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Articles 1 to 20 of 96 Next Page >>


Flat grating lens utilizing widely variable transmission-phase via guided-modes

  • Takayuki Matsui, HIDEO IIZUKA, Hisayoshi Fujikawa, Shuichi Yamashita, and Hiroyuki Wado
  • received 10/20/2014; accepted 11/24/2014; posted 11/25/2014; Doc. ID 225229
  • [full text: PDF (1710) KB)]
  • Abstract: We experimentally demonstrate a polarization-independent flat grating lens in the near-infrared region. The grating lens consists of ridges in the square lattice arrangement and the ridge dimensions are gradually changed to distribute a phase map with focusing ability. It is well known that guided modes in gratings offer unity reflection at a resonance, and therefore the transmission phase is widely varied around the resonance. We employ such transmission phase behavior and show that high transmittance is obtained in each unit cell for wide variation range of the transmission phase at the operation wavelength by sharpening the resonance. This enables us to accomplish a highly efficient transmissive grating lens.

Keywords (OCIS):

  • (050.1950) Diffraction and gratings : Diffraction gratings
  • (050.1970) Diffraction and gratings : Diffractive optics
  • (050.1965) Diffraction and gratings : Diffractive lenses
  • (350.4238) Other areas of optics : Nanophotonics and photonic crystals

Ground-State Lasing in High Power InAs/GaAs Quantum Dots-in-a-Well Laser Using Active Multimode Interference Structure

  • Yuanbing Cheng, Jian Wu, Ling-Juan Zhao, Xianshu Luo, and Qijie Wang
  • received 10/29/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 225973
  • [full text: PDF (1105) KB)]
  • Abstract: We have designed and demonstrated InAs/GaAs quantum dots-in-a-well laser diodes with transverse fundamental mode operation by using active multimode interferometer (MMI) structure for the first time to the best of our knowledge. Room-temperature continous wave ground-state lasing at 1280 nm has been achieved with an output power of 116 mW per facet, which is 2.4 times higher than that of the conventional ridge laser diodes. By using the MMI structures, the excited-state (ES) lasing is effectively suppressed with no ES lasing even at a high injection current of 400 mA. This device has great potential for high-power single-mode laser emission with low electric power consumption and simple fabrication processes.

Keywords (OCIS):

  • (140.5960) Lasers and laser optics : Semiconductor lasers
  • (230.5590) Optical devices : Quantum-well, -wire and -dot devices
  • (230.7370) Optical devices : Waveguides

High power diode lasers at 1178 nm with high beam quality and narrow spectra

  • Katrin Paschke, Gunnar Blume, Frank Bugge, David Feise, and Goetz Erbert
  • received 09/26/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 223038
  • [full text: PDF (464) KB)]
  • Abstract: High-power Distributed Bragg Reflector tapered diode lasers (DBR-TPLs) at 1180 nm were developed based on highly-strained InGaAs quantum wells. The lasers emit a nearly diffraction-limited beam with more than two Watts with a narrow spectral width. These features are believed to make this type of diode laser a key component for the manufacturing of miniaturized laser modules in the yellow and orange spectral range by second harmonic generation to cover a spectral region currently not accessible with direct emitting diode lasers. Future applications might be the laser-cooling of sodium, high-resolution glucose-content measurements as well as spectroscopy on rare earth elements.

Keywords (OCIS):

  • (140.2020) Lasers and laser optics : Diode lasers
  • (140.3570) Lasers and laser optics : Lasers, single-mode
  • (230.1480) Optical devices : Bragg reflectors
  • (250.5960) Optoelectronics : Semiconductor lasers
  • (250.5590) Optoelectronics : Quantum-well, -wire and -dot devices

Controlling thermo-optic response in microresonators using bi-material cantilevers

  • Biswajeet Guha and Michal Lipson
  • received 09/22/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 223587
  • [full text: PDF (804) KB)]
  • Abstract: We demonstrate a novel platform to control the thermo-optic sensitivity in nanophotonic devices by evanescent coupling of light with bimaterial cantilevers. The cantilever can be designed to provide a negative thermal feedback to passively compensate for the positive thermo-optic effect the in waveguide core. We demonstrate athermal operation over 14 degrees in cantilever coupled Silicon ring resonators, limited only by fabrication tolerances. We also show how the same platform can provide positive thermal feedback and overcome the material thermo-optic limit for increasing sensitivity of resonant detectors and thermal imagers.

Keywords (OCIS):

  • (120.6780) Instrumentation, measurement, and metrology : Temperature
  • (220.4880) Optical design and fabrication : Optomechanics
  • (230.5750) Optical devices : Resonators
  • (040.6808) Detectors : Thermal (uncooled) IR detectors, arrays and imaging

DC-field assisted grating formation and nonlinear diffractions in methyl-red dye-doped Blue phase liquid crystals

  • Iam-Choon Khoo
  • received 09/25/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 223770
  • [full text: PDF (889) KB)]
  • Abstract: We report the observation of enhanced nonlinear optical responses of Methyl-red doped Blue-Phase liquid crystals by application of a DC field. We have observed strong multi-order nonlinear grating diffractions characterized by a nonlinear index coefficient n₂~ 0.5 cm²/Watt using unfocused CW laser power of ~1 mW and a DC field of a few V/μm. The underlying mechanisms are crystalline lattice and director axis reorientations by torques exerted by the dc field and photo-excited dye molecules.

Keywords (OCIS):

  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (160.2100) Materials : Electro-optical materials
  • (160.3710) Materials : Liquid crystals
  • (160.5320) Materials : Photorefractive materials
  • (160.5298) Materials : Photonic crystals

Monolithically Integrated 2.5 GHz Extended Cavity Mode-Locked Ring Laser with Intracavity Phase Modulators

  • Sylwester Latkowski, Valentina Moskalenko, M.S. Tahvili, Luc Augustin, Meint Smit, Kevin Williams, and Erwin Bente
  • received 10/10/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 224687
  • [full text: PDF (994) KB)]
  • Abstract: A mode-locked extended cavity quantum well ring laser at 1.58 µm with repetition rate of 2.5 GHz in the form of a photonic integrated circuit is presented. The device is realized using InP based active-passive integration technology. The 33mm long cavity contains gain, saturable absorption and passive waveguide sections as well as a phase shifter sections to enable fine tuning of the spectral position of the lasing modes. Passive and hybrid mode-locked operation along with the wavelength tuning of the laser modes are experimentally demonstrated. In the passive mode-locking regime a beat signal at the fundamental round trip frequency with a 3 dB bandwidth of 6.1 kHz is produced on a fast photo diode.

Keywords (OCIS):

  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (140.5960) Lasers and laser optics : Semiconductor lasers
  • (250.5300) Optoelectronics : Photonic integrated circuits

Properties of Two-Dimensional Resonant Reflectors with Zero-Contrast Gratings

  • Robert Magnusson and Mehrdad Shokooh-Saremi
  • received 09/08/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 222619
  • [full text: PDF (2211) KB)]
  • Abstract: The spectral properties of high-reflection mirrors imbued with two-dimensional (2D) subwavelength periodicity are investigated. The reflectors are designed in a silicon-on-glass film that is partially etched to implement a zero-contrast interface between the grating pillars and the sublayer thereby annulling local reflections and phase changes. This approach has shown impressive results for 1D polarized reflectors; here we strive to discover analogous wideband unpolarized reflectors. Using particle swarm optimization, we report various wideband unpolarized reflectors in the 1.4-2.0 μm wavelength band. A 2D reflector with square pillars exhibits a 99% reflectance across a bandwidth exceeding 350 nm and possesses tolerance against angular deviations. The complementary structure with rectangular periodic voids, achieves a bandwidth of 370 nm. A comparable 2D high–contrast grating reflector with grating pillars residing directly on the substrate yields a 99% bandwidth of 240 nm.

Keywords (OCIS):

  • (050.1950) Diffraction and gratings : Diffraction gratings
  • (050.5745) Diffraction and gratings : Resonance domain
  • (050.6624) Diffraction and gratings : Subwavelength structures

Graphene Q-switched Ho3+-doped ZBLAN fiber laser at 1190nm

  • Xiushan Zhu, Shujing Liu, Gongwen Zhu, Kaushik Balakrishnan, Jie Zong, Arturo Chavez-Pirson, Kort Wiersma, Robert Norwood, and Nasser Peyghambarian
  • received 10/02/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 224374
  • [full text: PDF (915) KB)]
  • Abstract: We report Q-switched pulse operation of holmium (Ho3+)-doped ZrF4-BaF2-LaF3-AlF3-NaF at ~1190 nm in an all-fiber ring laser by using a fiber-optic graphene saturable absorber, which was fabricated by depositing graphene onto the flat surface of a side-polished D-shaped fiber. Stable Q-switched operation was established at a pump power of 180 mW with a repetition rate of 24 kHz and pulse width of 5.7 µs. When the pump power was increased to 1125 mW, 0. 44 μJ Q-switched pulses with a repetition rate of 111 kHz and a pulse width of 0.8 μs were generated.

