired spectral range of the supercontinuum source.

  10. Mode-field adapter for tapered-fiber-bundle signal and pump combiners.

    PubMed

    Koška, Pavel; Baravets, Yauhen; Peterka, Pavel; Bohata, Jan; Písařík, Michael

    2015-02-01

    We report on a novel mode-field adapter that is proposed to be incorporated inside tapered fused-fiber-bundle pump and signal combiners for high-power double-clad fiber lasers. Such an adapter allows optimization of signal-mode-field matching on the input and output fibers. Correspondingly, losses of the combiner signal branch are significantly reduced. The mode-field adapter optimization procedure is demonstrated on a combiner based on commercially available fibers. Signal wavelengths of 1.55 and 2 μm are considered. The losses can be further improved by using specially designed intermediate fiber and by dopant diffusion during splicing as confirmed by preliminary experimental results. PMID:25967784

  11. High sensitivity refractive index sensor based on adiabatic tapered optical fiber deposited with nanofilm by ALD.

    PubMed

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Dong, Yanhua; Wang, Tingyun

    2015-06-01

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractive index sensor based on an adiabatic tapered optical fiber. Different thickness of Al2O3 nanofilm is coated around fiber taper precisely and uniformly under different deposition cycles. Attributed to the high refractive index of the Al2O3 nanofilm, an asymmetry Fabry-Perot like interferometer is constructed along the fiber taper. Based on the ray-optic analysis, total internal reflection happens on the nanofilm-surrounding interface. With the ambient refractive index changing, the phase delay induced by the Goos-Hänchen shift is changed. Correspondingly, the transmission resonant spectrum shifts, which can be utilized for realizing high sensitivity sensor. The high sensitivity sensor with 6008 nm/RIU is demonstrated by depositing 3000 layers Al2O3 nanofilm as the ambient refractive index is close to 1.33. This high sensitivity refractive index sensor is expected to have wide applications in biochemical sensors.

  12. High sensitivity refractive index sensor based on adiabatic tapered optical fiber deposited with nanofilm by ALD.

    PubMed

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Dong, Yanhua; Wang, Tingyun

    2015-06-01

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractive index sensor based on an adiabatic tapered optical fiber. Different thickness of Al2O3 nanofilm is coated around fiber taper precisely and uniformly under different deposition cycles. Attributed to the high refractive index of the Al2O3 nanofilm, an asymmetry Fabry-Perot like interferometer is constructed along the fiber taper. Based on the ray-optic analysis, total internal reflection happens on the nanofilm-surrounding interface. With the ambient refractive index changing, the phase delay induced by the Goos-Hänchen shift is changed. Correspondingly, the transmission resonant spectrum shifts, which can be utilized for realizing high sensitivity sensor. The high sensitivity sensor with 6008 nm/RIU is demonstrated by depositing 3000 layers Al2O3 nanofilm as the ambient refractive index is close to 1.33. This high sensitivity refractive index sensor is expected to have wide applications in biochemical sensors. PMID:26072758

  13. Simultaneous measurement of strain, temperature and refractive index based on multimode interference, fiber tapering and fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Oliveira, Ricardo; Osório, Jonas H.; Aristilde, Stenio; Bilro, Lúcia; Nogueira, Rogerio N.; Cordeiro, Cristiano M. B.

    2016-07-01

    We report the development of an optical fiber sensor capable of simultaneously measuring strain, temperature and refractive index. The sensor is based on the combination of two fiber Bragg gratings written in a standard single-mode fiber, one in an untapered region and another in a tapered region, spliced to a no-core fiber. The possibility of simultaneously measuring three parameters relies on the different sensitivity responses of each part of the sensor. The results have shown the possibility of measuring three parameters simultaneously with a resolution of 3.77 με, 1.36 °C and 5  ×  10‑4, respectively for strain, temperature and refractive index. On top of the multiparameter ability, the simple production and combination of all the parts involved on this optical-fiber-based sensor is an attractive feature for several sensing applications.

  14. Research and application of multimode tapered optical fiber use in desktop rapid prototyping system

    NASA Astrophysics Data System (ADS)

    Yang, Jiquan; Hou, Liya; Zhang, Weiyi; Yin, Zhidong; Chen, Li

    2001-10-01

    A new non-communication optical fiber--Multimode Tapered Optical Fiber (MTOF) is designed for Desktop Rapid Prototyping System(DRPS), which delivers much greater output energy than non-MTOF of the same output diameter. Its transmission ratio much increased. The DRPS' process is introduced, followed by the choose and design of MTOF, coupling and focusing of UV light. MTOF has some advantages, such as flexibility,low cost,high efficiency. The application of MTOF in DRPS that requires low cost will make concrete fundamental for populating the system.

  15. High sensitivity refractive index sensor based on a tapered small core single-mode fiber structure.

    PubMed

    Liu, Dejun; Mallik, Arun Kumar; Yuan, Jinhui; Yu, Chongxiu; Farrell, Gerald; Semenova, Yuliya; Wu, Qiang

    2015-09-01

    A high sensitivity refractive index (RI) sensor based on a tapered small core single-mode fiber (SCSMF) structure sandwiched between two traditional single-mode fibers (SMF28) is reported. The microheater brushing technique was employed to fabricate the tapered fiber structures with different waist diameters of 12.5, 15.0, and 18.8 μm. Experiments demonstrate that the fiber sensor with a waist diameter of 12.5 μm offers the best sensitivity of 19212.5  nm/RIU (RI unit) in the RI range of 1.4304 to 1.4320. All sensors fabricated in this Letter show good linearity in terms of the spectral wavelength shift versus changes in RI. Furthermore, the sensor with the best sensitivity to RI was also used to measure relative humidity (RH) without any coating materials applied to the fiber surface. Experimental results show that the spectral wavelength shift changes exponentially as the RH varies from 60% to 95%. A maximum sensitivity of 18.3 nm per relative humidity unit (RHU) was achieved in the RH range of 90.4% to 94.5% RH. PMID:26368738

  16. Enlarged-taper tailored Fiber Bragg grating with polyvinyl alcohol coating for humidity sensing

    NASA Astrophysics Data System (ADS)

    Liang, Yanhong; Yan, Guofeng; He, Sailing

    2015-08-01

    In this paper, a novel optical fiber sensor based on an enlarged-taper tailored fiber Bragg grating (FBG) is proposed and experimentally demonstrated for the measurement of relative humidity. The enlarged-taper works as a multifunctional joint that not only excites cladding modes but also recouples the cladding modes reflected by the FBG back into the leading single mode fiber. Due to the fact that cladding modes have a strong evanescent field penetrating into the ambient medium, the intensity of the reflected cladding modes is greatly influenced by the refractive index (RI) of the ambient medium. Polyvinyl alcohol (PVA) film is plated on the fiber surface by dip-coating technique, as a humidity-to-refractive index transducer, whose RI variance from 1.49 to 1.34 when the ambient humidity increases from 20%RH to 95%RH. The relative humidity response of the sensing structure is investigated in our home-made humidity chamber with a commercial hygrometer. By monitoring the intensity of the reflected cladding modes, the RH variance can be demodulated. Experimental results show that RH sensitivity depends on the RH value, and a sensitivity up to 1.2 dB/%RH can be achieved within the RH range of 30-90%. A fast and reversible time response has also been investigated. Such a probe-type and reusable fiber-optic RH sensor is a very promising technology for biochemical sensing applications, e.g., breath analysis, chemical reaction monitoring.

  17. Tapering photonic crystal fibers for generating self-similar ultrashort pulses at 1550 nm

    NASA Astrophysics Data System (ADS)

    Manimegalai, Annamalai; Senthilnathan, Krishnamoorthy; Nakkeeran, Kaliyaperumal; Babu, Padmanabhan Ramesh

    2016-06-01

    The generation of high-quality self-similar ultrashort pulses at 1550 nm by tapering the photonic crystal fibers (PCFs) is numerically demonstrated. We taper the PCF to achieve the exponentially decreasing dispersion and exponentially increasing nonlinearity profiles, which turn out to be the fundamental requirements for generating the chirped self-similar pulses. Further, we find that the chirped solitons could also be generated with the other three possible exponential variations. Thus, for the first time, we attempt tapering the PCFs for bringing in these exponentially varying dispersion and nonlinear profiles. We carry out the detailed pulse compression studies for various decay rates of the dispersion profiles as the decay rates of dispersion depend on the initial chirp and hence on compression factor, too. The unique feature of this pulse compressor lies in the fact that the required length of the tapered PCF is about 20 times less than that of the previously reported pulse compressor operating at 850 nm.

  18. Single mode tapered fiber-optic interferometer based refractive index sensor and its application to protein sensing.

    PubMed

    Yadav, T K; Narayanaswamy, R; Abu Bakar, M H; Kamil, Y Mustapha; Mahdi, M A

    2014-09-22

    We demonstrate refractive index sensors based on single mode tapered fiber and its application as a biosensor. We utilize this tapered fiber optic biosensor, operating at 1550 nm, for the detection of protein (gelatin) concentration in water. The sensor is based on the spectroscopy of mode coupling based on core modes-fiber cladding modes excited by the fundamental core mode of an optical fiber when it transitions into tapered regions from untapered regions. The changes are determined from the wavelength shift of the transmission spectrum. The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V. PMID:25321749

  19. Numerical analysis of double chirp effect in tapered and linearly chirped fiber Bragg gratings.

    PubMed

    Markowski, Konrad; Jedrzejewski, Kazimierz; Osuch, Tomasz

    2016-06-10

    In this paper, a theoretical analysis of recently developed tapered chirped fiber Bragg gratings (TCFBG) written in co-directional and counter-directional configurations is presented. In particular, the effects of the synthesis of chirps resulting from both a fused taper profile and a linearly chirped fringe pattern of the induced refractive index changes within the fiber core are extensively examined. For this purpose, a numerical model based on the transfer matrix method (TMM) and the coupled mode theory (CMT) was developed for such a grating. The impact of TCFBG parameters, such as grating length and steepness of the taper transition, as well as the effect of the fringe pattern chirp rate on the spectral properties of the resulting gratings, are presented. Results show that, by using the appropriate design process, TCFBGs with reduced or enhanced resulting chirp, and thus with widely tailored spectral responses, can be easily achieved. In turn, it reveals a great potential application of such structures. The presented numerical approach provides an excellent tool for TCFBG design. PMID:27409005

  20. All-fiber dual wavelength passive Q-switched fiber laser using a dispersion-decreasing taper fiber in a nonlinear loop mirror.

    PubMed

    Ahmad, Harith; Dernaika, Mohamad; Harun, Sulaiman Wadi

    2014-09-22

    This paper describes a proposal and successful demonstration of a dual wavelength all-fiber passively Q-switched erbium-doped fiber ring laser. The Q-switch operation was realized by using a nonlinear loop mirror that incorporated an unbalanced dispersion-decreasing taper fiber to act as a saturable absorber without additional elements. This setup enabled a fiber ring laser to achieve a performance of 48.7 kHz repetition rate with pulse duration of around 3.2 μs and approximate pulse energy of 20 nJ. PMID:25321748

  1. Modeling of coherent beam combining from multimillijoule chirped pulse tapered fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Andrianov, A. V.; Kim, A. V.; Anashkina, E. A.; Meyerov, I. B.; Lebedev, S. A.; Sergeev, A. M.; Koenig, K.; Mourou, G.

    2015-10-01

    The amplification of high energy chirped pulses in Large Mode Area tapered fiber amplifiers and their coherent combining have been investigated numerically. We have developed a three-dimensional model of strongly chirped nanosecond pulse amplification and compression back to femtosecond duration fully taking into account transverse and longitudinal variations of refractive index profile and distribution of active ions in the fiber, wavelength dependence of emission and absorption cross sections, gain saturation and Kerr nonlinearity. Modeling of Yb-doped fiber amplifier shows that up to 3 mJ of output energy can be extracted in 1 ns pulse with single-mode beam quality. Finally, we have investigated numerically the capabilities of compression and coherent combining of up to 36 perturbed amplifying channels in which high-order modes were excited and have obtained more than 70% combining efficiency and 380 fs compressed pulse duration.

  2. Fiber optic reference frequency distribution to remote beam waveguide antennas

    NASA Technical Reports Server (NTRS)

    Calhoun, Malcolm; Kuhnle, Paul; Law, Julius

    1995-01-01

    In the NASA/JPL Deep Space Network (DSN), radio science experiments (probing outer planet atmospheres, rings, gravitational waves, etc.) and very long-base interferometry (VLBI) require ultra-stable, low phase noise reference frequency signals at the user locations. Typical locations for radio science/VLBI exciters and down-converters are the cone areas of the 34 m high efficiency antennas or the 70 m antennas, located several hundred meters from the reference frequency standards. Over the past three years, fiber optic distribution links have replaced coaxial cable distribution for reference frequencies to these antenna sites. Optical fibers are the preferred medium for distribution because of their low attenuation, immunity to EMI/IWI, and temperature stability. A new network of Beam Waveguide (BWG) antennas presently under construction in the DSN requires hydrogen maser stability at tens of kilometers distance from the frequency standards central location. The topic of this paper is the design and implementation of an optical fiber distribution link which provides ultra-stable reference frequencies to users at a remote BWG antenna. The temperature profile from the earth's surface to a depth of six feet over a time period of six months was used to optimize the placement of the fiber optic cables. In-situ evaluation of the fiber optic link performance indicates Allan deviation on the order of parts in 10(exp -15) at 1000 and 10,000 seconds averaging time; thus, the link stability degradation due to environmental conditions still preserves hydrogen maser stability at the user locations. This paper reports on the implementation of optical fibers and electro-optic devices for distributing very stable, low phase noise reference signals to remote BWG antenna locations. Allan deviation and phase noise test results for a 16 km fiber optic distribution link are presented in the paper.

  3. Nonlinear Silicon Waveguides for Integrated Fiber Laser Systems

    NASA Astrophysics Data System (ADS)

    Wong, Chi Yan

    Silicon-on-insulator (SOI) based photonic devices have attracted great interest from photonics community because of its compatibility with state-of-the-art CMOS fabrication processes and its potential of making energy efficient and low cost photonic integrated circuits (PICs) for high bandwidth optical interconnects and integrated optical sensors. Wavelength division multiplexing (WDM) is already widely used in optical communications and is also of interest for optical sensors, providing advantages of low cost, and high speed compared with single wavelength approach. However, the cost and the bulkiness of WDM systems increase proportionally with the number of wavelengths if conventional external laser source is used. Therefore, low cost and compact laser source with stable and high line quality is of great interest for integrated sensors. In this thesis, we investigate the incorporation of silicon photonic devices as intracavity elements in fiber lasers for various applications. Therefore, the high flexibly and rich functionalities of fiber lasers can be directly used in the PIC. Also, high-speed feedback control of the cavity becomes possible. The possibility of applying nonlinear SOI waveguides to fiber lasers is investigated. We propose and demonstrate a multiwavelength erbium-doped fiber laser stabilized by four-wave mixing (FWM) in a nonlinear SOI waveguide. Such multiwavelength lasers are potentially suitable for WDM sensing. The wavelength selectivity was achieved by an intracavity Fabry-Perot comb filter. Making use of the nonlinearity of the SOI waveguide, a multiwavelength laser with six output wavelengths at 0.8 nm spacing was achieved. We study a passive mode-locked erbium-doped fiber ring laser based on a nonlinear SOI microring resonator (MRR). By using the MRR as the comb filter and the nonlinear medium, a stable mode-locked pulse train at 100 GHz was produced by filter-driven four-wave mixing. Such lasers can act as high repetition rate optical

  4. Coherence properties of supercontinuum spectra generated in photonic crystal and tapered optical fibers.

    PubMed

    Dudley, John M; Coen, Stéphane

    2002-07-01

    Numerical simulations have been used in studies of the temporal and spectral features of supercontinuum generation in photonic crystal and tapered optical fibers. In particular, an ensemble average over multiple simulations performed with random quantum noise on the input pulse allows the coherence of the supercontinuum to be quantified in terms of the dependence of the degree of first-order coherence on the wavelength. The coherence is shown to depend strongly on the input pulse's duration and wavelength, and optimal conditions for the generation of coherent supercontinua are discussed. PMID:18026400

  5. Irreversible adsorption of gold nanospheres on fiber optical tapers and microspheres

    PubMed Central

    Yi, Jihaeng; Jao, Chih-Yu; Kandas, Ishac L. N.; Liu, Bo; Xu, Yong; Robinson, Hans D.

    2012-01-01

    We study the adsorption of gold nanospheres onto cylindrical and spherical glass surfaces from quiescent particle suspensions. The surfaces consist of tapers and microspheres fabricated from optical fibers and were coated with a polycation, enabling irreversible nanosphere adsorption. Our results fit well with theory, which predicts that particle adsorption rates depend strongly on surface geometry and can exceed the planar surface deposition rate by over two orders of magnitude when particle diffusion length is large compared to surface curvature. This is particularly important for plasmonic sensors and other devices fabricated by depositing nanoparticles from suspensions onto surfaces with non-trivial geometries. PMID:22550356

  6. 1 W at 531 nm generated in a ppMgO:LN planar waveguide by means of frequency doubling of a DBR tapered diode laser

    NASA Astrophysics Data System (ADS)

    Jedrzejczyk, D.; Feise, D.; Güther, R.; Paschke, K.; Erbert, G.

    2011-03-01

    In this work, we investigate experimentally second-harmonic generation (SHG) in a periodically poled 5 %mol MgO doped LiNbO3 (ppMgO:LN) planar waveguide. As a pump source a 6 mm long distributed Bragg reflector (DBR) tapered diode laser is applied. The laser emits nearly diffraction limited, spectrally single-mode continuous-wave radiation at 1063 nm and is therefore well suited for the SHG process. With the applied lens system in a bench-top experiment a coupling efficiency into the planar waveguide of 73 % is reached. A maximal SH power of 1.07 W is generated at an opto-optical and electro-optical conversion efficiency of 26 % and 8.4 %, respectively. This is, to the best of our knowledge, the highest power level generated in a waveguide structure by means of frequency doubling of diode laser radiation in a single-pass configuration.

  7. Modal demultiplexing properties of tapered and nanostructured optical fibers for in vivo optogenetic control of neural activity.

    PubMed

    Pisanello, Marco; Della Patria, Andrea; Sileo, Leonardo; Sabatini, Bernardo L; De Vittorio, Massimo; Pisanello, Ferruccio

    2015-10-01

    Optogenetic approaches to manipulate neural activity have revolutionized the ability of neuroscientists to uncover the functional connectivity underlying brain function. At the same time, the increasing complexity of in vivo optogenetic experiments has increased the demand for new techniques to precisely deliver light into the brain, in particular to illuminate selected portions of the neural tissue. Tapered and nanopatterned gold-coated optical fibers were recently proposed as minimally invasive multipoint light delivery devices, allowing for site-selective optogenetic stimulation in the mammalian brain [Pisanello , Neuron82, 1245 (2014)]. Here we demonstrate that the working principle behind these devices is based on the mode-selective photonic properties of the fiber taper. Using analytical and ray tracing models we model the finite conductance of the metal coating, and show that single or multiple optical windows located at specific taper sections can outcouple only specific subsets of guided modes injected into the fiber. PMID:26504650

  8. Modal demultiplexing properties of tapered and nanostructured optical fibers for in vivo optogenetic control of neural activity

    PubMed Central

    Pisanello, Marco; Della Patria, Andrea; Sileo, Leonardo; Sabatini, Bernardo L.; De Vittorio, Massimo; Pisanello, Ferruccio

    2015-01-01

    Optogenetic approaches to manipulate neural activity have revolutionized the ability of neuroscientists to uncover the functional connectivity underlying brain function. At the same time, the increasing complexity of in vivo optogenetic experiments has increased the demand for new techniques to precisely deliver light into the brain, in particular to illuminate selected portions of the neural tissue. Tapered and nanopatterned gold-coated optical fibers were recently proposed as minimally invasive multipoint light delivery devices, allowing for site-selective optogenetic stimulation in the mammalian brain [Pisanello, Neuron 82, 1245 (2014)24881834]. Here we demonstrate that the working principle behind these devices is based on the mode-selective photonic properties of the fiber taper. Using analytical and ray tracing models we model the finite conductance of the metal coating, and show that single or multiple optical windows located at specific taper sections can outcouple only specific subsets of guided modes injected into the fiber. PMID:26504650

  9. Modal demultiplexing properties of tapered and nanostructured optical fibers for in vivo optogenetic control of neural activity.

    PubMed

    Pisanello, Marco; Della Patria, Andrea; Sileo, Leonardo; Sabatini, Bernardo L; De Vittorio, Massimo; Pisanello, Ferruccio

    2015-10-01

    Optogenetic approaches to manipulate neural activity have revolutionized the ability of neuroscientists to uncover the functional connectivity underlying brain function. At the same time, the increasing complexity of in vivo optogenetic experiments has increased the demand for new techniques to precisely deliver light into the brain, in particular to illuminate selected portions of the neural tissue. Tapered and nanopatterned gold-coated optical fibers were recently proposed as minimally invasive multipoint light delivery devices, allowing for site-selective optogenetic stimulation in the mammalian brain [Pisanello , Neuron82, 1245 (2014)]. Here we demonstrate that the working principle behind these devices is based on the mode-selective photonic properties of the fiber taper. Using analytical and ray tracing models we model the finite conductance of the metal coating, and show that single or multiple optical windows located at specific taper sections can outcouple only specific subsets of guided modes injected into the fiber.

  10. Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Taguchi, Y.; Saiki, T.; Nagasaka, Y.

    2012-12-01

    A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

  11. A Sensitivity-Enhanced Refractive Index Sensor Using a Single-Mode Thin-Core Fiber Incorporating an Abrupt Taper

    PubMed Central

    Shi, Jie; Xiao, Shilin; Yi, Lilin; Bi, Meihua

    2012-01-01

    A sensitivity-enhanced fiber-optic refractive index (RI) sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF) between two sections of single-mode fibers (SMFs). The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI). An abrupt taper (tens of micrometers long) made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity. PMID:22666052

  12. Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center

    SciTech Connect

    Liebermeister, Lars Petersen, Fabian; Münchow, Asmus v.; Burchardt, Daniel; Hermelbracht, Juliane; Tashima, Toshiyuki; Schell, Andreas W.; Benson, Oliver; Meinhardt, Thomas; Krueger, Anke; Stiebeiner, Ariane; Rauschenbeutel, Arno; Weinfurter, Harald; Weber, Markus

    2014-01-20

    A diamond nano-crystal hosting a single nitrogen vacancy (NV) center is optically selected with a confocal scanning microscope and positioned deterministically onto the subwavelength-diameter waist of a tapered optical fiber (TOF) with the help of an atomic force microscope. Based on this nano-manipulation technique, we experimentally demonstrate the evanescent coupling of single fluorescence photons emitted by a single NV-center to the guided mode of the TOF. By comparing photon count rates of the fiber-guided and the free-space modes and with the help of numerical finite-difference time domain simulations, we determine a lower and upper bound for the coupling efficiency of (9.5 ± 0.6)% and (10.4 ± 0.7)%, respectively. Our results are a promising starting point for future integration of single photon sources into photonic quantum networks and applications in quantum information science.

  13. Tapered Velocity Couplers and Devices: a Treatise

    NASA Astrophysics Data System (ADS)

    Kim, Hyoun Soo

    A polarization independent device is highly desirable for use in single-mode fiber optical communication systems. Tapered velocity coupler (TVC) is expected to play an important role since its operation is polarization independent as well as wavelength insensitive. Thus far, TVC has received little attention primarily because of the unusually long device length required for complete power transfer. In this dissertation we establish that a TVC with an acceptable device length for integration can be indeed realized and integrated by tapering in index as well as in dimension. We demonstrate, for the first time, that complete power transfer can be achieved in a tapered, both in index and in dimension, velocity coupler in Ti:LiNbO _3 with device length reduced to one quarter of that of conventional TVC. The coupler is analyzed by use of step transition model in conjunction with local normal modes of the grade index TVC, overcoming the deficiency of the five-layer step index model. We further demonstrate a Ti:LiNbO_3 digital optical switch with the smallest voltage length product reported to date, namely, 7.2 Vcm for TM and 24 Vcm TE mode with a 15 dB cross talk. In an effort to extend the tapered, both in index and in dimension, velocity coupler concepts to step index compound semiconductor waveguides, we introduce proton exchanged periodically segmented (PEPS) waveguides. PEPS waveguides in LiNbO_3 are first studied theoretically and experimentally. The mode index of PEPS waveguides increases linearly and saturates finally with increase of duty cycle. Next, segmented waveguides in AlGaAs/GaAs are characterized in terms of propagation loss and modal size with respect to duty cycle. These segmented waveguides will be utilized in the development of step index tapered velocity couplers. Finally, we present an application for TVC as an optical interconnect. In particular, a tapered waveguide interconnect between a single quantum well (SQW) laser and a multi-quantum well

  14. Real-time monitoring of intracellular signal transduction in PC12 cells by non-adiabatic tapered optical fiber biosensor

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Asadollahi, A.; Noraeipoor, Z.; Dargahi, L.

    2014-05-01

    Real-time observation of intracellular process of signal transduction is very useful for biomedical and pharmaceutical applications as well as for basic research work of cell biology. For feasible and reagentless observation of intracellular alterations in real time, we examined the use of a nonadiabatic tapered optical fiber (NATOF) biosensor for monitoring of intracellular signal transduction that was mainly translocation of protein kinase C via refractive index change in PC12 cells adhered on tapered fiber sensor without any indicator reagent. PC12 cells were stimulated with KCl . Our results suggest that complex intracellular reactions could be real-time monitored and characterized by NATOF biosensor.

  15. Simultaneous measurement of strain and temperature by two peanut tapers with embedded fiber Bragg grating.

    PubMed

    Lv, Lingya; Wang, Sumei; Jiang, Lan; Zhang, Fei; Cao, Zhitao; Wang, Peng; Jiang, Yi; Lu, Yongfeng

    2015-12-20

    A compact optical fiber sensor for simultaneous measurement of strain and temperature is designed and experimentally investigated. The proposed sensor consists of a two-peanut-taper Mach-Zehnder interferometer (MZI) and in-line embedded fiber Bragg grating (FBG). The sensor at a length of 35 mm presents strain sensitivities 1.07  pm/με and 0.891  pm/με, the temperature sensitivities are 55.35  pm/°C and 10.85  pm/°C, for MZI and FBG, respectively. Through tapering the center of the sensor by a fusion splicer, the strain sensitivity of the MZI is improved to 1.93  pm/με. The resolutions for strain and temperature measurement are ±3.104  με and ±0.194°C with the wavelength resolution of 5 pm. The experimental results show that the sensor is able to simultaneously measure strain and temperature by sensitivity matrix with advantages such as simple structure, compact size, ease of fabrication, low cost, etc. PMID:26837035

  16. Low threshold fiber taper coupled rare earth ion-doped chalcogenide microsphere laser

    NASA Astrophysics Data System (ADS)

    Li, Chao-Ran; Dai, Shi-Xun; Zhang, Qing-Yuan; Shen, Xiang; Wang, Xun-Si; Zhang, Pei-Qing; Lu, Lai-Wei; Wu, Yue-Hao; Lv, She-Qin

    2015-04-01

    We report the applications of a low-cost and environmentally friendly chalcogenide glass, 75GeS2-15Ga2S3-10CsI, in building active microsphere laser oscillators. A silica fiber taper is used as the coupling mechanism. With an 808-nm laser diode as a pump source, we show that a high-Q (˜ 6×104) laser mode could be obtained from a 75-μm diameter microsphere that is coupled with a 1.77-μm waist-diameter fiber taper. The threshold of the incident pump power is 1.39 mW, which is considerably lower than those of previously reported free-space coupled chalcogenide microsphere lasers. We also note an apparent enhancement in laser power generated from this chalcogenide microsphere laser. Project supported by the National Natural Science Foundation of China (Grant Nos. 61177087 and 61435009), the National Key Basic Research Program of China (Grant No. 2012CB722703), the Program for Innovative Research Team of Ningbo City, China (Grant No. 2009B21007) , the K. C. Wong Magna Fund in Ningbo University, the Open Fund of the State Key Laboratory of Luminescent Materials and Devices (South China University of Technology), China (Grant No. 2014-skllmd-01), and the Natural Science Foundation of Ningbo City, China (Grant No. 2014A610125).

  17. Single tapered fiber tip for simultaneous measurements of thickness, refractive index and distance to a sample.

    PubMed

    Moreno-Hernández, Carlos; Monzón-Hernández, David; Hernández-Romano, Iván; Villatoro, Joel

    2015-08-24

    We demonstrate the capability of an air cavity Fabry-Perot interferometer (FPI), built with a tapered lead-in fiber tip, to measure three parameters simultaneously, distance, group refractive index and thickness of transparent samples introduced in the cavity. Tapering the lead-in fiber enhances the light coupling back efficiency, therefore is possible to enlarge the air cavity without a significant deterioration of the fringe visibility. Fourier transformation, used to analyze the reflected optical spectrum of our FPI, simplify the calculus to determine the position, thickness and refractive index. Samples made of 7 different glasses; fused silica, BK7, BalF5, SF2, BaF51, SF15, and glass slides were used to test our FPI. Each sample was measured nine times and the results for position, thickness and refractive index showed differences of ± 0.7%, ± 0.1%, and ± 0.16% respectively. The evolution of thickness and refractive index of a block of polydimethylsiloxane (PDMS) elastomer due to temperature changes in the range of 25°C to 90°C were also measured. The coefficients of the thermal expansion and thermo-optic estimated were α = 4.71x10(-4)/°C and dn/dT = -4.66 x10(-4) RIU/°C, respectively.

  18. Single tapered fiber tip for simultaneous measurements of thickness, refractive index and distance to a sample.

    PubMed

    Moreno-Hernández, Carlos; Monzón-Hernández, David; Hernández-Romano, Iván; Villatoro, Joel

    2015-08-24

    We demonstrate the capability of an air cavity Fabry-Perot interferometer (FPI), built with a tapered lead-in fiber tip, to measure three parameters simultaneously, distance, group refractive index and thickness of transparent samples introduced in the cavity. Tapering the lead-in fiber enhances the light coupling back efficiency, therefore is possible to enlarge the air cavity without a significant deterioration of the fringe visibility. Fourier transformation, used to analyze the reflected optical spectrum of our FPI, simplify the calculus to determine the position, thickness and refractive index. Samples made of 7 different glasses; fused silica, BK7, BalF5, SF2, BaF51, SF15, and glass slides were used to test our FPI. Each sample was measured nine times and the results for position, thickness and refractive index showed differences of ± 0.7%, ± 0.1%, and ± 0.16% respectively. The evolution of thickness and refractive index of a block of polydimethylsiloxane (PDMS) elastomer due to temperature changes in the range of 25°C to 90°C were also measured. The coefficients of the thermal expansion and thermo-optic estimated were α = 4.71x10(-4)/°C and dn/dT = -4.66 x10(-4) RIU/°C, respectively. PMID:26368188

  19. All-fiber tunable laser based on an acousto-optic tunable filter and a tapered fiber.

    PubMed

    Huang, Ligang; Song, Xiaobo; Chang, Pengfa; Peng, Weihua; Zhang, Wending; Gao, Feng; Bo, Fang; Zhang, Guoquan; Xu, Jingjun

    2016-04-01

    An all-fiber tunable laser was fabricated based on an acousto-optic tunable filter and a tapered fiber. The structure was of a high signal-to-noise ratio, therefore, no extra gain flattening was needed in the laser. In the experiment, the wavelength of the laser could be tuned from 1532.1 nm to 1570.4 nm with a 3-dB bandwidth of about 0.2 nm. Given enough nonlinearity in the laser cavity, it could also generate a sliding-frequency pulse train. The laser gains advantages of fast tuning and agility in pulse generation, and its simple structure is low cost for practical applications. PMID:27137035

  20. Analysis of surface plasmon resonance based bimetal coated tapered fiber optic sensor with enhanced sensitivity through radially polarized light

    NASA Astrophysics Data System (ADS)

    Goswami, Nabamita; Chauhan, Kamlesh Kumar; Saha, Ardhendu

    2016-11-01

    The presented proposal of surface plasmon resonance (SPR) configuration with tapered fiber structure and radially polarized light beam is a new and different analysis towards the sensitivity enhancement in the field of SPR based fiber optic sensors. Here the taper waist region of optical fiber having diameter around 330 μm is deposited with 40 nm thin Ag layer, 10 nm thin Au layer and the sensing layer with refractive index 1.333-1.353 respectively for achieving the bimetal coated taper fiber optic sensor with SPR configuration. The cylindrical symmetry and special radial field distribution of radially polarized light make its more interesting SPR study and leads to the enhanced excitation of surface plasmon wave. This results 10 times better sensitivity of fiber optic sensor output response as compared to p-polarized light beam with wavelength interrogation technique and 2.307 times better sensitivity with intensity interrogation technique. Also including the temperature effect in proposed taper bimetallic structure, this sensitivity analysis provides an evidence, for exploring a new idea towards the enhanced excitation of SPR which expedites the new avenues in the field of sensor applications with radially polarized light.

  1. Tunable and switchable dual-wavelength mode-locked Tm3+-doped fiber laser based on a fiber taper.

    PubMed

    Wang, Yazhou; Li, Jianfeng; Zhai, Bo; Hu, Yunxiao; Mo, Kundong; Lu, Rongguo; Liu, Yong

    2016-07-11

    We demonstrate a self-starting dual-wavelength mode-locked fiber laser at a 2 μm spectral region by using a fiber taper in a Tm3+-doped ring fiber cavity. The fiber taper fabricated with a flame brushing technique was used as a periodic filter with a modulation depth of ~3.61 dB and a modulation period of ~7.3 nm, respectively. Diverse dual-wavelength regimes including continuous wave (CW)/multi-soliton, soliton/multi-soliton, and soliton/soliton regimes were obtained by adjusting pump power. Wavelength tuning for the dual-wavelength was also precisely controllable through stretching the fiber taper carefully. The tuning range was ~7 nm which was limited by the modulation period of the taper. By inserting a 10.0 m dispersion compensation fiber (DCF) into the fiber cavity, a stable dual-wavelength dissipative-soliton operation was obtained at 2 μm spectral region for the first time. PMID:27410806

  2. Tunable and switchable dual-wavelength mode-locked Tm3+-doped fiber laser based on a fiber taper.

    PubMed

    Wang, Yazhou; Li, Jianfeng; Zhai, Bo; Hu, Yunxiao; Mo, Kundong; Lu, Rongguo; Liu, Yong

    2016-07-11

    We demonstrate a self-starting dual-wavelength mode-locked fiber laser at a 2 μm spectral region by using a fiber taper in a Tm3+-doped ring fiber cavity. The fiber taper fabricated with a flame brushing technique was used as a periodic filter with a modulation depth of ~3.61 dB and a modulation period of ~7.3 nm, respectively. Diverse dual-wavelength regimes including continuous wave (CW)/multi-soliton, soliton/multi-soliton, and soliton/soliton regimes were obtained by adjusting pump power. Wavelength tuning for the dual-wavelength was also precisely controllable through stretching the fiber taper carefully. The tuning range was ~7 nm which was limited by the modulation period of the taper. By inserting a 10.0 m dispersion compensation fiber (DCF) into the fiber cavity, a stable dual-wavelength dissipative-soliton operation was obtained at 2 μm spectral region for the first time.

  3. CMOS-compatible spot-size converter for optical fiber to sub-μm silicon waveguide coupling with low-loss low-wavelength dependence and high tolerance to misalignment

    NASA Astrophysics Data System (ADS)

    Picard, Marie-Josée.; Latrasse, Christine; Larouche, Carl; Painchaud, Yves; Poulin, Michel; Pelletier, François; Guy, Martin

    2016-03-01

    One of the biggest challenges of silicon photonics is the efficient coupling of light between the sub-micron SiP waveguides and a standard optical fiber (SMF-28). We recently proposed a novel approach based on a spot-size converter (SSC) that fulfills this need. The SSC integrates a tapered silicon waveguide and a superimposed structure made of a plurality of rods of high index material, disposed in an array-like configuration and embedded in a cladding of lower index material. This superimposed structure defines a waveguide designed to provide an efficient adiabatic transfer, through evanescent coupling, to a 220 nm thick Si waveguide tapered down to a narrow tip on one side, while providing a large mode overlap to the optical fiber on the other side. An initial demonstration was made using a SSC fabricated with post-processing steps. Great coupling to a SMF-28 fiber with a loss of 0.6 dB was obtained for TEpolarized light at 1550 nm with minimum wavelength dependence. In this paper, SSCs designed for operation at 1310 and 1550 nm for TE/TM polarizations and entirely fabricated in a CMOS fab are presented.

