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October


Yellow solid state laser for metrological application

  • Giacomo Bolognesi, Daniela Parisi, Davide Calonico, Giovanni Costanzo, Filippo Levi, Philip Metz, Christian Kraenkel, Guenter Huber, and Mauro Tonelli
  • received 08/22/2014; accepted 10/20/2014; posted 10/20/2014; Doc. ID 221477
  • [full text: PDF (873) KB)]
  • Abstract: We present laser results obtained from a Dy3+-Tb3+ co-doped LiLuF₄ crystal, pumped by a blue emitting InGaN laser diode, aiming for the generation of a compact 578 nm source. We exploit the yellow Dy3+ transition 4F9/2 ==> 6H13/2 to generate yellow laser emission. The lifetime of the lower laser level is quenched via energy transfer to co-doped Tb3+ ions in the fluoride crystal. We report the growth technique, spectroscopic study and room temperature continuous wave (cw) laser results in a hemispherical cavity at 574 nm and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden ¹S₀-³P₀ Ytterbium clock transition, which is recommended as a secondary representation of the second in the international system (SI) of units.

Keywords (OCIS):

  • (120.3940) Instrumentation, measurement, and metrology : Metrology
  • (140.3480) Lasers and laser optics : Lasers, diode-pumped
  • (140.3580) Lasers and laser optics : Lasers, solid-state
  • (140.7300) Lasers and laser optics : Visible lasers
  • (160.3380) Materials : Laser materials

A 41 W ZnGeP2 optical parametric oscillator pumped by a Q-switched Ho:YAG laser

  • yingjie shen, baoquan yao, Xiaoming Duan, Tongyu Dai, Youlun Ju, and Yuezhu Wang
  • received 09/08/2014; accepted 10/20/2014; posted 10/20/2014; Doc. ID 222569
  • [full text: PDF (558) KB)]
  • Abstract: We reported a high power ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumped by a Q-switched Ho:YAG laser. The maximum output power of the ZGP OPO was 41.2 W at 107.0 W incident Ho pump power, corresponding to a slope efficiency of 44.6 %. The ZGP OPO produced 16 ns mid-IR pulse laser in the 3.74-3.98 μm and 4.38-4.76 μm spectral regions simultaneously. A beam quality of M2 was less than 4.5. The continuous wave maximum average output power of the Ho:YAG laser was 128W, corresponding to a slope efficiency of 65.8%.

Keywords (OCIS):

  • (140.0140) Lasers and laser optics : Lasers and laser optics
  • (140.3070) Lasers and laser optics : Infrared and far-infrared lasers
  • (140.3540) Lasers and laser optics : Lasers, Q-switched
  • (190.4970) Nonlinear optics : Parametric oscillators and amplifiers

Experimental demonstration of a microdisk resonator based filter for filtering and buffering applications utilizing two-mode interference

  • Qingzhong Huang, Juguang Chen, Ge Song, Yi Wang, Jinsong Xia, Jinzhong Yu, kun jie, and Zhenzheng wang
  • received 09/23/2014; accepted 10/20/2014; posted 10/20/2014; Doc. ID 223632
  • [full text: PDF (2929) KB)]
  • Abstract: We have experimentally demonstrated a microdisk resonator (MDR) based filter for filtering and buffering applications utilizing two-mode interference. Optical filtering or buffering behavior can be generated by the coherent interference between two orthogonal whispering-gallery modes (WGMs) in a MDR symmetrically coupled to two bus waveguides. MDRs were fabricated using nanofabrication processes on a silicon-on-insulator platform. Multiple resonances of WGMs are excited in a MDR and unique filter characteristics have been observed for spectrally nearby two resonances. The measured results agree with the theoretical simulation well. Band-pass filtering is achieved with a 3-dB bandwidth of 0.65 nm and an in-band ripple less than 1 dB when the two resonances are detuned, while the filter can function as an optical buffer with an insertion loss of 5.85 dB and a predicted time delay of 15 ps when the two resonances are approximately aligned. Furthermore, the influence of resonance spacing is analyzed on the performance of this filter.

Keywords (OCIS):

  • (030.4070) Coherence and statistical optics : Modes
  • (130.3120) Integrated optics : Integrated optics devices
  • (070.5753) Fourier optics and signal processing : Resonators
  • (130.7408) Integrated optics : Wavelength filtering devices
  • (130.3990) Integrated optics : Micro-optical devices

Wideband co-site interference cancellation based on hybrid electrical and optical techniques

  • Mable P. Fok, Hanlin Feng, Qi Zhou, and Guy Scott
  • received 07/30/2014; accepted 10/19/2014; posted 10/20/2014; Doc. ID 220050
  • [full text: PDF (1471) KB)]
  • Abstract: A wideband co-site co-channel interference cancellation system based on hybrid electrical and optical techniques is proposed and is experimentally demonstrated. The demonstrated cancellation system subtracts the in-band wideband interfering signal from the received signal such that the weak signal of interest can be recovered. Our system utilizes a broadband radio frequency (RF) Balun transformer to invert the phase of the interfering signal, while electro-absorption modulated lasers are used for converting the RF signals into optical domain to enable fine adjustment with the hybrid interference cancellation system. We experimentally achieve 45 dB of cancellation over a 220-MHz of bandwidth, and over 57 dB of cancellation for a 10-MHz bandwidth at center frequency of 900 MHz. The proposed system also experimentally shows good cancellation (30 dB) over an enormously wide bandwidth of 5.5-GHz. To the best of our knowledge, this is the first demonstration of such a wide bandwidth cancellation with good cancellation depth. This property is extremely useful when there are multiple interference signals at various frequency bands. The proposed hybrid ICS has a spurious-free dynamic range (SFDR) of 93.2 dBm/Hz2/3. Moreover, a 10-Gb/s signal of interest is recovered from a strong interfering signal sweeping over 3-GHz bandwidth, a widely open eye diagram as well as error free bit-error rate measurement are experimentally achieved with the use of the hybrid ICS. The approach also works well for various frequency bands that are within the bandwidth of the Balun transformer and electro-absorption modulated lasers.

Keywords (OCIS):

  • (060.2310) Fiber optics and optical communications : Fiber optics
  • (350.4010) Other areas of optics : Microwaves
  • (060.5625) Fiber optics and optical communications : Radio frequency photonics

Optical fiber poling by induction

  • Pier Sazio, Francesco De Lucia, Ding Huang, Costantino Corbari, and Noel Healy
  • received 08/11/2014; accepted 10/19/2014; posted 10/20/2014; Doc. ID 220697
  • [full text: PDF (1718) KB)]
  • Abstract: Conventional thermal poling methods require direct physical contact to internal fiber electrodes. Here, we report an indirect electrostatic induction technique using electrically floating wires inside the fiber combined with external electric fields that can allow for facile poling of complex microstructured fibers (MOFs) of arbitrarily long lengths. The formation of a permanent second-order nonlinearity is unequivocally demonstrated by realizing quasi-phase matched frequency doublers using periodic UV erasure methods in the induction poled fibers. The second order susceptibility created inside the fiber is driven by the potential difference established between the floating electrodes which we calculate via numerical simulations.

Keywords (OCIS):

  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4360) Nonlinear optics : Nonlinear optics, devices
  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (230.1150) Optical devices : All-optical devices

Twin extra high photoluminescence in resonant double-period quantum wells

  • Wen-Jeng Hsueh, C. H. Chang, and Y. H. Cheng
  • received 08/13/2014; accepted 10/17/2014; posted 10/20/2014; Doc. ID 220862
  • [full text: PDF (845) KB)]
  • