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July


Cascaded uncoupled dual-ring modulator

  • Tingyi Gu, Young-Kai Chen, Chee Wei Wong, and Po Dong
  • received 06/26/2014; accepted 07/17/2014; posted 07/21/2014; Doc. ID 214817
  • [full text: PDF (1386) KB)]
  • Abstract: We demonstrate that by coherent driving two uncoupled rings in same direction, the effective photon circulating time in the dual ring modulator is reduced, with increased modulation quality. The inter-ring detuning dependent photon dynamics, Q-factor, extinction ratio and optical modulation amplitude of two cascaded silicon ring resonators are studied and compared with that of a single ring modulator. Experimentally measured eye diagrams, together with coupled mode theory simulations, demonstrate the enhancement of dual ring configuration at 20 Gbps with a Q ~ 20,000.

Keywords (OCIS):

  • (130.0130) Integrated optics : Integrated optics
  • (230.4110) Optical devices : Modulators
  • (230.5750) Optical devices : Resonators

Mid-infrared frequency comb for broadband high precision and sensitivity molecular spectroscopy

  • Francesco Cappelli, Iacopo Galli, Davide Mazzotti, Giovanni Giusfredi, Naota Akikusa, Masamichi Yamanishi, Paolo De Natale, Saverio Bartalini, and Pablo Cancio Pastor
  • received 06/06/2014; accepted 07/17/2014; posted 07/17/2014; Doc. ID 213106
  • [full text: PDF (422) KB)]
  • Abstract: We report on the experimental demonstration of the metrological and spectroscopic performances of a mid-infrared comb generated by a non-linear down-conversion process from a Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase locked to a single tooth of this mid-infrared comb and its frequency-noise power spectral density was measured. The mid-infrared comb itself was also used as a multi-frequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Pérot cavity.

Keywords (OCIS):

  • (120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
  • (140.3590) Lasers and laser optics : Lasers, titanium
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (190.4223) Nonlinear optics : Nonlinear wave mixing
  • (140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade

Precise frequency measurement and characterization of a continuous scanning single-mode laser with an optical frequency comb

  • Masatoshi Misono, Akiko Nishiyama, and Ayumi Matsuba
  • received 06/27/2014; accepted 07/17/2014; posted 07/17/2014; Doc. ID 214345
  • [full text: PDF (525) KB)]
  • Abstract: We developed a high-precision frequency measurement system for continuously scanning single-mode continuous-wave (cw) lasers. The high precision for wide frequency range is realized by employing an optical frequency comb. The developed system operates as a strong tool for analyzing the spectral profile and scan characteristics of lasers, which is suitable for high-resolution molecular spectroscopy. We demonstrated the ability of our system with Doppler-free spectroscopy of molecular iodine.

Keywords (OCIS):

  • (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (300.6320) Spectroscopy : Spectroscopy, high-resolution
  • (300.6390) Spectroscopy : Spectroscopy, molecular

PT-symmetric microring laser-absorber

  • Stefano Longhi and Liang Feng
  • received 06/19/2014; accepted 07/17/2014; posted 07/17/2014; Doc. ID 214428
  • [full text: PDF (360) KB)]
  • Abstract: The lasing and coherent perfect absorption (CPA) properties of $\mathcal{PT}$-symmetric microrings with mixed index and gain gratings, externally coupled to a bus waveguide, are theoretically investigated. For a complex grating at the $\mathcal{PT}$ symmetry breaking point, perfect unidirectional (either clockwise or counterclockwise) laser emission can be realized, however the grating does not discriminate longitudinal modes and CPA can not be simultaneously achieved. Above the grating $\mathcal{PT}$ symmetry breaking point, single mode emission and simultaneous CPA can be obtained, with unbalanced and controllable excitation of clockwise and counterclockwise modes in the ring.

Keywords (OCIS):

  • (130.3120) Integrated optics : Integrated optics devices
  • (140.3490) Lasers and laser optics : Lasers, distributed-feedback
  • (140.3560) Lasers and laser optics : Lasers, ring
  • (140.3570) Lasers and laser optics : Lasers, single-mode

Using shadows to measure spatial coherence

  • Miguel Alonso, James Wood, Katelynn Sharma, Thomas Brown, and Seongkeun Cho
  • received 06/23/2014; accepted 07/16/2014; posted 07/17/2014; Doc. ID 214526
  • [full text: PDF (2568) KB)]
  • Abstract: We present a very simple method for measuring the spatial coherence of quasimonochromatic fields through the comparison of two measurements of the radiant intensity, with and without a small obscuration at the test plane. From these measurements, one can measure simultaneously the field's coherence at all pairs of points whose centroid is the centroid of the obstacle. This method can be implemented without the need of any refractive or diffractive focusing elements.