Keywords (OCIS):

  • (060.2390) Fiber optics and optical communications : Fiber optics, infrared
  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (140.3540) Lasers and laser optics : Lasers, Q-switched

THz-bandwidth photonic Hilbert transformers based on fiber Bragg gratings in transmission

  • María R. Fernández-Ruiz, Lixian Wang, Alejandro Carballar, Maurizio Burla, Jose Azana, and Sophie LaRochelle
  • received 10/06/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 224440
  • [full text: PDF (723) KB)]
  • Abstract: THz-bandwidth photonic Hilbert transformers (PHTs) are implemented for the first time, to the best of our knowledge, based on fiber Bragg grating (FBG) technology. To increase the practical bandwidth limitation of FBGs (typically < 200 GHz), a superstructure based on two superimposed linearly-chirped FBGs operating in transmission has been employed. The use of a transmission FBG involves first a conversion of the non-minimum phase response of the PHT into a minimum-phase response by adding an anticipated instantaneous component to the desired system temporal impulse response. Using this methodology, a 3 THz-bandwidth integer PHT and a fractional (order 0.81) PHT are designed, fabricated and successfully characterized.

Keywords (OCIS):

  • (050.5080) Diffraction and gratings : Phase shift
  • (060.5060) Fiber optics and optical communications : Phase modulation
  • (230.1150) Optical devices : All-optical devices
  • (060.3735) Fiber optics and optical communications : Fiber Bragg gratings
  • (070.7145) Fourier optics and signal processing : Ultrafast processing

Core-shell nanostructures of covalently grafted polyaniline–multiwalled carbon nanotube hybrids for improved optical limiting

  • John Honey, Pramod Gopinath, and Remyamol T
  • received 09/24/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 223633
  • [full text: PDF (787) KB)]
  • Abstract: Polyaniline-MWNT hybrids are synthesized by the in situ polymerization of aniline in the presence of phenylenediamine functionalized MWNT. Along with aniline monomer, the aniline moiety on the surface of phenylenediamine functionalized MWNT also participates in the polymerization and acts as a covalent bridge between polyaniline and MWNT. The photoluminescence quenching in the hybrid due to the electron transfer between polyaniline and MWNT and the resulting improvement in optical limiting are also discussed. The large nonlinear absorption coefficient with low limiting threshold of the hybrids compared to polyaniline is attributed to the combined NLO mechanisms and the photoinduced electron transfer interactions.

Keywords (OCIS):

  • (160.4330) Materials : Nonlinear optical materials
  • (160.5470) Materials : Polymers
  • (190.0190) Nonlinear optics : Nonlinear optics
  • (190.4400) Nonlinear optics : Nonlinear optics, materials
  • (160.4236) Materials : Nanomaterials

Investigating the frequency-dependent amplification of a tapered amplifier in atom interferometers

  • Zhongkun HU, Xiaochun Duan, Minkang Zhou, Su Zhan, Huibin Yao, and Wenjie Xu
  • received 10/01/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 222423
  • [full text: PDF (404) KB)]
  • Abstract: We present the investigation on the frequency-dependent amplification of a tapered amplifier (TA) and the corresponding influence on Raman-type atom interferometers. In our interferometer, the output of two external-cavity diode lasers, which are phase-locked, is injected into a TA to generate Raman beams. The frequency of one diode laser is chirped during the interfering process, which induces a variance of the Raman lasers power as a result of the frequency-dependent amplification of the TA. The induced power ratio variation of the two beams in Raman lasers is measured by beat note method, which shows a linear variation with a slope of −0.087(4)/GHz when the laser frequency changes over 2 GHz at 780 nm. The corresponding error related to AC Stark effect due to this frequency-dependent variation is estimated for our atom interferometer. The investigation presented here may provide hints for other experiments involving TAs.

Keywords (OCIS):

  • (020.6580) Atomic and molecular physics : Stark effect
  • (140.3280) Lasers and laser optics : Laser amplifiers
  • (020.3320) Atomic and molecular physics : Laser cooling

Frequency comb-based multiple-access ultrastable frequency dissemination with 7×10-17 instability

  • Jy Zhao and Shuangyou zhang
  • received 09/23/2014; accepted 11/20/2014; posted 11/21/2014; Doc. ID 223688
  • [full text: PDF (816) KB)]
  • Abstract: In this paper, we demonstrate frequency-comb-based multiple-access ultrastable frequency dissemination over a 10-km single mode fiber link. First, we synchronize optical pulse trains from an Er-fiber frequency comb to the remote site by using a simple and robust phase-conjugate stabilization method, without actively stabilizing the fiber length. The fractional frequency-transfer instability at the remote site is 2.6×10-14 and 4.9 ×10-17 for averaging times of 1 s and 10,000 s, respectively. Then, we reproduce the harmonic of the repetition rate from the disseminated optical pulse trains at an arbitrary point along the fiber link to test comb-based multiple-access performance, and demonstrate frequency instability of 4×10−14 and 7×10−17 at 1 s and 10,000 s averaging time, respectively. The proposed comb-based multiple-access frequency dissemination can easily archive highly stable wideband microwave extraction along the whole link.

Keywords (OCIS):

  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (320.7090) Ultrafast optics : Ultrafast lasers
  • (060.5625) Fiber optics and optical communications : Radio frequency photonics

Resonator integrated optic gyro employing trapezoidal phase modulation technique

  • Junjie Wang, Li Shuang Feng, Yinzhou Zhi, and Yichuang Tang
  • received 10/22/2014; accepted 11/20/2014; posted 11/21/2014; Doc. ID 225120
  • [full text: PDF (761) KB)]
  • Abstract: Resonator integrated optic gyro (RIOG) employing trapezoidal phase modulation (TZPM) technique is proposed, analyzed and demonstrated for the first time. This technique can provide more information about the whole gyro system without complicating the light circuit structure, making it possible to compensate the gyro output real-timely. The experimental results of the RIOG prototype show that the standard deviation is greatly reduced after compensation, which proves the viability and effectiveness of the TZPM technique. A bias stability of 0.09deg/s with an integration time of 10s over 3000s is achieved, which is, to our knowledge, the best long-term performance that ever been reported in resonator integrated optic gyro based on silica waveguide ring resonator.

Keywords (OCIS):

  • (060.2800) Fiber optics and optical communications : Gyroscopes
  • (130.6010) Integrated optics : Sensors
  • (230.5750) Optical devices : Resonators

Dual-bandgap hollow-core photonic crystal fibers for third harmonic generation

  • Zev Montz and Amiel Ishaaya
  • received 10/09/2014; accepted 11/20/2014; posted 11/21/2014; Doc. ID 224586
  • [full text: PDF (6630) KB)]
  • Abstract: We present two novel hybrid photonic structures made of silica that possess two well-separated frequency bandgaps. The addition of interstitial air holes in a precise location and size allows these bandgaps to open up with a ratio of ~3 between their central frequencies at the air line ck_z/w = 1, thus fulfilling the basic guidance condition for third harmonic generation in hollow-core fibers. In addition, these designs may serve for high-power laser delivery of two well-separated wavelengths, such as visible and near infrared.

Keywords (OCIS):

  • (060.2280) Fiber optics and optical communications : Fiber design and fabrication
  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers

Look through a small hole using three laser scatterings

  • chenfei jin, Zitong Song, Siqi Zhang, Jianhua Zhai, and Yuan Zhao
  • received 10/13/2014; accepted 11/20/2014; posted 11/21/2014; Doc. ID 224843
  • [full text: PDF (4070) KB)]
  • Abstract: An approach was proposed and developed to recover the 3D shape concealed in a shelter with a small hole by only using three laser scatterings. This approach extends reconstruction of concealed 3D shape from “around a corner” to “through a small hole”. Based on principle of rectilinear propagation of light, a simple geometric mapping tentative theoretical frame independent of scene was proposed to extract 3D information of concealed objects. Experimental setup mainly consists of a nanosecond laser and a single-photon APD both are commercially available. The 3D reconstructions of three hidden objects were acquired with a resolution of centimeters.

Keywords (OCIS):

  • (030.5260) Coherence and statistical optics : Photon counting
  • (110.6880) Imaging systems : Three-dimensional image acquisition
  • (280.3640) Remote sensing and sensors : Lidar

Ultra-compact channel drop fifilter based on photonic crystal nanobeam cavities utilizing a resonant tunneling effect

  • Yaocheng Shi, Xiaochen Ge, and Sailing He
  • received 10/13/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 224854
  • [full text: PDF (1760) KB)]
  • Abstract: The design, fabrication and characterization of a compact photonic crystal nanobeam drop filter based on the tunneling effect of the degenerate modes are presented. The accidental degeneracy was achieved by tuning the coupling distance between the nanobeam and input/output waveguides. The tunneling effect of degenerate resonances with different symmetries has been verified experimentally. Channel drop filters with an extinction ratio larger than 10 dB and a quality factor of ~5000 have been experimentally demonstrated.