  4. High Sensitivity Refractometer Based on TiO2-Coated Adiabatic Tapered Optical Fiber via ALD Technology

    PubMed Central

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun

    2016-01-01

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO2) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO2 nanofilm compared to that of silica, an asymmetric Fabry–Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO2 nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO2 on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373–1.3500. Due to TiO2’s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field. PMID:27537885

  5. Fixation strength of taper connection at head-neck junction in retrieved carbon fiber-reinforced PEEK hip stems.

    PubMed

    Nakahara, Ichiro; Takao, Masaki; Bandoh, Shunichi; Sugano, Nobuhiko

    2014-12-01

    Carbon fiber-reinforced polyetheretherketone (CFR-PEEK) hip prostheses possess numerous advantages over metal prostheses; however, the security of the taper connection between the CFR-PEEK stem and the modular femoral head in vivo has not been verified. Therefore, we mechanically examined the taper connection of retrieved in vivo loaded CFR-PEEK stems in comparison with in vivo loaded titanium alloy stems. CFR-PEEK and titanium alloy femoral stems with a 12/14 taper trunnion were implanted in ovine hips. A 22-mm ceramic head was intraoperatively impacted to the stem. Retrieved specimens were obtained following weight-bearing conditions for up to 39 postoperative weeks and taper junction pull-off tests were conducted. Postoperative retrieved CFR-PEEK stem pull-off strength was significantly greater than that at time zero. Postoperative retrieved CFR-PEEK stem pull-off strength was also significantly higher than that of postoperative retrieved titanium alloy stem. Microscopic findings of the taper surface revealed no obvious damage in the retrieved CFR-PEEK stems, whereas fretting and corrosion were observed in the retrieved titanium alloy stems. The present findings suggest that the taper connection between the ceramic head and the 12/14 CFR-PEEK stem trunnion is more secure than that between the ceramic head and the titanium alloy trunnion. PMID:25190272

  6. Double crucible method in the fiber optic image guides (tapers) manufacturing

    NASA Astrophysics Data System (ADS)

    Kociszewski, Longin; Pysz, Dariusz; Stepien, Ryszard

    1993-11-01

    Fiber optic image guides (tapers) are one of the most important elements used to build many optoelectronic Instruments for technical purposes and medicine. Application of these elements has croated entirely new technical possibilities for image processing. They are applied in X- ray units, apparatuses for endoscopy, LLLTV cameras as Well as in modern types of night vision devices. The images obtained with the use of image guides may be observed in real time on a television monitor. The images feature high resoution and contrast. The other advantage may also be pointed out, such as the possibility to register and edit the image with the use of computer or the possibility to reduce the exposure tme and intensity in X-ray units.

  7. SPR based cone tapered fiber optic chemical sensor for the detection of low water in ethanol

    NASA Astrophysics Data System (ADS)

    Pathak, A. K.; Bhardwaj, V.; Gangwar, R. K.; Singh, V. K.

    2016-05-01

    In this paper a cone tapered surface plasmon resonance (SPR) based chemical fiber sensor is fabricated and demonstrated for the detection of low water content in ethanol. Here the 11nm thickness of Aluminum (Al) is used to coat tip of probe to generate Plasmon wave. The output power has been found to increase linearly with water content in the range 1-10% due to the increase in refractive index (RI) of ethanolabove which, as the percentage of water increases in step of 20% it shows abrupt decrease in RI hence decrease in the output power. The compact size of sensor and its low cost fabrication makes it useful for many applications in the field of chemical and biochemical sensing.

  8. U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring.

    PubMed

    Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

    2016-02-01

    To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes' Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide-silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0-536 μm.

  9. Dissociation constant measurement using combination tapered fiber optic biosensor (CTFOB) dip-probes

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Wei; Kapoor, Rakesh

    2010-02-01

    The document reports a novel method of measuring dissociation constant (kD) of antibody-antigen interaction using evanescent wave based combination tapered fiber-optic biosensor (CTFOB) dip-probes. The method was demonstrated by measuring the dissociation constant of human Interleukin-6 (IL-6) and anti-IL-6 interaction. Sandwich immunoassay was used to generate fluorescence signal proportional to antigen-antibody conjugate pairs. A portable CCD based spectrometer setup was used to record spectral profile of the fluorescence signal. The measured value of dissociation constant kD for IL-6 and capture anti-IL-6 (clone MQ2-13A5) antibodies at room temperature is588 +/-19 pM .

  10. Nonadiabatic tapered optical fiber sensor for measuring interaction nicotine with DNA

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Pourbeyram, H.; Gholami, M.; Taghipour, Z.; Saeedian, Z.; Hosseini, S. M.

    2011-05-01

    A nonadiabatic tapered optical fiber sensor was utilized for studying of bimolecular interactions including DNA-DNA and DNA-Drug interaction. This work presents a simple evanescent wave sensing system based on an interferometric approach, suitable to meet the requirements of lable-free sensor systems for detecting biomolecular interactions. We have demonstrated the measuring refractive index and the real time detection of interactions between biomolecules. Furthermore basic experiments were carried out, for detecting the hybridization of 25-mer DNA with an immobilized counterpart on the surface. The overall shift after the successful DNA hybridization was 9.5 nm. In this work, a new approach for studying DNA-drug interactions was successfully tested. Nicotine as a carcinogenic compound in cigarette smoke plays an important role in interaction with DNA. Different concentrations of nicotine were applied to observe the Longmuir interaction with DNA.

  11. U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring.

    PubMed

    Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

    2016-02-01

    To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes' Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide-silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0-536 μm. PMID:26977344

  12. U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring

    PubMed Central

    Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

    2016-01-01

    To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes’ Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide–silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0–536 μm. PMID:26977344

  13. Self referenced Yb-fiber-laser frequency comb using a dispersion micromanaged tapered holey fiber.

    PubMed

    Pal, Parama; Knox, Wayne H; Hartl, Ingmar; Fermann, Martin E

    2007-09-17

    We demonstrate a fully stabilized frequency comb in the 1mum spectral region based on an Yb-fiber oscillator and a cladding pumped chirped pulse Yb-fiber amplifier whose output is spectrally broadened in a dispersion micromanaged holey fiber. The dispersion micromanaged fiber is used to generate efficient, low noise spectral components at 523nm which are heterodyned with the second harmonic of the amplifier output for standard f-to-2f self-referenced carrier envelope offset frequency detection. For comb stabilization we phase-lock this offset frequency and the oscillator repetition frequency simultaneously to an RF reference by feedback controlling the oscillator pump diode current and the driving voltage of an intracavity piezo-electric fiber stretcher respectively. PMID:19547582

  14. Exact optical self-similar solutions in a tapered graded-index nonlinear-fiber amplifier with an external source

    NASA Astrophysics Data System (ADS)

    He, Jun-Rong; Yi, Lin

    2014-06-01

    We study the propagations of optical self-similar solutions in a tapered graded-index nonlinear-fiber amplifier with an external source through asymmetric twin-core fiber amplifiers. Various types of exact self-similar solutions, including the W-shaped and U-shaped solutions, trigonometric function solutions, and periodic wave solutions are found. The results show that these different types of self-similar optical structures can be generated and effectively controlled by modulating the amplitude of the source. The influences of nonlinear tunneling effects on the propagation of optical pulses are investigated as well. The obtained results may have potential applications in a tapered graded-index nonlinear-fiber amplifier with an external source.

  15. Q-switched mode-locked erbium-doped fiber laser based on topological insulator Bi(2)Se(3) deposited fiber taper.

    PubMed

    Gao, Lei; Huang, Wei; Zhang, Jing Dong; Zhu, Tao; Zhang, Han; Zhao, Chu Jun; Zhang, Wei; Zhang, Hua

    2014-08-10

    We have demonstrated the passive Q-switching mode-locking operation in an erbium-doped fiber (EDF) laser by using topological insulator Bi(2)Se(3) deposited on fiber taper, whose damage threshold can be further increased by the large evanescent field interacting length. Due to the low saturation intensity, stable Q-switched mode-locked fiber lasers centered at 1562 nm can be generated at a pump power of 10 mW. The temporal and spectral characteristics for different pump strengths have also been investigated. To the best of our knowledge, it is the first time a Q-switched mode-locked EDF laser based on the fiber taper deposited by Bi(2)Se(3) was generated. PMID:25320919

  16. Q-switched mode-locked erbium-doped fiber laser based on topological insulator Bi(2)Se(3) deposited fiber taper.

    PubMed

    Gao, Lei; Huang, Wei; Zhang, Jing Dong; Zhu, Tao; Zhang, Han; Zhao, Chu Jun; Zhang, Wei; Zhang, Hua

    2014-08-10

    We have demonstrated the passive Q-switching mode-locking operation in an erbium-doped fiber (EDF) laser by using topological insulator Bi(2)Se(3) deposited on fiber taper, whose damage threshold can be further increased by the large evanescent field interacting length. Due to the low saturation intensity, stable Q-switched mode-locked fiber lasers centered at 1562 nm can be generated at a pump power of 10 mW. The temporal and spectral characteristics for different pump strengths have also been investigated. To the best of our knowledge, it is the first time a Q-switched mode-locked EDF laser based on the fiber taper deposited by Bi(2)Se(3) was generated.

  17. A 160 W single-frequency laser based on an active tapered double-clad fiber amplifier

    NASA Astrophysics Data System (ADS)

    Trikshev, A. I.; Kurkov, A. S.; Tsvetkov, V. B.; Filatova, S. A.; Kertulla, J.; Filippov, V.; Chamorovskiy, Yu K.; Okhotnikov, O. G.

    2013-06-01

    We present a CW single-frequency laser at 1062 nm (linewidth <3 MHz) with 160 W of total output power based on a two stage fiber amplifier. A GTWave fiber is used for the first stage of the amplifier. A tapered double-clad fiber (T-DCF) is used for the second stage of the amplifier. The high output power is achieved due to the amplified spontaneous emission (ASE) filtering and increased stimulated Brillouin scattering (SBS) threshold inherent to the axially non-uniform geometry.

  18. Further developments of capillary absorption spectrometers using small hollow-waveguide fibers

    SciTech Connect

    Kelly, James F.; Sams, Robert L.; Blake, Thomas A.; Kriesel, Jason M.

    2014-05-01

    Our objective is to enhance quantification of stable carbon and oxygen isotope ratios to better than 1‰ relative isotope precision for sample sizes < 1 pico-mole. A newer variant Capillary Absorption Spectrometer (CAS) is described using a proprietary linear-taper hollow waveguide in conjunction with wavelength and frequency modulation techniques of tunable laser absorption spectrometry. Previous work used circular capillaries with uniform 1 mm ID to measure 13C/12C ratios with ≥ 20 pico-mole samples to ≤ 10 ppm (1‰ precision against standards) [1]. While performing fairly well, it generated residual modal noise due to multipath propagation in the hollow-waveguides (HWGs). This system has been utilized with laser ablation-catalytic combustion techniques to analyze small resolution (~ 25 μm spot diameter) laser ablation events on solids. Using smaller ID capillary waveguides could improve detection limits and spatial resolutions. Reducing an IR compatible hollow waveguide’s inner diameter (ID) to < 300 μm, reduces modal noise significantly for mid-IR operation, but feedback noise with high gain semiconductor lasers can become problematic. A proprietary linear-taper small waveguide (mean ID = 0.35 mm, L = 1 m) was tested to understand whether modal noise and optical feedback effects could be simultaneously reduced. We see better mode filtering and, significant reductions of feedback noise under favorable coupling of a multi-spatial mode QC laser to the smaller ID of the linear-tapered HWG. We demonstrate that better modal coupling operation is consistent with Liouville’s theorem, where greater suppression of feedback from spurious scatter within the HWG occurs by injecting the laser into the smaller ID port. Our progress on developing lighter weight, potentially fieldable alternatives to Isotope Ratio Mass Spectrometers (IRMS) with a small volume (≤ 0.1 cm3) CAS system will be discussed and compared to other competitive systems.

  19. Adiabatically tapered microstructured mode converter for selective excitation of the fundamental mode in a few mode fiber.

    PubMed

    Taher, Aymen Belhadj; Di Bin, Philippe; Bahloul, Faouzi; Tartaret-Josnière, Etienne; Jossent, Mathieu; Février, Sébastien; Attia, Rabah

    2016-01-25

    We propose a new technique to selectively excite the fundamental mode in a few mode fiber (FMF). This method of excitation is made from a single mode fiber (SMF) which is inserted facing the FMF into an air-silica microstructured cane before the assembly is adiabatically tapered. We study theoretically and numerically this method by calculating the effective indices of the propagated modes, their amplitudes along the taper and the adiabaticity criteria, showing the ability to achieve an excellent selective excitation of the fundamental mode in the FMF with negligible loss. We experimentally demonstrate that the proposed solution provides a successful mode conversion and allows an almost excellent fundamental mode excitation in the FMF (representing 99.8% of the total power).

  20. Adiabatically tapered microstructured mode converter for selective excitation of the fundamental mode in a few mode fiber.

    PubMed

    Taher, Aymen Belhadj; Di Bin, Philippe; Bahloul, Faouzi; Tartaret-Josnière, Etienne; Jossent, Mathieu; Février, Sébastien; Attia, Rabah

    2016-01-25

    We propose a new technique to selectively excite the fundamental mode in a few mode fiber (FMF). This method of excitation is made from a single mode fiber (SMF) which is inserted facing the FMF into an air-silica microstructured cane before the assembly is adiabatically tapered. We study theoretically and numerically this method by calculating the effective indices of the propagated modes, their amplitudes along the taper and the adiabaticity criteria, showing the ability to achieve an excellent selective excitation of the fundamental mode in the FMF with negligible loss. We experimentally demonstrate that the proposed solution provides a successful mode conversion and allows an almost excellent fundamental mode excitation in the FMF (representing 99.8% of the total power). PMID:26832518

  1. A simple in-line fiber polarizer based on tapered flat-clad microfiber with a liquid cladding overlay

    NASA Astrophysics Data System (ADS)

    Lee, C.-L.; Chuang, H.-P.; Lai, K.-C.; Hsieh, I.-S.; Chang, T.-F.; Fan, J.-X.; Tsao, H.-H.; Hsu, K.-C.; Chen, N.-K.

    2008-11-01

    A novel and simple in-line fiber polarizer is presented. The proposed device is fabricated by tapering an anisotropic flat-cladding birefringent micro-fiber surrounding with low-dispersion optical-liquid cladding. We also presented a theoretical analysis for dispersive birefringence of flat-clad micro-fiber with liquid overlay. The proposed device can be useful as all-fiber polarizer for optical communications. Simulation results show the birefringence of the device can be enhanced when the aspect is larger. In the experimental measurement for polarization extinction ratio (PER) of the proposed device, a fiber-pigtailed 1549.25 nm DFB laser light was used as light source. The PER about 30 dB was demonstrated when the liquid with refractive index nD = 1.45 was used.

  2. Simultaneous measurement of temperature and strain using a long-period fiber grating with a micro-taper

    NASA Astrophysics Data System (ADS)

    Geng, Tao; Li, Jian; Yang, Wenlei; An, Maowei; Zeng, Hongyi; Yang, Fan; Cui, Zhengji; Yuan, Libo

    2016-08-01

    An all-fiber Mach-Zehnder interferometer (MZI) consisting of a long-period fiber grating with a micro-taper is proposed for simultaneous measurement of temperature and strain. The experimental results demonstrate that the temperature and strain sensitivities of the proposed MZI are 83 pm/°C and -2.6 pm/μɛ, respectively. The strain sensitivity is 20 times as high as that of a long-period fiber written by CO2 laser pulses combined with a fiber bitaper. In addition, the interferometer requires only a common single-mode fiber, and it is easy to fabricate and is inexpensive for temperature and strain sensing applications.

  3. Fan-in/out polymer optical waveguide for a multicore fiber fabricated using the mosquito method.

    PubMed

    Suganuma, Daisuke; Ishigure, Takaaki

    2015-01-26

    A fan-in/out polymer optical waveguide with 25-μm cores and 40-μm interchannel pitch is fabricated for a multimode multicore fiber using a microdispenser. We design a fan-in/out structure to which the Mosquito method is applicable since the Mosquito method is capable of drawing a circular graded-index core three-dimensionally. Then, we experimentally fabricate a 10-cm long fan-in/out polymer waveguide with seven cores, which is expected to connect a multicore fiber and a fiber ribbon. A minimum insertion loss of 5.26 dB at 850-nm wavelength for a 10-cm long fan-in/out waveguide is experimentally observed. Causes of variation in the insertion loss and interchannel pitch are discussed.

  4. The measurement of sucrose concentration by two-tapered all-fiber Mach-Zehnder interferometer employing different coupling structures and manufacture processes

    NASA Astrophysics Data System (ADS)

    Zhu, Yu-Sheng; Wang, Hsin-Wen; Hsu, Yi-Cheng

    2016-08-01

    The sucrose concentration measurement and characteristics of light coupling taper structure on sensitivity with various fabrication processes of taper structure for all-fiber Mach-Zehnder interferometer (AFMZI) are presented. Using fusion splicer with electrical discharge, the standard single-mode fiber is employed to be fabricated as conical coupling/decoupling taper structure. The basic two fabrication processes are designed as single fusion-stretching (SFS), multiple fusions without stretching (MF). The third advanced process is composed of SFS and multiple fusions without stretching processes, and called multiple fusions with single stretching (MFSS). Various types of coupling/decoupling taper structures were fabricated based on the three kinds of fabrication processes. The effects of geometry shape including taper waist, taper angle, and sensing length on sensing sensitivity of AFMZIs are estimated. The modifications of fiber core and cladding induced by thermal effect affect the refractive index distributions and shapes of taper structure. The effects of refractive index changes of fiber core and cladding on sensing sensitivity are also discussed. The AFMZI was tested by measuring aqueous sucrose solution of refractive index unit (RIU) from 1.333 to 1.420 RIU. The optical spectrums are measured by a spectrometer. The spectrum dip shifts and sensing sensitivity was measured and calculated, respectively. As shown in results, sensing sensitivities of AFMZIs of taper structure fabricated by MFSS and multiple fusions without stretching processing are generally higher than SFS. The reasons could be aimed on materials modification through thermal effect on blurring fiber core-cladding interface and proper taper angle of taper structure. The more homogeneous refractive index distribution on fiber core-cladding interface, the more detecting light power decoupled through core-cladding interface to interact with exterior environment and enhance the sensing sensitivity

  5. Assembly of optical fibers for the connection of polymer-based waveguide

    NASA Astrophysics Data System (ADS)

    Ansel, Yannick; Grau, Daniel; Holzki, Markus; Kraus, Silvio; Neumann, Frank; Reinhard, Carsten; Schmitz, Felix

    2003-03-01

    This paper describes the realization of polymer-based optical structures and the assembly and packaging strategy to connect optical fiber ribbons to the waveguides. For that a low cost fabrication process using the SU-8TM thick photo-resist is presented. This process consists in the deposition of two photo-structurized resist layers filled up with epoxy glue realising the core waveguide. For the assembly, a new modular vacuum gripper was realised and installed on an automatic pick and place assembly robot to mount precisely and efficiently the optical fibers in the optical structures. First results have shown acceptable optical propagation loss for the complete test structure.

  6. Annular arrayed-waveguide fiber for autofocusing Airy-like beams.

    PubMed

    Deng, Hongchang; Yuan, Yonggui; Yuan, Libo

    2016-02-15

    We propose and theoretically demonstrate a novel optical fiber with an annular arrayed-waveguide to implement Airy phase and amplitude modulation, and generate an abruptly autofocusing circular Airy beam. The properties of wave propagation in Airy fiber and free space are studied by using the coupled-mode theory and angular spectrum method. The calculated results show that the output beam from such a fiber has a circular Airy-like pattern and can autofocus with the intensity maxima following a parabolic trajectory. We also show that the position of the focus point of the output beam from the Airy fiber can be easily controlled by changing input wavelength.

  7. High extinction-ratio dual thin-taper fiber interferometer fabricated by arc-discharge and its performance as sensors

    NASA Astrophysics Data System (ADS)

    Dong, Bo; Ge, Yao; Wang, Yixin; Yu, Changyuan

    2015-11-01

    We demonstrate an arc discharge fabrication method for a high extinction-ratio (ER) single mode fiber (SMF) based dual thin-taper modal interferometer (MI) and investigate the performance of the MI as thermal and refractive index (RI) sensors. With the optimized discharge parameters of a commercial fusion splicer and a simple mechanical taper setup, the MI with about 24 dB ER could be achieved if fabricating two thin-tapers with 20-μm waist diameter on the common SMF. It can be used as a highly sensitive thermal sensor with a thermal sensitivity of -72.8 pm/°C. However, for the high ER MI, the propagation position of the cladding mode is more close to that of core mode in the MI. Hence, its sensitivity to ambient RI variation is not very high, about 10.299 nm/RIU. If using it for dual parameter measurement, its thermal and RI measurement resolutions are ±1.1 °C and ±0.009, respectively, and are 6.6 and 2.4 times bigger than those of the other fiber sensors.

  8. Coherent beam combination of fiber lasers with a strongly confined waveguide: numerical model.

    PubMed

    Tao, Rumao; Si, Lei; Ma, Yanxing; Zhou, Pu; Liu, Zejin

    2012-08-20

    Self-imaging properties of fiber lasers in a strongly confined waveguide (SCW) and their application in coherent beam combination (CBC) are studied theoretically. Analytical formulas are derived for the positions, amplitudes, and phases of the N images at the end of an SCW, which is important for quantitative analysis of waveguide CBC. The formulas are verified with experimental results and numerical simulation of a finite difference beam propagation method (BPM). The error of our analytical formulas is less than 6%, which can be reduced to less than 1.5% with Goos-Hahnchen penetration depth considered. Based on the theoretical model and BPM, we studied the combination of two laser beams based on an SCW. The effects of the waveguide refractive index and Gaussian beam waist are studied. We also simulated the CBC of nine and 16 fiber lasers, and a single beam without side lobes was achieved.

  9. Planar dielectric waveguides in rotation are optical fibers: comparison with the classical model.

    PubMed

    Peña García, Antonio; Pérez-Ocón, Francisco; Jiménez, José Ramón

    2008-01-21

    A novel and simpler method to calculate the main parameters in fiber optics is presented. This method is based in a planar dielectric waveguide in rotation and, as an example, it is applied to calculate the turning points and the inner caustic in an optical fiber with a parabolic refractive index. It is shown that the solution found using this method agrees with the standard (and more complex) method, whose solutions for these points are also summarized in this paper.

  10. Planar dielectric waveguides in rotation are optical fibers: comparison with the classical model.

    PubMed

    Peña García, Antonio; Pérez-Ocón, Francisco; Jiménez, José Ramón

    2008-01-21

    A novel and simpler method to calculate the main parameters in fiber optics is presented. This method is based in a planar dielectric waveguide in rotation and, as an example, it is applied to calculate the turning points and the inner caustic in an optical fiber with a parabolic refractive index. It is shown that the solution found using this method agrees with the standard (and more complex) method, whose solutions for these points are also summarized in this paper. PMID:18542167

  11. Phase-shift detection in a Fourier-transform method for temperature sensing using a tapered fiber microknot resonator.

    PubMed

    Larocque, Hugo; Lu, Ping; Bao, Xiaoyi

    2016-04-01

    Phase-shift detection in a fast-Fourier-transform (FFT)-based spectrum analysis technique for temperature sensing using a tapered fiber microknot resonator is proposed and demonstrated. Multiple transmission peaks in the FFT spectrum of the device were identified as optical modes having completed different amounts of round trips within the ring structure. Temperature variation induced phase shifts for each set of peaks were characterized, and experimental results show that different peaks have distinct temperature sensitivities reaching values up to -0.542  rad/°C, which is about 10 times greater than that of a regular adiabatic taper Mach-Zehnder interferometer when using similar phase-tracking schemes. PMID:27192232

  12. Coupling of a high-power tapered diode laser beam into a single-mode-fiber within a compact module

    NASA Astrophysics Data System (ADS)

    Jedrzejczyk, D.; Sahm, A.; Carstens, C.; Urban, G.; Pulka, M.; Eppich, B.; Scholz, F.; Paschke, K.

    2015-03-01

    In this work, coupling of radiation generated by a distributed Bragg reflector (DBR) tapered diode laser around 1064 nm into a single-mode-fiber (SMF) within a butterfly module with a footprint < 10 cm2 is demonstrated. The module comprises temperature stabilizing components, a brightness maintaining micro optical assembly mounted with submicrometer precision and a standard FC/APC output connector. The aim of the introduced concept is to improve the beam quality and to eliminate the current dependent beam astigmatism, characteristic for tapered diode lasers and amplifiers, and, thus, provide an efficient, multi-Watt laser light source characterized by a narrow-band spectrum and a stigmatic, nearly Gaussian laser beam independent of the operating point. A maximum power ex SMF of 2.5 W at a coupling efficiency of 57 % is reached in the presented butterfly module.

  13. Two-photon excited fluorescence from a pseudoisocyanine-attached gold-coated tip via a thin tapered fiber under a weak continuous wave excitation.

    PubMed

    Ren, Fang; Takashima, Hideaki; Tanaka, Yoshito; Fujiwara, Hideki; Sasaki, Keiji

    2013-11-18

    A simple tapered fiber based photonic-plasmonic hybrid nanostructure composed of a thin tapered fiber and a pseudoisocyanine (PIC)-attached Au-coated tip was demonstrated. Using this simple hybrid nanostructure, we succeeded in observing two-photon excited fluorescence from the PIC dye molecules under a weak continuous wave excitation condition. From the results of the tip-fiber distance dependence and excitation polarization dependence, we found that using a thin tapered fiber and an Au-coated tip realized efficient coupling of the incident light (~95%) and LSP excitation at the Au-coated tip, suggesting the possibility of efficiently inducing two-photon excited fluorescence from the PIC dye molecules attached on the Au-coated tip. This simple photonic-plasmonic hybrid system is one of the promising tools for single photon sources, highly efficient plasmonic sensors, and integrated nonlinear plasmonic devices.

  14. Design of mid-infrared amplifiers based on fiber taper coupling to erbium-doped microspherical resonator.

    PubMed

    Mescia, Luciano; Bia, Pietro; De Sario, Marco; Di Tommaso, Annalisa; Prudenzano, Francesco

    2012-03-26

    A dedicated 3D numerical model based on coupled mode theory and solving the rate equations has been developed to analyse, design and optimize an optical amplifier obtained by using a tapered fiber and a Er³⁺-doped chalcogenide microsphere. The simulation model takes into account the main transitions among the erbium energy levels, the amplified spontaneous emission and the most important secondary transitions pertaining to the ion-ion interactions. The taper angle of the optical fiber and the fiber-microsphere gap have been designed to efficiently inject into the microsphere both the pump and the signal beams and to improve their spatial overlapping with the rare earth doped region. In order to reduce the computational time, a detailed investigation of the amplifier performance has been carried out by changing the number of sectors in which the doped area is partitioned. The simulation results highlight that this scheme could be useful to develop high efficiency and compact mid-infrared amplifiers.

  15. Design of mid-infrared amplifiers based on fiber taper coupling to erbium-doped microspherical resonator.

    PubMed

    Mescia, Luciano; Bia, Pietro; De Sario, Marco; Di Tommaso, Annalisa; Prudenzano, Francesco

    2012-03-26

    A dedicated 3D numerical model based on coupled mode theory and solving the rate equations has been developed to analyse, design and optimize an optical amplifier obtained by using a tapered fiber and a Er³⁺-doped chalcogenide microsphere. The simulation model takes into account the main transitions among the erbium energy levels, the amplified spontaneous emission and the most important secondary transitions pertaining to the ion-ion interactions. The taper angle of the optical fiber and the fiber-microsphere gap have been designed to efficiently inject into the microsphere both the pump and the signal beams and to improve their spatial overlapping with the rare earth doped region. In order to reduce the computational time, a detailed investigation of the amplifier performance has been carried out by changing the number of sectors in which the doped area is partitioned. The simulation results highlight that this scheme could be useful to develop high efficiency and compact mid-infrared amplifiers. PMID:22453441

  16. Detection of avian influenza antigens in proximity fiber, droplet, and optical waveguide microfluidics

    NASA Astrophysics Data System (ADS)

    Yoon, Jeong-Yeol; Heinze, Brian C.; Gamboa, Jessica; You, David J.

    2009-05-01

    Virus antigens of avian influenza subtype H3N2 were detected on two different microfluidic platforms: microchannel and droplet. Latex immunoagglutination assays were performed using 920-nm highly carboxylated polystyrene beads that are conjugated with antibody to avian influenza virus. The bead suspension was merged with the solutions of avian influenza virus antigens in a Y-junction of a microchannel made by polydimethylsiloxane soft lithography. The resulting latex immunoagglutinations were measured with two optical fibers in proximity setup to detect 45° forward light scattering. Alternatively, 10 μL droplets of a bead suspension and an antigen solution were merged on a superhydrophobic surface (water contact angle = 155°), whose movement was guided by a metal wire, and 180° back light scattering is measured with a backscattering optical probe. Detection limits were 0.1 pg mL-1 for both microchannel with proximity fibers and droplet microfluidics, thanks to the use of micro-positioning stages to help generate reproducible optical signals. Additionally, optical waveguide was tested by constructing optical waveguide channels (filled with mineral oil) within a microfluidic device to detect the same light scattering. Detection limit was 0.1 ng mL-1 for an optical waveguide device, with a strong potential of improvement in the near future. The use of optical waveguide enabled smaller device setup, easier operation, smaller standard deviations and broader linear range of assay than proximity fiber microchannel and droplet microfluidics. Total assay time was less than 10 min.

  17. Fiber-coupled dual-mode waveguide interferometer with lambda/130 fringe spacing.

    PubMed

    Jenkins, Richard M; Blockley, Andrew F; Banerji, J; Davies, Alan R

    2008-04-25

    Predictions and measurements of a multimode waveguide interferometer operating in a fiber-coupled, "dual-mode" regime are reported. With a 1.32 microm source, a complete switching cycle of the output beam is produced by a 10.0 nm incremental change in the 8.0 microm width of the hollow planar mirror waveguide. This equates to a fringe spacing of approximately lambda/130. This is an order of magnitude smaller than previously reported results for this form of interferometer. PMID:18518197

  18. Low-loss hollow waveguide fibers for mid-infrared quantum cascade laser sensing applications.

    PubMed

    Patimisco, Pietro; Spagnolo, Vincenzo; Vitiello, Miriam S; Scamarcio, Gaetano; Bledt, Carlos M; Harrington, James A

    2013-01-21

    We report on single mode optical transmission of hollow core glass waveguides (HWG) coupled with an external cavity mid-IR quantum cascade lasers (QCLs). The QCL mode results perfectly matched to the hybrid HE(11) waveguide mode and the higher losses TE-like modes have efficiently suppressed by the deposited inner dielectric coating. Optical losses down to 0.44 dB/m and output beam divergence of ~5 mrad were measured. Using a HGW fiber with internal core size of 300 µm we obtained single mode laser transmission at 10.54 µm and successful employed it in a quartz enhanced photoacoustic gas sensor setup.

  19. The influence of temperature to a refractive index sensor based on a macro-bending tapered plastic optical fiber

    NASA Astrophysics Data System (ADS)

    Teng, Chuan-xin; Yu, Fang-da; Jing, Ning; Zheng, Jie

    2016-09-01

    The temperature influence to a refractive index (RI) sensor based on a macro-bending tapered plastic optical fiber (POF) was investigated experimentally. The total temperature dependence loss (TDLtotal) and total temperature dependence RI deviation (TDRtotal) were measured at different temperature (10-60 °C) over an RI range of 1.33-1.41. The temperature dependence RI deviation of the sensor itself was obtained by subtracting the temperature dependence RI of measured liquid from TDRtotal. Therefore, the influence of temperature variation to the sensor was characterized and corrected.

  20. A switchable and stable single-longitudinal-mode, dual-wavelength erbium-doped fiber laser assisted by Rayleigh backscattering in tapered fiber

    SciTech Connect

    Gu, Jian; Yang, Yanfu Zhang, Jianyu; Wang, Xiaorui; Yuan, Yijun; Yao, Yong; Liu, Meng

    2015-09-14

    We have proposed and demonstrated a novel switchable single-longitudinal-mode (SLM), dual-wavelength erbium-doped fiber laser (DWEDFL) assisted by Rayleigh backscattering (RBS) in a tapered fiber in a ring laser configuration. The RBS feedback in a tapered fiber is a key mechanism as linewidth narrowing for laser output. A compound laser cavity ensured that the EDFL operated in the SLM state and a saturable absorber (SA) is employed to form a gain grating for both filtering and improving wavelength stability. The fiber laser can output dual wavelengths simultaneously or operate at single wavelength in a switchable manner. Experiment results show that with the proper SA, the peak power drift was improved from 1–2 dB to 0.31 dB and the optical signal to noise ratio was higher than 60 dB. Under the assistance of RBS feedback, the laser linewidths are compressed by around three times and the Lorentzian 3 dB linewidths of 445 Hz and 425 Hz are obtained at 1550 nm and 1554 nm, respectively.

  1. Improvement of efficient coupling and optical resonances by using taper-waveguides coupled to cascade of UV210 polymer micro-resonators

    NASA Astrophysics Data System (ADS)

    Castro-Beltran, R.; Huby, N.; Loas, G.; Lhermite, H.; Pluchon, D.; Bêche, B.

    2014-12-01

    In this paper, we report the overall design, fabrication and optical characterization of single and multiple resonant micro-structures patterned on UV210 polymer and shaped by using deep-UV lithography procedures. Various families of ring and racetrack forms are investigated with different geometrical dimensions linked to the micro-resonators and the specific taper-waveguides and gaps allowing the optimized coupling. Well defined photonic structures families in the sub-micrometer range obtained by this deep UV-light process are clearly confirmed through scanning electron microscopy. In order to evaluate and quantify the efficiency of the sub-micrometer coupling, the recirculation of the light and the quality of the optical resonance aspects, a global study including top view intensity imaging, spectral measurements and fast Fourier transform analysis is performed for all these devices based on single and multiple family resonators. The experimental TE-mode resonance transmissions reveal a complete agreement with the period of the theoretically expected resonances. A maximum value of the quality factor Q = 3.5  ×  103 at 1035 nm with a 3.2 times higher resonance contrast is assessed for cascade of triple micro-resonators with respect to photonic devices based on only one micro-resonator. In addition, UV210 circuits made of specific tapers coupling to cascade loops act directly on the improvement of the evanescent coupling and resonances in terms of quality factor and extinction rate by selecting the optical mode resonance successively and more precisely. All these designs have low cost technological reproducible steps, and the devices and protocol measurements are markedly suitable for mass fabrication and metrology applications.

  2. Lasing and waveguiding in smectic A liquid crystal optical fibers.

    PubMed

    Peddireddy, Karthik; Jampani, V S R; Thutupalli, Shashi; Herminghaus, Stephan; Bahr, Christian; Muševič, Igor

    2013-12-16

    We demonstrate a new class of soft matter optical fibers, which are self-assembled in a form of smectic-A liquid crystal microtubes grown in an aqueous surfactant dispersion of a smectic-A liquid crystal. The diameter of the fibers is highly uniform and the fibers are highly birefringent. They are characterized by a line topological defect in the core of the fiber with an optical axis pointing from the defect core towards the surface. We demonstrate guiding of light along the fiber and Whispering Gallery Mode (WGM) lasing in a plane perpendicular to the fiber. The light guiding as well as the lasing threshold are significantly dependent on the polarization of the excitation beam. The observed threshold for WGM lasing is very low (≈ 75μJ/cm(2)) when the pump beam polarization is perpendicular to the direction of the laser dye alignment and is similar to the lasing threshold in nematic droplets. The smectic-A fibers are soft and flexible and can be manipulated with laser tweezers demonstrating a promising approach for realization of soft photonic circuits. PMID:24514602

  3. Lasing and waveguiding in smectic A liquid crystal optical fibers.

    PubMed

    Peddireddy, Karthik; Jampani, V S R; Thutupalli, Shashi; Herminghaus, Stephan; Bahr, Christian; Muševič, Igor

    2013-12-16

    We demonstrate a new class of soft matter optical fibers, which are self-assembled in a form of smectic-A liquid crystal microtubes grown in an aqueous surfactant dispersion of a smectic-A liquid crystal. The diameter of the fibers is highly uniform and the fibers are highly birefringent. They are characterized by a line topological defect in the core of the fiber with an optical axis pointing from the defect core towards the surface. We demonstrate guiding of light along the fiber and Whispering Gallery Mode (WGM) lasing in a plane perpendicular to the fiber. The light guiding as well as the lasing threshold are significantly dependent on the polarization of the excitation beam. The observed threshold for WGM lasing is very low (≈ 75μJ/cm(2)) when the pump beam polarization is perpendicular to the direction of the laser dye alignment and is similar to the lasing threshold in nematic droplets. The smectic-A fibers are soft and flexible and can be manipulated with laser tweezers demonstrating a promising approach for realization of soft photonic circuits.

  4. Single Fiber Star Couplers. [optical waveguides for spacecraft communication

    NASA Technical Reports Server (NTRS)

    Asawa, C. K.

    1979-01-01

    An ion exchange process was developed and used in the fabrication of state-of-the-art planar star couplers for distribution of optical radiation between optical fibers. An 8 x 8 planar transmission star coupler was packaged for evaluation purposes with sixteen fiber connectors and sixteen pigtails. Likewise a transmission star coupler and an eight-port reflection star coupler with eight-fiber ribbons rigidly attached to these couplers, and a planar coupler with silicon guides and a parallel channel guide with pigtails were also fabricated. Optical measurements of the transmission star couplers are included with a description of the manufacturing process.