Keywords (OCIS):

  • (030.0030) Coherence and statistical optics : Coherence and statistical optics
  • (030.1640) Coherence and statistical optics : Coherence
  • (260.1960) Physical optics : Diffraction theory

Measurements of the third- and fifth-order optical nonlinearities of water at 532 nm and 1064 nm using the D4σ method

  • Georges Boudebs, Côme Schnebelin, Christophe Cassagne, and Cid Bartolomeu de Araujo
  • received 06/19/2014; accepted 07/16/2014; posted 07/17/2014; Doc. ID 214367
  • [full text: PDF (468) KB)]
  • Abstract: The nonlinear response of liquid water was investigated at 1064 nm and 532 nm using a Nd: YAG laser delivering pulses of 17 ps and its second harmonic. The experiments were performed using the D4σ method combined with the Z-scan technique. Nonlinear refractive indices of third- and fifth-order were determined as well as the three-photon absorption coefficient for both wavelengths used. A good agreement was found between theory and experiment.

Keywords (OCIS):

  • (190.0190) Nonlinear optics : Nonlinear optics
  • (190.3270) Nonlinear optics : Kerr effect
  • (190.4180) Nonlinear optics : Multiphoton processes
  • (190.4420) Nonlinear optics : Nonlinear optics, transverse effects in

Ultrafast laser inscription of mid-IR directional couplers for stellar interferometry

  • Alexander Arriola, Lucas Labadie, Robert Thomson, Debaditya Choudhury, and Sebabrata Mukherjee
  • received 05/27/2014; accepted 07/16/2014; posted 07/17/2014; Doc. ID 212768
  • [full text: PDF (717) KB)]
  • Abstract: We report the ultrafast laser fabrication and mid-IR characterization (3.39 μm) of four-port evanescent field directional couplers. The couplers were fabricated in a commercial gallium lanthanum sulphide glass substrate using sub-picosecond laser pulses of 1030 nm light. Straight waveguides inscribed using optimal fabrication parameters were found to exhibit propagation losses of ∼ 0.8 dB·cm−1. A series of couplers were inscribed with different interaction lengths, and we demonstrate power splitting ratios of between 8% and 99% for mid-IR light with a wavelength of 3.39 μm. These results clearly demonstrate that ultrafast laser inscription can be used to fabricate high quality evanescent field couplers for future applications in astronomical interferometry.

Keywords (OCIS):

  • (130.0130) Integrated optics : Integrated optics
  • (140.3390) Lasers and laser optics : Laser materials processing
  • (220.4000) Optical design and fabrication : Microstructure fabrication
  • (130.2755) Integrated optics : Glass waveguides

Implications of Raman scattering and phase noise on multiple four-wave mixing processes in an optical fiber

  • Bhaskar Khubchandani
  • received 05/07/2014; accepted 07/16/2014; posted 07/17/2014; Doc. ID 211695
  • [full text: PDF (1271) KB)]
  • Abstract: Implications of spontaneous and stimulated Raman scattering (SSRS), and phase noise on the spatial evolution of multiple order sidebands arising from four-wave mixing (FWM) along the length of an optical fiber are investigated. A modified split-step Fourier method is used to solve the governing coupled nonlinear Schrodinger equations. The phase noise overcomes the depletive nature of SSRS and stabilizes the FWM sidebands, in good agreement with experimental results.

Keywords (OCIS):

  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing

High-speed silicon modulator with band equalization

  • yude yu, xianyao li, Xi Xiao, Hao Xu, Pei-Ji Zhou, Zhi-Yong Li, and Jinzhong Yu
  • received 04/22/2014; accepted 07/16/2014; posted 07/16/2014; Doc. ID 210222
  • [full text: PDF (1274) KB)]
  • Abstract: Electro-optic modulation up to 70 Gbit/s has been demonstrated using a silicon Mach–Zehnder modulator with a bias voltage of -1.5 V. In a wide frequency range from DC, an increasing input impedance of the modulator was designed to equalize its electro-optic frequency response. Without a bias voltage, the 3-dB bandwidth was measured as 35 GHz and it is predicted as high as 55 GHz at -3 V bias. Frequency responses of the modulator operated with counter-propagating waves were tested to verify the proposed prediction model.