Keywords (OCIS):

  • (230.5298) Optical devices : Photonic crystals
  • (230.7408) Optical devices : Wavelength filtering devices

Graphene plasmons propagation on corrugated silicon substrates

  • Qing Dai, Xiang-Tian Kong, and Bing Bai
  • received 10/20/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 225144
  • [full text: PDF (383) KB)]
  • Abstract: The configuration of graphene on a silicon substrate is potentially compatible to the microelectronic technology. But the maintained plasmons have significant ohmic losses because of silicon's large permittivity. We propose to introduce air grooves in the silicon surface to reduce the optical thickness of silicon and hence decrease the propagation loss. The properties of graphene plasmons on the corrugated silicon substrates are numerically investigated, in terms of the photon frequency and the geometrical parameters of the corrugated layer. The propagation length of the plasmons on corrugated silicon substrates can reach more than twice of that on flat silicon in a broadband in mid-infrared. This study may be useful for designing graphene-based plasmonic waveguides for future applications of photonic integrated circuits.

Keywords (OCIS):

  • (230.7370) Optical devices : Waveguides
  • (240.6680) Optics at surfaces : Surface plasmons
  • (050.6624) Diffraction and gratings : Subwavelength structures

Continuous-wave anti-Stokes Raman laser based on phase-matched nondegenerate four-wave mixing

  • Shin-ichi Zaitsu and Totaro Imasaka
  • received 10/01/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 223637
  • [full text: PDF (529) KB)]
  • Abstract: We demonstrate phase-matched nondegenerate four-wave mixing in a high-finesse optical cavity using a gaseous Raman-active medium pumped by two independent continuous-wave lasers. Efficient upconversion is achieved for pump beams at different wavelengths under phase-matched conditions by optimizing the total dispersion of the hydrogen-filled optical cavity. The independent control of the pump-beam polarizations leads to further enhancement of the upconversion efficiency arising from a larger Raman gain than that in degenerate four-wave mixing. This approach offers a promising alternative for a narrow-linewidth tunable light source for highly precise laser spectroscopy.

Keywords (OCIS):

  • (140.3550) Lasers and laser optics : Lasers, Raman
  • (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing

Reconfigurable dual-channel dropping filters based on a self coupled resonator Sagnac interferometer

  • Xuenan Zhang, Yundong Zhang, Xiaoqi Liu, Kaiyang Wang, Chi Xu, Yongfeng Wu, and Ping Yuan
  • received 09/24/2014; accepted 11/19/2014; posted 11/20/2014; Doc. ID 223778
  • [full text: PDF (900) KB)]
  • Abstract: We report a reconfigurable dual-mode resonator based dual-channel dropping filter (DRDDF) in a self coupled resonator Sagnac interferometer (SCRSNI). The dual dropping channels are generated within a free spectral range (FSR) via the interference between the electromagnetically induced transparency (EIT)-like and electromagnetically induced absorption (EIA)-like resonances despite only one resonator used in the DRDDF. Depending on the phase tuning, the reconfiguration of the dual channels enabling the truly on/off switching mechanism is realized, and the output modes resembling the add/drop/neutral states are provided. The compact, reliable, flexible, versatile, and extendable DRDDF has profound implications for wavelength division multiplexing (WDM) applications in optical interconnection networks.

Keywords (OCIS):

  • (130.3120) Integrated optics : Integrated optics devices
  • (230.5750) Optical devices : Resonators
  • (230.4555) Optical devices : Coupled resonators
  • (130.4815) Integrated optics : Optical switching devices
  • (130.7408) Integrated optics : Wavelength filtering devices

Precise Evaluation of the Helholtz Equation for Optical Propagation

  • George Sutton and John Pond
  • received 07/28/2014; accepted 11/19/2014; posted 11/20/2014; Doc. ID 209304
  • [full text: PDF (612) KB)]
  • Abstract: The Helmholtz equation for electromagnetic propagation has been numerically evaluated with no approximations or linearization using a 64 bit processor, for a uniform monochromatic beam from a circular aperture, permitting very large values of the ratio of the aperture size to the wavelength, ~105. The multiple spots of Arago are clearly visible for a very large ratio of aperture size to wavelength, as is the intensity distribution.

Keywords (OCIS):

  • (050.1940) Diffraction and gratings : Diffraction
  • (140.0140) Lasers and laser optics : Lasers and laser optics

Articles 1 to 20 of 96 Next Page >>

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