  5. High-sensitivity DNA biosensor based on optical fiber taper interferometer coated with conjugated polymer tentacle.

    PubMed

    Huang, Yunyun; Tian, Zhuang; Sun, Li-Peng; Sun, Dandan; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2015-10-19

    A sensitive bio-probe to in situ detect unlabeled single-stranded DNA targets based on optical microfiber taper interferometer coated by a high ordered pore arrays conjugated polymer has been presented. The polymer coating serves as tentacles to catch single-stranded DNA molecules by π-π conjugated interaction and varies the surface refractive index of the optical microfiber. The microfiber taper interferometer translates the refractive index information into wavelength shift of the interference fringe. The sensor exhibits DNA concentration sensitivity of 2.393 nm/log M and the lowest detection ability of 10(-10) M or even lower.

  6. High-sensitivity DNA biosensor based on optical fiber taper interferometer coated with conjugated polymer tentacle.

    PubMed

    Huang, Yunyun; Tian, Zhuang; Sun, Li-Peng; Sun, Dandan; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2015-10-19

    A sensitive bio-probe to in situ detect unlabeled single-stranded DNA targets based on optical microfiber taper interferometer coated by a high ordered pore arrays conjugated polymer has been presented. The polymer coating serves as tentacles to catch single-stranded DNA molecules by π-π conjugated interaction and varies the surface refractive index of the optical microfiber. The microfiber taper interferometer translates the refractive index information into wavelength shift of the interference fringe. The sensor exhibits DNA concentration sensitivity of 2.393 nm/log M and the lowest detection ability of 10(-10) M or even lower. PMID:26480357

  7. Fan-in/out polymer optical waveguide for a multicore fiber fabricated using the Mosquito method

    NASA Astrophysics Data System (ADS)

    Suganuma, D.; Ishigure, T.

    2015-02-01

    A fan-in/out polymer optical waveguide is fabricated for connecting multimode multicore (7 cores) fiber with onedimensionally aligned parallel optical components such as a VCSEL/PD array or a multimode fiber ribbon, which is fabricated using the Mosquito method. The Mosquito method we have proposed is a fabrication technique for circular and graded index (GI) cores. One of the unique characteristics of the Mosquito method is a capability of forming threedimensional wirings. In the fan-in/out waveguides, high-density hexagonal alignment of 7 cores at one end is converted to one dimensional alignment with a wider pitch at the other end. For realizing the fan-in/out waveguides, we have issues about low insertion loss, low crosstalk, and the connectability with multicore fibers and optical components. In this paper, we focus in the pitch accuracy of the fan-in/out waveguide. In the Mosquito method, the viscosities of the core and cladding monomers are an important factor of the core figure and the core alignment because the viscosities have a relation to monomer liquid-flow, which could devastate the core alignment. Hence, we investigate the influence of the viscosities of the core and cladding monomers on the interchannel pitch accuracy of the fabricated fan-in/out polymer optical waveguide. With increasing the viscosities of core and cladding monomers, the pitch accuracy is improved, while the appropriate monomer viscosity conditions that can fix all the issues: core circularity and pitch accuracy in both ends still needs to be investigated.

  8. Method for improving the spectral flatness of the supercontinuum at 1.55 μm in tapered microstructured optical fibers

    NASA Astrophysics Data System (ADS)

    Vukovic, N.; Broderick, N. G. R.

    2010-10-01

    We propose a method for enhancing the flatness of a supercontinuum centered at 1.55 μm by the use of specially designed tapered microstructured optical fibers (MOFs). Based on the procedure presented one can determine the linear taper profile parameters and the optimum launching conditions needed to achieve the broadest supercontinuum spectra (SC) and the best spectra flatness. We quantify the maximally broad and flat SC using the calculated standard deviation of the spectra at the required wavelength range and show that it is possible to obtain significantly better results than those obtained by using an untapered fiber.

  9. Grating-assisted glass waveguide devices and fiber-optic parametric amplifiers for optical communication systems

    NASA Astrophysics Data System (ADS)

    Kim, Jaeyoun

    The theory, design, and implementation of several photonics devices for the generation, amplification, and processing of optical signals in optical communication systems are described. A cascaded fiber-optic parametric amplifier based on a quasi-phase matching technique is implemented. This cascaded implementation is the first explicit application of quasi-phase matching techniques to a fiber-optic parametric amplifier and results in a 12 dB gain enhancement using a 3-stage structure. For the generation and the wavelength-sensitive processing of optical signals, distributed Bragg reflector (DBR) waveguide devices are fabricated in un-doped and Er/Yb co-doped glass substrates using Ag+ and K+ ion-exchange, respectively. Wavelength-selective operation is realized by implementing the DBRs using a high refractive index overlay technique. This technique allows DBR fabrication on substrates with hard-to-etch surfaces and can produce very short, high efficiency reflectors by utilizing the enhanced interactions between the waveguide and the high index overlay DBR. The development of methods for overlay/waveguide design, thin-film characterization, and optimum thickness deposition are reported. Using this technique, an Er/Yb co-doped glass waveguide DBR laser with a 30 mW lasing threshold and a 8.5% slope efficiency is demonstrated. An optical add-drop multiplexer with a 24 dB transmission dip and a 0.5 nm wide 3 dB bandwidth is also designed and fabricated based on the same technique.

  10. Glass Solder Approach for Robust, Low-Loss, Fiber-to-Waveguide Coupling

    NASA Technical Reports Server (NTRS)

    McNeil, Shirley; Battle, Philip; Hawthorne, Todd; Lower, John; Wiley, Robert; Clark, Brett

    2012-01-01

    The key advantages of this approach include the fact that the index of interface glass (such as Pb glass n = 1.66) greatly reduces Fresnel losses at the fiber-to-waveguide interface, resulting in lower optical losses. A contiguous structure cannot be misaligned and readily lends itself for use on aircraft or space operation. The epoxy-free, fiber-to-waveguide interface provides an optically pure, sealed interface for low-loss, highpower coupling. Proof of concept of this approach has included successful attachment of the low-melting-temperature glass to the x-y plane of the crystal, successful attachment of the low-meltingtemperature glass to the end face of a standard SMF (single-mode fiber), and successful attachment of a wetted lowmelting- temperature glass SMF to the end face of a KTP crystal. There are many photonic components on the market whose performance and robustness could benefit from this coupling approach once fully developed. It can be used in a variety of fibercoupled waveguide-based components, such as frequency conversion modules, and amplitude and phase modulators. A robust, epoxy-free, contiguous optical interface lends itself to components that require low-loss, high-optical-power handling capability, and good performance in adverse environments such as flight or space operation.

  11. Laser diode pumped high efficiency Yb:YAG crystalline fiber waveguide lasers

    NASA Astrophysics Data System (ADS)

    Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth

    2015-02-01

    Single-clad and double-clad Yb:YAG crystalline fiber waveguides (CFWs) have been prepared with Adhesive-Free Bonding (AFB®) technology. By using a fiber coupled laser diode as pump source, a single-mode laser with near diffraction limited beam quality M2=1.02 has been demonstrated in a double-clad CFW. The laser output power and efficiency are 13.2 W and 34%, respectively. In a single-clad CFW, core pumping was used. The laser output has top-hat beam profile. An output power of 28 W and a slope efficiency of 78% have been achieved respectively.

  12. A double-taper optical fiber-based radiation wave other than evanescent wave in all-fiber immunofluorescence biosensor for quantitative detection of Escherichia coli O157:H7.

    PubMed

    Zhang, Zhonghuan; Hua, Fei; Liu, Ting; Zhao, Yong; Li, Jun; Yang, Ruifu; Yang, Changxi; Zhou, Lei

    2014-01-01

    Cylindrical or taper-and-cylinder combination optical fiber probe based on evanescent wave has been widely used for immunofluorescence biosensor to detect various analytes. In this study, in contrast to the contradiction between penetration depth and analyte diameter of optical fiber probe-based evanescent wave, we demonstrate that double-taper optical fiber used in a radiation wave-based all-fiber immunofluorescence biosensor (RWAIB) can detect micron-scale analytes using Escherichia coli O157:H7 as representative target. Finite-difference time-domain method was used to compare the properties of evanescent wave and radiation wave (RW). Ray-tracing model was formulated to optimize the taper geometry of the probe. Based on a commercial multi-mode fiber, a double-taper probe was fabricated and connected with biosensor through a "ferrule connector" optical fiber connector. The RWAIB configuration was accomplished using commercial multi-mode fibers and fiber-based devices according to the "all-fiber" method. The standard sample tests revealed that the sensitivity of the proposed technique for E. coli O157:H7 detection was 10(3) cfu · mL(-1). Quantitation could be achieved within the concentration range of 10(3) cfu · mL(-1) to 107 cfu · mL(-1). No non-specific recognition to ten kinds of food-borne pathogens was observed. The results demonstrated that based on the double-taper optical fiber RWAIB can be used for the quantitative detection of micron-scale targets, and RW sensing is an alternative for traditional evanescent wave sensing during the fabrication of fiber-optic biosensors. PMID:24805354

  13. Performance of large aperture tapered fiber phase conjugate mirror with high pulse energy and 1-kHz repetition rate.

    PubMed

    Zhao, Zhigang; Dong, Yantao; Pan, Sunqiang; Liu, Chong; Chen, Jun; Tong, Lixin; Gao, Qingsong; Tang, Chun

    2012-01-16

    A large aperture fused silica tapered fiber phase conjugate mirror is presented with a maximum 70% stimulated Brillouin scattering (SBS) reflectivity, which is obtained with 1 kHz repetition rate, 15 ns pulse width and 38 mJ input pulse energy. To the best of our knowledge, this is the highest SBS reflectivity ever reported by using optical fiber as a phase conjugate mirror for such high pulse repetition rate (1 kHz) and several tens of millijoule (mJ) input pulse energy. The influences of fiber end surface quality and pump pulse widths on SBS reflectivity are investigated experimentally. The results show that finer fiber end surface quality and longer input pulse widths are preferred for obtaining higher SBS reflectivity with higher input pulse energy. Double passing amplification experiments are also performed. 52 mJ pulse energy is achieved at 1 kHz repetition rate, with a reflected SBS pulse width of 1.5 ns and a M(2) factor of 2.3. The corresponding peak power reaches 34.6 MW. Obvious beam quality improvement is observed. PMID:22274534

  14. Intensity modulation type fiber-optic strain sensor based on a Mach-Zehnder interferometer constructed by an up-taper with a LPG

    NASA Astrophysics Data System (ADS)

    Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying

    2016-04-01

    A highly sensitive and compact fiber-optic strain sensor was presented and experimentally demonstrated. The sensor is based on an in-line fiber Mach-Zehnder interferometer (MZI), which is constructed by connecting a long-period fiber grating (LPG) with an up-taper. With the increasing of the axial strain on the sensor, both of the up-taper's diameter and the light coupling efficiency decreased. By measuring the transmission intensity changes of the resonant dips at wavelength ~1553.4 nm under the fiber axial strain ranging from 0 to 590 με, the sensitivity of 0.026 dB/με was obtained, which is almost 2 times of the existing similar strain sensor. And the results were also confirmed by simulations.

  15. Manipulation of single nanodiamonds to ultrathin fiber-taper nanofibers and control of NV-spin states toward fiber-integrated λ-systems

    NASA Astrophysics Data System (ADS)

    Fujiwara, Masazumi; Yoshida, Kazuma; Noda, Tetsuya; Takashima, Hideaki; Schell, Andreas W.; Mizuochi, Norikazu; Takeuchi, Shigeki

    2016-11-01

    We report on the coupling of single nitrogen vacancy (NV) centers to ultrathin fiber-taper nanofibers by the manipulation of single diamond nanocrystals on the nanofibers under real-time observation of nanodiamond fluorescence. Spin-dependent fluorescence of the single NV centers is efficiently detected through the nanofiber. We show control of the spin sub-level structure of the electronic ground state using an external magnetic field and clearly observe a frequency fine tuning of {m}{{S}}=| +/- 1> . This observation demonstrates a possibility of realizing fiber-integrated quantum λ-systems, which can be used for various quantum information devices including push–pull quantum memory and quantum gates.

  16. Design of intrinsically single-mode double clad crystalline fiber waveguides for high power lasers

    NASA Astrophysics Data System (ADS)

    Li, Da; Hong, Pengda; Meissner, Stephanie K.; Meissner, Helmuth E.

    2016-03-01

    Recently, double-clad crystalline fiber waveguides (CFWs), consisting of single crystalline or ceramic RE3+:YAG cores of square cross section and inner claddings of either undoped or laser-inactive-ion-doped YAG and outer claddings of sapphire, have been successfully demonstrated. These waveguides, manufactured by an Adhesive-Free Bonding (AFB®) technique, can be precisely engineered and fabricated with predictable beam propagation behavior. In this work, with high power laser designs in mind, minimum thicknesses for inner cladding are derived for different core cross sections and refractive index differences between the core and inner cladding and sapphire as outer cladding material for common laser core dopants such as Nd3+, Yb3+, Er3+, Tm3+ and Ho3+. All designs are intended to use high NA high power laser diode pumping to obtain high power intrinsically single transverse mode laser output. The obtained data are applicable to any crystalline fiber waveguide design, regardless of fabrication technique. As an example, a CFW with 40 μm × 40 μm 4% Tm:YAG core, 5% Yb:YAG inner cladding, and sapphire outer cladding was calculated to be intrinsically single transverse mode, with the minimum inner cladding width of 21.7 μm determined by the effective index technique [1].

  17. Suspended mid-infrared fiber-to-chip grating couplers for SiGe waveguides

    NASA Astrophysics Data System (ADS)

    Favreau, Julien; Durantin, Cédric; Fédéli, Jean-Marc; Boutami, Salim; Duan, Guang-Hua

    2016-03-01

    Silicon photonics has taken great importance owing to the applications in optical communications, ranging from short reach to long haul. Originally dedicated to telecom wavelengths, silicon photonics is heading toward circuits handling with a broader spectrum, especially in the short and mid-infrared (MIR) range. This trend is due to potential applications in chemical sensing, spectroscopy and defense in the 2-10 μm range. We previously reported the development of a MIR photonic platform based on buried SiGe/Si waveguide with propagation losses between 1 and 2 dB/cm. However the low index contrast of the platform makes the design of efficient grating couplers very challenging. In order to achieve a high fiber-to-chip efficiency, we propose a novel grating coupler structure, in which the grating is locally suspended in air. The grating has been designed with a FDTD software. To achieve high efficiency, suspended structure thicknesses have been jointly optimized with the grating parameters, namely the fill factor, the period and the grating etch depth. Using the Efficient Global Optimization (EGO) method we obtained a configuration where the fiber-to-waveguide efficiency is above 57 %. Moreover the optical transition between the suspended and the buried SiGe waveguide has been carefully designed by using an Eigenmode Expansion software. Transition efficiency as high as 86 % is achieved.

  18. Experimental observation of mid-infrared higher-order soliton fission in a tapered tellurite microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Cheng, Tonglei; Xue, Xiaojie; Liu, Lai; Suzuki, Takenobu; Ohishi, Yasutake

    2016-06-01

    The evolution of mid-infrared (MIR) higher-order soliton fission in a tapered tellurite microstructured optical fiber (TMOF) is experimentally investigated. From ∼30 to 80 mW, the redshift of the first fundamental soliton is obvious. From ∼80 to 120 mW, two fundamental solitons are obtained by the fission of higher-order solitons. The redshift of the first fundamental soliton almost stops because the increased pump power is preferentially distributed to the second fundamental soliton. From ∼120 to 180 mW, an obvious redshift of the first fundamental soliton is observed again, and a third fundamental soliton is obtained at ∼180 mW. The evolution of each soliton is determined by the power distribution, which is, to the best of our knowledge, reported for the first time.

  19. Low-Loss Hollow Waveguide Fibers for Mid-Infrared Quantum Cascade Laser Sensing Applications

    PubMed Central

    Patimisco, Pietro; Spagnolo, Vincenzo; Vitiello, Miriam S.; Scamarcio, Gaetano; Bledt, Carlos M.; Harrington, James A.

    2013-01-01

    We report on single mode optical transmission of hollow core glass waveguides (HWG) coupled with an external cavity mid-IR quantum cascade lasers (QCLs). The QCL mode results perfectly matched to the hybrid HE11 waveguide mode and the higher losses TE-like modes have efficiently suppressed by the deposited inner dielectric coating. Optical losses down to 0.44 dB/m and output beam divergence of ∼5 mrad were measured. Using a HGW fiber with internal core size of 300 μm we obtained single mode laser transmission at 10.54 μm and successful employed it in a quartz enhanced photoacoustic gas sensor setup. PMID:23337336

  20. Analysis of the polarization rotation effect in the inversely tapered spot size converter.

    PubMed

    Jia, Lianxi; Zhou, Haifeng; Liow, Tsung-Yang; Song, Junfeng; Huang, Ying; Tu, Xiaoguang; Luo, Xianshu; Li, Chao; Fang, Qing; Yu, Mingbin; Lo, Guoqiang

    2015-10-19

    Inversely tapered spot size converter (SSC) is widely used to connect silicon waveguide with fiber in silicon photonics. However, the tapered structure may cause polarization rotation and further generate interference fluctuation in the transmission spectrum even of a straight waveguide. We analyzed the light propagation in a straight waveguide with SSC at the both ends with coupling matrix and transmission matrix methods. The analysis results matched with the phenomena we observed in the transmission spectrum. Combining the analysis with the measurement results, we calculated the polarization rotation efficiency of the SSC in different samples and analyzed the origin of the polarization rotation effect. Finally, we discussed the influence of the effect to the DP-QPSK signal and proposed several methods to release the impact.

  1. Polymer waveguide overlays for side-polished fiber devices.

    PubMed

    Lee, S G; Sokoloff, J P; McGinnis, B P; Sasabe, H

    1998-01-20

    Several polymers often used as hosts in guest-host organic thin-film systems were investigated for their suitability as overlays for side-polished fiber (SPF) devices. Good optical quality, ~10-mum-thick films were fabricated by spin coating and applied to SPF's by use of a decal deposition technique to produce passive devices such as channel-dropping (CD) filters, bandpass filters, and polarizers with good throughput and high contrast ratios. The main CD features can be quantitatively explained by a weak coupled-mode model. SPF structures with doped overlays were also examined. These measurements provided a means of determining several SPF device parameters and also allowed estimates of the nonlinearities required to make all-optical and electro-optic devices. PMID:18268606

  2. Calculated Coupling Efficiency Between an Elliptical-Core Optical Fiber and a Silicon Oxynitride Rib Waveguide [Corrected Copy

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L.; Beheim, Glenn

    1995-01-01

    The effective-index method and Marcatili's technique were utilized independently to calculate the electric field profile of a rib channel waveguide. Using the electric field profile calculated from each method, the theoretical coupling efficiency between a single-mode optical fiber and a rib waveguide was calculated using the overlap integral. Perfect alignment was assumed and the coupling efficiency calculated. The coupling efficiency calculation was then repeated for a range of transverse offsets.

  3. Formation of a wedge-shaped element on an end face of a microstrip optical waveguide designed to minimize loss when coupling with an optical fiber

    NASA Astrophysics Data System (ADS)

    Balya, V. K.; Denisyuk, I. Yu.

    2015-10-01

    We have investigated a method for forming microstrip optical waveguides of variable cross section designed for coupling a planar waveguide with an optical fiber. The method is based on the use of combined reactive-ion etching of polymer cladding and photoresist. It is shown that butt expansions and a microstrip waveguide can be formed in one technological process. The influence of the conditions of reactive-ion etching on the quality of the waveguide optical surface is analyzed.

  4. Fabrication of a miniaturized capillary waveguide integrated fiber-optic sensor for fluoride determination.

    PubMed

    Xiong, Yan; Wang, Chengjie; Tao, Tao; Duan, Ming; Tan, Jun; Wu, Jiayi; Wang, Dong

    2016-05-10

    Fluoride concentration is a key aspect of water quality and essential for human health. Too much or too little fluoride intake from water supplies is harmful to public health. In this study, a capillary waveguide integrated fiber-optic sensor was fabricated for fluoride measurement in water samples. The sensor was modularly designed with three parts, i.e., a light source, capillary flow cell and detector. When light propagated from a light emitting diode (LED) to the capillary waveguide cell through an excitation fiber, it interacted with the sensing reagent, and its intensity changed with different fluoride concentrations. Then, the light propagated to the detector through a detection fiber for absorption determination of fluoride according to Beer's law. This miniaturized sensor showed advantages of fast analysis (9.2 s) and small reagent demand (200 μL) per sample, and it also had a low detection limit (8 ppb) and high selectivity for fluoride determination. The sensor was applied to fluoride determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and ion chromatography, showing agreement and validating the sensor's potential application.

  5. Calculated coupling efficiency between an elliptical-core optical fiber and an optical waveguide over temperature

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L.; Weisshaar, Andreas; Li, Jian; Beheim, Glenn

    1995-01-01

    To determine the feasibility of coupling the output of a single-mode optical fiber into a single-mode rib waveguide in a temperature varying environment, a theoretical calculation of the coupling efficiency between the two was investigated. Due to the complex geometry of the rib guide, there is no analytical solution to the wave equation for the guided modes, thus, approximation and/or numerical techniques must be utilized to determine the field patterns of the guide. In this study, three solution methods were used for both the fiber and guide fields; the effective-index method (EIM), Marcatili's approximation, and a Fourier method. These methods were utilized independently to calculate the electric field profile of each component at two temperatures, 20 C and 300 C, representing a nominal and high temperature. Using the electric field profile calculated from each method, the theoretical coupling efficiency between an elliptical-core optical fiber and a rib waveguide was calculated using the overlap integral and the results were compared. It was determined that a high coupling efficiency can be achieved when the two components are aligned. The coupling efficiency was more sensitive to alignment offsets in the y direction than the x, due to the elliptical modal field profile of both components. Changes in the coupling efficiency over temperature were found to be minimal.

  6. Fabrication of a miniaturized capillary waveguide integrated fiber-optic sensor for fluoride determination.

    PubMed

    Xiong, Yan; Wang, Chengjie; Tao, Tao; Duan, Ming; Tan, Jun; Wu, Jiayi; Wang, Dong

    2016-05-10

    Fluoride concentration is a key aspect of water quality and essential for human health. Too much or too little fluoride intake from water supplies is harmful to public health. In this study, a capillary waveguide integrated fiber-optic sensor was fabricated for fluoride measurement in water samples. The sensor was modularly designed with three parts, i.e., a light source, capillary flow cell and detector. When light propagated from a light emitting diode (LED) to the capillary waveguide cell through an excitation fiber, it interacted with the sensing reagent, and its intensity changed with different fluoride concentrations. Then, the light propagated to the detector through a detection fiber for absorption determination of fluoride according to Beer's law. This miniaturized sensor showed advantages of fast analysis (9.2 s) and small reagent demand (200 μL) per sample, and it also had a low detection limit (8 ppb) and high selectivity for fluoride determination. The sensor was applied to fluoride determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and ion chromatography, showing agreement and validating the sensor's potential application. PMID:27067512

  7. Ultrashort optical waveguide excitations in uniaxial silica fibers: elastic collision scenarios.

    PubMed

    Kuetche, Victor K; Youssoufa, Saliou; Kofane, Timoleon C

    2014-12-01

    In this work, we investigate the dynamics of an uniaxial silica fiber under the viewpoint of propagation of ultimately ultrashort optical waveguide channels. As a result, we unveil the existence of three typical kinds of ultrabroadband excitations whose profiles strongly depend upon their angular momenta. Looking forward to surveying their scattering features, we unearth some underlying head-on scenarios of elastic collisions. Accordingly, we address some useful and straightforward applications in nonlinear optics through secured data transmission systems, as well as laser physics and soliton theory with optical soliton dynamics.

  8. Arrayed waveguide grating interrogator for fiber Bragg grating sensors: measurement and simulation.

    PubMed

    Koch, Jan; Angelmahr, Martin; Schade, Wolfgang

    2012-11-01

    A fiber Bragg grating (FBG) interrogation system based on an intensity demodulation and demultiplexing of an arrayed waveguide grating (AWG) module is examined in detail. The influence of the spectral line shape of the FBG on the signal obtained from the AWG device is discussed by accomplishing the measurement and simulation of the system. The simulation of the system helps to create quickly and precisely calibration functions for nonsymmetric, tilted, or nonapodized FBGs. Experiments show that even small sidebands of nonapodized FBGs have strong influences on the signal resulted by an AWG device with a Gaussian profile. PMID:23128724

  9. Arrayed waveguide grating interrogator for fiber Bragg grating sensors: measurement and simulation.

    PubMed

    Koch, Jan; Angelmahr, Martin; Schade, Wolfgang

    2012-11-01

    A fiber Bragg grating (FBG) interrogation system based on an intensity demodulation and demultiplexing of an arrayed waveguide grating (AWG) module is examined in detail. The influence of the spectral line shape of the FBG on the signal obtained from the AWG device is discussed by accomplishing the measurement and simulation of the system. The simulation of the system helps to create quickly and precisely calibration functions for nonsymmetric, tilted, or nonapodized FBGs. Experiments show that even small sidebands of nonapodized FBGs have strong influences on the signal resulted by an AWG device with a Gaussian profile.

  10. Characterization of Si3N4/SiO2 optical channel waveguides by photon scanning tunneling microscopy

    NASA Technical Reports Server (NTRS)

    Wang, Yan; Chudgar, Mona H.; Jackson, Howard E.; Miller, Jeffrey S.; De Brabander, Gregory N.; Boyd, Joseph T.

    1993-01-01

    Photon scanning tunneling microscopy (PSTM) is used to characterize Si3N4/Si02 optical channel waveguides being used for integrated optical-micromechanical sensors. PSTM utilizes an optical fiber tapered to a fine point which is piezoelectrically positioned to measure the decay of the evanescent field intensity associated with the waveguide propagating mode. Evanescent field decays are recorded for both ridge channel waveguides and planar waveguide regions. Values for the local effective refractive index are calculated from the data for both polarizations and compared to model calculations.

  11. Real-time association rate constant measurement using combination tapered fiber-optic biosensor (CTFOB) dip-probes

    PubMed Central

    Simmonds, Boris; Wang, Chun-Wei; Kapoor, Rakesh

    2011-01-01

    This document reports a novel method of measuring association rate constant (ka) for antibody-antigen interaction using evanescent wave-based combination tapered fiber-optic biosensor (CTFOB) dip-probes. The method was demonstrated by measuring association rate constant for bovine serum albumin (BSA) and anti-BSA antibody interaction. “Direct method” was used for detection; goat anti-BSA “capture” antibodies were immobilized on the probe surfaces while the antigen (BSA) was directly labeled with Alexa 488 dye. The probes were subsequently submerged in 3 nM Labeled BSA in egg albumin (1 mg/ml). The fluorescence signal recorded was proportional to BSA anti-BSA conjugates and continuous signal was acquired suing a fiber optic spectrometer (Ocean Optics, Inc.). A 476 nm diode laser was use as an excitation source. Association constant was estimated from a plot of signal as a function of time. Measured association rate constant ka for the binding of BSA with anti-BSA at room temperature is (8.33 ± 0.01) ×104 M−1 s−1. PMID:21643496

  12. 5 W frequency stabilized 976 nm tapered diode lasers

    NASA Astrophysics Data System (ADS)

    Friedmann, Patrick; Gilly, Jürgen; Moritz, Stefan; Ostendorf, Ralf; Kelemen, Márc T.

    2008-02-01

    More and more applications, like tunable frequency doubling of diode lasers for blue-green outputs, non linear spectroscopy, or pump laser sources for fiber lasers necessitate diffraction-limited tunable narrow linewidths and high output powers in the multiwatt regime. For these applications, tapered lasers based on a tapered amplifier with gain-guided design can be used in an external cavity set up to guarantee both - frequency stabilization and tunability. We have realized frequency stabilized high-power ridge-waveguide tapered diode lasers with more than 4W of cw output power. These low modal gain, single quantum well InGaAs/AlGaAs devices emitting between 920nm and 1064nm were grown by molecular beam epitaxy. Tapered single emitters consist of an index-guided ridge section and a gain-guided taper section with an overall length of 3.5mm. The taper angle was 6°. With a high-reflectivity coating on the rear facet and an antireflection coating on the front facet more than 10W of output power have been demonstrated. To optimize the beam quality at higher output power the two different sections have been operated by different operation currents. For this purpose the tapered diodes have been mounted p-side down on structured submounts. For wavelength tunability and frequency stabilization the tapered diodes, provided with AR coatings on both facets, have been used in external cavity setup in Littrow configuration. The influence of the different operation currents on the electrooptical and beam characteristics has been carefully investigated in detail. Within this operation mode a nearly diffraction limited behavior up to 5W has been established.

  13. Examination of tapered plastic multimode fiber-based sensor performance with silver coating for different concentrations of calcium hypochlorite by soft computing methodologies--a comparative study.

    PubMed

    Zakaria, Rozalina; Sheng, Ong Yong; Wern, Kam; Shamshirband, Shahaboddin; Wahab, Ainuddin Wahid Abdul; Petković, Dalibor; Saboohi, Hadi

    2014-05-01

    A soft methodology study has been applied on tapered plastic multimode sensors. This study basically used tapered plastic multimode fiber [polymethyl methacrylate (PMMA)] optics as a sensor. The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 and 10 mm, respectively. In addition, a tapered PMMA probe, which was coated by silver film, was fabricated and demonstrated using a calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observation increment in the transmission of the sensor that is immersed in solutions at high concentrations. As the concentration was varied from 0 to 6 ppm, the output voltage of the sensor increased linearly. The silver film coating increased the sensitivity of the proposed sensor because of the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. In this study, the polynomial and radial basis function (RBF) were applied as the kernel function of the support vector regression (SVR) to estimate and predict the output voltage response of the sensors with and without silver film according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf were used in an attempt to minimize the generalization error bound so as to achieve generalized performance. An adaptive neuro-fuzzy interference system (ANFIS) approach was also investigated for comparison. The experimental results showed that improvements in the predictive accuracy and capacity for generalization can be achieved by the SVR_poly approach in comparison to the SVR_rbf methodology. The same testing errors were found for the SVR_poly approach and the ANFIS approach. PMID:24979634

  14. Examination of tapered plastic multimode fiber-based sensor performance with silver coating for different concentrations of calcium hypochlorite by soft computing methodologies--a comparative study.

    PubMed

    Zakaria, Rozalina; Sheng, Ong Yong; Wern, Kam; Shamshirband, Shahaboddin; Wahab, Ainuddin Wahid Abdul; Petković, Dalibor; Saboohi, Hadi

    2014-05-01

    A soft methodology study has been applied on tapered plastic multimode sensors. This study basically used tapered plastic multimode fiber [polymethyl methacrylate (PMMA)] optics as a sensor. The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 and 10 mm, respectively. In addition, a tapered PMMA probe, which was coated by silver film, was fabricated and demonstrated using a calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observation increment in the transmission of the sensor that is immersed in solutions at high concentrations. As the concentration was varied from 0 to 6 ppm, the output voltage of the sensor increased linearly. The silver film coating increased the sensitivity of the proposed sensor because of the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. In this study, the polynomial and radial basis function (RBF) were applied as the kernel function of the support vector regression (SVR) to estimate and predict the output voltage response of the sensors with and without silver film according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf were used in an attempt to minimize the generalization error bound so as to achieve generalized performance. An adaptive neuro-fuzzy interference system (ANFIS) approach was also investigated for comparison. The experimental results showed that improvements in the predictive accuracy and capacity for generalization can be achieved by the SVR_poly approach in comparison to the SVR_rbf methodology. The same testing errors were found for the SVR_poly approach and the ANFIS approach.

  15. Fiber-Type Random Laser Based on a Cylindrical Waveguide with a Disordered Cladding Layer

    PubMed Central

    Zhang, Wei Li; Zheng, Meng Ya; Ma, Rui; Gong, Chao Yang; Yang, Zhao Ji; Peng, Gang Ding; Rao, Yun Jiang

    2016-01-01

    This letter reports a fiber-type random laser (RL) which is made from a capillary coated with a disordered layer at its internal surface and filled with a gain (laser dye) solution in the core region. This fiber-type optical structure, with the disordered layer providing randomly scattered light into the gain region and the cylindrical waveguide providing confinement of light, assists the formation of random lasing modes and enables a flexible and efficient way of making random lasers. We found that the RL is sensitive to laser dye concentration in the core region and there exists a fine exponential relationship between the lasing intensity and particle concentration in the gain solution. The proposed structure could be a fine platform of realizing random lasing and random lasing based sensing. PMID:27220636

  16. Sensitive detection of beryllium using a fiber optic liquid waveguide cell.

    PubMed

    Deng, Gang; Wei, Lily; Collins, Greg E

    2003-05-28

    The metallochromic chelating agent, Chromazurol S, has been utilized in conjunction with a fiber optic liquid waveguide capillary cell to enable the sensitive detection of beryllium in solution (30 ng l(-1) detection limit) and following extraction from a contaminated plexiglas surface (0.5 ng cm(-2) detection limit). The addition of a cationic surfactant, cetylpyridinium chloride, to Chromazurol S at pH 10 in Tris-HCl buffer results in the formation of two bathochromic peaks in the visible spectrum following metal chelation by beryllium. The first absorbance band, at 515 nm, is intermediate in nature, permitting maximal sensitivity for low beryllium concentrations, but diminishing in intensity at concentrations above 100 mug l(-1). The second absorbance band, centered at 610 nm, dominates for beryllium concentrations of 100 mug l(-1) and above. Experimental conditions including pH, buffer type, additive surfactants, masking agents, and dye concentration were investigated in order to optimize detection sensitivity and selectivity. A fiber optic spectrometer is used with both a liquid waveguide capillary cell and 1 cm cuvette cell, to give a sensitive and broad dynamic range for beryllium detection that capitalizes on both beryllium metal chelate absorbance bands formed under these conditions.

  17. Mode converter based on an inverse taper for multimode silicon nanophotonic integrated circuits.

    PubMed

    Dai, Daoxin; Mao, Mao

    2015-11-01

    An inverse taper on silicon is proposed and designed to realize an efficient mode converter available for the connection between multimode silicon nanophotonic integrated circuits and few-mode fibers. The present mode converter has a silicon-on-insulator inverse taper buried in a 3 × 3μm(2) SiN strip waveguide to deal with not only for the fundamental mode but also for the higher-order modes. The designed inverse taper enables the conversion between the six modes (i.e., TE(11), TE(21), TE(31), TE(41), TM(11), TM(12)) in a 1.4 × 0.22μm(2) multimode SOI waveguide and the six modes (like the LP(01), LP(11a), LP(11b) modes in a few-mode fiber) in a 3 × 3μm(2) SiN strip waveguide. The conversion efficiency for any desired mode is higher than 95.6% while any undesired mode excitation ratio is lower than 0.5%. This is helpful to make multimode silicon nanophotonic integrated circuits (e.g., the on-chip mode (de)multiplexers developed well) available to work together with few-mode fibers in the future.

  18. Mode converter based on an inverse taper for multimode silicon nanophotonic integrated circuits.

    PubMed

    Dai, Daoxin; Mao, Mao

    2015-11-01

    An inverse taper on silicon is proposed and designed to realize an efficient mode converter available for the connection between multimode silicon nanophotonic integrated circuits and few-mode fibers. The present mode converter has a silicon-on-insulator inverse taper buried in a 3 × 3μm(2) SiN strip waveguide to deal with not only for the fundamental mode but also for the higher-order modes. The designed inverse taper enables the conversion between the six modes (i.e., TE(11), TE(21), TE(31), TE(41), TM(11), TM(12)) in a 1.4 × 0.22μm(2) multimode SOI waveguide and the six modes (like the LP(01), LP(11a), LP(11b) modes in a few-mode fiber) in a 3 × 3μm(2) SiN strip waveguide. The conversion efficiency for any desired mode is higher than 95.6% while any undesired mode excitation ratio is lower than 0.5%. This is helpful to make multimode silicon nanophotonic integrated circuits (e.g., the on-chip mode (de)multiplexers developed well) available to work together with few-mode fibers in the future. PMID:26561108

  19. Ultrathin niobium nanofilms on fiber optical tapers – a new route towards low-loss hybrid plasmonic modes

    PubMed Central

    Wieduwilt, Torsten; Tuniz, Alessandro; Linzen, Sven; Goerke, Sebastian; Dellith, Jan; Hübner, Uwe; Schmidt, Markus A.

    2015-01-01

    Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3–4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal nanofilms. These results demonstrate that ultrathin niobium nanofilms can serve as a new platform for biomedical diagnostics, superconducting photonics, ultrathin metasurfaces or new types of optoelectronic devices. PMID:26593209

  20. Ultrathin niobium nanofilms on fiber optical tapers--a new route towards low-loss hybrid plasmonic modes.

    PubMed

    Wieduwilt, Torsten; Tuniz, Alessandro; Linzen, Sven; Goerke, Sebastian; Dellith, Jan; Hübner, Uwe; Schmidt, Markus A

    2015-01-01

    Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3-4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal nanofilms. These results demonstrate that ultrathin niobium nanofilms can serve as a new platform for biomedical diagnostics, superconducting photonics, ultrathin metasurfaces or new types of optoelectronic devices. PMID:26593209

  1. Ultra-low power fiber-coupled gallium arsenide photonic crystal cavity electro-optic modulator.

    PubMed

    Shambat, Gary; Ellis, Bryan; Mayer, Marie A; Majumdar, Arka; Haller, Eugene E; Vučković, Jelena

    2011-04-11

    We demonstrate a gallium arsenide photonic crystal cavity injection-based electro-optic modulator coupled to a fiber taper waveguide. The fiber taper serves as a convenient and tunable waveguide for cavity coupling with minimal loss. Localized electrical injection of carriers into the cavity region via a laterally doped p-i-n diode combined with the small mode volume of the cavity enable ultra-low energy modulation at sub-fJ/bit levels. Speeds of up to 1 GHz are demonstrated with photoluminescence lifetime measurements revealing that the ultimate limit goes well into the tens of GHz.