Keywords (OCIS):

  • (230.0250) Optical devices : Optoelectronics
  • (250.5300) Optoelectronics : Photonic integrated circuits
  • (250.7360) Optoelectronics : Waveguide modulators

High-fidelity spatially resolved multiphoton counting for quantum imaging applications

  • Radoslaw Chrapkiewicz, Wojciech Wasilewski, and Konrad Banaszek
  • received 05/19/2014; accepted 07/15/2014; posted 07/16/2014; Doc. ID 211545
  • [full text: PDF (4661) KB)]
  • Abstract: We present a method for spatially resolved multiphoton counting based on an intensified camera with the retrieval of multimode photon statistics fully accounting for non-linearities in the detection process. The scheme relies on one-time quantum tomographic calibration of the detector. Faithful, high-fidelity reconstruction of single- and two-mode statistics of multiphoton states is demonstrated for coherent states and their statistical mixtures. The results consistently exhibit classical values of Mandel and Fano parameters in contrast to raw statistics of camera photo-events. Detector operation is reliable for illumination levels up to the average of one photon per an event area, substantially higher than in previous approaches to characterize quantum statistical properties of light with spatial resolution.

Keywords (OCIS):

  • (030.5260) Coherence and statistical optics : Photon counting
  • (270.5290) Quantum optics : Photon statistics
  • (270.5570) Quantum optics : Quantum detectors

Demonstration of tunable optical generation of higher-Order modulation formats using nonlinearities and coherent frequency comb

  • Mohammad Reza Chitgarha, Salman Khaleghi, Morteza Ziyadi, ahmed almaiman, Amirhossein Mohajerin Ariaei, Ori Gerstel, Loukas Paraschis, Carsten Langrock, Martin Fejer, Joseph Touch, and Alan Willner
  • received 05/09/2014; accepted 07/15/2014; posted 07/17/2014; Doc. ID 211820
  • [full text: PDF (789) KB)]
  • Abstract: We demonstrate a tunable, optical generation scheme of higher-order modulation formats including pulse-amplitude-modulation (PAM) and quadrature-amplitude-modulation (QAM). Using this method, 100.4-Gbit/s 16-QAM, and 120-Gbit/s 64-QAM were generated from 50.2- and 40-Gbit/s QPSK signals at EVMs of 7.8% and 6.4%, and 80-Gbit/s 8-PAM were generated at an EVM of 8.1% using three 20-Gbit/s BPSK signals. We also demonstrated a successful transmission of 80-Gbit/s 16-QAM through 80-km SMF-28 after compensating with 20-km DCF. All signals were generated, transmitted, and detected with BER below the forward error correction (FEC) threshold.

Keywords (OCIS):

  • (060.1660) Fiber optics and optical communications : Coherent communications
  • (060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
  • (070.4340) Fourier optics and signal processing : Nonlinear optical signal processing

Extended parametric gain range in photonic crystal fibers with strongly frequency-dependent field distributions

  • Sidsel Petersen, Thomas Alkeskjold, Christina Olausson, and Jesper Laegsgaard
  • received 07/04/2014; accepted 07/15/2014; posted 07/16/2014; Doc. ID 214720
  • [full text: PDF (1124) KB)]
  • Abstract: The parametric gain range of a degenerate four-wave mixing process is determined in the undepleted pump regime. The gain range is considered with and without taking the mode field distributions of the four-wave mixing components into account. It is found, that the mode field distributions have to be included to evaluate the parametric gain correctly in dispersion-tailored speciality fibers and that mode profile engineering can provide a way to increase the parametric gain range.