  2. Thinnest optical waveguide: experimental test.

    PubMed

    Sumetsky, M; Dulashko, Y; Domachuk, P; Eggleton, B J

    2007-04-01

    A thin dielectric waveguide with a subwavelength diameter can exhibit very small transmission loss only if its diameter is greater than a threshold value, while for smaller diameters, waveguide loss grows dramatically. The threshold diameter of transition between these waveguiding and nonwaveguiding regimes is primarily determined by the wavelength of propagating light and, to a much lesser degree, by the characteristic length of the waveguide's long-range nonuniformity. For this reason, the transmission spectrum of a thin waveguide allows immediate and quite accurate determination of its thickness. An experimental test of these facts is performed for a tapered microfiber. Good agreement with the recently developed theory of adiabatic microfiber tapers is demonstrated.

  3. Numerical model of tapered fiber Bragg gratings for comprehensive analysis and optimization of their sensing and strain-induced tunable dispersion properties.

    PubMed

    Osuch, Tomasz; Markowski, Konrad; Jędrzejewski, Kazimierz

    2015-06-10

    A versatile numerical model for spectral transmission/reflection, group delay characteristic analysis, and design of tapered fiber Bragg gratings (TFBGs) is presented. This approach ensures flexibility with defining both distribution of refractive index change of the gratings (including apodization) and shape of the taper profile. Additionally, sensing and tunable dispersion properties of the TFBGs were fully examined, considering strain-induced effects. The presented numerical approach, together with Pareto optimization, were also used to design the best tanh apodization profiles of the TFBG in terms of maximizing its spectral width with simultaneous minimization of the group delay oscillations. Experimental verification of the model confirms its correctness. The combination of model versatility and possibility to define the other objective functions of Pareto optimization creates a universal tool for TFBG analysis and design. PMID:26192856

  4. Non-adiabatic tapered optical fiber sensor for measuring the interaction between α-amino acids in aqueous carbohydrate solution

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Karami, M.; Gholami, M.; Hosseini, S. M.; Ghezelayagh, M. H.

    2010-10-01

    A single-mode non-adiabatic tapered optical fiber (NATOF) sensor was utilized for sensing the variation in refractive index (RI) with concentration of d-glucose in deionized water and measurement of the RI of amino acids (AAs) in carbohydrate solutions. This method showed a rewarding ability in understanding the basis of biomolecular interactions in biological systems. Due to high sensitivity, ease of application, low cost and real-time measurement, this method is more efficient in comparison with other techniques, such as calorimetric titration, NMR, UV absorption spectroscopy, x-ray crystallography, computer calculations, kinetic studies and chromatography data. The NATOF is fabricated by the heat pulling method, utilizing a CO2 laser. The limit of detection of the NATOF was 55 ppm for a d-glucose concentration ranging from 0 to 80 mg ml-1, and the limit of detection of the RI measurement corresponding to these concentrations in the range from 1.3330 to 1.3447 was 8.2 × 10-6 as a refractometer sensor. The response of the NATOF shows that different kinds of interactions of various groups of AAs, such as l-alanine, l-leucine and l-cysteine with d-glucose, sucrose and water molecules, depend on functional groups in AAs such as OH, SH, CH2, NH+3 and COO-. These results can be interpreted in terms of solute-solute and solute-solvent interactions and the structure making/breaking ability of solutes in the given solution. Such a study helps in the better understanding of the interactions occurring between AA molecules and entities present in biological matrices.

  5. Master-oscillator power-amplifier scheme for efficient green-light generation in a planar MgO:PPLN waveguide.

    PubMed

    Sakai, Kiyohide; Koyata, Yasuharu; Shimada, Naoyuki; Shibata, Kimitaka; Hanamaki, Yoshihiko; Itakura, Shigetaka; Yagi, Tetsuya; Hirano, Yoshihito

    2008-03-01

    We developed a new master-oscillator power-amplifier scheme consisting of a tapered semiconductor amplifier and a fiber-grating-stabilized laser diode for efficient green-light generation in a planar MgO:PPLN waveguide, and demonstrated cw green-light generation of 346 mW. PMID:18311282

  6. Arrayed waveguide collimators for integrating free-space optics on polymeric waveguide devices.

    PubMed

    Shin, Jin-Soo; Lee, Chang-Hee; Shin, Sang-Yung; Huang, Guang-Hao; Chu, Woo-Sung; Oh, Min-Cheol; Noh, Young-Ouk; Lee, Hyung-Jong

    2014-10-01

    Array-type optical devices are important for wavelength-division multiplexing optical communication system to achieve small footprint, mass production, and reliability. For fabricating transmitter module in an array configuration, it is difficult to achieve a passive alignment of isolator, collimating lens, and laser diode. To facilitate array isolator integration, a waveguide collimator is proposed in this work by using a low-contrast, large-core polymer waveguide. The diffraction of a guided mode propagating through a free-space region is suppressed by enlarging the guided mode. The fiber coupling loss due to the enlarged mode was overcome by incorporating an adiabatic taper structure. The excess loss of waveguide collimator including the loss through a 400-μm free-propagation region was less than 1.0 dB. PMID:25321959

  7. Photonic lantern with multimode fibers embedded

    NASA Astrophysics Data System (ADS)

    Yu, Hai-Jiao; Yan, Qi; Huang, Zong-Jun; Tian, He; Jiang, Yu; Liu, Yong-Jun; Zhang, Jian-Zhong; Sun, Wei-Min

    2014-08-01

    A photonic lantern is studied which is formed by seven multimode fibers inserted into a pure silica capillary tube. The core of the tapered end has a uniform refractive index because the polymer claddings are removed before the fibers are inserted. Consequently, the light distribution is also uniform. Two theories describing a slowly varying waveguide and multimode coupling are used to analyze the photonic lantern. The transmission loss decreases as the length of the tapered part increases. For a device with a taper length of 3.4 cm, the loss is about 1.06 dB on average for light propagating through the taper from an inserted fiber to the tapered end and 0.99 dB in the reverse direction. For a device with a taper length of 0.7 cm, the two loss values are 2.63 dB and 2.53 dB, respectively. The results show that it is possible to achieve a uniform light distribution with the tapered end and a low-loss transmission in the device if parameters related to the lantern are reasonably defined.

  8. Watt-level second-harmonic generation at 589  nm with a PPMgO:LN ridge waveguide crystal pumped by a DBR tapered diode laser.

    PubMed

    Bege, R; Jedrzejczyk, D; Blume, G; Hofmann, J; Feise, D; Paschke, K; Tränkle, G

    2016-04-01

    A DBR tapered diode laser in continuous wave operation was used to generate second-harmonic radiation at 589 nm in a PPMgO:LN ridge waveguide crystal. An optical output power of 0.86 W at an optical-to-optical and an electrical-to-optical efficiency of 42% and 11%, respectively, was achieved. The visible radiation was characterized by a spectral bandwidth ΔνFWHM of 230 MHz and a beam propagation parameter M1/e22 better than 1.1. The integration of such a system into a housing of a small footprint will enable a portable and highly efficient module featuring a visible output power in the watt-level range. PMID:27192279

  9. Power scaling estimate of crystalline fiber waveguides with rare earth doped YAG cores

    NASA Astrophysics Data System (ADS)

    Li, Da; Hong, Pengda; Meissner, Stephanie K.; Meissner, Helmuth E.

    2016-03-01

    Power scaling analysis based on the model by Dawson et al. [1,2] for circular core fibers has been applied to estimating power scaling of crystalline fiber waveguides (CFWs) with RE3+ doped single crystalline or ceramic YAG (RE=rare earth: Yb, Er, Tm and Ho). Power scaling limits include stimulated Brillouin scattering, thermal lensing effect, and limits to coupling of pump light into CFWs. The CFW designs we have considered consist, in general, of a square doped RE3+:YAG core, an inner cladding of either undoped or laser-inactive-ion-doped YAG and an outer cladding of sapphire. The presented data have been developed for the structures fabricated using the Adhesive-Free Bonding (AFB®) technique, but the results should be essentially independent of fabrication technique, assuming perfect core/inner cladding/outer cladding interfaces. Hard power scaling limits exist for a specific CFW design and are strongly based on the physical constants of the material and its spectroscopic specifics. For example, power scaling limit was determined as ~16 kW for 2.5% ceramic Yb:YAG/YAG (core material/inner cladding material) at fiber length of 1.7 m and core diameter of 69 μm. Considering the present manufacturing limit for CFW length to be, e.g., 0.5 m, the actual maximum output power will be limited to ~4.4 kW for a Yb:YAG/YAG CFW. Power limit estimates have also been computed for Er3+, Tm3+ and Ho3+doped core based CFWs.

  10. Optical waveguide modeling of refractive index mediated pH responses in silica nanocomposite thin film based fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Ohodnicki, P. R.; Wang, C.

    2016-02-01

    Recent experiments have demonstrated a pH-dependent optical transmission of silica based nanocomposite thin film enabled evanescent wave absorption spectroscopy based fiber optic sensors in aqueous solutions. Although the response was observed to linearly correlate with the pH-dependent surface charge density of the silica matrix, the responsible mechanism was not fully clarified. In this manuscript, an optical waveguide model is applied to describe observed responses through a modified effective refractive index of the silica matrix layer as a function of the solution phase pH. The refractive index dependence results from a surface charge dependent ionic adsorption, resulting in concentration of ionic species at charged surfaces. The resultant effective index modification to porous silica is estimated through effective medium theories and applied to an optical waveguide model of a multi-mode fiber optic based sensor response capable of reproducing all experimental observations reported to date.

  11. Nanosecond pulse shaping at 780 nm with fiber-based electro-optical modulators and a double-pass tapered amplifier

    NASA Astrophysics Data System (ADS)

    Rogers, C. E.; Gould, P. L.

    2016-02-01

    We describe a system for generating frequency-chirped and amplitude-shaped pulses on time scales from sub-nanosecond to ten nanoseconds. The system starts with cw diode-laser light at 780 nm and utilizes fiber-based electro-optical phase and intensity modulators, driven by an arbitrary waveform generator, to generate the shaped pulses. These pulses are subsequently amplified to several hundred mW with a tapered amplifier in a delayed double-pass configuration. Frequency chirps up to 5 GHz in 2 ns and pulse widths as short as 0.15 ns have been realized.

  12. Nanosecond pulse shaping at 780 nm with fiber-based electro-optical modulators and a double-pass tapered amplifier.

    PubMed

    Rogers, C E; Gould, P L

    2016-02-01

    We describe a system for generating frequency-chirped and amplitude-shaped pulses on time scales from sub-nanosecond to ten nanoseconds. The system starts with cw diode-laser light at 780 nm and utilizes fiber-based electro-optical phase and intensity modulators, driven by an arbitrary waveform generator, to generate the shaped pulses. These pulses are subsequently amplified to several hundred mW with a tapered amplifier in a delayed double-pass configuration. Frequency chirps up to 5 GHz in 2 ns and pulse widths as short as 0.15 ns have been realized. PMID:26906832

  13. Broad band waveguide spectrometer

    DOEpatents

    Goldman, Don S.

    1995-01-01

    A spectrometer for analyzing a sample of material utilizing a broad band source of electromagnetic radiation and a detector. The spectrometer employs a waveguide possessing an entry and an exit for the electromagnetic radiation emanating from the source. The waveguide further includes a surface between the entry and exit portions which permits interaction between the electromagnetic radiation passing through the wave guide and a sample material. A tapered portion forms a part of the entry of the wave guide and couples the electromagnetic radiation emanating from the source to the waveguide. The electromagnetic radiation passing from the exit of the waveguide is captured and directed to a detector for analysis.

  14. Multipoint-emitting optical fibers for spatially addressable in vivo optogenetics.

    PubMed

    Pisanello, Ferruccio; Sileo, Leonardo; Oldenburg, Ian A; Pisanello, Marco; Martiradonna, Luigi; Assad, John A; Sabatini, Bernardo L; De Vittorio, Massimo

    2014-06-18

    Optical stimulation and silencing of neural activity is a powerful technique for elucidating the structure and function of neural circuitry. In most in vivo optogenetic experiments, light is delivered into the brain through a single optical fiber. However, this approach limits illumination to a fixed volume of the brain. Here a focused ion beam is used to pattern multiple light windows on a tapered optical fiber. We show that such fibers allow selective and dynamic illumination of different brain regions along the taper. Site selection is achieved by a simple coupling strategy at the fiber input, and the use of a single tapered waveguide minimizes the implant invasiveness. We demonstrate the effectiveness of this approach for multipoint optical stimulation in the mammalian brain in vivo by coupling the fiber to a microelectrode array and performing simultaneous extracellular recording and stimulation at multiple sites in the mouse striatum and cerebral cortex. PMID:24881834

  15. Multipoint-emitting optical fibers for spatially addressable in vivo optogenetics.

    PubMed

    Pisanello, Ferruccio; Sileo, Leonardo; Oldenburg, Ian A; Pisanello, Marco; Martiradonna, Luigi; Assad, John A; Sabatini, Bernardo L; De Vittorio, Massimo

    2014-06-18

    Optical stimulation and silencing of neural activity is a powerful technique for elucidating the structure and function of neural circuitry. In most in vivo optogenetic experiments, light is delivered into the brain through a single optical fiber. However, this approach limits illumination to a fixed volume of the brain. Here a focused ion beam is used to pattern multiple light windows on a tapered optical fiber. We show that such fibers allow selective and dynamic illumination of different brain regions along the taper. Site selection is achieved by a simple coupling strategy at the fiber input, and the use of a single tapered waveguide minimizes the implant invasiveness. We demonstrate the effectiveness of this approach for multipoint optical stimulation in the mammalian brain in vivo by coupling the fiber to a microelectrode array and performing simultaneous extracellular recording and stimulation at multiple sites in the mouse striatum and cerebral cortex.

  16. Magnetic field sensing based on magnetic-fluid-clad fiber-optic structure with taper-like and lateral-offset fusion splicing.

    PubMed

    Dong, Shaohua; Pu, Shengli; Wang, Haotian

    2014-08-11

    A kind of magnetic field sensor composed of magnetic fluid surrounding a segment of singlemode fiber is proposed. The taper-like and lateral-offset fusion splicing techniques are employed. The sensing principle is based on cladding mode interference. The interference valley wavelength or transmission loss of the sensing structure is sensitive to the external magnetic field, which is utilized for magnetic field sensing. The linear response regions are obtained in the range of 38-225 Oe and 250-475 Oe. For the valley-wavelength-shift-type sensing, the sensitivities are 14.1 pm/Oe and 26 pm/Oe at low and high field ranges, respectively. For the transmission-loss-variation-type sensing, the sensitivity of -0.024 dB/Oe is achieved for the magnetic field strength ranging from 250 to 475 Oe. PMID:25320997

  17. Evanescent straight tapered-fiber coupling of ultra-high Q optomechanical micro-resonators in a low-vibration helium-4 exchange-gas cryostat.

    PubMed

    Rivière, R; Arcizet, O; Schliesser, A; Kippenberg, T J

    2013-04-01

    We developed an apparatus to couple a 50-μm diameter whispering-gallery silica microtoroidal resonator in a helium-4 cryostat using a straight optical tapered-fiber at 1550 nm wavelength. On a top-loading probe specifically adapted for increased mechanical stability, we use a specifically-developed "cryotaper" to optically probe the cavity, allowing thus to record the calibrated mechanical spectrum of the optomechanical system at low temperatures. We then demonstrate excellent thermalization of a 63-MHz mechanical mode of a toroidal resonator down to the cryostat's base temperature of 1.65 K, thereby proving the viability of the cryogenic refrigeration via heat conduction through static low-pressure exchange gas. In the context of optomechanics, we therefore provide a versatile and powerful tool with state-of-the-art performances in optical coupling efficiency, mechanical stability, and cryogenic cooling.

  18. Magnetic field tunability of optical microfiber taper integrated with ferrofluid.

    PubMed

    Miao, Yinping; Wu, Jixuan; Lin, Wei; Zhang, Kailiang; Yuan, Yujie; Song, Binbin; Zhang, Hao; Liu, Bo; Yao, Jianquan

    2013-12-01

    Optical microfiber taper has unique propagation properties, which provides versatile waveguide structure to design the tunable photonic devices. In this paper, the S-tapered microfiber is fabricated by using simple fusion spicing. The spectral characteristics of microfiber taper integrated with ferrofluid under different magnetic-field intensities have been theoretically analyzed and experimentally demonstrated. The spectrum are both found to become highly magnetic-field-dependent. The results indicate the transmission and wavelength of the dips are adjustable by changing magnetic field intensity. The response of this device to the magnetic field intensity exhibits a Langvin function. Moreover, there is a linear relationship between the transmission loss and magnetic field intensity for a magnetic field intensity range of 25 to 200Oe, and the sensitivities as high as 0.13056dB/Oe and 0.056nm/Oe have been achieved, respectively. This suggests a potential application of this device as a tunable all-in-fiber photonic device, such as magneto-optic modulator, filter, and sensing element. PMID:24514542

  19. Evanescent field absorption based photonic polymer waveguide biosensor

    NASA Astrophysics Data System (ADS)

    Boiragi, Indrajit; Makkar, Roshan; Choudhury, Bikash Dev; Mukherji, Soumyo; Chalapathi, K.

    2011-08-01

    This paper details the design and fabrication of an integrated optical waveguide biosensor for antibody/antigen detection. SU-8 polymer is used as the core material to have a bi-conical tapered waveguide fabricated on a silicon substrate. PDMS is used as a buffer layer. The waist diameter of the biconical tapered waveguide has been optimized using Opti-BPM CAD software before fabrication. In addition, the fabrication technique employs simultaneous and single-step formation of the polymer waveguide structures for the guidance of light with V-grooves for low-cost passive alignment of glass optical fiber. The designed biosensor chip demonstrates sensing of FITC tagged goat anti human IgG (GaHIgG) and HIgG immobilized over the sensor surface was the bio receptor. The sensor uses the evanescent field that is present at the surface of the core for rapid and accurate sensing of antibody/antigen in the range of few micrograms per ml.

  20. Evanescent field absorption based photonic polymer waveguide biosensor

    NASA Astrophysics Data System (ADS)

    Boiragi, Indrajit; Makkar, Roshan; Choudhury, Bikash Dev; Mukherji, Soumyo; Chalapathi, K.

    2010-12-01

    This paper details the design and fabrication of an integrated optical waveguide biosensor for antibody/antigen detection. SU-8 polymer is used as the core material to have a bi-conical tapered waveguide fabricated on a silicon substrate. PDMS is used as a buffer layer. The waist diameter of the biconical tapered waveguide has been optimized using Opti-BPM CAD software before fabrication. In addition, the fabrication technique employs simultaneous and single-step formation of the polymer waveguide structures for the guidance of light with V-grooves for low-cost passive alignment of glass optical fiber. The designed biosensor chip demonstrates sensing of FITC tagged goat anti human IgG (GaHIgG) and HIgG immobilized over the sensor surface was the bio receptor. The sensor uses the evanescent field that is present at the surface of the core for rapid and accurate sensing of antibody/antigen in the range of few micrograms per ml.

  1. A miniaturized fiber-optic colorimetric sensor for nitrite determination by coupling with a microfluidic capillary waveguide.

    PubMed

    Xiong, Yan; Wang, Cheng-Jie; Tao, Tao; Duan, Ming; Fang, Shen-Wen; Zheng, Min

    2016-05-01

    A microfluidic-capillary-waveguide-coupled fiber-optic sensor was developed for colorimetric determination of hazardous nitrite based on the Griess-Ilosvay reaction. The sensor was modularly designed by use of a light-emitting diode as the light source, silica fiber as the light transmission element, and a capillary waveguide tube as the light reaction flow cell. With the light interacting with the azo dye generated by the Griess-Ilosvay reaction between nitrite and Griess reagents, nitrite could be determined by a colorimetric method according to Beer's law. By use of the inexpensive and micro-sized elements mentioned above, the sensor provided a new low-cost and portable method for in situ and online measurement of nitrite. The sensor had a wide linear range for nitrite from 0.02 to 1.8 mg L(-1) and a low detection limit of 7 μg L(-1) (3σ), with a relative standard deviation of 0.37% (n = 10). With a low reagent demand of 200 μL, a short response time of 6.24 s, and excellent selectivity, the sensor is environmentally friendly and has been applied to nitrite determination in different water samples. The results were compared with those obtained by conventional spectrophotometry and ion chromatography, indicating the sensor's potential for practical applications.

  2. Superluminescent diode monolithically integrated with novel Y-branch by bundle integrated waveguide for fiber optic gyroscope

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Zhao, Ling-Juan; Chen, Wei-Xi; Pan, Jiao-Qing; Zhou, Fan; Zhu, Hong-Liang; Wang, Wei

    2008-01-01

    We have developed a novel InP-based, ridge-waveguide photonic integrated circuit (PIC), which consists of a 1.1-um wavelength Y-branch optical waveguide with low loss and improved far field pattern and a 1.3-um wavelength strained InGaAsP-InP multiple quantum-well superluminescent diode, with bundle integrated guide (BIG) as the scheme for monolithic integration. The simulations of BIG and Y-branches show low losses and improved far-field patterns, based on the beam propagation method (BPM). The amplified spontaneous emission of the device is up to 10 mW at 120 mA with no threshold and saturation. Spectral characteristics of about 30 nm width and less than 1 dB modulation are achieved using the built-in anti-lasing ability of Y-branch. The beam divergence angles in horizontal and vertical directions are optimized to as small as 12°×8°, resulting in good fiber coupling. The compactness, simplicity in fabrication, good superluminescent performance, low transmission loss and estimated low coupling loss prove the BIG and Y-branch method to be a feasible way for integration and make the photonic integrated circuit of Y-branch and superluminescent diode an promising candidate for transmitter and transceiver used in fiber optic gyroscope.

  3. A miniaturized fiber-optic colorimetric sensor for nitrite determination by coupling with a microfluidic capillary waveguide.

    PubMed

    Xiong, Yan; Wang, Cheng-Jie; Tao, Tao; Duan, Ming; Fang, Shen-Wen; Zheng, Min

    2016-05-01

    A microfluidic-capillary-waveguide-coupled fiber-optic sensor was developed for colorimetric determination of hazardous nitrite based on the Griess-Ilosvay reaction. The sensor was modularly designed by use of a light-emitting diode as the light source, silica fiber as the light transmission element, and a capillary waveguide tube as the light reaction flow cell. With the light interacting with the azo dye generated by the Griess-Ilosvay reaction between nitrite and Griess reagents, nitrite could be determined by a colorimetric method according to Beer's law. By use of the inexpensive and micro-sized elements mentioned above, the sensor provided a new low-cost and portable method for in situ and online measurement of nitrite. The sensor had a wide linear range for nitrite from 0.02 to 1.8 mg L(-1) and a low detection limit of 7 μg L(-1) (3σ), with a relative standard deviation of 0.37% (n = 10). With a low reagent demand of 200 μL, a short response time of 6.24 s, and excellent selectivity, the sensor is environmentally friendly and has been applied to nitrite determination in different water samples. The results were compared with those obtained by conventional spectrophotometry and ion chromatography, indicating the sensor's potential for practical applications. PMID:26939671

  4. Characterization of silver halide fiber optics and hollow silica waveguides for use in the construction of a mid-infrared attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy probe.

    PubMed

    Damin, Craig A; Sommer, André J

    2013-11-01

    Advances in fiber optic materials have allowed for the construction of fibers and waveguides capable of transmitting infrared radiation. An investigation of the transmission characteristics associated with two commonly used types of infrared-transmitting fibers/waveguides for prospective use in a fiber/waveguide-coupled attenuated total internal reflection (ATR) probe was performed. Characterization of silver halide polycrystalline fiber optics and hollow silica waveguides was done on the basis of the transmission of infrared light using a conventional fiber optic coupling accessory and an infrared microscope. Using the fiber optic coupling accessory, the average percent transmission for three silver halide fibers was 18.1 ± 6.1% relative to a benchtop reflection accessory. The average transmission for two hollow waveguides (HWGs) using the coupling accessory was 8.0 ± 0.3%. (Uncertainties in the relative percent transmission represent the standard deviations.) Reduced transmission observed for the HWGs was attributed to the high numerical aperture of the coupling accessory. Characterization of the fibers/waveguides using a zinc selenide lens objective on an infrared microscope indicated 24.1 ± 7.2% of the initial light input into the silver halide fibers was transmitted. Percent transmission obtained for the HWGs was 98.7 ± 0.1%. Increased transmission using the HWGs resulted from the absence or minimization of insertion and scattering losses due to the hollow air core and a better-matched numerical aperture. The effect of bending on the transmission characteristics of the fibers/waveguides was also investigated. Significant deviations in the transmission of infrared light by the solid-core silver halide fibers were observed for various bending angles. Percent transmission greater than 98% was consistently observed for the HWGs at the bending angles. The combined benefits of high percent transmission, reproducible instrument responses, and increased bending

  5. Electro-optical line cards with multimode polymer waveguides for chip-to-chip interconnects

    NASA Astrophysics Data System (ADS)

    Zhu, Long Xiu; Immonen, Marika; Wu, Jinhua; Yan, Hui Juan; Shi, Ruizhi; Chen, Peifeng; Rapala-Virtanen, Tarja

    2014-10-01

    In this paper, we report developments of electro-optical PCBs (EO-PCB) with low-loss (<0.05dB/cm) polymer waveguides. Our results shows successful fabrication of complex waveguide structures part of hybrid EO-PCBs utilizing production scale process on standard board panels. Test patterns include 90° bends of varying radii (40mm - 2mm), waveguide crossing with varied crossing angles (90°-20°), cascaded bends with varying radii, splitters and tapered waveguides. Full ranges of geometric configurations are required to meet practical optical routing functions and layouts. Moreover, we report results obtained to realize structures to integrate optical connectors with waveguides. Experimental results are shown for MT in-plane and 90° out-of-plane optical connectors realized with coupling loss < 2dB and < 2.5 dB, respectively. These connectors are crucial to realize efficient light coupling from/to TX/RX chip-to-waveguide and within waveguide-to-fiber connections in practical optical PCBs. Furthermore, we show results for fabricating electrical interconnect structures e.g. tracing layers, vias, plated vias top/bottom and through optical layers. Process compatibility with accepted practices and production scale up for high volumes are key concerns to meet the yield target and cost efficiency. Results include waveguide characterization, transmission loss, misalignment tolerance, and effect of lamination. Critical link metrics are reported.

  6. Low-temperature-sensitive relative humidity sensor based on tapered square no-core fiber coated with SiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Miao, Yinping; Ma, Xixi; He, Yong; Zhang, Hongmin; Zhang, Hao; Song, Binbin; Liu, Bo; Yao, Jianquan

    2016-05-01

    A low-temperature-sensitive relative humidity (RH) sensor based on multimode interference effects has been proposed. The sensor consists of a section of tapered square no-core fiber (TSNCF) coated with SiO2 nanoparticles which is fabricated by splicing the TSNCF with two single-mode fibers (SMFs). The refractive index of SiO2 nanoparticles changes with the variation of environmental humidity levels. Characteristics of the transmission spectral have been investigated under different humidity levels. The wavelength shifts up to 10.2 nm at 1410 nm and 11.5 nm at 1610 nm for a RH range of 43.6-98.6% have been experimentally achieved, and the corresponding sensitivities reach 456.21 pm/%RH and 584.2 pm/%RH for a RH range of 83-96.6%, respectively. The temperature response of the proposed sensor has also been experimentally investigated. Due to the fact that the sensing head is made of a pure silica rod with a low thermal expansion coefficient and the thermo-optic coefficient, the transmission spectrum shows a low temperature sensitivity of about 6 pm/°C for an environmental temperature of 20.9-80 °C, which is a desirable merit to resolve the temperature cross sensitivity. Therefore, the proposed sensor could be applied to breath analysis applications with low temperature fluctuations.

  7. Thermally controlled coupling of a rolled-up microtube integrated with a waveguide on a silicon electronic-photonic integrated circuit.

    PubMed

    Zhong, Qiuhang; Tian, Zhaobing; Veerasubramanian, Venkat; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

    2014-05-01

    We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up microtube and a waveguide on a silicon electronic-photonic integrated circuit. The microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the microtube and the waveguide using localized heaters, the microtube-waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0-6 V.

  8. Response characterization of a fiber optic sensor array with dye-coated planar waveguide for detection of volatile organic compounds.

    PubMed

    Lee, Jae-Sung; Yoon, Na-Rae; Kang, Byoung-Ho; Lee, Sang-Won; Gopalan, Sai-Anand; Jeong, Hyun-Min; Lee, Seung-Ha; Kwon, Dae-Hyuk; Kang, Shin-Won

    2014-07-01

    We have developed a multi-array side-polished optical-fiber gas sensor for the detection of volatile organic compound (VOC) gases. The side-polished optical-fiber coupled with a polymer planar waveguide (PWG) provides high sensitivity to alterations in refractive index. The PWG was fabricated by coating a solvatochromic dye with poly(vinylpyrrolidone). To confirm the effectiveness of the sensor, five different sensing membranes were fabricated by coating the side-polished optical-fiber using the solvatochromic dyes Reinhardt's dye, Nile red, 4-aminophthalimide, 4-amino-N-methylphthalimide, and 4-(dimethylamino)cinnamaldehyde, which have different polarities that cause changes in the effective refractive index of the sensing membrane owing to evanescent field coupling. The fabricated gas detection system was tested with five types of VOC gases, namely acetic acid, benzene, dimethylamine, ethanol, and toluene at concentrations of 1, 2,…,10 ppb. Second-regression and principal component analyses showed that the response properties of the proposed VOC gas sensor were linearly shifted bathochromically, and each gas showed different response characteristics.

  9. Response Characterization of a Fiber Optic Sensor Array with Dye-Coated Planar Waveguide for Detection of Volatile Organic Compounds

    PubMed Central

    Lee, Jae-Sung; Yoon, Na-Rae; Kang, Byoung-Ho; Lee, Sang-Won; Gopalan, Sai-Anand; Jeong, Hyun-Min; Lee, Seung-Ha; Kwon, Dae-Hyuk; Kang, Shin-Won

    2014-01-01

    We have developed a multi-array side-polished optical-fiber gas sensor for the detection of volatile organic compound (VOC) gases. The side-polished optical-fiber coupled with a polymer planar waveguide (PWG) provides high sensitivity to alterations in refractive index. The PWG was fabricated by coating a solvatochromic dye with poly(vinylpyrrolidone). To confirm the effectiveness of the sensor, five different sensing membranes were fabricated by coating the side-polished optical-fiber using the solvatochromic dyes Reinhardt's dye, Nile red, 4-aminophthalimide, 4-amino-N-methylphthalimide, and 4-(dimethylamino)cinnamaldehyde, which have different polarities that cause changes in the effective refractive index of the sensing membrane owing to evanescent field coupling. The fabricated gas detection system was tested with five types of VOC gases, namely acetic acid, benzene, dimethylamine, ethanol, and toluene at concentrations of 1, 2,…,10 ppb. Second-regression and principal component analyses showed that the response properties of the proposed VOC gas sensor were linearly shifted bathochromically, and each gas showed different response characteristics. PMID:24988381

  10. BRIEF COMMUNICATIONS: Influence of γ irradiation on the temperature dependence of the optical losses in quartz glass-polymer fiber waveguides

    NASA Astrophysics Data System (ADS)

    Andreev, A. Ts; Borkina, G. Yu; Bubnov, M. M.; Voĭtsekhovskiĭ, V. V.; Dianov, Evgenii M.; Kotov, V. M.; Pryakhina, Tatiana A.

    1981-08-01

    A study was made of the influence of γ irradiation on the temperature dependences of the optical losses in quartz glass-polymer fiber waveguides. The working temperature range was extended by γ irradiation to subzero temperatures in the case of two types of waveguide: those with a cladding made of SIÉL commercial silicone rubber and those made by the Quartz-Silice firm. The results obtained were explained by changes in the structure of silicone rubber under the action of γ irradiation.

  11. Biconical tapered optical fiber biosensor for measuring refractive index of a-amino acids in aqueous D-glucose and sucrose solution

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Karami, M.; Gholami, M.; Hosseini, S. M.; Ghezelayagh, M. H.

    2010-04-01

    A single-mode biconical tapered optical fiber (BTOF) sensor was utilized for sensing the variation of refractive index (RI) with concentration of D-glucose in double distilled deionized water and measuring of RI of amino acids (AAs) in carbohydrate solutions. This method showed a rewarding ability in understanding the basis of biomolecular interactions in biological systems. The BTOF is fabricated by heat pulling method, utilizing a CO2 laser. The detection limit of the BTOF was 50 ppb for the D-glucose concentration ranging from 0 to 80 ppm, and RI detection limit corresponding to these concentrations in the range at 1.3333 to 1.3404 was 5.4×10-6 as a refractometer sensor. The response of the BTOF shows that the different kinds of interactions of various groups of AAs such as L-alanine, L-leucine, and L-cystein with D-glucose, sucrose and water molecules depend on functional groups in AAs such as OH, SH;CH2;NH3+ ,COO-. These results can be interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.

  12. Infrared evanescent field sensing with quantum cascade lasers and planar silver halide waveguides.

    PubMed

    Charlton, Christy; Katzir, Abraham; Mizaikoff, Boris

    2005-07-15

    We demonstrate the first midinfrared evanescent field absorption measurements with an InGaAs/AlInAs/InP distributed feedback (DFB) quantum cascade laser (QCL) light source operated at room temperature coupled to a free-standing, thin-film, planar, silver halide waveguide. Two different analytes, each matched to the emission frequency of a QCL, were investigated to verify the potential of this technique. The emission of a 1650 cm(-1) QCL overlaps with the amide absorption band of urea, which was deposited from methanol solution, forming urea crystals at the waveguide surface after solvent evaporation. Solid urea was detected down to 80.7 microg of precipitate at the waveguide surface. The emission frequency of a 974 cm(-1) QCL overlaps with the CH3-C absorption feature of acetic anhydride. Solutions of acetic anhydride in acetonitrile have been detected down to a volume of 0.01 microL (10.8 microg) of acetic anhydride solution after deposition at the planar waveguide (PWG) surface. Free-standing, thin-film, planar, silver halide waveguides were produced by press-tapering heated, cylindrical, silver halide fiber segments to create waveguides with a thickness of 300-190 microm, a width of 3 mm, and a length of 35 mm. In addition, Fourier transform infrared (FT-IR) evanescent field absorption measurements with planar silver halide waveguides and transmission absorption QCL measurements verify the obtained results.

  13. Feasibility of Coupling Between a Single-Mode Elliptical-Core Fiber and a Single Mode Rib Waveguide Over Temperature. Ph.D. Thesis - Akron Univ., Aug. 1995

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L.

    1995-01-01

    To determine the feasibility of coupling the output of an optical fiber to a rib waveguide in a temperature environment ranging from 20 C to 300 C, a theoretical calculation of the coupling efficiency between the two was investigated. This is a significant problem which needs to be addressed to determine whether an integrated optic device can function in a harsh temperature environment. Because the behavior of the integrated-optic device is polarization sensitive, a polarization-preserving optic fiber, via its elliptical core, was used to couple light with a known polarization into the device. To couple light energy efficiently from an optical fiber into a channel waveguide, the design of both components should provide for well-matched electric field profiles. The rib waveguide analyzed was the light input channel of an integrated-optic pressure sensor. Due to the complex geometry of the rib waveguide, there is no analytical solution to the wave equation for the guided modes. Approximation or numerical techniques must be utilized to determine the propagation constants and field patterns of the guide. In this study, three solution methods were used to determine the field profiles of both the fiber and guide: the effective-index method (EIM), Marcatili's approximation, and a Fourier method. These methods were utilized independently to calculate the electric field profile of a rib channel waveguide and elliptical fiber at two temperatures, 20 C and 300 C. These temperatures were chosen to represent a nominal and a high temperature that the device would experience. Using the electric field profile calculated from each method, the theoretical coupling efficiency between the single-mode optical fiber and rib waveguide was calculated using the overlap integral and results of the techniques compared. Initially, perfect alignment was assumed and the coupling efficiency calculated. Then, the coupling efficiency calculation was repeated for a range of transverse offsets at

  14. Improvements in Fabrication of 3D SU-8 Prisms for Low-Coupling-Loss Interconnections Between Fibers and Waveguides

    NASA Astrophysics Data System (ADS)

    Nguyen, Minh-Hang; Chu, Thi-Xuan; Nguyen, Long; Nguyen, Hai-Binh; Lee, Chun-Wei; Tseng, Fan-Gang; Chen, Te-Chang; Lee, Ming-Chang

    2016-07-01

    Fabrication of three-dimensional (3D) SU-8 (an epoxy-based negative photoresist from MicroChem) prisms as low-loss couplers for interconnection between optical components, particularly optical fibers and silicon-on-isolator waveguides (SOI WGs), which have mismatched mode sizes, has been investigated. With an interfacial structure formed by a 3D SU-8 prism partly overlaying an SOI WG end with a portion of buried oxide (BOX) removed under the interface, low-loss coupling is ensured and the transmission efficiency can reach 70%. To fabricate these 3D SU-8 prisms, a simple method with two photolithography steps was used for SU-8 hinges and CYTOP (an amorphous fluoropolymer from AGC Chemicals) prism windows, with mild soft and hard bakes, to define the prism profiles with diluted SU-8 filled in the CYTOP prism windows. A buffered oxide etchant is used to remove BOX parts under the interfaces. Some of the fabricated structures were tested, demonstrating the contribution of overlaying SU-8 prisms to the transmission efficiency of optical interconnections between fibers and SOI WGs.

  15. Improvements in Fabrication of 3D SU-8 Prisms for Low-Coupling-Loss Interconnections Between Fibers and Waveguides

    NASA Astrophysics Data System (ADS)

    Nguyen, Minh-Hang; Chu, Thi-Xuan; Nguyen, Long; Nguyen, Hai-Binh; Lee, Chun-Wei; Tseng, Fan-Gang; Chen, Te-Chang; Lee, Ming-Chang

    2016-11-01

    Fabrication of three-dimensional (3D) SU-8 (an epoxy-based negative photoresist from MicroChem) prisms as low-loss couplers for interconnection between optical components, particularly optical fibers and silicon-on-isolator waveguides (SOI WGs), which have mismatched mode sizes, has been investigated. With an interfacial structure formed by a 3D SU-8 prism partly overlaying an SOI WG end with a portion of buried oxide (BOX) removed under the interface, low-loss coupling is ensured and the transmission efficiency can reach 70%. To fabricate these 3D SU-8 prisms, a simple method with two photolithography steps was used for SU-8 hinges and CYTOP (an amorphous fluoropolymer from AGC Chemicals) prism windows, with mild soft and hard bakes, to define the prism profiles with diluted SU-8 filled in the CYTOP prism windows. A buffered oxide etchant is used to remove BOX parts under the interfaces. Some of the fabricated structures were tested, demonstrating the contribution of overlaying SU-8 prisms to the transmission efficiency of optical interconnections between fibers and SOI WGs.

  16. Optical fiber waveguide sagnac interferometer. Phase 1: Multiturn one meter diameter, single mode. [optical gyroscopes

    NASA Technical Reports Server (NTRS)

    Vali, V.

    1977-01-01

    A rotating ring interferometer was constructed using a 100 meters of single mode optical fiber wound on a crystal cylinder. A 20 inch diameter fiber interferometer gyroscope was built and its sensitivity was evaluated. Major noise sources were identified and improvements for the next phase of development were determined. The accuracy of .01 of a fringe can be improved to .0001 by the removal of the noise source.

  17. Funneling single photons into ridge-waveguide photonic integrated circuits

    NASA Astrophysics Data System (ADS)

    Fattah poor, S.; Midolo, L.; Li, L. H.; Linfield, E. H.; Schouwenberg, J. F. P.; Xia, T.; van Otten, F. W. M.; Hoang, T. B.; Fiore, A.

    2013-02-01

    The generation, manipulation and detection of single photons enable quantum communication, simulation and potentially computing protocols. However scaling to several qubits requires the integration of these functionalities in a single chip. A promising approach to the integration of single-photon sources in a chip is the use of single quantum dots embedded in photonic crystal waveguides or cavities. To this aim, efficient coupling of the emission from single quantum dots in photonic crystal cavities to low-loss ridge-waveguide (RWG) circuits is needed. This is usually hampered by the large mode mismatch between the two systems. In this work the emission of a photonic crystal (PhC) cavity realized on a GaAs/AlGaAs membrane and pumped by quantum dots has been effectively coupled and transferred through a long RWG (~1mm). By continuous tapering in both horizontal and vertical direction, transmission values (fiber-in, fiber-out) around 0.16 and 0.08% for RWG and coupled PhC waveguide-RWG have been achieved, respectively. This corresponds to about 2.8% coupling efficiency between the center of the PhC waveguide and the single-mode output fiber, a value much higher than what is achieved by top collection. It further shows that around 70% of the light in the PhC waveguide is coupled to the RWG. The emission from quantum dots in the cavity has been clearly identified by exciting from the top and collecting the photoluminescence from the cleaved facet of the device 1mm away from the cavity which enables the efficient coupling of single photons to RWG and detector circuits.

  18. Biosensing platform with tapered optical microfibers: new results

    NASA Astrophysics Data System (ADS)

    King, Branden J.; Idehenre, Ighodalo; Powers, Peter E.; Haus, Joseph W.; Hansen, Karolyn M.

    2014-03-01

    Our research demonstrates the design and fabrication of a biosensor based on the tapered optical fiber. The fiber is tapered biconically to a diameter of approximately 7 μm, which allows the evanescent field of propagating light to interact with molecules attached to the tapered surface. This sensing platform is capable of fast, continuous, specific, sensitive, and label-free molecular detection in the aqueous phase. Detection is demonstrated across multiple fibers, and the individual fibers are reusable. The system described previously has been modified for detection of volatile organic compounds. The fabrication of the modified design is also shown with preliminary results.

  19. Optical Tapers as White-Light WGM Resonators

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry V.; Matsko, Andrey B.; Savchenkov, Anatoliy A.

    2010-01-01

    A theoretical analysis has revealed that tapered optical waveguides could be useful as white-light whispering-gallery-mode (WGM) optical resonators. The compactness and the fixed-narrow-frequency-band nature of the resonances of prior microdisk and microsphere WGM resonators are advantageous in low-power, fixed-narrow-frequency-band applications. However for optical-processing applications in which there are requirements for power levels higher and/or spectral responses broader than those of prior microdisk and microsphere WGM resonators, white-light WGM resonators in the form of optical tapers would be preferable. The theoretical analysis was performed for a multimode, axisymmetric, circular-cross-section waveguide having a taper sufficiently smooth and gradual to justify the approximation of adiabaticity. In this approximation, the equation for the dependence of the electromagnetic field upon the axial (longitudinal) waveguide coordinate can be separated from the equation for the dependence upon the radius and the azimuthal angle.

  20. Transmission performance of one waveguide and double micro-ring resonator using 3×3 optical fiber coupler

    NASA Astrophysics Data System (ADS)

    Zhao, Chao Ying; Tan, Wei Han

    2016-09-01

    This paper investigates theoretically the transmission characteristics of one waveguide and double micro-ring resonator using 3 × 3 optical fibre coupler. Our analytical solution of transmittance is suitable for either linearly distributed coupler or circularly symmetric distributed coupler. The all-optical analogue to electromagnetic inducted transparency spectrum of one waveguide and double micro-ring resonators can be controlled by changing the coupling strength between waveguide and micro-rings, the absorption coefficient around micro-rings, as well as the asymmetric coupling coefficients between non-adjacent waveguides. The curves show that the transitions of transmission spectra sensitively depend on asymmetric coupling coefficients.

  1. Deep subwavelength waveguiding and focusing based on designer surface plasmons.

    PubMed

    Zhao, Wangshi; Eldaiki, Omar M; Yang, Ruoxi; Lu, Zhaolin

    2010-09-27

    We experimentally demonstrate focusing and guiding electromagnetic (EM) waves in a designer surface plasmonic waveguide with deep subwavelength mode cross section. Our experiments show that a metal grating with suitable parameters, functioning as a designer surface plasmonic waveguide, can support deep subwavelength surface modes and the width of the modes can be squeezed also into deep subwavelength by tapering the width of the waveguide. The results provide a new insight into deep subwavelength waveguiding and focusing.

  2. Fiber Optic Surface Plasmon Resonance-Based Biosensor Technique: Fabrication, Advancement, and Application.

    PubMed

    Liang, Gaoling; Luo, Zewei; Liu, Kunping; Wang, Yimin; Dai, Jianxiong; Duan, Yixiang

    2016-05-01

    Fiber optic-based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic-based SPR sensor technology are discussed.

  3. Polarization rotation and coupling between silicon waveguide and hybrid plasmonic waveguide.

    PubMed

    Kim, Sangsik; Qi, Minghao

    2015-04-20

    We present a polarization rotation and coupling scheme that rotates a TE(0) mode in a silicon waveguide and simultaneously couples the rotated mode to a hybrid plasmonic (HP(0)) waveguide mode. Such a polarization rotation can be realized with a partially etched asymmetric hybrid plasmonic waveguide consisting of a silicon strip waveguide, a thin oxide spacer, and a metal cap made from copper, gold, silver or aluminum. Two implementations, one with and one without the tapering of the metal cap are presented, and different taper shapes (linear and exponential) are also analyzed. The devices have large 3 dB conversion bandwidths (over 200 nm at near infrared) and short length (< 5 μm), and achieve a maximum coupling factor of ∼ 78% with a linearly tapered silver metal cap.

  4. Photoneuron: dynamically reconfigurable information processing control element utilizing embedded-fiber waveguide interconnects

    NASA Astrophysics Data System (ADS)

    Glista, Andrew S., Jr.

    1991-12-01

    The term `photoneuron' describes an electro-optic hardware element that permits an optical implementation of the postulated information transfer processes of the neurons in the human brain. The photoneuron provides a dynamic activation and control mechanism for highly parallel computers and permits immediate implementation of reconfigurable high speed optical interconnects. The suggested method for interconnecting processors in a photoneuronic network consists of embedded optical fibers in composite materials to form optical backplanes utilizing `smart skin' technology. This method eliminates the environmental concerns and technological barriers posed by free space optics and integrated optics, while providing a sound engineering approach leading to the all optical computer. This paper briefly reviews the physiological activity of neurons in the human brain. Optical analogies for processor activation in neural networks corresponding to the nerve impulse activation in the brain are then described. The paper then suggests the utilization of optical signal parameters and encoding to emulate the information exchange of neurotransmitters provided by first and second messenger molecular activity across the synaptic `connections' of neurons in the brain. This represents a departure from most neural networks which dwell on threshold processor activation and ignore the exceedingly complex molecular information exchange mechanisms of the brain. Digital, analog, and combinatorial alternatives are described.

  5. Microfabricated bragg waveguide

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Hadley, G. Ronald

    2004-10-19

    A microfabricated Bragg waveguide of semiconductor-compatible material having a hollow core and a multilayer dielectric cladding can be fabricated by integrated circuit technologies. The microfabricated Bragg waveguide can comprise a hollow channel waveguide or a hollow fiber. The Bragg fiber can be fabricated by coating a sacrificial mandrel or mold with alternating layers of high- and low-refractive-index dielectric materials and then removing the mandrel or mold to leave a hollow tube with a multilayer dielectric cladding. The Bragg channel waveguide can be fabricated by forming a trench embedded in a substrate and coating the inner wall of the trench with a multilayer dielectric cladding. The thicknesses of the alternating layers can be selected to satisfy the condition for minimum radiation loss of the guided wave.

  6. Radiation Effects on Fused Biconical Taper Wavelength Division Multiplexers

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C.; Swift, Gary M.; Dubovitsky, Serge; Bartman, Randall K.; Barnes, Charles E.; Dorsky, Leonard

    1994-01-01

    The effects of radiation on fused biconical taper wavelength division multiplexers are presented. A theoretical model indicates that index changes in the fiber are primarily responsible for the degradation of these devices.

  7. Research of polarization properties of the birefringent waveguides coupling point at different polish angles

    NASA Astrophysics Data System (ADS)

    Shulepov, V. A.; Aksarin, S. M.

    2016-08-01

    Integrated optical birefringent waveguides are widely used in the field of phase interferometric fiber optic sensors. In sensors integrated optical waveguides are coupled to birefringent fiber waveguides. Due to different optical properties polarization conversion occurs at waveguides coupling point which may cause parasite interference to the signal of fiber optic sensors.

  8. Carbon fibre slotted waveguide arrays

    NASA Astrophysics Data System (ADS)

    Wagner, R.

    Spaceborne SARs call for antennas of large aperture and high structural performance; attention is accordingly given to the slotted waveguide antenna concept, which yields high aperture efficiency, good beam-shaping, and low losses in conjunction with great compactness and high stiffness. A distinctive technology for the manufacture of such waveguides from metallized carbon fiber-reinforced plastics, as well as for the construction of radiating arrays for such waveguides, is presented.

  9. Propagation characteristics of optical fiber structures with arbitrary shape and index variation

    NASA Technical Reports Server (NTRS)

    Manshadi, F.

    1990-01-01

    The application of the scalar wave-fast Fourier transform (SW-FFT) technique to the computation of the propagation characteristics of some complex optical fiber structures is presented. The SW-FFT technique is based on the numerical solution of the scalar wave equation by a forward-marching fast Fourier transform method. This solution yields the spatial configuration of the fields as well as its modal characteristics in and around the guiding structure. The following are treated by the SW-FFT method: analysis of coupled optical fibers and computation of their odd and even modes and coupling length; the solution of tapered optical waveguides (transitions) and the study of the effect of the slope of the taper on mode conversion; and the analysis of branching optical fibers and demonstration of their mode-filtering and/or power-dividing properties.

  10. Internal excitation and superfocusing of surface plasmon polaritons on a silver-coated optical fiber tip

    SciTech Connect

    Ding, W.; Andrews, S. R.; Maier, S. A.

    2007-06-15

    We have theoretically studied the conversion of radially polarized waveguide modes of a tapered optical fiber into surface plasmon polaritons (SPPs) propagating at the outer surface of an apertureless silver-coated optical tip. Optimization of this process is important in exploiting SPP superfocusing in scanning near-field optical microscopy without the need for external illumination. Our approach is based on analyzing the evolution of the local modal index as a function of the fiber radius. The influence of mode projection, intermodal coupling, and metal dissipation are treated analytically, while a numerical finite integration technique is used to model radiation coupling. The results identify and quantify the mode conversion processes that need to be taken into account. We estimate that at least 10% of the modal energy in an uncoated fiber taper can be fed into the superfocusing mode at a silver-coated tip.

  11. Optofluidic waveguides: II. Fabrication and structures

    PubMed Central

    Schmidt, Holger

    2011-01-01

    We review fabrication methods and common structures for optofluidic waveguides, defined as structures capable of optical confinement and transmission through fluid filled cores. Cited structures include those based on total internal reflection, metallic coatings, and interference based confinement. Configurations include optical fibers and waveguides fabricated on flat substrates (integrated waveguides). Some examples of optofluidic waveguides that are included in this review are Photonic Crystal Fibers (PCFs) and two-dimensional photonic crystal arrays, Bragg fibers and waveguides, and Anti Resonant Reflecting Optical Waveguides (ARROWs). An emphasis is placed on integrated ARROWs fabricated using a thin-film deposition process, which illustrates how optofluidic waveguides can be combined with other microfluidic elements in the creation of lab-on-a-chip devices. PMID:21603122

  12. Tapered structure construction

    DOEpatents

    Smith, Eric D.; Takata, Rosalind K.; Slocum, Alexander H.; Nayfeh, Samir A.

    2016-04-05

    Feeding stock used to form a tapered structure into a curving device such that each point on the stock undergoes rotational motion about a peak location of the tapered structure; and the stock meets a predecessor portion of stock along one or more adjacent edges.

  13. Biocompatible silk step-index optical waveguides

    PubMed Central

    Applegate, Matthew B.; Perotto, Giovanni; Kaplan, David L.; Omenetto, Fiorenzo G.

    2015-01-01

    Biocompatible optical waveguides were constructed entirely of silk fibroin. A silk film (n=1.54) was encapsulated within a silk hydrogel (n=1.34) to form a robust and biocompatible waveguide. Such waveguides were made using only biologically and environmentally friendly materials without the use of harsh solvents. Light was coupled into the silk waveguides by direct incorporation of a glass optical fiber. These waveguides are extremely flexible, and strong enough to survive handling and manipulation. Cutback measurements showed propagation losses of approximately 2 dB/cm. The silk waveguides were found to be capable of guiding light through biological tissue. PMID:26600988

  14. Microminiature optical waveguide structure and method for fabrication

    DOEpatents

    Strand, O.T.; Deri, R.J.; Pocha, M.D.

    1998-12-08

    A method for manufacturing low-cost, nearly circular cross section waveguides comprises starting with a substrate material that a molten waveguide material can not wet or coat. A thin layer is deposited of an opposite material that the molten waveguide material will wet and is patterned to describe the desired surface-contact path pedestals for a waveguide. A waveguide material, e.g., polymer or doped silica, is deposited. A resist material is deposited and unwanted excess is removed to form pattern masks. The waveguide material is etched away to form waveguide precursors and the masks are removed. Heat is applied to reflow the waveguide precursors into near-circular cross-section waveguides that sit atop the pedestals. The waveguide material naturally forms nearly circular cross sections due to the surface tension effects. After cooling, the waveguides will maintain the round shape. If the width and length are the same, then spherical ball lenses are formed. Alternatively, the pedestals can be patterned to taper along their lengths on the surface of the substrate. This will cause the waveguides to assume a conical taper after reflowing by heat. 32 figs.

  15. Microminiature optical waveguide structure and method for fabrication

    DOEpatents

    Strand, Oliver T.; Deri, Robert J.; Pocha, Michael D.

    1998-01-01

    A method for manufacturing low-cost, nearly circular cross section waveguides comprises starting with a substrate material that a molten waveguide material can not wet or coat. A thin layer is deposited of an opposite material that the molten waveguide material will wet and is patterned to describe the desired surface-contact path pedestals for a waveguide. A waveguide material, e.g., polymer or doped silica, is deposited. A resist material is deposited and unwanted excess is removed to form pattern masks. The waveguide material is etched away to form waveguide precursors and the masks are removed. Heat is applied to reflow the waveguide precursors into near-circular cross-section waveguides that sit atop the pedestals. The waveguide material naturally forms nearly circular cross sections due to the surface tension effects. After cooling, the waveguides will maintain the round shape. If the width and length are the same, then spherical ball lenses are formed. Alternatively, the pedestals can be patterned to taper along their lengths on the surface of the substrate. This will cause the waveguides to assume a conical taper after reflowing by heat.

  16. Narrow linewidth comb realized with a mode-locked fiber laser using an intra-cavity waveguide electro-optic modulator for high-speed control.

    PubMed

    Iwakuni, Kana; Inaba, Hajime; Nakajima, Yoshiaki; Kobayashi, Takumi; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2012-06-18

    We have developed an optical frequency comb using a mode-locked fiber ring laser with an intra-cavity waveguide electro-optic modulator controlling the optical length in the laser cavity. The mode-locking is achieved with a simple ring configuration and a nonlinear polarization rotation mechanism. The beat note between the laser and a reference laser and the carrier envelope offset frequency of the comb were simultaneously phase locked with servo bandwidths of 1.3 MHz and 900 kHz, respectively. We observed an out-of-loop beat between two identical combs, and obtained a coherent δ-function peak with a signal to noise ratio of 70 dB/Hz.

  17. Ray analysis of parabolic-index segmented planar waveguides.

    PubMed

    Rastogi, V; Ghatak, A K; Ostrowsky, D B; Thyagarajan, K; Shenoy, M R

    1998-07-20

    A ray analysis of periodically segmented waveguides with parabolic-index variation in the high-index region is presented. We carried out the analysis using ray transfer matrices, which is convenient to implement and which can be extended to study different types of graded-index segmented waveguide. Results of this ray tracing approach clearly illustrate the waveguiding properties and the existence of stable and unstable regions of operation in segmented waveguides. We also illustrate the tapering action exhibited by segmented waveguides in which the duty cycle varies along the length of the waveguide. This analysis, although restricted to multimode structures, provides a clear visualization of the waveguiding properties in terms of ray propagation in segmented waveguides.

  18. Germanium-on-silicon mid-infrared grating couplers with low-reflectivity inverse taper excitation.

    PubMed

    Alonso-Ramos, Carlos; Nedeljkovic, Milos; Benedikovic, Daniel; Penadés, Jordi Soler; Littlejohns, Callum G; Khokhar, Ali Z; Pérez-Galacho, Diego; Vivien, Laurent; Cheben, Pavel; Mashanovich, Goran Z

    2016-09-15

    A broad transparency range of its constituent materials and compatibility with standard fabrication processes make germanium-on-silicon (Ge-on-Si) an excellent platform for the realization of mid-infrared photonic circuits. However, the comparatively large Ge waveguide thickness and its moderate refractive index contrast with the Si substrate hinder the implementation of efficient fiber-chip grating couplers. We report for the first time, to the best of our knowledge, a single-etch Ge-on-Si grating coupler with an inversely tapered access stage, operating at a 3.8 μm wavelength. Optimized grating excitation yields a coupling efficiency of -11  dB (7.9%), the highest value reported for a mid-infrared Ge-on-Si grating coupler, with reflectivity below -15  dB (3.2%). The large periodicity of our higher-order grating design substantially relaxes the fabrication constraints. We also demonstrate that a focusing geometry allows a 10-fold reduction in inverse taper length, from 500 to 50 μm. PMID:27628388

  19. Slow light in the GaAs-rod-loaded metallic waveguide for terahertz wave.

    PubMed

    Wang, Wei; He, Jinlong; Li, Xiangjun; Hong, Zhi

    2010-05-24

    The modes in a circular metallic waveguide loaded with a high permittivity dielectric rod may possess similar dispersion relations to the modes in the left-handed metamaterial (LHM) waveguide. Therefore such dielectric-loaded metallic waveguide may also support slow light with parameters properly selected. The slow light in the GaAs-rod-loaded metallic waveguide is numerically studied. The results show that the wavelength of slow light varies with the parameters of the waveguide. A linearly tapered waveguide and other realizable simple structures are proposed accordingly to realize the "trapped rainbow" phenomena. Moreover, the practical lossy tapered waveguide is also investigated in the terahertz region. It is shown that the slow light with low loss can be achieved in a realistic GaAs-loaded metallic waveguide.

  20. Deep-blue supercontinnum sources with optimum taper profiles--verification of GAM.

    PubMed

    Sørensen, S T; Møller, U; Larsen, C; Moselund, P M; Jakobsen, C; Johansen, J; Andersen, T V; Thomsen, C L; Bang, O

    2012-05-01

    We use an asymmetric 2 m draw-tower photonic crystal fiber taper to demonstrate that the taper profile needs careful optimisation if you want to develop a supercontinuum light source with as much power as possible in the blue edge of the spectrum. In particular we show, that for a given taper length, the downtapering should be as long as possible. We argue how this may be explained by the concept of group-acceleration mismatch (GAM) and we confirm the results using conventional symmetrical short tapers made on a taper station, which have varying downtapering lengths. PMID:22565689

  1. Mach-Zehnder interferometer based on tapered PCF with an up-tapered joint for curvature, strain and temperature interrogation

    NASA Astrophysics Data System (ADS)

    Narayan Dash, Jitendra; Jha, Rajan

    2016-10-01

    We propose a Mach-Zehnder interferometric sensor based on tapered Photonic Crystal Fiber (PCF) with up-tapered collapsed region for measurement of parameters such as curvature, strain and temperature. The up-tapered collapsed region helps in excitation of the cladding modes in PCF and these modes interfere with each other at the tapered region of PCF which is completely collapsed. Three tapered PCFs with varying geometry are fabricated and their effect on curvature sensitivity is analyzed. Experimental results show that the proposed sensor has a curvature sensitivity of 7.56 nm m-1 with negligible hysteresis effect. Moreover, the proposed sensor shows a strain sensitivity of 1.6 pm/μɛ along with a maximum temperature sensitivity of 51.6 pm °C-1. In addition to this, the response of the interference pattern to all these parameters is found to be linear.

  2. Transmission of photonic quantum polarization entanglement in a nanoscale hybrid plasmonic waveguide.

    PubMed

    Li, Ming; Zou, Chang-Ling; Ren, Xi-Feng; Xiong, Xiao; Cai, Yong-Jing; Guo, Guo-Ping; Tong, Li-Min; Guo, Guang-Can

    2015-04-01

    Photonic quantum technologies have been extensively studied in quantum information science, owing to the high-speed transmission and outstanding low-noise properties of photons. However, applications based on photonic entanglement are restricted due to the diffraction limit. In this work, we demonstrate for the first time the maintaining of quantum polarization entanglement in a nanoscale hybrid plasmonic waveguide composed of a fiber taper and a silver nanowire. The transmitted state throughout the waveguide has a fidelity of 0.932 with the maximally polarization entangled state Φ(+). Furthermore, the Clauser, Horne, Shimony, and Holt (CHSH) inequality test performed, resulting in value of 2.495 ± 0.147 > 2, demonstrates the violation of the hidden variable model. Because the plasmonic waveguide confines the effective mode area to subwavelength scale, it can bridge nanophotonics and quantum optics and may be used as near-field quantum probe in a quantum near-field micro/nanoscope, which can realize high spatial resolution, ultrasensitive, fiber-integrated, and plasmon-enhanced detection. PMID:25775140

  3. Transmission of photonic quantum polarization entanglement in a nanoscale hybrid plasmonic waveguide.

    PubMed

    Li, Ming; Zou, Chang-Ling; Ren, Xi-Feng; Xiong, Xiao; Cai, Yong-Jing; Guo, Guo-Ping; Tong, Li-Min; Guo, Guang-Can

    2015-04-01

    Photonic quantum technologies have been extensively studied in quantum information science, owing to the high-speed transmission and outstanding low-noise properties of photons. However, applications based on photonic entanglement are restricted due to the diffraction limit. In this work, we demonstrate for the first time the maintaining of quantum polarization entanglement in a nanoscale hybrid plasmonic waveguide composed of a fiber taper and a silver nanowire. The transmitted state throughout the waveguide has a fidelity of 0.932 with the maximally polarization entangled state Φ(+). Furthermore, the Clauser, Horne, Shimony, and Holt (CHSH) inequality test performed, resulting in value of 2.495 ± 0.147 > 2, demonstrates the violation of the hidden variable model. Because the plasmonic waveguide confines the effective mode area to subwavelength scale, it can bridge nanophotonics and quantum optics and may be used as near-field quantum probe in a quantum near-field micro/nanoscope, which can realize high spatial resolution, ultrasensitive, fiber-integrated, and plasmon-enhanced detection.

  4. Silicon Hybrid Plasmonic Waveguides and Passive Devices

    NASA Astrophysics Data System (ADS)

    Wu, Marcelo

    The field of plasmonics has offered the promise to combine electronics and photonics at the nanometer scale for ultrafast information processing speeds and compact integration of devices. Various plasmonic waveguide schemes were proposed with the potential to achieve switching functionalities and densely integrated circuits using optical signals instead of electrons. Among these, the hybrid plasmonic waveguide stands out thanks to two sought-out properties: long propagation lengths and strong modal confinement. In this work, hybrid plasmonic waveguides and passive devices were theoretically investigated and experimentally demonstrated on an integrated silicon platform. A thin SiO2 gap between a gold conductive layer and a silicon core provides subwavelength confinement of light inside the gap. A long propagation length of 40mum was experimentally measured. A system of taper coupler connects the plasmonic waveguide to conventional photonic waveguides at a high efficiency of 80%. Passive devices were also fabricated and characterized, including S-bends and Y-splitters.

  5. Waveguide apparatuses and methods

    DOEpatents

    Spencer, James E.

    2016-05-10

    Optical fiber waveguides and related approaches are implemented to facilitate communication. As may be implemented in accordance with one or more embodiments, a waveguide has a substrate including a lattice structure having a plurality of lattice regions with a dielectric constant that is different than that of the substrate, a defect in the lattice, and one or more deviations from the lattice. The defect acts with trapped transverse modes (e.g., magnetic and/or electric modes) and facilitates wave propagation along a longitudinal direction while confining the wave transversely. The deviation(s) from the lattice produces additional modes and/or coupling effects.

  6. Square dielectric THz waveguides.

    PubMed

    Aflakian, N; Yang, N; LaFave, T; Henderson, R M; O, K K; MacFarlane, D L

    2016-06-27

    A holey cladding dielectric waveguide with square cross section is designed, simulated, fabricated and characterized. The TOPAS waveguide is designed to be single mode across the broad frequency range of 180 GHz to 360 GHz as shown by finite-difference time domain simulation and to robustly support simultaneous TE and TM mode propagation. The square fiber geometry is realized by pulling through a heat distribution made square by appropriate furnace design. The transmitted mode profile is imaged using a vector network analyzer with a pinhole at the receiver module. Good agreement between the measured mode distribution and the calculated mode distribution is demonstrated. PMID:27410645

  7. Control of evanescent field using a dynamic waveguide composed of gelatin-coated few-layer fiber.

    PubMed

    Chatterjee, Sudip K; Chaudhuri, Partha Roy

    2016-07-01

    We report here the results of our studies on dynamic refractive-index (RI) profile few-layer fibers in view of controlling the mode-field profile, in particular the evanescent tails under varying structural configuration. We experimentally fabricate dynamic RI profile few-layer fibers using thin gelatin coating on selectively etched fibers and illustrate how the excitation of various modes and the evanescent field at the interface can be controlled with changing humidity parameter. As a technology outcome of this research, we demonstrate through an optimized structural configuration a well performing fiber-optic high (70%-98%) relative humidity (RH) sensor with sensitivity as high as -1.07  dBm/%RH.

  8. Broadband efficient directional coupling to short-range plasmons: towards hybrid fiber nanotips.

    PubMed

    Tuniz, Alessandro; Schmidt, Markus A

    2016-04-01

    We present a broadband and efficient short-range plasmonic directional coupler design, for the delivery and collection of deeply sub-wavelength radiation to tapered plasmonic nanowires. We show a proof-of-concept design using a planar geometry operating at wavelengths between 1.2 -2.4 μm, showing that the propagation characteristics predicted by an Eigenmode analysis are in excellent agreement with finite element simulations. This analytical formulation is straightforward to implement and immediately provides the power-exchange properties of hybrid plasmonic waveguides. An investigation of both waveguide delivery and collection performance to and from a plasmonic nano-tip is performed. We show that this design strategy can be straightforwardly adapted to a realistic hybrid fiber geometry, containing wire diameters more than one order of magnitude larger than the planar geometries, with important applications in all-fiber plasmonic superfocussing, and nonlinear plasmonics. PMID:27137040

  9. Large bandwidth mode order converter by differential waveguides.

    PubMed

    Oner, B B; Üstün, K; Kurt, H; Okyay, A K; Turhan-Sayan, G

    2015-02-01

    In this article, we propose a large bandwidth mode-order converter design by dielectric waveguides with equal lengths but different cross-sectional areas. The efficient conversion between even and odd modes is verified by inducing required phase difference between the equal length waveguides of different widths. Y-junctions are composed of both tapered mode splitter and combiner to connect mono-mode waveguide to multi-mode waveguide. The converted mode profiles at the output port show that the device operates successfully at designed wavelengths with wide bandwidth. This study provides a novel technique to implement compact mode order converters and direction selective/sensitive photonic structures.

  10. Overmoded waveguide components for the ECH system on PDX

    SciTech Connect

    Doane, J.L.

    1984-01-01

    Waveguide components designed specifically for transmitting power into PDX for electron cyclotron heating (ECH) at 60 GHz are described. These include mode converters from the circular electric TE01 mode to the polarized HE11 mode, compact corrugated waveguide bends with a hyperbolic secant curvature variation, compact corrugated waveguide diameter tapers with a parabolic profile, and a high voltage dc break incorporating a section of dielectric waveguide, all designed for low-loss HE11 propagation. Optimization of the corrugation depth and curvature for bends propagating TE01 is also discussed.

  11. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    Lapointe, Donat J. E. (Inventor); Wright, Lawrence T. (Inventor); Vincent, Laurence J. (Inventor)

    1987-01-01

    A tapered tubular polyester sleeve is described to serve as the flexible foundation for a spacesuit limb covering. The tube has a large end and a small end with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end. A requisite number of warp yarns extend the full length of the sleeve. Other warp yarns extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel, heated in an oven, and then attached to the arm or other limb of the spacesuit.

  12. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    LaPointe, Donat J. E. (Inventor); Vincent, Laurence J. (Inventor); Wright, Lawrence T. (Inventor)

    1988-01-01

    A tapered tubular polyester sleeve as set forth. It has a large end 12 and a small end 14 with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end 12. A requisite number of warp yarns 16 extend the full length of the sleeve. Other warp yarns exemplified at 18, 22, 26, 28, 30 and 32 extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn 40 which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel 42, heated in an oven 44 and is thereafter placed on the arm or other limb of a space suit exemplified at 50.

  13. The MCVD synthesis and characterization of water tolerant fiber optic waveguides based on alkaline earth-doped silicas

    NASA Astrophysics Data System (ADS)

    Farley, Kevin F.

    Optical fibers that transmit throughout the entire telecommunications spectrum (1.2--1.7 mum) are presently manufactured by the removal of hydrogen or OH from the host preform glass. Hydrogen-oxygen torches are utilized in the conventional preform manufacturing process, but result in the formation of hydroxyls in germanium-doped silica fiber. The hydroxyl species generate unacceptably high losses for long haul telecommunications systems. This thesis has explored an alternative strategy for reducing OH-related absorption in silica-based glasses. Alkaline earth modifiers have been introduced via the modified chemical vapor deposition (MCVD) process to successfully damp out and dramatically reduce the extrinsic attenuation associated with both water and hydrogen. Specifically, alkaline earth ions were introduced into alumino-silicate glasses to form MgO-Al2O3-SiO2, CaO-Al 2O3-SiO2, and SrO-Al2O3-SiO 2 compositions. The utilization of halide precursors based on the vapor delivery of rare earths was incorporated into the existing MCVD set-up to fabricate these optical preforms. Both the bulk preforms and fibers drawn from them were characterized to determine relevant optical properties, including the attenuation, index profiles and extinction coefficients arising from OH in each host. The data indicate that modification of the silica glass structure through the additions of modifying ions can significantly reduce OH related absorption. For example, the doping of alkaline earth ions decreased the extinction coefficient measured at the 1.39 mum) OH overtone, to values < 0.2 L/(mol*cm). Prompt gamma activation analysis (PGAA) measurements conducted at the National Institute of Standards and Technology (NIST) found OH concentrations in the glasses in the range from 10 to 27.5 ppm. The alkaline earth-doped fibers exhibited lower OH absorption at 1.39 mum) than germanium and aluminum-doped reference fibers. Fibers doped with either magnesium, calcium or strontium displayed up

  14. Interfacing ion-exchanged waveguide for the efficient excitation of surface plasmons (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Beltran Madrigal, Josslyn; Berthel, Martin; Gardillou, Florent; Tellez Limon, Ricardo; Couteau, Christophe; Barbier, Denis; Drezet, Aurelien; Salas-Montiel, Rafael; Huant, Serge; Blaize, Sylvain

    2015-09-01

    Several works have already shown that the excitation of plasmonic structures through waveguides enables a strong light confinement and low propagation losses [1]. This kind of excitation is currently exploited in areas such as biosensing [2], nanocircuits[3] and spectroscopy[4]. Efficient excitation of surface plasmon modes (SPP) with guided modes supported by high-index-contrast waveguides, such as silicon-on-insulator waveguides, had already been shown [1,5], however, the use of weak-confined guided modes of an ion exchanged waveguide on glass as a source of excitation of SPP represents a scientific and technological breakthrough. This is because the integration of plasmonic structures into low-index-contrast waveguide increases the bandwidth of operation and compatibility with conventional optical fibers. In this work, we describe how an adiabatic tapered coupler formed by an intermediate high-index-contrast layer placed between a plasmonic structure and an ion-exchanged waveguide decreases the mismatch between effective indices, size, and shape of the guided modes. This hybrid structure concentrates the electromagnetic energy from the micrometer to the nanometer scale with low coupling losses to radiative modes. The electromagnetic mode confined to the high-index-contrast waveguide then works as an efficient source of SPP supported by metallic nanostructures placed on its surface. We theoretically studied the modal properties and field distribution along the adiabatic coupler structure. In addition, we fabricated a high-index-contrast waveguide by electron beam lithography and thermal evaporation on top of an ion-exchanged waveguide on glass. This structure was characterized with the use of near field scanning optical microscopy (NSOM). Numerical simulations were compared with the experimental results. [1] N. Djaker, R. Hostein, E. Devaux, T. W. Ebbesen, and H. Rigneault, and J. Wenger, J. Phys. Chem. C 114, 16250 (2010). [2] P. Debackere, S. Scheerlinck, P

  15. Compound taper milling machine

    NASA Technical Reports Server (NTRS)

    Campbell, N. R.

    1969-01-01

    Simple, inexpensive milling machine tapers panels from a common apex to a uniform height at panel edge regardless of the panel perimeter configuration. The machine consists of an adjustable angled beam upon which the milling tool moves back and forth above a rotatable table upon which the workpiece is held.