Keywords (OCIS):

  • (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers

Efficient excitation of photoluminescence in a two-dimensional waveguide consisting of a QD-polymer heterostructure

  • Isaac Suárez, Martinez Pastor, Vladimir Chirvony, Rafael Abargues, Pedro Rodríguez-Cantó, G almuneau, and Alexandre Larrue
  • received 04/23/2014; accepted 07/15/2014; posted 07/17/2014; Doc. ID 210615
  • [full text: PDF (722) KB)]
  • Abstract: In this work we study numerically and experimentally a new kind of organic polymer waveguide combining an ultrathin (10-50 nm) layer of compactly packed CdSe/ZnS core/shell colloidal quantum dots (QDs) sandwiched between two cladding Poly(methyl methacrylate) (PMMA) layers. When a pumping laser beam is coupled into the waveguide edge, light is mostly confined around the QD-layer improving the efficiency of excitation. Moreover, the absences of losses in the claddings allow the propagation of the pumping laser beam along the entire waveguide length and hence a high intensity photoluminescence (PL) is produced. Furthermore, a novel fabrication technology is developed to pattern the PMMA into ridge structures by UV lithography, in order to provide additional light confinement. The heterostructure-like waveguide is analyzed in comparison to a similar one formed by a PMMA film homogeneously doped by the same QDs. A 100 fold enhancement in the waveguided PL is found in the heterostructure-like case due to the higher concentration of QDs inside the waveguide.

Keywords (OCIS):

  • (250.2080) Optoelectronics : Polymer active devices
  • (250.5460) Optoelectronics : Polymer waveguides
  • (250.4745) Optoelectronics : Optical processing devices

One-way optical transmission in silicon grating-photonic crystal structures

  • Guo Ping Wang, Yanyu Zhang, and Qiang kan
  • received 05/14/2014; accepted 07/15/2014; posted 07/16/2014; Doc. ID 212072
  • [full text: PDF (760) KB)]
  • Abstract: One-way optical transmission through a composite structure of grating-photonic crystals (PCs) is presented. Such non-reciprocal transportation property is originated from the role of diffraction of gratings, which change the direction of the incident light with frequencies falling into the pseudobandgaps of the PCs to its passbands. Numerical simulation shows that a light beam in a certain range of frequencies can transmit the composite structure when it is incident from the grating interface but is completely reflected by the structure as it is incident from the PC interface, which is further verified experimentally. The present structure may provide another more compact way for designing on-chip optical diode-like integrated devices.

Keywords (OCIS):

  • (050.1950) Diffraction and gratings : Diffraction gratings
  • (130.3120) Integrated optics : Integrated optics devices
  • (050.5298) Diffraction and gratings : Photonic crystals

Plasmonic Routing in Aperiodic Graphene Sheet Arrays

  • Peixiang Lu, Bing Wang, Huang He, Kai Wang, and Hua Long
  • received 05/16/2014; accepted 07/15/2014; posted 07/16/2014; Doc. ID 212217
  • [full text: PDF (392) KB)]
  • Abstract: We discover deep-subwavelength, low-loss, and diffraction-free surface plasmon polariton (SPP) beam routing effects in aperiodic graphene sheet arrays (a-GSAs). The a-GSAs are constructed by varying either the interlayer space between graphene or individual graphene chemical potentials. The SPP beams can be accelerated or decelerated in the a-GSAs, benefiting to beam routing in different paths. The routing of the SPP beams depends on the spatial arrangement or chemical potential distribution of graphene sheets. The wave fronts of the beams are always parallel to the propagation direction, allowing of generating transverse radiation pressure. All these behaviors of SPPs are demonstrated by fully-vectorial simulations and Hamilton optics analysis.

Keywords (OCIS):

  • (060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
  • (240.6680) Optics at surfaces : Surface plasmons
  • (080.1238) Geometric optics : Array waveguide devices
  • (310.6628) Thin films : Subwavelength structures, nanostructures

Cost ecient delay generator for fast terahertz imaging

  • Thorsten Probst, Stefan Busch, Sangam Chatterjee, Martin Koch, Arno Rehn, and Maik Scheller
  • received 05/22/2014; accepted 07/15/2014; posted 07/16/2014; Doc. ID 212644
  • [full text: PDF (790) KB)]
  • Abstract: We present a fast and low-cost delay generator for terahertz (THz) waves which transfers a rotational motion of a transparent dielectric cube into an eective THz delay. The device is easily implemented in the THz beam path and allows for coherent sampling over 40 picoseconds with scan rate of hundreds of Hertz. Furthermore, we show that our approach is particularly suitable for fast THz imaging.