  16. Single rolled-up InGaAs/GaAs quantum dot microtubes integrated with silicon-on-insulator waveguides.

    PubMed

    Tian, Zhaobing; Veerasubramanian, Venkat; Bianucci, Pablo; Mukherjee, Shouvik; Mi, Zetian; Kirk, Andrew G; Plant, David V

    2011-06-20

    We report on single rolled-up microtubes integrated with silicon-on-insulator waveguides. Microtubes with diameters of ~7 μm, wall thicknesses of ~250 nm, and lengths greater than 100 μm are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from the handling GaAs substrate. The microtubes are then transferred from their host substrate to silicon-on-insulator waveguides by an optical fiber abrupt taper. The Q-factor of the waveguide coupled microtube is measured to be 1.5×10(5), the highest recorded for a semiconductor microtube cavity to date. The insertion loss and extinction ratio of the microtube are 1 dB and 34 dB respectively. By pumping the microtube with a 635 nm laser, the resonance wavelength is shifted by 0.7 nm. The integration of InGaAs/GaAs microtubes with silicon-on-insulator waveguides provides a simple, low loss, high extinction passive filter solution in the C+L band communication regime.

  17. Radio-frequency and microwave load comprising a carbon-bonded carbon fiber composite

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Johnson, Arvid C.; Everleigh, Carl A.; Moorhead, Arthur J.

    1998-01-01

    A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads.

  18. Radio-frequency and microwave load comprising a carbon-bonded carbon fiber composite

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Johnson, A.C.; Everleigh, C.A.; Moorhead, A.J.

    1998-04-21

    A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads. 9 figs.

  19. In-resonator variation of waveguide cross-sections for dispersion control of aluminum nitride micro-rings.

    PubMed

    Jung, Hojoong; Poot, Menno; Tang, Hong X

    2015-11-30

    We propose and demonstrate a dispersion control technique by combination of different waveguide cross sections in an aluminum nitride micro-ring resonator. Narrow and wide waveguides with normal and anomalous dispersion, respectively, are linked with tapering waveguides and enclosed in a ring resonator to produce a total dispersion near zero. The mode-coupling in multimoded waveguides is also effectively suppressed. This technique provides new degrees of freedom and enhanced flexibility in engineering the dispersion of microcomb resonators.

  20. Photorefractive waveguides

    NASA Astrophysics Data System (ADS)

    Kip, Detlef; Hukriede, Joerg; Wesner, Monika; Kratzig, Eckhard

    1999-09-01

    Photorefractive effects in optical waveguides link two interesting research areas: First, light-induced refractive index changes in optical materials, and second waveguide structures that are the basis for integrated optical devices. In the last two decades several devices based on photorefractive waveguides have been proposed, and static and dynamic elements have been experimentally demonstrated. Two of these applications of photorefractive waveguides will be discussed in more detail. Permanent refractive index gratings in waveguide devices are of considerable interest for, e.g., integrated waveguide lasers or wavelength multiplexers that make use of the high spectral selectivity of holographic filters. Thermal fixing of holographic gratings has been investigated in channel LiNbO3:Ti:Fe waveguides. A wavelength filter for infrared light around 1.55 micrometer has been fabricated with a peak reflectivity of over 99%, a bandwidth of 0.1 nm and nearly polarization independent properties. As another example, we have demonstrated the formation of photorefractive spatial solitons in a planar strontium-barium niobate waveguide. In such a geometry (1 + 1)-dimensional solitons are formed in a true (1 + 1)- dimensional medium, thus getting rid of the transverse instability that is inherent to soliton propagation in bulk crystals. We show that coherent collisions between two photorefractive solitons result in fusion, repelling, energy exchange, or the creation of a third soliton.

  1. Metal-based 1X2 plastic optical fiber (POF) splitter for video over POF system application

    NASA Astrophysics Data System (ADS)

    Ehsan, A. A.; Shaari, S.; Abd Rahman, M. K.

    2009-11-01

    A 1X2 POF splitter based on a Y-branch metal hollow POF coupler design has been developed. The device is composed of three sections: an input POF waveguide, an intermediate hollow waveguide taper and output POF waveguides. Simulation based on non-sequential ray tracings have been performed on the POF splitter. Low cost aluminum based material has been used for the device substrate. Fabrication of the POF splitters are done by producing the device mold insert using high speed CNC machining tool and short POF fibers at the input and output sections are inserted inside the mold insert before the interfaces of the hollow waveguide taper. The POF splitter has an average insertion loss of 5.8 +/- 0.2 dB, excess loss of 2.8 dB and coupling ratio of 1:1. A video-over POF system test-bed consisting of a POF video transmitter and receiver has been constructed with a total transmission length of 10 m. The POF splitter has been tested in the video-over POF system and shows no significant signal degradation.

  2. Gain saturation and high-power pulsed operation of GaSb-based tapered diode lasers with separately contacted ridge and tapered section

    NASA Astrophysics Data System (ADS)

    Pfahler, C.; Eichhorn, M.; Kelemen, M. T.; Kaufel, G.; Mikulla, M.; Schmitz, J.; Wagner, J.

    2006-07-01

    (AlGaIn)(AsSb) ridge-waveguide tapered diode lasers with separately contacted ridge and tapered sections, emitting at 1.93μm, have been analyzed in pulsed mode with respect to their high-power capability and wavelength tunability. Operating the ridge section above saturation, a variation of the current through this section resulted in a change in lasing wavelength, while changing the current injected into the tapered section at a constant ridge current allowed to vary the output power at constant lasing wavelength. Furthermore, the optical power required to saturate the tapered amplifier section has been derived from a comparison of the experimental characteristics with beam propagation method calculations.

  3. Fundamental mode evolution in long, large-core (>100 μm) adiabatic tapers

    NASA Astrophysics Data System (ADS)

    Kerttula, Juho; Filippov, Valery; Chamorovskii, Yuri; Ustimchik, Vasily; Okhotnikov, Oleg G.

    2013-03-01

    We have experimentally investigated fundamental mode propagation in few-meter-long adiabatic step-index tapers with high numerical aperture, core diameter up to 117μm (V=38), and tapering ratio up to 18. We confirmed single fundamental mode guiding in tapers with uniform core index profile by several experiments. We observed an annular near field distribution and degraded beam quality for large output core diameters, found to occur due to intrinsic mechanical stress in the fibers. We expect that eliminating the stress would prevent the mode deformation and allow constructing single-mode, diffraction-limited tapered large-mode-area amplifiers with a good beam shape.

  4. Tapered capillary optics

    DOEpatents

    Hirsch, Gregory

    1998-01-01

    A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

  5. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  6. Gold-reinforced silver nanoprisms on optical fiber tapers—A new base for high precision sensing

    NASA Astrophysics Data System (ADS)

    Wieduwilt, T.; Zeisberger, M.; Thiele, M.; Doherty, B.; Chemnitz, M.; Csaki, A.; Fritzsche, W.; Schmidt, M. A.

    2016-09-01

    Due to their unique optical properties, metallic nanoparticles offer a great potential for important applications such as disease diagnostics, demanding highly integrated device solutions with large refractive index sensitivity. Here we introduce a new type of monolithic localized surface plasmon resonance (LSPR) waveguide sensor based on the combination of an adiabatic optical fiber taper and a high-density ensemble of immobilized gold-reinforced silver nanoprisms, showing sensitivities up to 900 nm/RIU. This result represents the highest value reported so far for a fiber optic sensor using the LSPR effect and exceeds the corresponding value of the bulk solution by a factor of two. The plasmonic resonance is efficiently excited via the evanescent field of the propagating taper mode, leading to pronounced transmission dips (-20 dB). The particle density is so high (approx. 210 particle/μm2) that neighboring particles are able to interact, boosting the sensitivity, as confirmed by qualitative infinite element simulations. We additionally introduce a qualitative model explaining the interaction of plasmon resonance and taper mode on the basis of light extinction, allowing extracting key parameters of the plasmonic taper (e.g., modal attenuation). Due to the monolithic design and the extremely high sensitivity we expect our finding to be relevant in fields such as biomedicine, disease diagnostics, and molecular sensing.

  7. Integrated dual-mode 3 dB power coupler based on tapered directional coupler

    PubMed Central

    Luo, Yuchan; Yu, Yu; Ye, Mengyuan; Sun, Chunlei; Zhang, Xinliang

    2016-01-01

    A dual-mode 3 dB power coupler based on silicon-on-insulator platform for mode division multiplexing system is proposed and demonstrated. The device, which consists of a tapered directional coupler and two output bend waveguides, has a 50:50 coupling ratio around the wavelength of 1550 nm for both fundamental and first order transverse magnetic (TM0 and TM1) modes. Based on asymmetrical tapered structure, a short common coupling length of ~15.2 μm for both modes is realized by optimizing the width of the tapered waveguide. The measured insertion loss for both modes is less than 0.7 dB. The crosstalks are about −14.3 dB for TM0 mode and −18.1 dB for TM1 mode. PMID:27002747

  8. Thermal tuning of hollow waveguides fabricated by controlled thin-film buckling.

    PubMed

    Epp, E; Ponnampalam, N; McMullin, J N; Decorby, R G

    2009-09-28

    We describe the thermal tuning of air-core Bragg waveguides, fabricated by controlled formation of delamination buckles within a multilayer stack of chalcogenide glass and polymer. The upper cladding mirror is a flexible membrane comprising high thermal expansion materials, enabling large tuning of the air-core dimensions for small changes in temperature. Measurements on the temperature dependence of feature heights showed good agreement with theoretical predictions. We applied this mechanism to the thermal tuning of modal cutoff conditions in waveguides with a tapered core profile. Due to the omnidirectional nature of the cladding mirrors, these tapers can be viewed as waveguide-coupled, tunable Fabry-Perot filters.

  9. Intensity modulated SMF cascaded tapers with a hollow core PCF based microcavity for curvature sensing

    NASA Astrophysics Data System (ADS)

    Dass, Sumit; Narayan Dash, Jitendra; Jha, Rajan

    2016-03-01

    We propose a highly sensitive curvature sensor based on cascaded single mode fiber (SMF) tapers with a microcavity. The microcavity is created by splicing a small piece of hollow core photonic crystal fiber (HCPCF) at the end of an SMF to obtain a sharp interference pattern. Experimental results show that two SMF tapers enhance the curvature sensitivity of the system and by changing the tapering parameters of the second taper, the curvature sensitivity of the system can be tailored, together with the fringe contrast of the interference pattern. A maximum curvature sensitivity of 10.4 dB/m-1 is observed in the curvature range 0 to 1 m-1 for a second taper diameter of 18 μm. The sensing setup is highly stable and shows very low temperature sensitivity. As the interrogation is intensity based, a low cost optical power meter can be utilized to determine the curvature.

  10. LOADED WAVEGUIDES

    DOEpatents

    Mullett, L.B.; Loach, B.G.; Adams, G.L.

    1958-06-24

    >Loaded waveguides are described for the propagation of electromagnetic waves with reduced phase velocities. A rectangular waveguide is dimensioned so as to cut-off the simple H/sub 01/ mode at the operating frequency. The waveguide is capacitance loaded, so as to reduce the phase velocity of the transmitted wave, by connecting an electrical conductor between directly opposite points in the major median plane on the narrower pair of waveguide walls. This conductor may take a corrugated shape or be an aperature member, the important factor being that the electrical length of the conductor is greater than one-half wavelength at the operating frequency. Prepared for the Second U.N. International ConferThe importance of nuclear standards is duscussed. A brief review of the international callaboration in this field is given. The proposal is made to let the International Organization for Standardization (ISO) coordinate the efforts from other groups. (W.D.M.)

  11. Finite-aperture tapered unstable resonator lasers

    NASA Astrophysics Data System (ADS)

    Bedford, Robert George

    The development of high power, high brightness semiconductor lasers is important for applications such as efficient pumping of fiber amplifiers and free space communication. The ability to couple directly into the core of a single-mode fiber can vastly increase the absorption of pump light. Further, the high mode-selectivity provided by unstable resonators accommodates single-mode operation to many times the threshold current level. The objective of this dissertation is to investigate a more efficient semiconductor-based unstable resonator design. The tapered unstable resonator laser consists of a single-mode ridge coupled to a tapered gain region. The ridge, aided by spoiling grooves, provides essential preparation of the fundamental mode, while the taper provides significant amplification and a large output mode. It is shown a laterally finite taper-side mirror (making the laser a "finite-aperture tapered unstable resonator laser") serves to significantly improve differential quantum efficiency. This results in the possibility for higher optical powers while still maintaining single-mode operation. Additionally, the advent of a detuned second order grating allows for a low divergent, quasicircular output beam emitted from the semiconductor surface, easing packaging tolerances, and making two dimensional integrated arrays possible. In this dissertation, theory, design, fabrication, and characterization are presented. Material theory is introduced, reviewing gain, carrier, and temperature effects on field propagation. Coupled-mode and coupled wave theory is reviewed to allow simulation of the passive grating. A numerical model is used to investigate laser design and optimization, and effects of finite-apertures are explored. A microfabrication method is introduced to create the FATURL in InAlGaAs/-InGaAsP/InP material emitting at about 1410 nm. Fabrication consists of photolithography, electron-beam lithography, wet etch and dry etching processes, metal and

  12. Wave front adaptation using a deformable mirror for adiabatic nanofocusing along an ultrasharp gold taper.

    PubMed

    Schmidt, Slawa; Engelke, Pascal; Piglosiewicz, Björn; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Groß, Petra

    2013-11-01

    We describe and demonstrate the use of an adaptive wave front optimization scheme for enhancing the efficiency of adiabatic nanofocusing of surface plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic nanofocusing is an emerging and promising scheme for controlled focusing of far field light into nanometric volumes. It comprises three essential steps: SPP excitation by coupling far field light to an SPP waveguide, SPP propagation along the waveguide and adiabatic SPP nanofocusing towards a geometric singularity. For commonly used complex waveguide geometries, such as, e.g., conical metal tapers, a realistic modeling and efficiency optimization is challenging. Here, we use a deformable mirror to adaptively control the wave front of the incident far field light. We demonstrate an eight-fold enhancement in nanofocusing efficiency and analyze the shape of the resulting optimized wave front. The introduced wave front optimization scheme is of general interest for guiding and controlling light on the nanoscale.

  13. Fiber Optic Surface Plasmon Resonance-Based Biosensor Technique: Fabrication, Advancement, and Application.

    PubMed

    Liang, Gaoling; Luo, Zewei; Liu, Kunping; Wang, Yimin; Dai, Jianxiong; Duan, Yixiang

    2016-05-01

    Fiber optic-based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic-based SPR sensor technology are discussed. PMID:27119268

  14. Chemical-Assisted Femtosecond Laser Writing of Lab-in-Fiber Sensors

    NASA Astrophysics Data System (ADS)

    Haque, Moez

    Three-dimensional (3D) patterning inside optical fiber was shown to be a powerful tool for embedding refractive index and microfluidic structures inside the flexible glass fiber for enabling novel sensing opportunities with lab-in-fibers (LIFs). A femtosecond laser was tightly focused into optical fibers using an oil-immersion lens to eliminate extreme optical aberrations from the cladding-air interface. The laser interactions were then optimized to bring ˜12 nm rms surfaces for the first time inside the fiber cladding by precisely conforming planar nanograting structures when assembled by the writing laser. Further, the unprecedented integration of cladding waveguides, X-couplers, fiber Bragg gratings (FBGs), microholes, mirrors, optofluidic resonators, and microfluidic reservoirs defined the building blocks for facile interconnection of inline core-waveguide devices with fiber cladding optofluidics. Laser templating was restricted to the single mode fiber (SMF) cladding or formed inside all-fused silica coreless optical fibers to meet with buried laser-formed waveguides that were fused to SMFs for novel seamless inline probing while avoiding undesired concave surface profiles and negative lensing losses associated with writing optofluidic templates across the germanium-doped SMF core waveguide. With these components, more advanced, integrated, and multiplexed fiber microsystems were demonstrated for fluorescence detection, Fabry Perot interferometer (FPI) refractometry, and simultaneous sensing of refractive index, temperature, and bending strain. Tapered access ports were found to minimize fiber mechanical weakening and thereby avoid fiber breakage during optofluidic sensing. Optical resonator arrays (ORAs) were then explored to deepen fringe contrasts beyond that available with a single FPI for opening new prospects for fiber inline pass-band optical filters and broadband reflectors. Finally, wavefront splitting interferometers (WSIs) were targeted to improve

  15. Highly-efficient fully resonant vertical couplers for InP active-passive monolithic integration using vertically phase matched waveguides.

    PubMed

    López, Oscar García; Lasaosa, Daniel; López-Amo, Manuel; Galarza, Marko

    2013-09-23

    A new active-passive monolithic integration approach for photonic components based on vertical evanescent coupling is presented. Two vertically stacked waveguides are used in order to provide full resonant power transfer between them and avoiding the need of tapered structures. Light confinement in each waveguide is achieved combining strong lateral asymmetric structures and bent waveguides, both defined during lithography. Low propagation losses for the active waveguide and coupling efficiencies to the passive section as high as 97% have been obtained.

  16. Waveguides formed by quasi-steady-state photorefractive spatial solitons.

    PubMed

    Morin, M; Duree, G; Salamo, G; Segev, M

    1995-10-15

    We show that a quasi-steady-state photorefractive spatial soliton forms a waveguide structure in the bulk of a photorefractive material. Although the optically induced waveguide is formed by a very low-power (microwatts) soliton beam, it can guide a powerful (watt) beam of a longer wavelength at which the medium is nonphotosensitive. Furthermore, the waveguide survives, either in the dark or when guiding the longerwavelength beam, for a long time after the soliton beam is turned off. We take advantage of the solitons' property of evolution from a relatively broad input beam into a narrow channel and show that the soliton induces a tapered waveguide (an optical funnel) that improves the coupling efficiency of light into the waveguiding structure.

  17. Characterization of tapered slot antenna feeds and feed arrays

    NASA Technical Reports Server (NTRS)

    Kim, Young-Sik; Yngvesson, K. Sigfrid

    1990-01-01

    A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements.

  18. a Reformulation of Coupled Mode Theory for Multimode Guides with Application to a Specialized Graded-Index Optical Fiber Coupler.

    NASA Astrophysics Data System (ADS)

    Saleh, Salama Abul-Seoud

    Coupled mode theory for parallel dielectric waveguides is reformulated for the case of a multimode multiwaveguide system. This theory is derived on the basis of a generalized reciprocity theorem. Analytical relations among the coupling coefficients are derived and applied to the coupled mode equations. It is found that even for lossless identical fibers the coupling coefficients from the m^ {th} mode in fiber "a" to the n ^{th} mode in fiber "b" and from the n^{th} mode in fiber "b" to the m^{th} mode in fiber "a" described by K_sp{rm m,n}{rm(a,b)} and K _sp{rm n,m}{rm (b,a)} , respectively, are not related simply as complex conjugates. With the appropriate use of the overlap integrals, the new theory satisfies both the reciprocity and the power conservation relations exactly. The symmetric (hermitian) orthogonality of the supermode eigenvectors with a weighting matrix given by the overlap intergrals matrix is demonstrated in the lossy (and lossless) case. A system consisting of two identical coupled graded -index slab fibers is studied. The coupling length for maximum power transfer of the higher order modes from the excited to the coupled fiber, leaving as much power of the lowest mode as possible to continue in the excited fiber, is computed for different graded-index slab fibers. This desired coupling length is shown to be independent of the incident light beam. To achieve control of the effective coupling length between the two fibers, special means for separating them at some point are needed for some applications. For this purpose, a tapered section is introduced. The stairwise approximation is used to compute the fields propagated through the tapered section, and mode matching method is used to connect the fields at the junctions between the successive segments. Both linear and curved tapers are considered. The electric fields are computed at the output of the system for incident optical beams with different axial displacements and beams launched on axis

  19. TAPERED DEFINING SLOT

    DOEpatents

    Pressey, F.W.

    1959-09-01

    An improvement is reported in the shape and formation of the slot or opening in the collimating slot member which forms part of an ion source of the type wherein a vapor of the material to be ionized is bombarded by electrons in a magnetic field to strike an arc-producing ionization. The defining slot is formed so as to have a substantial taper away from the cathode, causing the electron bombardment from the cathode to be dispersed over a greater area reducing its temperature and at the same time bringing the principal concentration of heat from the electron bombardment nearer the anode side of the slot, thus reducing deterioration and prolonging the life of the slot member during operation.

  20. Detection of recombinant growth hormone by evanescent cascaded waveguide coupler on silica-on-silicon.

    PubMed

    Ozhikandathil, Jayan; Packirisamy, Muthukumaran

    2013-05-01

    An evanescent wave based biosensor is developed on the silica-on-silicon (SOS) with a cascaded waveguide coupler for the detection of recombinant growth hormone. So far, U -bends and tapered waveguides are demonstrated for increasing the penetration depth and enhancing sensitivity of the evanescent wave sensor. In this work, a monolithically integrated sensor platform containing a cascaded waveguide coupler with optical power splitters and combiners designed with S -bends and tapper waveguides is demonstrated for an enhanced detection of recombinant growth hormone. In the cascaded waveguide coupler, a large surface area to bind the antibody with increased penetration depth of evanescent wave to excite the tagged-rbST is obtained by splitting the waveguide into multiple paths using Y splitters designed with s -bends and subsequently combining them back to a single waveguide through tapered waveguide and combiners. Hence a highly sensitive fluoroimmunoassay sensor is realized. Using the 2D FDTD (Finite-difference time-domain method) simulation of waveguide with a point source in Rsoft FullWAVE, the fluorescence coupling efficiency of straight and bend section of waveguide is analyzed. The sensor is demonstrated for the detection of fluorescently-tagged recombinant growth hormone with the detection limit as low as 25 ng/ml.

  1. Tapered undulator for SASE FELs

    SciTech Connect

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2001-09-14

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

  2. Spectral tuning of a locally bent microfiber taper interferometer with a nanosized liquid crystal overlay.

    PubMed

    Luo, Haimei; Wang, Changjing; Ji, Yinghua; Yuan, Wen; Zhang, Guoping; Wang, Yifan; Hong, Zehua; Wang, Xianping

    2016-09-10

    In this paper, the tuning characteristics of locally bent microfiber taper covered with a nanosized high-refractive-index liquid crystal (LC) layer under different temperatures and electric field intensities have been theoretically analyzed and experimentally investigated. A locally bent microfiber taper interferometer with a waist diameter of ∼3.72  μm is fabricated by using the flame brushing technique, followed by bending the transition region of the taper to form a modal interferometer and later by placing a ∼200  nm LC layer over the uniform taper waist region. Experimental results indicate that a high-efficiency thermal or electric tuning of an LC-coated locally bent microfiber taper interferometer could be achieved. This suggests a potential application of this device as tunable all-fiber photonic devices, such as filters, modulators, and sensing elements.

  3. Spectral tuning of a locally bent microfiber taper interferometer with a nanosized liquid crystal overlay.

    PubMed

    Luo, Haimei; Wang, Changjing; Ji, Yinghua; Yuan, Wen; Zhang, Guoping; Wang, Yifan; Hong, Zehua; Wang, Xianping

    2016-09-10

    In this paper, the tuning characteristics of locally bent microfiber taper covered with a nanosized high-refractive-index liquid crystal (LC) layer under different temperatures and electric field intensities have been theoretically analyzed and experimentally investigated. A locally bent microfiber taper interferometer with a waist diameter of ∼3.72  μm is fabricated by using the flame brushing technique, followed by bending the transition region of the taper to form a modal interferometer and later by placing a ∼200  nm LC layer over the uniform taper waist region. Experimental results indicate that a high-efficiency thermal or electric tuning of an LC-coated locally bent microfiber taper interferometer could be achieved. This suggests a potential application of this device as tunable all-fiber photonic devices, such as filters, modulators, and sensing elements. PMID:27661380

  4. "Photonic lantern" spectral filters in multi-core Fiber.

    PubMed

    Birks, T A; Mangan, B J; Díez, A; Cruz, J L; Murphy, D F

    2012-06-18

    Fiber Bragg gratings are written across all 120 single-mode cores of a multi-core optical Fiber. The Fiber is interfaced to multimode ports by tapering it within a depressed-index glass jacket. The result is a compact multimode "photonic lantern" filter with astrophotonic applications. The tapered structure is also an effective mode scrambler.

  5. Tapered undulators for SASE FELs

    NASA Astrophysics Data System (ADS)

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2002-05-01

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

  6. Side illuminated optical fiber as a multiplexing element for spectroscopic systems

    NASA Astrophysics Data System (ADS)

    Egalon, Claudio O.; Matta, Michael P.; Lavezzari, Delbert C.; Insley, Robert Y.; Jaring, Carolyn C.; Quiday, Marie F.

    2013-09-01

    A new type of colorimeter with multiple channels was demonstrated using a side illuminated optical fiber. When different spots of a properly modified fiber are side illuminated, multiple signals are generated and guided by the waveguide: the essence of multiplexing. This configuration is simple, low cost, does not require a sensitive coating and can analyze several samples along the fiber with a single detector: the most expensive component. Since regular colorimeters use one detector per sample, our new configuration considerably lowers the cost of analyzing multiple samples. This system consists of a fiber mounted over a support, three LEDs, an LED driver, a photo diode and a read-out: to increase the signal, the fiber was tapered. For calibration purposes, six solutions of different concentrations of food dye were prepared, placed inside cuvettes along the fiber length and illuminated by the LEDs. This light passes through the solution, strikes the fiber and is guided to the detector: the darker the solution the lower the signal intensity. Several calibration curves were obtained using different light intensities: it was found that the greater the intensity, the higher the colorimeter sensitivity. This simple capability can be used to easily control the device's sensitivity and its resolution. Although built for three samples only, this device can be modified to accommodate more. With cuvettes measuring 1 cm, it is possible to accommodate one sample per cm of fiber. Also, with minor modifications, this colorimeter can be used for fluorescence, scattering and index of refraction measurements.

  7. The structural damping of composite beams with tapered boundaries

    NASA Astrophysics Data System (ADS)

    Coni, M.; Benchekchou, B.; White, R. G.

    1994-11-01

    Most metallic and composite structures of conventional construction are lightly damped. It is obviously advantageous, in terms of response to in-service dynamic loading, if damping can be increased with minimal weight addition. This report describes finite element analyses and complementary experiments carried out on composite, carbon fiber reinforced plastic, beams with tapered boundaries composed of layers of highly damped composite material. It is shown that modal damping of the structure may be significantly increased by this method.

  8. First demonstration of a novel 2D-waveguiding solar concentrator

    NASA Astrophysics Data System (ADS)

    Huang, R.; Liu, Y.; Madsen, C. K.

    2014-10-01

    The first experimental demonstration results will be presented for a novel, two-dimensional waveguiding solar concentrator consisting of a primary concentrator (a microlens array) and a secondary concentrator (tapered multimode waveguides). The microlens array collects the incident sun light and focuses it onto a turning mirror. The turning mirror couples the light into a tapered multimode waveguide, which alleviates connection, cooling and uniformity issues associated with conventional solar concentrating systems. Therefore, a large area of light can be efficiently concentrated to a small waveguide cross-section and guided to an array of co-located photovoltaic cells with high optical efficiency. To achieve the maximum coupling efficiency of the light to the waveguide, the design of the turning mirror and waveguides are optimized to avoid any inherent decoupling loss in the subsequent waveguide propagation. Experimental results indicate that a 38 mm diameter lens with a multimode waveguide that is 3 mm x 3 mm x 10 cm, using only total internal reflection surfaces, can achieve 126x concentration with 62.8% optical efficiency. We will present details on the experimental device characterization. A critical requirement for this design is maintaining low waveguide propagation losses, which as we demonstrate can be less than 0.1 dB/cm. Considering 100% TIR coupling and the use of antireflection layers, the theoretical efficiency limit for this particular system is ~88%.

  9. Fiber

    MedlinePlus

    ... broccoli, spinach, and artichokes legumes (split peas, soy, lentils, etc.) almonds Look for the fiber content of ... salsa, taco sauce, and cheese for dinner. Add lentils or whole-grain barley to your favorite soups. ...

  10. Fabrication of Optical Fiber Devices

    NASA Astrophysics Data System (ADS)

    Andres, Miguel V.

    In this paper we present the main research activities of the Laboratorio de Fibras Opticas del Instituto de Ciencia de los Materiales de la Universidad de Valencia. We show some of the main results obtained for devices based on tapered fibers, fiber Bragg gratings, acousto-optic effects and photonic crystal fibers.

  11. Single-mode tapered terahertz quantum cascade lasers with lateral gratings

    NASA Astrophysics Data System (ADS)

    Yao, C.; Xu, T. H.; Wan, W. J.; Li, H.; Cao, J. C.

    2016-08-01

    We report on tapered terahertz quantum cascade lasers with lateral gratings. The proposed devices exhibit not only low horizontal divergence due to tapered structure but also single-mode operation by using lateral grating structure. The tapered region and lateral gratings can be fabricated with the ridged waveguide in one etching step without inducing complexity into the fabrication. Side-mode suppression ratio ∼20 dB is obtained for proposed devices from threshold to rollover currents at all measure temperatures, with the peak output power of ∼30 mW at 10 K in pulsed mode and lateral divergence angle reduced by half. The proposed devices are good candidates for high-power, single-mode operation and low-divergence laser with easy fabrication.

  12. Development of high-power gyrotrons with gradually tapered cavity

    SciTech Connect

    Lei Chaojun; Yu Sheng; Niu Xinjian; Liu Yinghui; Li Hongfu; Li Xiang

    2012-12-15

    In high power gyrotrons, the parasitic modes coupled with the operating mode cannot be avoided in the beam-wave interaction. These parasitic modes will decrease the efficiency of the gyrotrons. The purity of the operating mode affected by different tapers should be carefully studied. The steady-state self-consistent nonlinear theory for gyrotron with gradually tapered cavity is developed in this paper. A steady-state calculation code including 'cold cavity' and 'hot cavity' is designed. By comparison, a time-domain model analysis of gyrotron operation is also studied by particle-in-cell (PIC). It is found that the tapers of gyrotron have different influences on the modes coupling between the operating mode and the parasitic modes. During the study, an example of 94 GHz gyrotron with pure operating mode TE{sub 03} has been designed. The purity of the operating mode in the optimized cavity is up to -77 dB, and in output waveguide of the cavity is up to -76 dB. At the same time, the beam-wave interaction in the designed cavity has been simulated, too. An output power of 120 kW, corresponding to 41.6% efficiency and an oscillation frequency of 94.099 GHz have been achieved with a 50 kV, 6 A helical electron beam at a guiding magnetic field of 3.5485 T. The results show that the power in spurious modes of the optimized cavity may be kept far below than that of the traditional tapered cavity.

  13. Four-wave-mixing in the loss low submicrometer Ta₂O₅ channel waveguide.

    PubMed

    Wu, Chung-Lun; Chiu, Yi-Jen; Chen, Cong-Long; Lin, Yuan-Yao; Chu, Ann-Kuo; Lee, Chao-Kuei

    2015-10-01

    A degenerate four-wave-mixing (FWM) operation in the Ta2O5 submicrometer channel waveguide has been successfully demonstrated. The propagation loss of 1.5  dB/cm and total insertion loss of 5.1 dB are realized in a 12.6 mm long waveguide with inverse taper structure. The wavelength and quadratic pumping power-dependent measurements on optical transmission confirm FWM performance and characterize the nonlinearity of waveguide. The conversion efficiency of -50  dB at coupled pump power of 40 mW is observed, suggesting that the nonlinear refractive index of Ta2O5 waveguide at 1550 nm is estimated to be 1×10(-14)  cm2/W. Our primary results indicate that the Ta2O5 submicrometer channel waveguide has great potential in developing nonlinear waveguide applications.

  14. High-power high-brightness semiconductor tapered diode lasers for the red and near infrared spectral range

    NASA Astrophysics Data System (ADS)

    Sumpf, B.; Wenzel, H.; Erbert, G.

    2010-02-01

    The most promising concept to achieve high-output power together with a good beam quality is the tapered laser consisting of a straight ridge waveguide (RW) section and a tapered gain-region. The RW section should support only the fundamental guided mode and should suppress higher order modes. The taper angle has to be selected with respect to the lateral divergence of the beam propagating from the RW to the tapered section. High brightness tapered devices in the wavelength range between 635 nm and 1085 nm will be presented. For red emitting tapered lasers around 650 nm, the output power is limited to about 1 W due to the properties of the laser material. At this output power a beam propagation ratio M2 of 1.3 and a brightness of 100 MW•cm-2•sr-1 will be shown. Devices made from laser structures with low vertical divergence down to 25° (95% power included) without a significant deterioration of device parameters will be presented for the longer wavelength range near 1 μm. For tapered lasers manufactured from these structures, nearly diffraction limited output powers larger than 10 W and a brightness of 1 GW•cm-2•sr-1 were measured.

  15. Waveguide-Based Biosensors for Pathogen Detection

    PubMed Central

    Mukundan, Harshini; Anderson, Aaron S.; Grace, W. Kevin; Grace, Karen M.; Hartman, Nile; Martinez, Jennifer S.; Swanson, Basil I.

    2009-01-01

    Optical phenomena such as fluorescence, phosphorescence, polarization, interference and non-linearity have been extensively used for biosensing applications. Optical waveguides (both planar and fiber-optic) are comprised of a material with high permittivity/high refractive index surrounded on all sides by materials with lower refractive indices, such as a substrate and the media to be sensed. This arrangement allows coupled light to propagate through the high refractive index waveguide by total internal reflection and generates an electromagnetic wave—the evanescent field—whose amplitude decreases exponentially as the distance from the surface increases. Excitation of fluorophores within the evanescent wave allows for sensitive detection while minimizing background fluorescence from complex, “dirty” biological samples. In this review, we will describe the basic principles, advantages and disadvantages of planar optical waveguide-based biodetection technologies. This discussion will include already commercialized technologies (e.g., Corning’s EPIC® Ô, SRU Biosystems’ BIND™, Zeptosense®, etc.) and new technologies that are under research and development. We will also review differing assay approaches for the detection of various biomolecules, as well as the thin-film coatings that are often required for waveguide functionalization and effective detection. Finally, we will discuss reverse-symmetry waveguides, resonant waveguide grating sensors and metal-clad leaky waveguides as alternative signal transducers in optical biosensing. PMID:22346727

  16. Hot-embossed polymeric optical waveguides

    NASA Astrophysics Data System (ADS)

    Choi, Choon-Gi; Kim, Jin-Tae; Han, Sang-Pil; Ahn, Seung-Ho

    2004-10-01

    Polymer waveguides have attracted a great deal of attention for their potential applications as optical components in optical communications, optical interconnections and optical sensors because they are easy to manufacture at a low temperature, and they have a low processing cost. Hot embossing is powerful and effective tools to produce a large volume of waveguides and structure high-precision micro/nano patterns of thin polymer films using a stamp for optical applications. In this work, fabrication techniques of hot embossed polymeric optical waveguides for parallel optical interconnection module, multi-channel variable optical attenuator and optical printed circuit boards are demonstrated. The single- and multi-mode waveguides are produced by core filling and UV curing processes. New approaches to fabricating single-mode polymeric waveguides with the high thermal stability in thermosetting polymers and two-dimensional multi-mode polymeric waveguides for high-density parallel optical interconnections as well as a simultaneous fabrication of single-mode polymeric waveguides with micro pedestals for passive fiber alignment are also reported.

  17. A new model for broadband waveguide to microstrip transition design

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Downey, Alan N.

    1986-01-01

    A new model is presented which permits the prediction of the resonant frequencies created by antipodal finline waveguide to microstrip transitions. The transition is modeled as a tapered transmission line in series with an infinite set of coupled resonant circuits. The resonant circuits are modeled as simple microwave resonant cavities of which the resonant frequencies are easily determined. The model is developed and the resonant frequencies determined for several different transitions. Experimental results are given to confirm the models.

  18. Evanescent field sensors and the implementation of waveguiding nanostructures

    SciTech Connect

    Boerner, Sandra; Orghici, Rozalia; Waldvogel, Siegfried R.; Willer, Ulrike; Schade, Wolfgang

    2009-02-01

    Conventional fiber optic evanescent-field gas sensors are based on a high number of total reflections while the gas is passing the active bare core fiber and of course a suitable laser light source. The use of miniaturized laser sources for sensitive detection of CO2 in gaseous and water-dissolved phase for environmental monitoring are studied for signal enhancing purposes. Additionally, the fiber optic sensor, consisting of a coiled bare multimode fiber core, was sensitized by an active polymer coating for the detection of explosive TNT. The implementation of ZnO waveguiding nanowires is discussed for surface and sensitivity enhancing coating of waveguiding elements, considering computational and experimental results.

  19. Photonic lantern with cladding-removable fibers

    NASA Astrophysics Data System (ADS)

    Sun, Weimin; Yan, Qi; Bi, Yao; Yu, Haijiao; Liu, Xiaoqi; Xue, Jiuling; Tian, He; Liu, Yongjun

    2014-07-01

    Recently, spectral measurement becomes an important tool in astronomy to find exoplanets etc. The fibers are used to transfer light from the focal plate to spectrometers. To get high-resolution spectrum, the input slits of the spectrometers should be as narrow as possible. In opposite, the light spots from the fibers are circle, which diameters are clearly wider than the width of the spectrometer slits. To reduce the energy loss of the fiber-guide star light, many kinds of image slicers were designed and fabricated to transform light spot from circle to linear. Some different setup of fiber slicers are introduced by different research groups around the world. The photonic lanterns are candidates of fiber slicers. Photonic lantern includes three parts: inserted fibers, preform or tubing, taped part of the preform or tubing. Usually the optical fields concentrate in the former-core area, so the light spots are not uniform from the tapered end of the lantern. We designed, fabricated and tested a special kind of photonic lantern. The special fibers consist polymer cladding and doped high-index core. The polymer cladding could be easily removed using acetone bath, while the fiber core remains in good condition. We inserted the pure high-index cores into a pure silica tubing and tapered it. During the tapering process, the gaps between the inserted fibers disappeared. Finally we can get a uniform tapered multimode fiber end. The simulation results show that the longer the taper is, the lower the loss is. The shape of the taper should be controlled carefully. A large-zone moving-flame taper machine was fabricated to make the special photonic lantern. Three samples of photonic lanterns were fabricated and tested. The lanterns with cladding-removable fibers guide light uniform in the tapered ends that means these lanterns could collect more light from those ends.

  20. Polymer waveguide technology for flexible display applications

    NASA Astrophysics Data System (ADS)

    Okuda, Yuuto; Fujieda, Ichiro

    2012-03-01

    We consider applications of wave-guiding technologies for flexible displays. First, a flexible backlight can be constructed by guiding laser light through an optical fiber arranged in a spiral manner. The light leaks out via the grooves fabricated on the optical fiber. For uniform illumination, the probability of light extraction at each groove and the pitch of the grooves are adjusted. Second, a polymer waveguide with successive branches distributes the optical power from a laser to two-dimensional emission points on a plane. The division ratio at each branch is an important design parameter for uniform light output. At each branch and emission point, a mirror is placed for 90-degree optical path redirection. This constitutes a flexible backlight. Third, in a more technically demanding design, a mirror based on the micro-electro-mechanical systems technology scans a laser beam on the entrance surface of the waveguide and each emission point is addressed sequentially. An image can be displayed by intensity modulation of the laser light synchronized to this scanning action. The precision of the waveguide fabrication and the beam scanning accuracy would determine the display resolution. Finally, such a waveguide may be applied for concentrated photovoltaic applications. An array of lenses is stacked on the waveguide so that the optical power is focused on each mirror. The direction of the light propagation is reversed. Now the exit surface of the waveguide is coupled to solar cells. In all these cases, the polymer waveguide technology offers a cost advantage due to its feasibility for the roll-to-roll process.

  1. Alignment algorithms for planar optical waveguides

    NASA Astrophysics Data System (ADS)

    Zheng, Yu; Duan, Ji-an

    2012-10-01

    Planar optical waveguides are the key elements in a modern, high-speed optical network. An important problem facing the optical fiber communication system is optical-axis alignment and coupling between waveguide chips and transmission fibers. The advantages and disadvantages of the various algorithms used for the optical-axis alignment, namely, hill-climbing, pattern search, and genetic algorithm are analyzed. A new optical-axis alignment for planar optical waveguides is presented which is a composite of a genetic algorithm and a pattern search algorithm. Experiments have proved the proposed alignment's feasibility; compared with hill climbing, the search process can reduce the number of movements by 88% and reduce the search time by 83%. Moreover, the search success rate in the experiment can reach 100%.

  2. Linear permittivity tapering in a Cerenkov microwave source with a pre-bunched beam

    SciTech Connect

    Poole, B. R.; Harris, J. R.

    2013-04-15

    Cerenkov microwave sources use a dielectric-lined waveguide to reduce the velocity of the electromagnetic wave and provide efficient energy transfer between the wave and the driving electron beam. Tapering the permittivity of the dielectric to maintain synchronism between the beam and the wave as the beam loses energy can increase the efficiency of these devices. Here, we consider such a structure driven by an electron beam with a harmonic density perturbation. Particle-In-Cell (PIC) simulations and a macro-particle model based on the slowly varying envelope approximation are first used to examine an un-tapered baseline case. PIC simulations of the source with linear tapers over the entire amplifier length as well as over only a section of the amplifier where the beam executes synchrotron oscillations are examined. The efficiency for the baseline un-tapered source is 18%, while efficiencies up to approximately 48% are found using a taper in dielectric permittivity. Results of the best performing cases are presented. Detailed examination of longitudinal phase space, particle energy distributions, evolution of longitudinal wavenumber, and phase dynamics are presented from the PIC simulations.

  3. Linear permittivity tapering in a Cerenkov microwave source with a pre-bunched beam

    NASA Astrophysics Data System (ADS)

    Poole, B. R.; Harris, J. R.

    2013-04-01

    Cerenkov microwave sources use a dielectric-lined waveguide to reduce the velocity of the electromagnetic wave and provide efficient energy transfer between the wave and the driving electron beam. Tapering the permittivity of the dielectric to maintain synchronism between the beam and the wave as the beam loses energy can increase the efficiency of these devices. Here, we consider such a structure driven by an electron beam with a harmonic density perturbation. Particle-In-Cell (PIC) simulations and a macro-particle model based on the slowly varying envelope approximation are first used to examine an un-tapered baseline case. PIC simulations of the source with linear tapers over the entire amplifier length as well as over only a section of the amplifier where the beam executes synchrotron oscillations are examined. The efficiency for the baseline un-tapered source is 18%, while efficiencies up to approximately 48% are found using a taper in dielectric permittivity. Results of the best performing cases are presented. Detailed examination of longitudinal phase space, particle energy distributions, evolution of longitudinal wavenumber, and phase dynamics are presented from the PIC simulations.

  4. Novel adiabatic tapered couplers for active III-V/SOI devices fabricated through transfer printing.

    PubMed

    Dhoore, Sören; Uvin, Sarah; Van Thourhout, Dries; Morthier, Geert; Roelkens, Gunther

    2016-06-13

    We present the design of two novel adiabatic tapered coupling structures that allow efficient and alignment tolerant mode conversion between a III-V membrane waveguide and a single-mode SOI waveguide in active heterogeneously integrated devices. Both proposed couplers employ a broad intermediate waveguide to facilitate highly alignment tolerant coupling. This robustness is needed to comply with the current misalignment tolerance requirements for high-throughput transfer printing. The proposed coupling structures are expected to pave the way for transfer-printing-based heterogeneous integration of active III-V devices such as semiconductor optical amplifiers (SOAs), photodetectors, electro-absorption modulators (EAMs) and single wavelength lasers on silicon photonic integrated circuits. PMID:27410317

  5. Compact waveguide circular polarizer

    DOEpatents

    Tantawi, Sami G.

    2016-08-16

    A multi-port waveguide is provided having a rectangular waveguide that includes a Y-shape structure with first top arm having a first rectangular waveguide port, a second top arm with second rectangular waveguide port, and a base arm with a third rectangular waveguide port for supporting a TE.sub.10 mode and a TE.sub.20 mode, where the end of the third rectangular waveguide port includes rounded edges that are parallel to a z-axis of the waveguide, a circular waveguide having a circular waveguide port for supporting a left hand and a right hand circular polarization TE.sub.11 mode and is coupled to a base arm broad wall, and a matching feature disposed on the base arm broad wall opposite of the circular waveguide for terminating the third rectangular waveguide port, where the first rectangular waveguide port, the second rectangular waveguide port and the circular waveguide port are capable of supporting 4-modes of operation.

  6. Columnar structures from asymmetrically tapered biphenylamide.

    PubMed

    Park, Soo-Jin; Hwang, Seok-Ho; Kim, Namil; Kuo, Shiao-Wei; Kim, Hak Yong; Park, Seul-Ki; Kim, Young-Jin; Nah, Changwoon; Lee, Joong Hee; Jeong, Kwang-Un

    2009-10-15

    An asymmetrically tapered N,N'-tris[[(2-dodecylaminocarbonyl)ethyl]methyl]-4-biphenylamide (asym-C(12)PhA, where n is the number of carbon atoms in the alkyl chains, n = 12) was newly designed and synthesized. In this asymmetrically tapered asym-C(12)PhA biphenylamide, H-bondable hydrophilic amide moieties are located at between a rigid hydrophobic biphenyl rod and three flexible hydrophobic alkyl chains. Computer energy minimization indicated that three-dimensional (3D) geometry of asym-C(12)PhA biphenylamide looks like a cone with dimensions of 3.01 nm in height and 1.44 nm in bottom radius. Phase transitions and supra-molecular structures were identified utilizing the combined techniques of differential scanning calorimetry, 1D wide-angle X-ray diffraction (1D WAXD), Fourier-transform infrared spectroscopy, and solid-state (13)C nuclear magnetic resonance analyses. The asym-C(12)PhA self-assembled into a highly ordered columnar mesophase just below the isotropization temperature and then transformed to 3D columnar crystalline phase (Phi(Cr)) on further cooling. Selected area electron diffractions in transmission electron microscopy (TEM) along with 1D WAXD and cross-polarized optical microscopy suggested that discotic building blocks were constructed by rotating 120 degrees of three asym-C(12)PhA with respect to neighboring ones and the tmb (top-middle-bottom) stacked discotic building blocks further self-organized into columns. These columns are laterally intercalated to form the Phi(Cr) phase. On the basis of the TEM image and polyethylene surface decoration technology, it was identified that the self-assembled asym-C(12)PhA fibers with approximately 1 mum in diameter and several millimeters in length were braids of tiny single crystals.

  7. Variety of neutron sensors based on scintillating glass waveguides

    NASA Astrophysics Data System (ADS)

    Bliss, Mary; Craig, Richard A.

    1995-04-01

    Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate glass scintillating fiber waveguide neutron sensors via a hot-downdraw process. These fibers typically have a transmission length (e-1 length) of greater than 2 meters. The underlying physics of, the properties of, and selected devices incorporating these fibers are described. These fibers constitute an enabling technology for a wide variety of neutron sensors.

  8. Double-pass tapered amplifier diode laser with an output power of 1 W for an injection power of only 200 μW.

    PubMed

    Bolpasi, V; von Klitzing, W

    2010-11-01

    A 1 W tapered amplifier requiring only 200 μW of injection power at 780 nm is presented in this paper. This is achieved by injecting the seeding light into the amplifier from its tapered side and feeding the amplified light back into the small side. The amplified spontaneous emission of the tapered amplifier is suppressed by 75 dB. The double-passed tapered laser, presented here, is extremely stable and reliable. The output beam remains well coupled to the optical fiber for a timescale of months, whereas the injection of the seed light did not require realignment for over a year of daily operation. PMID:21133462

  9. Up-taper-based Mach-Zehnder interferometer for temperature and strain simultaneous measurement.

    PubMed

    Kang, Zexin; Wen, Xiaodong; Li, Chao; Sun, Jiang; Wang, Jing; Jian, Shuisheng

    2014-04-20

    A novel all-fiber sensing configuration for simultaneous measurements of temperature and strain based on the up-taper Mach-Zehnder interferometer (MZI) with an in-line embedded fiber Bragg grating (FBG) is proposed and experimentally demonstrated. This configuration consists of two up-tapers fabricated by an excessive fusion splicing method and a short segment of inscribed FBG. Due to the different responses of the up-taper MZI and the FBG to the uniform variation of temperature and strain, the simultaneous measurement for these two variables could be achieved by real-time monitoring the transmission spectrum. For 0.01 nm wavelength resolution, a resolution of 0.311°C in temperature can be achieved, and the average strain resolution is 10.07 με. PMID:24787597

  10. A double-strip plasmonic waveguide coupled to an electrically driven nanowire LED.

    PubMed

    No, You-Shin; Choi, Jae-Hyuck; Ee, Ho-Seok; Hwang, Min-Soo; Jeong, Kwang-Yong; Lee, Eun-Khwang; Seo, Min-Kyo; Kwon, Soon-Hong; Park, Hong-Gyu

    2013-02-13

    We demonstrate the efficient integration of an electrically driven nanowire (NW) light source with a double-strip plasmonic waveguide. A top-down-fabricated GaAs NW light-emitting diode (LED) is placed between two straight gold strip waveguides with the gap distance decreasing to 30 nm at the end of the waveguide and operated by current injection through the p-contact electrode acting as a plasmonic waveguide. Measurements of polarization-resolved images and spectra show that the light emission from the NW LED was coupled to a plasmonic waveguide mode, propagated through the waveguide, and was focused onto a subwavelength-sized spot of surface plasmon polaritons at the tapered end of the waveguide. Numerical simulation agreed well with these experimental results, confirming that a symmetric plasmonic waveguide mode was excited on the top surface of the waveguide. Our demonstration of a plasmonic waveguide coupled to an electrically driven NW LED represents important progress toward further miniaturization and practical implementation of ultracompact photonic integrated circuits.

  11. Thread gauge for tapered threads

    DOEpatents

    Brewster, Albert L.

    1994-01-11

    The thread gauge permits the user to determine the pitch diameter of tapered threads at the intersection of the pitch cone and the end face of the object being measured. A pair of opposed anvils having lines of threads which match the configuration and taper of the threads on the part being measured are brought into meshing engagement with the threads on opposite sides of the part. The anvils are located linearly into their proper positions by stop fingers on the anvils that are brought into abutting engagement with the end face of the part. This places predetermined reference points of the pitch cone of the thread anvils in registration with corresponding points on the end face of the part being measured, resulting in an accurate determination of the pitch diameter at that location. The thread anvils can be arranged for measuring either internal or external threads.

  12. Thread gauge for tapered threads

    DOEpatents

    Brewster, A.L.

    1994-01-11

    The thread gauge permits the user to determine the pitch diameter of tapered threads at the intersection of the pitch cone and the end face of the object being measured. A pair of opposed anvils having lines of threads which match the configuration and taper of the threads on the part being measured are brought into meshing engagement with the threads on opposite sides of the part. The anvils are located linearly into their proper positions by stop fingers on the anvils that are brought into abutting engagement with the end face of the part. This places predetermined reference points of the pitch cone of the thread anvils in registration with corresponding points on the end face of the part being measured, resulting in an accurate determination of the pitch diameter at that location. The thread anvils can be arranged for measuring either internal or external threads. 13 figures.

  13. Cyclic fatigue resistance of two variable-taper rotary file systems: ProTaper universal and V-Taper.

    PubMed

    Whipple, Sterling J; Kirkpatrick, Timothy C; Rutledge, Richard E

    2009-04-01

    The cyclic fatigue resistance of ProTaper Universal (Dentsply Tulsa Dental Specialties, Tulsa, OK) and V-Taper (Guidance Endo, Albuquerque, NM) files was measured while rotating files around a 5-mm radius curve with 90 degrees of maximum flexure. The files were rotated at 250 rpm with a continuous axial oscillation of 4 mm at 1 Hz. The number of cycles to failure was calculated and analyzed by using univariate analysis of variance and the Tukey HSD posthoc test with results confirmed by nonparametric Kruskal-Wallis and Mann-Whitney U tests with a Bonferroni correction. The fracture faces of representative files were imaged with a scanning electron microscope to confirm cyclic fatigue as the mode of fracture. For the instruments tested, the ProTaper files appeared to resist fracture better than the V-Taper files. At each tip size tested, the ProTaper files either outperformed or were not statistically different than V-Taper files.

  14. High-efficiency transition between rectangular waveguide and domino plasmonic waveguide

    NASA Astrophysics Data System (ADS)

    Liu, Liangliang; Li, Zhuo; Xu, Bingzheng; Gu, Changqing; Chen, Chen; Ning, Pingping; Yan, Jian; Chen, Xingyu

    2015-02-01

    In this work, we propose an optimized transition structure to realize smooth and high efficiency conversion from the guided wave supported by a conventional rectangular waveguide (CRW) to the domino plasmon polaritons (DPPs) supported by a domino plasmonic waveguide (DPW) and vice versa in the X-band (8.2GHz˜12.4GHz). This transition structure consists of two tapered CRWs connected by a gradient domino array with optimized gradient heights and lateral widths. Experimental results of the S-parameters show excellent agreement with the simulations and the optimization scheme can be readily extended to other bands. Furthermore, a domino plasmonic power divider is implemented to demonstrate the application of the transition structure in the integration of conventional microwave circuits with plasmonic devices.

  15. Waveguide-coupled hybrid plasmonic modulator based on graphene.

    PubMed

    Huang, Bao-Hu; Lu, Wei-Bing; Li, Xiao-Bing; Wang, Jian; Liu, Zhen-Guo

    2016-07-20

    In this paper, we propose a low-transmission-loss, high-speed, graphene-based electro-absorption modulator with a hybrid plasmonic waveguide at 1.55 μm. In the proposed device, double-layer graphene is placed on top of the horizontal hybrid plasmonic waveguide to enhance the light-graphene interaction. The adjustment of the in-plane permittivity of the anisotropy graphene causes a significant modulation of the absorption at the operating bandwidth of 0.4 THz, with modulation length of 8.5 μm and modulator footprint of 1.6  μm2. A taper silicon coupler is used for waveguide coupling, and 80% coupling efficiency is achieved. In addition, the modulation potential on a smaller footprint is further shown. PMID:27463912

  16. Wideband slow-light propagation with no distortion in a nanofiber-plane-grating composite waveguide

    NASA Astrophysics Data System (ADS)

    Ma, Chengju; Ren, Liyong; Guo, Wenge; Fu, Haiwei; Xu, Yiping; Liu, Yinggang; Zhang, Xiaozhen

    2016-06-01

    A nanofiber-plane-grating composite slow-light waveguide to achieve wideband slowlight propagation with no distortion is proposed. The waveguide is formed by embedding a tapered nanofiber into a V-groove on a plane-grating surface. By optimizing the waveguide structural parameters, a slow-light effect with bandwidth of about 1453 GHz is obtained. Based on finite-difference time-domain (FDTD) method, we analyze the waveguide's optical properties and slow-light characteristics. Simulation results show that a picosecond optical pulse propagating in the slow-light waveguide can be delayed for about 980 fs and without distortion. The group velocity of the optical pulse can be reduced to about 0.3c (c is the speed of light in vacuum). This study will provide important theoretical basis and innovative ideas for the development of new-type slow-light elements.

  17. Mechanically assisted taper corrosion in modular TKA.

    PubMed

    Arnholt, Christina M; MacDonald, Daniel W; Tohfafarosh, Mariya; Gilbert, Jeremy L; Rimnac, Clare M; Kurtz, Steven M; Klein, Gregg; Mont, Michael A; Parvizi, Javad; Cates, Harold E; Lee, Gwo-Chin; Malkani, Arthur; Kraay, Mattheuw

    2014-09-01

    The purpose of this study was to characterize the prevalence of taper damage in modular TKA components. One hundred ninety-eight modular components were revised after 3.9±4.2 years of implantation. Modular components were evaluated for fretting corrosion using a semi-quantitative 4-point scoring system. Design features and patient information were assessed as predictors of fretting corrosion damage. Mild-to-severe fretting corrosion (score ≥2) was observed in 94/101 tapers on the modular femoral components and 90/97 tapers on the modular tibial components. Mixed alloy pairs (p=0.03), taper design (p<0.001), and component type (p=0.02) were associated with taper corrosion. The results from this study supported the hypothesis that there is taper corrosion in TKA. However the clinical implications remain unclear.

  18. COMPUTER SIMULATIONS OF WAVEGUIDE WINDOW AND COUPLER IRIS FOR PRECISION MATCHING

    SciTech Connect

    Lee, Sung-Woo; Kang, Yoon W; Shin, Ki; Vassioutchenko, Alexandre V

    2011-01-01

    A tapered ridge waveguide iris input coupler and a waveguide ceramic disk windows are used on each of six drift tube linac (DTL) cavities in the Spallation Neutron Source (SNS). The coupler design employs rapidly tapered double ridge waveguide to reduce the cross section down to a smaller low impedance transmission line section that can couple to the DTL tank easily. The impedance matching is done by adjusting the dimensions of the thin slit aperture between the ridges that is the coupling element responsible for the power delivery to the cavity. Since the coupling is sensitive to the dimensional changes of the aperture, it requires careful tuning for precise matching. Accurate RF simulation using latest 3-D EM code is desirable to help the tuning for maintenance and spare manufacturing. Simulations are done for the complete system with the ceramic window and the coupling iris on the cavity to see mutual interaction between the components as a whole.

  19. A broadband gyrotron backward-wave oscillator with tapered interaction structure and magnetic field

    SciTech Connect

    Li, G. D.; Chang, P. C.; Chiang, W. Y.; Lin, P. N.; Kao, S. H.; Lin, Y. N.; Huang, Y. J.; Barnett, L. R.; Chu, K. R.; Chen, H. Y.; Fan, C. T.

    2015-11-15

    The gyro-monotron and gyrotron backward-wave oscillator (gyro-BWO) are the two oscillator versions of gyrotrons. While serving different functions, they are also radically different in the RF field formation mechanisms. The gyro-monotron RF field profile is essentially fixed by the resonant interaction structure, while the gyro-BWO possesses an extra degree of freedom in that the axial RF field profile is self-determined by the beam-wave interaction in a waveguide structure. The present study examines ways to utilize the latter feature for bandwidth broadening with a tapered magnetic field, while also employing a tapered waveguide to enhance the interaction efficiency. We begin with a mode competition analysis, which suggests the theoretical feasibility of broadband frequency tuning in single-mode operation. It is then shown in theory that, by controlling the RF field profile with an up- or down-tapered magnetic field, the gyro-BWO is capable of efficient operation with a much improved tunable bandwidth.

  20. Forecast analysis of optical waveguide bus performance

    NASA Technical Reports Server (NTRS)

    Ledesma, R.; Rourke, M. D.

    1979-01-01

    Elements to be considered in the design of a data bus include: architecture; data rate; modulation, encoding, detection; power distribution requirements; protocol, work structure; bus reliability, maintainability; interterminal transmission medium; cost; and others specific to application. Fiber- optic data bus considerations for a 32 port transmissive star architecture, are discussed in a tutorial format. General optical-waveguide bus concepts, are reviewed. The electrical and optical performance of a 32 port transmissive star bus, and the effects of temperature on the performance of optical-waveguide buses are examined. A bibliography of pertinent references and the bus receiver test results are included.

  1. Elastic buckling of tapered circular plates

    NASA Astrophysics Data System (ADS)

    Wang, C. M.; Hong, G. M.; Tan, T. J.

    1995-06-01

    This paper is concerned with the elastic buckling of tapered circular plates. The study is prompted by the fact that results hitherto available are restricted to a narrow range of taper parameters and are somewhat different from each other. For the buckling analysis, a simple and yet accurate numerical method is presented. It is based on the shooting method and the Rayleigh-Ritz approach. Comprehensive generic buckling results of circular plates with linearly and parabolically varying thicknesses are generated. Comparison studies of the buckling results showed that some of the existing results were erroneous. Optimal values of taper parameters for such tapered plates are also given.

  2. Theory and Simulations of Tapered Diblock Polymers

    NASA Astrophysics Data System (ADS)

    Hall, Lisa M.; Seo, Youngmi; Brown, Jonathan R.

    We study tapered block polymers, AB diblock polymers with a gradient region inserted between the pure A and B blocks such that composition smoothly transitions from A to B (or B to A in the case of inverse tapers). Phase diagrams were created using self consistent field theory (SCFT), and coarse-grained molecular dynamics (MD) simulations were used to study polymer conformations and diffusion, including diffusion of monomer-sized penetrants preferentially dissolved in one of the phases. As has been observed experimentally, we find that tapering makes the A and B blocks more miscible, decreasing domain spacing and shifting the order to disorder transition to lower temperatures. We predict a widening of the bicontinuous double gyroid region of the phase diagram for moderate length normal tapers versus diblocks, suggesting taper length can be used as a control parameter to obtain network phases even at high molecular weight, as may be desirable in transport applications. Additionally, in some inverse tapered systems, SCFT predicts phases not present in the standard AB diblock phase diagram, and MD simulations show how the chains fold back and forth across the interface. In these inverse tapered polymers, as segregation strength is increased, the competing effects of folding and stretching produces lamellae that have domain spacing nearly independent of temperature. We also find that diffusion of penetrants in normal tapers is significantly faster than that in inverse tapers, which is likely related to their unusual conformations. This material is based upon work supported by DOE Grant SC0014209.

  3. Property and Shape Modulation of Carbon Fibers Using Lasers.

    PubMed

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes. PMID:27227575

  4. Property and Shape Modulation of Carbon Fibers Using Lasers.

    PubMed

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes.

  5. Micromachined Silicon Waveguide Circuits

    NASA Technical Reports Server (NTRS)

    McGrath, W. R.

    1995-01-01

    Rectangular waveguides are commonly used as circuit elements in remote-sensing heterodyne receivers at millimeter wavelengths. The advantages of waveguides are low loss and mechanical tunability. However, conventional machining techniques for waveguide components operating above a few hundred GHz are complicated and costly. Waveguides micromachined from silicon however would have several important advantages including low-cost; small size for very high frequency (submillimeter wave) operation; high dimensional accuracy (important for high-Q circuits); atomically smooth walls, thereby reducing rf losses; and the ability to integrate active and passive devices directly in the waveguide on thin membranes, thereby solving the traditional problem of mounting thin substrates.

  6. Twisted waveguide accelerating structure.

    SciTech Connect

    Kang, Y. W.

    2000-08-15

    A hollow waveguide with a uniform cross section may be used for accelerating charged particles if the phase velocity of an accelerating mode is equal to or less than the free space speed of light. Regular straight hollow waveguides have phase velocities of propagating electromagnetic waves greater than the free-space speed of light. if the waveguide is twisted, the phase velocities of the waveguide modes become slower. The twisted waveguide structure has been modeled and computer simulated in 3-D electromagnetic solvers to show the slow-wave properties for the accelerating mode.

  7. Photonic integration using asymmetric twin-waveguides

    NASA Astrophysics Data System (ADS)

    Studenkov, Pavel V.

    A novel approach to fabrication of monolithic photonic integrated circuits based on the asymmetric twin- waveguide (ATG) structure is proposed and demonstrated. In contrast to the conventional integration methods relying on semiconductor regrowth, the ATG approach requires only one epitaxy step, while the integrated devices are defined by post-growth patterning. The ATG structure contains two evanescently coupled waveguide layers separated by a cladding layer. The upper layer provides optical gain for the active devices such as lasers and semiconductor optical amplifiers. The transparent lower layer is used to make waveguides and optical interconnects on the chip. Thus the ATG represents a versatile integration platform for cost- effective fabrication of photonic integrated circuits, similar in some respects to the electronic CMOS platform. Light propagation and coupling in the ATG structure are analyzed using the beam propagation method to optimize the layer design. It is shown that the asymmetric refractive index profile eliminates undesirable optical coupling between the waveguide layers. At the interfaces between the active and passive devices, lateral tapers are used to induce vertical coupling of light with a coupling loss of typically <1 dB. Therefore various integrated devices can be separately optimized to achieve performance close to that of the conventional discrete components. The design of taper couplers is described in detail, and their performance is experimentally verified. Using the ATG approach, several integrated devices were fabricated in the InGaAsP/InP material system for λ = 1.55 μm wavelength operation. Lasers and semiconductor optical amplifiers with integrated waveguides were characterized to test the integration approach. Single-frequency, distributed Bragg reflector (DBR) lasers achieved output power of 11 mW with a 40 dB side-mode suppression ratio. A DBR laser with integrated electroabsorption modulator had a 24 dB extinction ratio

  8. Non-silica microstructured optical fibers for mid-IR supercontinuum generation from 2 μm - 5 μm

    NASA Astrophysics Data System (ADS)

    Price, Jonathan H. V.; Monro, Tanya M.; Ebendorff-Heidepriem, Heike; Poletti, Francesco; Finazzi, Vittoria; Leong, Julie Y. Y.; Petropoulos, Periklis; Flanagan, Joanne C.; Brambilla, Gilberto; Feng, Xian; Richardson, David J.

    2006-02-01

    We have performed numerical simulations to investigate the optimization of compound glass microstructured optical fibers for mid IR supercontinuum generation beyond the low loss transmission window of silica, using pump wavelengths in the range 1.55-2.25 mm. Large mode area fibers for high powers, and small core fiber designs for low powers, are proposed for a variety of glasses. Modeling results showed that for Bismuth and lead oxide glasses, which have nonlinearities ~10 x that of silica, matching the dispersion profile to the pump wavelength is essential. For chalcogenide glasses, which have much higher nonlinearities, the dispersion profile is less important. The pump pulses have duration of <1 ps, and energy <30 nJ. The fiber lengths required for generating continuum were <40 mm, so the losses of the fibers were not a limiting factor. Compared to planar rib-waveguides or fiber-tapers, microstructured fiber technology has the advantages of greater flexibility for tailoring the dispersion profile over a broad wavelength span, and a much wider possible range of device lengths.

  9. Calculation of tapered monoplane wings

    NASA Technical Reports Server (NTRS)

    Amstutz, E

    1930-01-01

    The tapered wing shape increases the lift in the middle of the wing and thus reduces the bending moment of the lifting forces in the plane of symmetry. Since this portion of the wing is the thickest, the stresses of the wing material are reduced and desirable space is provided for stowing the loads in the wing. This statically excellent form of construction, however, has aerodynamic disadvantages which must be carefully weighed, if failures are to be avoided. This treatise is devoted to the consideration of these problems.

  10. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Novel Route to Fabrication of Metal-Sandwiched Nanoscale Tapered Structures

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Yu, Da-Peng

    2009-08-01

    Tapered dielectric structures in metal have exhibited extraordinary performance in both surface plasmon polariton (SPP) waveguiding and SPP focusing. This is crucial to plasmonic research and industrial plasmonic device integration. We present a method that facilitates easy fabrication of smooth-surfaced sub-micron tapered structures in large scale simply with electron beam lithography (EBL). When a PMMA layer is spin-coated on previously-EBL-defined PMMA structures, steep edges can be transformed into a declining slope to form tapered PMMA structures, scaled from 10 nm to 1000 nm. Despite the simplicity of our method, patterns with PMMA surface smoothness can be well-positioned and replicated in large numbers, which therefore gives scientists easy access to research on the properties of tapered structures.

  11. Simulations of the TJNAF FEL with tapered and inversely tapered undulators

    SciTech Connect

    A. Christodoulou; D. Lampiris; W.B. Colson; P.P. Crooker; J. Blau; R.D. McGinnis; Steve Benson; Joseph Gubeli; George Neil

    2001-12-01

    Experiments using the TJNAF FEL have explored the operation with both tapered and inversely tapered undulators. We present here numerical simulations using the TJNAF experimental parameters, including the effects of taper. Single-mode simulations show the effect of taper on gain. Multimode simulations describe the evolution of short optical pulses in the far infrared, and show how taper affects single-pass gain and steady-state power as a function of desynchronism. A short optical pulse presents an ever-changing field strength to each section of the electron pulse so that idealized operation is not possible. Yet, advantages for the recirculation of the electron beam can be explored.

  12. Design and construction of cost-effective tapered amplifier systems for laser cooling and trapping experiments

    NASA Astrophysics Data System (ADS)

    Kangara, Jayampathi C. B.; Hachtel, Andrew J.; Gillette, Matthew C.; Barkeloo, Jason T.; Clements, Ethan R.; Bali, Samir; Unks, Brett E.; Proite, Nicholas A.; Yavuz, Deniz D.; Martin, Paul J.; Thorn, Jeremy J.; Steck, Daniel A.

    2014-08-01

    We present plans for the construction and operation of a tapered optical amplifier (TA) system seeded by a single-mode, frequency-tunable, near-IR external-cavity diode laser. Our plans include machine drawings for the parts, electronic circuit diagrams, and information on prices and vendors. Instructions are provided on how to safely couple light into and out of the TA chip. Practical aspects of handling the chip are discussed as well. Because many cold atom experiments require light beams with Gaussian spatial profiles, measurements of the tapered amplifier light output through a single-mode optical fiber are presented as a function of seed intensity, polarization, and driving current.

  13. Assembly and performance of silicone polymer waveguides

    NASA Astrophysics Data System (ADS)

    Lostutter, Calob K.; Hodge, Malcolm H.; Marrapode, Thomas R.; Swatowski, Brandon W.; Weidner, W. Ken

    2016-03-01

    We report on the functionality and key performance properties of 50 μm x 50 μm flexible graded index silicone polymer waveguides. The materials show low optical propagation losses of < 0.04 dB/cm @ 850 nm over 1 m lengths as well as stability to 2000 hours 85°C/85% relative humidity and 5 cycles of 260°C solder wave reflow testing. Methods to fabricate large area panels are demonstrated for scaled manufacturing of polymer based optical printed wiring boards. The polymer waveguides are terminated with a passive direct fiber attach method. Fully MPO connectorized waveguide panels are realized and their optical performance properties assessed.

  14. Ytterbium-doped fiber laser passively mode locked by few-layer Molybdenum Disulfide (MoS2) saturable absorber functioned with evanescent field interaction.

    PubMed

    Du, Juan; Wang, Qingkai; Jiang, Guobao; Xu, Changwen; Zhao, Chujun; Xiang, Yuanjiang; Chen, Yu; Wen, Shuangchun; Zhang, Han

    2014-01-01

    By coupling few-layer Molybdenum Disulfide (MoS2) with fiber-taper evanescent light field, a new type of MoS2 based nonlinear optical modulating element had been successfully fabricated as a two-dimensional layered saturable absorber with strong light-matter interaction. This MoS2-taper-fiber device is not only capable of passively mode-locking an all-normal-dispersion ytterbium-doped fiber laser and enduring high power laser excitation (up to 1 W), but also functions as a polarization sensitive optical modulating component (that is, different polarized light can induce different nonlinear optical response). Thanks to the combined advantages from the strong nonlinear optical response in MoS2 together with the sufficiently-long-range interaction between light and MoS2, this device allows for the generation of high power stable dissipative solitons at 1042.6 nm with pulse duration of 656 ps and a repetition rate of 6.74 MHz at a pump power of 210 mW. Our work may also constitute the first example of MoS2-enabled wave-guiding photonic device, and potential y give some new insights into two-dimensional layered materials related photonics. PMID:25213108

  15. Ytterbium-doped fiber laser passively mode locked by few-layer Molybdenum Disulfide (MoS2) saturable absorber functioned with evanescent field interaction.

    PubMed

    Du, Juan; Wang, Qingkai; Jiang, Guobao; Xu, Changwen; Zhao, Chujun; Xiang, Yuanjiang; Chen, Yu; Wen, Shuangchun; Zhang, Han

    2014-09-12

    By coupling few-layer Molybdenum Disulfide (MoS2) with fiber-taper evanescent light field, a new type of MoS2 based nonlinear optical modulating element had been successfully fabricated as a two-dimensional layered saturable absorber with strong light-matter interaction. This MoS2-taper-fiber device is not only capable of passively mode-locking an all-normal-dispersion ytterbium-doped fiber laser and enduring high power laser excitation (up to 1 W), but also functions as a polarization sensitive optical modulating component (that is, different polarized light can induce different nonlinear optical response). Thanks to the combined advantages from the strong nonlinear optical response in MoS2 together with the sufficiently-long-range interaction between light and MoS2, this device allows for the generation of high power stable dissipative solitons at 1042.6 nm with pulse duration of 656 ps and a repetition rate of 6.74 MHz at a pump power of 210 mW. Our work may also constitute the first example of MoS2-enabled wave-guiding photonic device, and potential y give some new insights into two-dimensional layered materials related photonics.

  16. Ytterbium-doped fiber laser passively mode locked by few-layer Molybdenum Disulfide (MoS2) saturable absorber functioned with evanescent field interaction

    PubMed Central

    Du, Juan; Wang, Qingkai; Jiang, Guobao; Xu, Changwen; Zhao, Chujun; Xiang, Yuanjiang; Chen, Yu; Wen, Shuangchun; Zhang, Han

    2014-01-01

    By coupling few-layer Molybdenum Disulfide (MoS2) with fiber-taper evanescent light field, a new type of MoS2 based nonlinear optical modulating element had been successfully fabricated as a two-dimensional layered saturable absorber with strong light-matter interaction. This MoS2-taper-fiber device is not only capable of passively mode-locking an all-normal-dispersion ytterbium-doped fiber laser and enduring high power laser excitation (up to 1 W), but also functions as a polarization sensitive optical modulating component (that is, different polarized light can induce different nonlinear optical response). Thanks to the combined advantages from the strong nonlinear optical response in MoS2 together with the sufficiently-long-range interaction between light and MoS2, this device allows for the generation of high power stable dissipative solitons at 1042.6 nm with pulse duration of 656 ps and a repetition rate of 6.74 MHz at a pump power of 210 mW. Our work may also constitute the first example of MoS2-enabled wave-guiding photonic device, and potentially give some new insights into two-dimensional layered materials related photonics. PMID:25213108

  17. Dry-film polymer waveguide for silicon photonics chip packaging.

    PubMed

    Hsu, Hsiang-Han; Nakagawa, Shigeru

    2014-09-22

    Polymer waveguide made by dry film process is demonstrated for silicon photonics chip packaging. With 8 μm × 11.5 μm core waveguide, little penalty is observed up to 25 Gbps before or after the light propagate through a 10-km long single-mode fiber (SMF). Coupling loss to SMF is 0.24 dB and 1.31 dB at the polymer waveguide input and output ends, respectively. Alignment tolerance for 0.5 dB loss increase is +/- 1.0 μm along both vertical and horizontal directions for the coupling from the polymer waveguide to SMF. The dry-film polymer waveguide demonstrates promising performance for silicon photonics chip packaging used in next generation optical multi-chip module.