Keywords (OCIS):

  • (300.6500) Spectroscopy : Spectroscopy, time-resolved
  • (300.6495) Spectroscopy : Spectroscopy, teraherz
  • (170.6795) Medical optics and biotechnology : Terahertz imaging

Optical Limiting Properties of a Nonlinear Multilayer Fabry-Perot Resonator Containing Niobium Pentoxide as the Nonlinear Medium

  • Anton Ryzhov, Inna Belousova, yanzhi wang, Hongji Qi, and Jun Wang
  • received 05/20/2014; accepted 07/15/2014; posted 07/15/2014; Doc. ID 212404
  • [full text: PDF (311) KB)]
  • Abstract: In this work, an optical limiting effect was numerically simulated and experimentally observed for a 25-layer Fabry–Perot microresonators by 7 ns laser pulses at 532 nm. The sample, made by vacuum evaporation and consisting of alternating Nb₂O₅ and SiO₂ layers, has a 1 nm half-width line of transparency at near 532 nm within a wide spectral band of reflection. By adjusting simulated results in accordance with experimental dependencies of transmittance, reflectance and absorbance on incident light intensity, the coefficient of optical nonlinearity of Nb₂O₅ was estimated at (6 + 1i) · 10^(-12) cm²/W.

Keywords (OCIS):

  • (230.1150) Optical devices : All-optical devices
  • (230.4170) Optical devices : Multilayers
  • (250.6715) Optoelectronics : Switching
  • (310.6845) Thin films : Thin film devices and applications

Multiwatt-level Continuous-Wave Midwave-Infrared Generation using Difference Frequency Mixing in Periodically Poled Lithium Niobate

  • Shekhar Guha, Leonel Gonzalez, and Jacob Barnes
  • received 06/26/2014; accepted 07/15/2014; posted 07/24/2014; Doc. ID 214872
  • [full text: PDF (1477) KB)]
  • Abstract: Over 3.5 watts of continuous-wave power at 3.4 $\mu$m was obtained by single-pass difference frequency mixing of 1.064 $\mu$m and 1.55 $\mu$m fiber lasers in a 5 cm long periodically poled lithium niobate crystal.

Keywords (OCIS):

  • (140.3070) Lasers and laser optics : Infrared and far-infrared lasers
  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

Narrow-bandwidth, picosecond, 1064-nm pumped optical parametric generator for the mid-IR based on HgGa₂S₄

  • Riccardo Piccoli, Federico Pirzio, Antonio Agnesi, Dmitry Badikov, Dmitrii Badikov, Vladimir Panyutin, Georgi Marchev, and Valentin Petrov
  • received 06/26/2014; accepted 07/14/2014; posted 07/17/2014; Doc. ID 214875
  • [full text: PDF (453) KB)]
  • Abstract: We report on optical parametric generation in mercury thiogallate (HgGa₂S₄) crystal pumped by 16-ps, 1064 nm pulses at 250 kHz. Broad tuning range extending from 1.19 to 1.47 μm (signal) and from 3.85 to 10 μm (idler) is achieved. Narrow-bandwidth, quasi-Fourier limited operation with high beam quality for the signal/idler pulses and >14% pump depletion is obtained by continuous-wave seed injection at 1.29 μm.

Keywords (OCIS):

  • (160.4330) Materials : Nonlinear optical materials
  • (190.4970) Nonlinear optics : Parametric oscillators and amplifiers

Supression of nonlinear phonon relaxation in Yb:YAG thin disk via zero phonon line pumping

  • Martin Smrz, Taisuke Miura, Michal Chyla, Siva Nagisetty, Ondrej Novak, Akira Endo, and Tomas Mocek
  • received 05/22/2014; accepted 07/14/2014; posted 07/16/2014; Doc. ID 212570
  • [full text: PDF (1605) KB)]
  • Abstract: Quantitative comparison of conventional absorption line (940 nm) pumping and zero-phonon-line (969 nm) pumping of Yb:YAG thin disk lasers is reported. Characteristics of an output beam profile, surface temperature and deformation of a thin disk under the different pump wavelengths are evaluated. We found that the nonlinear phonon relaxation of the excited state in Yb:YAG, which induces nonlinear temperature rise and large aspheric deformation, was not appeared in case of a zero-phonon-line pumped Yb:YAG thin disk. It means that the advantage of zero-phonon-line pumping is not only the reduction of quantum defect but also the suppression of nonlinear phonon relaxation. The latter effect is more important for high power lasers.

Keywords (OCIS):

  • (140.3580) Lasers and laser optics : Lasers, solid-state
  • (140.6810) Lasers and laser optics : Thermal effects
  • (140.3615) Lasers and laser optics : Lasers, ytterbium

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