  18. The 650-nm variable optical attenuator based on polymer/silica hybrid waveguide

    NASA Astrophysics Data System (ADS)

    Yue-Yang, Yu; Xiao-Qiang, Sun; Lan-Ting, Ji; Guo-Bing, He; Xi-Bin, Wang; Yun-Ji, Yi; Chang-Ming, Chen; Fei, Wang; Da-Ming, Zhang

    2016-05-01

    Visible light variable optical attenuators (VOA) are essential devices in the application of channel power regulation and equalization in wavelength-division multiplexing cross-connect nodes in plastic optical fiber (POF) transmission systems. In this paper, a polymer/silica hybrid waveguide thermo-optic attenuator based on multimode interference (MMI) coupler is designed and fabricated to operate at 650 nm. The single-mode transmission condition, MMI coupler, and transition taper dimensions are optimized through the beam propagation method. Thermal analysis based on material properties provides the optimized heater placement angle. The fabricated VOA presents an attenuation of 26.5 dB with a 21-mW electrical input power at 650 nm. The rise time and fall time are 51.99 and 192 μs, respectively. The time-stability measurement results prove its working reliability. Project supported by the National Natural Science Foundation of China (Grant Nos. 61205032, 61475061, 61405070, 61177027, 61275033, and 61261130586) and the Science and Technology Development Plan of Jilin Province, China (Grant No. 20140519006JH).

  19. Interconnect Between a Waveguide and a Dielectric Waveguide Comprising an Impedance Matched Dielectric Lens

    NASA Technical Reports Server (NTRS)

    Decrossas, Emmanuel (Inventor); Chattopadhyay, Goutam (Inventor); Chahat, Nacer (Inventor); Tang, Adrian J. (Inventor)

    2016-01-01

    A lens for interconnecting a metallic waveguide with a dielectric waveguide is provided. The lens may be coupled a metallic waveguide and a dielectric waveguide, and minimize a signal loss between the metallic waveguide and the dielectric waveguide.

  20. Mechanically Assisted Taper Corrosion in Modular TKA

    PubMed Central

    Arnholt, Christina; MacDonald, Daniel W.; Tohfafarosh, Mariya; Gilbert, Jeremy L.; Rimnac, Clare M.; Kurtz, Steven M.; Klein, Gregg; Mont, Michael A.; Parvizi, Javad; Cates, Harold E.; Lee, Gwo-Chin; Malkani, Arthur; Kraay, Matthew

    2014-01-01

    The purpose of this study was to characterize the prevalence of taper damage in modular TKA components. 198 modular components were revised after 3.9±4.2y (range: 0.0–17.5y). Modular components were evaluated for fretting corrosion using a semi-quantitative 4-point scoring system. Flexural rigidity, stem diameter, alloy coupling, patient weight, age and implantation time were assessed as predictors of fretting corrosion damage. Mild-to-severe fretting corrosion (score≥2) was observed in 94/101 of the tapers on the modular femoral components and 90/97 of the modular tibial components. Mixed alloy pairs (p=0.03), taper design (p<0.001), and component type (p=0.02) were associated with taper corrosion. The results from this study supported the hypothesis that there is taper corrosion in TKA. However the clinical implications of fretting and corrosion in TKA remain unclear. PMID:24996586

  1. Waveguide disturbance detection method

    DOEpatents

    Korneev, Valeri A.; Nihei, Kurt T.; Myer, Larry R.

    2000-01-01

    A method for detection of a disturbance in a waveguide comprising transmitting a wavefield having symmetric and antisymmetric components from a horizontally and/or vertically polarized source and/or pressure source disposed symmetrically with respect to the longitudinal central axis of the waveguide at one end of the waveguide, recording the horizontal and/or vertical component or a pressure of the wavefield with a vertical array of receivers disposed at the opposite end of the waveguide, separating the wavenumber transform of the wavefield into the symmetric and antisymmetric components, integrating the symmetric and antisymmetric components over a broad frequency range, and comparing the magnitude of the symmetric components and the antisymmetric components to an expected magnitude for the symmetric components and the antisymmetric components for a waveguide of uniform thickness and properties thereby determining whether or not a disturbance is present inside the waveguide.

  2. Hollow waveguide delivery systems for laser technological application [review article

    NASA Astrophysics Data System (ADS)

    Jelínková, Helena; Němec, Michal; Šulc, Jan; Černý, Pavel; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    Hollow waveguides with internal coatings can be an attractive alternative to solid-core fibers. This paper reviews the results with the cyclic olefin polymer coated metal hollow glass waveguides which can be used as a delivery instrument in a wide band of wavelengths-from the visible up to the infrared. These waveguides have been shown to be capable of transmissions up to the 1.36 GW of Nd:YAG peak power and 5.8 W or 5.1 W of alexandrite or Er:YAG mean power, respectively. They can be utilized in many branches of medical or industrial applications.

  3. Interdependence of waveguide and material dispersion.

    PubMed

    Marcuse, D

    1979-09-01

    Theoretical work on dispersion in single-mode fibers sometimes uses the assumption that waveguide dispersion D(w) and material dispersion D(m) are separate effects that contribute additively to the total amount of dispersion D(m+w). Using Gloge's LP-mode approximation we compute the dispersion of the LP(0l) (HE(11)) mode by solving the eigenvalue equation taking dispersion of core and cladding materials into account. The dispersion of the LP(01) mode is computed by numerical differentiation of the solution of the eigenvalue equation. The difference D(m+w) - D(w) is compared to waveguide dispersion D(w), which is computed by ignoring the dispersive properties of the core and cladding materials. We find large percentage deviations between D(m+w) - D(m) and D(w). The assumption of additivity of material and waveguide dispersion is thus not quite correct. However, because of the small contribution of waveguide dispersion to the total dispersion of the LP(01) mode, even a large percentage error in the waveguide dispersion has little influence on the over-all dispersion of the LP(01) mode.

  4. Fiber optic sensors

    NASA Technical Reports Server (NTRS)

    Hesse, J.; Sohler, W.

    1984-01-01

    A survey of the developments in the field of fiber optics sensor technology is presented along with a discussion of the advantages of optical measuring instruments as compared with electronic sensors. The two primary types of fiber optics sensors, specifically those with multiwave fibers and those with monowave fibers, are described. Examples of each major sensor type are presented and discussed. Multiwave detectors include external and internal fiber optics sensors. Among the monowave detectors are Mach-Zender interferometers, Michelson interferometers, Sagnac interferometers (optical gyroscopes), waveguide resonators, and polarimeter sensors. Integrated optical sensors and their application in spectroscopy are briefly discussed.

  5. Corrugated waveguide monopulse feed

    NASA Astrophysics Data System (ADS)

    Elliott, R. D.; Clarricoats, P. J. B.

    1980-04-01

    The excitation coefficients of modes in a circular corrugated waveguide that arise when dominant modes are incident from a cluster of four square waveguides are calculated. Monopulse-like radiation patterns arise when modes in the input guides are appropriately phased. Factors influencing the crosspolar performance of the feed are discussed, and the dependence of the excitation coefficients on waveguide and junction parameters is predicted.

  6. Planar waveguide optical immunosensors

    NASA Astrophysics Data System (ADS)

    Choquette, Steven J.; Locascio-Brown, Laurie E.; Durst, Richard A.

    1991-03-01

    Monoclonal antibodies were covalently bonded to the surfaces of planar waveguides to confer immunoreacth''ity. Silver-ion diffused waveguides were used to measure theophylline concentrations in a fluorescence immunoassay and silicon nitride waveguides were used to detect theophylline in an absorbance-based immunoassay. Liposomes were employed in both assays as the optically detectable label in a competitive reaction to monitor antigen-antibody complexation. Regeneration of the active antibody site will be discussed.

  7. Enhancing the efficiency of slow-wave electron cyclotron masers with the tapered refractive index

    SciTech Connect

    Kong Lingbao; Hou Zhiling; Jing Jian; Jin Haibo; Du Chaohai

    2013-04-15

    The nonlinear analysis of slow-wave electron cyclotron masers (ECM) based on anomalous Doppler effect in a slab waveguide is presented. A method of tapered refractive index (TRI) is proposed to enhance the efficiency of slow-wave ECM. The numerical calculations show that the TRI method can significantly enhance the efficiency of slow-wave ECM with the frequency ranging from the microwave to terahertz band. The effect of beam velocity spread on the efficiency has also been studied. Although the velocity spread suppresses the efficiency significantly, a great enhancement of efficiency can still be introduced by the TRI method.

  8. A waveguide-coupled thermally isolated radiometric source

    NASA Astrophysics Data System (ADS)

    Rostem, K.; Chuss, D. T.; Lourie, N. P.; Voellmer, G. M.; Wollack, E. J.

    2013-04-01

    The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric, MF-117, is well approximated by Cv(T) = 0.12 T 2.06 mJ g-1 K-1 between 3.5 K and 15 K.

  9. A Waveguide-coupled Thermally-isolated Radiometric Source

    NASA Technical Reports Server (NTRS)

    Rostem, Karwan; Chuss, David T.; Lourie, Nathan P.; Voellmer, George M.; Wollack, Edward

    2013-01-01

    The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric MF-117 is well approximated by Cv(T) = 0.12 T(exp 2.06) mJ/g/K between 3.5 K and 15 K.

  10. A waveguide-coupled thermally isolated radiometric source.

    PubMed

    Rostem, K; Chuss, D T; Lourie, N P; Voellmer, G M; Wollack, E J

    2013-04-01

    The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric, MF-117, is well approximated by C(v)(T) = 0.12 T (2.06) mJ g(-1) K(-1) between 3.5 K and 15 K.

  11. Facet-embedded thin-film III-V edge-emitting lasers integrated with SU-8 waveguides on silicon.

    PubMed

    Palit, Sabarni; Kirch, Jeremy; Huang, Mengyuan; Mawst, Luke; Jokerst, Nan Marie

    2010-10-15

    A thin-film InGaAs/GaAs edge-emitting single-quantum-well laser has been integrated with a tapered multimode SU-8 waveguide onto an Si substrate. The SU-8 waveguide is passively aligned to the laser using mask-based photolithography, mimicking electrical interconnection in Si complementary metal-oxide semiconductor, and overlaps one facet of the thin-film laser for coupling power from the laser to the waveguide. Injected threshold current densities of 260A/cm(2) are measured with the reduced reflectivity of the embedded laser facet while improving single mode coupling efficiency, which is theoretically simulated to be 77%.

  12. Rotation sensing with a circular atomic waveguide

    NASA Astrophysics Data System (ADS)

    Zhao, Lian-jie; Yan, Xiao-jun; Zhang, Guo-wan; Zhang, An-ning

    2016-01-01

    The hollow metallic optical fibers not only retain the advantage of flexibility but possess a greater intensity gradient for atomic waveguide. Therefore, based on the vector model of Maxwell's equations, we exactly calculated the intensity distribution of the TE01 mode in a typical metallic fiber, and analyzed the optical potential for 85Rb atom. Most of all, based on a circular atomic waveguide, we creatively proposed a novel measurement scheme for rotation sensing, explained the specific measurement principle, and built a mathematical model for this novel scheme. By measuring the number of atoms in the final states, we could get the rotation rate for this typical rotation system. This novel rotation sensor not only possessed a higher measurement precision, but realized the continuity measurement. It will be widely used in navigation, geophysics and general relativity.

  13. Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion.

    PubMed

    Xing, Sida; Grassani, Davide; Kharitonov, Svyatoslav; Billat, Adrien; Brès, Camille-Sophie

    2016-05-01

    We experimentally demonstrate wavelength conversion in the 2 µm region by four-wave mixing in an AsSe and a GeAsSe chalcogenide photonic crystal fibers. A maximum conversion efficiency of -25.4 dB is measured for 112 mW of coupled continuous wave pump in a 27 cm long fiber. We estimate the dispersion parameters and the nonlinear refractive indexes of the chalcogenide PCFs, establishing a good agreement with the values expected from simulations. The different fiber geometries and glass compositions are compared in terms of performance, showing that GeAsSe is a more suited candidate for nonlinear optics at 2 µm. Building from the fitted parameters we then propose a new tapered GeAsSe PCF geometry to tailor the waveguide dispersion and lower the zero dispersion wavelength (ZDW) closer to the 2 µm pump wavelength. Numerical simulations shows that the new design allows both an increased conversion efficiency and bandwidth, and the generation of idler waves further in the mid-IR regions, by tuning the pump wavelength in the vicinity of the fiber ZDW. PMID:27137588

  14. Frequency coded sensors incorporating tapers

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor); Solie, Leland P. (Inventor)

    2010-01-01

    A surface acoustic wave device includes a piezoelectric substrate on which is formed a transducer that generates acoustic waves on the surface of the substrate from electrical waves received by the transducer. The waves are carried along an acoustic track to either a second transducer or a reflector. The transducers or transducer and reflector are formed of subsections that are constructed to operate at mutually different frequencies. The subsections of at least one of the transducers or transducer and reflector are out of alignment with respect to one another relative to the transverse of the propagation direction. The out of aligned subsections provide not only a frequency component but also a time to the signal output signal. Frequency response characteristics are improved. An alternative embodiment provides that the transducers and/or reflectors are continuously tapered instead of having discrete frequency subsections.

  15. Truly trapped rainbow by utilizing nonreciprocal waveguides

    PubMed Central

    Liu, Kexin; He, Sailing

    2016-01-01

    The concept of a “trapped rainbow” has generated considerable interest for optical data storage and processing. It aims to trap different frequency components of the wave packet at different positions permanently. However, all the previously proposed structures cannot truly achieve this effect, due to the difficulties in suppressing the reflection caused by strong intermodal coupling and distinguishing different frequency components simultaneously. In this article, we found a physical mechanism to achieve a truly “trapped rainbow” storage of electromagnetic wave. We utilize nonreciprocal waveguides under a tapered magnetic field to achieve this and such a trapping effect is stable even under fabrication disorders. We also observe hot spots and relatively long duration time of the trapped wave around critical positions through frequency domain and time domain simulations. The physical mechanism we found has a variety of potential applications ranging from wave harvesting and storage to nonlinearity enhancement. PMID:27453496

  16. Truly trapped rainbow by utilizing nonreciprocal waveguides

    NASA Astrophysics Data System (ADS)

    Liu, Kexin; He, Sailing

    2016-07-01

    The concept of a “trapped rainbow” has generated considerable interest for optical data storage and processing. It aims to trap different frequency components of the wave packet at different positions permanently. However, all the previously proposed structures cannot truly achieve this effect, due to the difficulties in suppressing the reflection caused by strong intermodal coupling and distinguishing different frequency components simultaneously. In this article, we found a physical mechanism to achieve a truly “trapped rainbow” storage of electromagnetic wave. We utilize nonreciprocal waveguides under a tapered magnetic field to achieve this and such a trapping effect is stable even under fabrication disorders. We also observe hot spots and relatively long duration time of the trapped wave around critical positions through frequency domain and time domain simulations. The physical mechanism we found has a variety of potential applications ranging from wave harvesting and storage to nonlinearity enhancement.

  17. Polymer waveguides for telecom, datacom, and sensor applications

    NASA Astrophysics Data System (ADS)

    Paatzsch, Thomas; Smaglinski, Ingo; Bauer, Hans-Dieter; Ehrfeld, Wolfgang

    1998-03-01

    LIGA, the process sequence of deep lithography, electroforming and molding has been used for the fabrication of polymer waveguide components with passive fiber-to-chip coupling. The variety of 3D structures that can be realized, the high precision that can be achieved and especially the possibility of cost-effective mass production make these components most relevant for telecom, datacom and sensor applications. A novel waveguide design for a singlemode Y- splitter acting as telecommunication wavelengths was developed and realized together with the coupling scheme described above. It shows superior performance to conventional layouts and is ideally adapted to a fabrication using LIGA. Combining LIGA with high precision diamond machining multi-level tools with the complementary waveguide and fiber alignment structures were fabricated. For the first time a very high precision of better than 1 micrometers was achieved for heights and widths of all critical structures. A large number of molded parts was fabricated by hot embossing in PMMA. Detailed investigations proved that a reproducibility of better than 0.5 micrometers for the replicated structures is possible. By filling in a suitable core material into the waveguide prestructures and fixing fibers in the fiber grooves, fully pigtailed Y-splitters have been fabricated. This is an easy passive fiber-to-waveguide alignment with a significant reduction of manufacturing costs. First optical measurements on the samples showed an excess loss of 3.5 dB. Uniformity values were less than 0.6 dB and already meet Bellcore specifications. As another application of this fiber-to-waveguide coupling scheme a novel 4 X 4 star coupler for use in multimode optical bus systems is presented. First samples show an insertion loss of less than 9 dB and a uniformity better than 2 dB.

  18. Endfire tapered slot antennas on dielectric substrates

    NASA Technical Reports Server (NTRS)

    Yngvesson, K. S.; Schaubert, D. H.; Korzeniowski, T. L.; Kollberg, E. L.; Thungren, T.

    1985-01-01

    Endfire-tapered slot antennas are suitable for many integrated circuit applications, imaging and phased arrays. An investigation of single elements of such antennas, including slots which are exponentially tapered (Vivaldi), linearly tapered, and constant width. For antennas of all types, a good general agreement is obtained for curves of beamwidth-versus-length, normalized to wavelength, when one compares the data with that for traveling-wave antennas published by Zucker (1961). An important condition for this agreement is that the effective dielectric thickness, defined in the text, is in a certain optimum range. This condition is qualitatively explained in terms of the theory for traveling-wave antennas.

  19. Tapered silicon nanowires for enhanced nanomechanical sensing

    NASA Astrophysics Data System (ADS)

    Malvar, O.; Gil-Santos, E.; Ruz, J. J.; Ramos, D.; Pini, V.; Fernandez-Regulez, M.; Calleja, M.; Tamayo, J.; San Paulo, A.

    2013-07-01

    We investigate the effect of controllably induced tapering on the resonant vibrations and sensing performance of silicon nanowires. Simple analytical expressions for the resonance frequencies of the first two flexural modes as a function of the tapering degree are presented. Experimental measurements of the resonance frequencies of singly clamped nanowires are compared with the theory. Our model is valid for any nanostructure with tapered geometry, and it predicts a reduction beyond two orders of magnitude of the mass detection limit for conical resonators as compared to uniform beams with the same length and diameter at the clamp.

  20. Morse-type tapers: factors that may influence taper strength during total hip arthroplasty.

    PubMed

    Pennock, Andrew T; Schmidt, Andrew H; Bourgeault, Craig A

    2002-09-01

    We studied the effect of varying impaction force, repeated impactions, and fluid contamination on the disassembly strength of Morse-type tapers in 4 commercially available, modular femoral total hip components. The effect of varying techniques of taper assembly on the distraction force was studied. Our results show a reproducible and linear relationship between the taper impaction force and the disassembly force. The force necessary to separate the taper for a given impaction force varied, however, among manufacturers. Repeated impactions added little strength, and we found that when multiple impactions of varying force are used, the strength is roughly equivalent to the expected strength from the single strongest blow. Fluid contamination at the taper interface had unpredictable effects on taper strength.

  1. Waveguide arrangements based on adiabatic elimination

    DOEpatents

    Suchowski, Haim; Mrejen, Michael; Wu, Chihhui; Zhang, Xiang

    2016-09-13

    This disclosure provides systems, methods, and apparatus related to nanophotonics. In one aspect, an arrangement of waveguides includes a substrate and three waveguides. Each of the three waveguides may be a linear waveguide. A second waveguide is positioned between a first waveguide and a third waveguide. The dimensions and positions of the first, the second, and the third waveguides are specified to substantially eliminate coupling between the first waveguide and the third waveguide over a distance of about 1 millimeter to 2 millimeters along lengths of the first waveguide, the second waveguide, and the third waveguide.

  2. Birefringent corrugated waveguide

    DOEpatents

    Moeller, Charles P.

    1990-01-01

    A corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations, provides birefringence for rotation of polarization in the HE.sub.11 mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminum of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R.sub.0 from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R.sub.1 less than R.sub.0 at centers +b and -b from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric corrugations. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  3. Zero-mode waveguides

    DOEpatents

    Levene, Michael J.; Korlach, Jonas; Turner, Stephen W.; Craighead, Harold G.; Webb, Watt W.

    2007-02-20

    The present invention is directed to a method and an apparatus for analysis of an analyte. The method involves providing a zero-mode waveguide which includes a cladding surrounding a core where the cladding is configured to preclude propagation of electromagnetic energy of a frequency less than a cutoff frequency longitudinally through the core of the zero-mode waveguide. The analyte is positioned in the core of the zero-mode waveguide and is then subjected, in the core of the zero-mode waveguide, to activating electromagnetic radiation of a frequency less than the cut-off frequency under conditions effective to permit analysis of the analyte in an effective observation volume which is more compact than if the analysis were carried out in the absence of the zero-mode waveguide.

  4. Nanocrystal waveguide (NOW) laser

    DOEpatents

    Simpson, John T.; Simpson, Marcus L.; Withrow, Stephen P.; White, Clark W.; Jaiswal, Supriya L.

    2005-02-08

    A solid state laser includes an optical waveguide and a laser cavity including at least one subwavelength mirror disposed in or on the optical waveguide. A plurality of photoluminescent nanocrystals are disposed in the laser cavity. The reflective subwavelength mirror can be a pair of subwavelength resonant gratings (SWG), a pair of photonic crystal structures (PC), or a distributed feedback structure. In the case of a pair of mirrors, a PC which is substantially transmissive at an operating wavelength of the laser can be disposed in the laser cavity between the subwavelength mirrors to improve the mode structure, coherence and overall efficiency of the laser. A method for forming a solid state laser includes the steps of providing an optical waveguide, creating a laser cavity in the optical waveguide by disposing at least one subwavelength mirror on or in the waveguide, and positioning a plurality of photoluminescent nanocrystals in the laser cavity.

  5. Efficient waveguide coupler based on metal materials

    NASA Astrophysics Data System (ADS)

    Wu, Wenjun; Yang, Junbo; Chang, Shengli; Zhang, Jingjing; Lu, Huanyu

    2015-10-01

    Because of the diffraction limit of light, the scale of optical element stays in the order of wavelength, which makes the interface optics and nano-electronic components cannot be directly matched, thus the development of photonics technology encounters a bottleneck. In order to solve the problem that coupling of light into the subwavelength waveguide, this paper proposes a model of coupler based on metal materials. By using Surface Plasmon Polaritons (SPPs) wave, incident light can be efficiently coupled into waveguide of diameter less than 100 nm. This paper mainly aims at near infrared wave band, and tests a variety of the combination of metal materials, and by changing the structural parameters to get the maximum coupling efficiency. This structure splits the plane incident light with wavelength of 864 nm, the width of 600 nm into two uniform beams, and separately coupled into the waveguide layer whose width is only about 80 nm, and the highest coupling efficiency can reach above 95%. Using SPPs structure will be an effective method to break through the diffraction limit and implement photonics device high-performance miniaturization. We can further compress the light into small scale fiber or waveguide by using the metal coupler, and to save the space to hold more fiber or waveguide layer, so that we can greatly improve the capacity of optical communication. In addition, high-performance miniaturization of the optical transmission medium can improve the integration of optical devices, also provide a feasible solution for the photon computer research and development in the future.

  6. Backscatter coefficient estimation using tapers with gaps.

    PubMed

    Luchies, Adam C; Oelze, Michael L

    2015-04-01

    When using the backscatter coefficient (BSC) to estimate quantitative ultrasound parameters such as the effective scatterer diameter (ESD) and the effective acoustic concentration (EAC), it is necessary to assume that the interrogated medium contains diffuse scatterers. Structures that invalidate this assumption can affect the estimated BSC parameters in terms of increased bias and variance and decrease performance when classifying disease. In this work, a method was developed to mitigate the effects of echoes from structures that invalidate the assumption of diffuse scattering, while preserving as much signal as possible for obtaining diffuse scatterer property estimates. Backscattered signal sections that contained nondiffuse signals were identified and a windowing technique was used to provide BSC estimates for diffuse echoes only. Experiments from physical phantoms were used to evaluate the effectiveness of the proposed BSC estimation methods. Tradeoffs associated with effective mitigation of specular scatterers and bias and variance introduced into the estimates were quantified. Analysis of the results suggested that discrete prolate spheroidal (PR) tapers with gaps provided the best performance for minimizing BSC error. Specifically, the mean square error for BSC between measured and theoretical had an average value of approximately 1.0 and 0.2 when using a Hanning taper and PR taper respectively, with six gaps. The BSC error due to amplitude bias was smallest for PR (Nω = 1) tapers. The BSC error due to shape bias was smallest for PR (Nω = 4) tapers. These results suggest using different taper types for estimating ESD versus EAC.

  7. An experimental TE sub 12 - TE sub 11 circular waveguide mode converter

    NASA Astrophysics Data System (ADS)

    Hoppe, D.

    1985-08-01

    Theoretical and experimental results for a prototype TE sub 12 to TE sub 11 circular waveguide mode converter are discussed. The system which requires such device, the high power Ka-Band transmitter is described briefly. A short review of coupled mode theory is given, and the theoretical performance of the final converter design is given. Experimental results for the fabricated converter are presented and compared with theory. A method of identifying the various circular waveguide modes in a multimode device is described. Given the close agreement between the theoretical predictions and experimental results, the computer code may be used with confidence in the design of future multimode tapers and mode converters.

  8. Photopolymer-based three-dimensional optical waveguide devices

    NASA Astrophysics Data System (ADS)

    Kagami, M.; Yamashita, T.; Yonemura, M.; Kawasaki, A.; Watanabe, O.; Tomiki, M.

    2012-02-01

    Photopolymer based three-dimensional (3D) waveguide devices are very attractive in low-cost optical system integration. Especially, Light-Induced Self-Written (LISW) technology is suitable for this application, and the technology enables low-loss 3D optical circuitry formation from an optical fiber tip which soaked in photopolymer solution by employing its photo-polymerization due to own irradiation from the fiber tip. This technology is expected drastic mounting cost reduction in fields of micro-optic and hybrid integration devices assembly. The principle of the LISW optical waveguides is self-trapping effect of the irradiation flux into the self-organized waveguide, where, used wavelength can be chosen to fit photopolymer's reactivity from visible to infrared. Furthermore, this effect also makes possible grating formation and "optical solder" interconnection. Actually fabricated self-written grating shows well defined deep periodic index contrast and excellent optical property for the wavelength selectivity. And the "optical solder" interconnection realizes a passive optical interconnection between two faceted fibers or devices by the LISW waveguide even if there is a certain amount of gap and a small degree of misalignment exist. The LISW waveguides grow towards each other from both sides to a central point where the opposing beams overlap and are then combined into one waveguide. This distinctive effect is confirmed in all kind optical fibers, such as from a singlemode to 1-mm-corediameter multimode optical fiber. For example of complicated WDM optical transceiver module, mounted a branchedwaveguide and filter elements, effectiveness of LISW technology is outstanding. In assembling and packaging process, neither dicing nor polishing is needed. In this paper, we introduce LISW technology principles and potential application to integrated WDM optical transceiver devices for both of singlemode and multimode system developed in our research group.

  9. Tapered plug foam spray apparatus

    NASA Technical Reports Server (NTRS)

    Allen, Peter B. (Inventor)

    1996-01-01

    A two-component foam spray gun is readily disassembled for cleaning. It includes a body (1) with reactant (12, 14) and purge gas (16) inlet ports. A moldable valve packing (32) inside the body has a tapered conical interior surface (142), and apertures which match the reactant ports. A valve/tip (40) has a conical outer surface (48) which mates with the valve packing (32). The valve/tip (40) is held in place by a moldable packing washer (34), held at non-constant pressure by a screw (36, 38). The interior of the valve/tip (40) houses a removable mixing chamber (50). The mixing chamber (50) has direct flow orifices (60) and an auxiliary flow path (58, 60) which ameliorate pressure surges. The spray gun can be disassembled for cleaning without disturbing the seal, by removing the valve/tip (40) to the rear, thereby breaking it free of the conical packing. Rotation of the valve/tip (40) relative to the body (1) shuts off the reactant flow, and starts the purge gas flow.

  10. A hybrid semiconductor-glass waveguide laser

    NASA Astrophysics Data System (ADS)

    Fan, Youwen; Oldenbeuving, Ruud M.; Klein, Edwin J.; Lee, Chris J.; Song, Hong; Khan, Muhammed R. H.; Offerhaus, Herman L.; van der Slot, Peter J. M.; Boller, Klaus-J.

    2014-05-01

    We report on a novel type of laser in which a semiconductor optical amplifier (SOA) receives frequency-selective feedback from a glass-waveguide circuit. The laser we present here is based on InP for operation in the 1.55 μm wavelength range. The Si3N4/SiO2 glass waveguide circuit comprises two sequential high-Q ring resonators. Adiabatic tapering is used for maximizing the feedback. The laser shows single-frequency oscillation with a record-narrow spectral linewidth of 24 kHz at an output power of 5.7 mW. The hybrid laser can be tuned over a broad range of 46.8 nm (1531 nm to 1577.8 nm). Such InP-glass hybrid lasers can be of great interest in dense wavelength division multiplexing (DWDM) and as phase reference in optical beam-forming networks (OBFN). The type of laser demonstrated here is also of general importance because it may be applied over a huge wavelength range including the visible, limited only by the transparency of glass (400 nm to 2.35 μm).

  11. Waveguides having patterned, flattened modes

    SciTech Connect

    Messerly, Michael J.; Pax, Paul H.; Dawson, Jay W.

    2015-10-27

    Field-flattening strands may be added to and arbitrarily positioned within a field-flattening shell to create a waveguide that supports a patterned, flattened mode. Patterning does not alter the effective index or flattened nature of the mode, but does alter the characteristics of other modes. Compared to a telecom fiber, a hexagonal pattern of strands allows for a three-fold increase in the flattened mode's area without reducing the separation between its effective index and that of its bend-coupled mode. Hexagonal strand and shell elements prove to be a reasonable approximation, and, thus, to be of practical benefit vis-a-vis fabrication, to those of circular cross section. Patterned flattened modes offer a new and valuable path to power scaling.

  12. Multimode waveguide based directional coupler

    NASA Astrophysics Data System (ADS)

    Ahmed, Rajib; Rifat, Ahmmed A.; Sabouri, Aydin; Al-Qattan, Bader; Essa, Khamis; Butt, Haider

    2016-07-01

    The Silicon-on-Insulator (SOI) based platform overcomes limitations of the previous copper and fiber based technologies. Due to its high index difference, SOI waveguide (WG) and directional couplers (DC) are widely used for high speed optical networks and hybrid Electro-Optical inter-connections; TE00-TE01, TE00-TE00 and TM00-TM00 SOI direction couplers are designed with symmetrical and asymmetrical configurations to couple with TE00, TE01 and TM00 in a multi-mode semi-triangular ring-resonator configuration which will be applicable for multi-analyte sensing. Couplers are designed with effective index method and their structural parameters are optimized with consideration to coupler length, wavelength and polarization dependence. Lastly, performance of the couplers are analyzed in terms of cross-talk, mode overlap factor, coupling length and coupling efficiency.

  13. Compound semiconductor optical waveguide switch

    DOEpatents

    Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

    2003-06-10

    An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

  14. Analysis of guided wave propagation in a tapered composite panel

    NASA Astrophysics Data System (ADS)

    Wandowski, Tomasz; Malinowski, Pawel; Moll, Jochen; Radzienski, Maciej; Ostachowicz, Wieslaw

    2015-03-01

    Many studies have been published in recent years on Lamb wave propagation in isotropic and (multi-layered) anisotropic structures. In this paper, adiabatic wave propagation phenomenon in a tapered composite panel made out of glass fiber reinforced polymers (GFRP) will be considered. Such structural elements are often used e.g. in wind turbine blades and aerospace structures. Here, the wave velocity of each wave mode does not only change with frequency and the direction of wave propagation. It further changes locally due to the varying cross-section of the GFRP panel. Elastic waves were excited using a piezoelectric transducer. Full wave-field measurements using scanning Laser Doppler vibrometry have been performed. This approach allows the detailed analysis of elastic wave propagation in composite specimen with linearly changing thickness. It will be demonstrated here experimentally, that the wave velocity changes significantly due to the tapered geometry of the structure. Hence, this work motivates the theoretical and experimental analysis of adiabatic mode propagation for the purpose of Non-Destructive Testing and Structural Health Monitoring.

  15. Subwavelength hybrid terahertz waveguides.

    PubMed

    Nam, Sung Hyun; Taylor, Antoinette J; Efimov, Anatoly

    2009-12-01

    We introduce and present general properties of hybrid terahertz waveguides. Weakly confined Zenneck waves on a metal-dielectric interface at terahertz frequencies can be transformed to a strongly confined yet low-loss subwavelength mode through coupling with a photonic mode of a nearby high-index dielectric strip. We analyze confinement, attenuation, and dispersion properties of this mode. The proposed design is suitable for planar integration and allows easy fabrication on chip scale. The superior waveguiding properties at terahertz frequencies could enable the hybrid terahertz waveguides as building blocks for terahertz integrated circuits.

  16. Optical waveguide enhanced photovoltaics.

    PubMed

    Rühle, Sven; Greenwald, Shlomit; Koren, Elad; Zaban, Arie

    2008-12-22

    Enhanced light to electric power conversion efficiency of photovoltaic cells with a low absorbance was achieved using waveguide integration. We present a proof of concept using a very thin dye-sensitized solar cell which absorbed only a small fraction of the light at normal incidence. The glass substrate in conjunction with the solar cells reflecting back contact formed a planar waveguide, which lead to more than four times higher conversion efficiency compared to conventional illumination at normal incidence. This illumination concept leads to a new type of multi-junction PV systems based on enforced spectral splitting along the waveguide.

  17. Octave-spanning supercontinuum generation in a silicon-rich nitride waveguide.

    PubMed

    Liu, Xing; Pu, Minhao; Zhou, Binbin; Krückel, Clemens J; Fülöp, Attila; Torres-Company, Victor; Bache, Morten

    2016-06-15

    We experimentally show octave-spanning supercontinuum generation in a nonstoichiometric silicon-rich nitride waveguide when pumped by femtosecond pulses from an erbium fiber laser. The pulse energy and bandwidth are comparable to results achieved in stoichiometric silicon nitride waveguides, but our material platform is simpler to manufacture. We also observe wave-breaking supercontinuum generation by using orthogonal pumping in the same waveguide. Additional analysis reveals that the waveguide height is a powerful tuning parameter for generating mid-infrared dispersive waves while keeping the pump in the telecom band. PMID:27304272

  18. Octave-spanning supercontinuum generation in a silicon-rich nitride waveguide

    NASA Astrophysics Data System (ADS)

    Liu, Xing; Pu, Minhao; Zhou, Binbin; Krückel, Clemens J.; Fülöp, Attila; Torres-Company, Victor; Bache, Morten

    2016-06-01

    We experimentally show octave-spanning supercontinuum generation in a non-stoichiometric silicon-rich nitride waveguide when pumped by femtosecond pulses from an erbium fiber laser. The pulse energy and bandwidth are comparable to results achieved in stoichiometric silicon nitride waveguides, but our material platform is simpler to manufacture. We also observe wave-breaking supercontinuum generation by using orthogonal pumping in the same waveguide. Additional analysis reveals that the waveguide height is a powerful tuning parameter for generating mid-infrared dispersive waves while keeping the pump in the telecom band.

  19. Evanescent-wave coupled right angled buried waveguide: Applications in carbon nanotube mode-locking

    SciTech Connect

    Mary, R.; Thomson, R. R.; Kar, A. K.; Brown, G.; Popa, D.; Sun, Z.; Torrisi, F.; Hasan, T.; Milana, S.; Bonaccorso, F.; Ferrari, A. C.

    2013-11-25

    We present an evanescent-field device based on a right-angled waveguide. This consists of orthogonal waveguides, with their points of intersection lying along an angled facet of the chip. Light guided along one waveguide is incident at the angled dielectric-air facet at an angle exceeding the critical angle, so that the totally internally reflected light is coupled into the second waveguide. By depositing a nanotube film on the angled surface, the chip is then used to mode-lock an Erbium doped fiber ring laser with a repetition rate of 26 MHz, and pulse duration of 800 fs.

  20. Waveguide image-slicers for ultrahigh resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Beckert, Erik; Strassmeier, Klaus G.; Woche, Manfred; Eberhardt, Ramona; Tünnermann, Andreas; Andersen, Michael

    2008-07-01

    Waveguide image-slicer prototypes with resolutions up to 310.000 for the fiber fed PEPSI echelle spectrograph at the LBT and single waveguide thicknesses of down to 30 μm have been manufactured. The waveguides were macroscopically prepared, stacked up to an order of 7 and thinned back to square stack cross sections. A high filling ratio was achieved by realizing homogenous adhesive gaps of 4.6 μm, using index matching adhesives for TIR within the waveguides. The image-slicer stacks can be used in immersion mode and are miniaturized to be implemented in a set of four, measurements indicate an overall efficiency of above 80% for them.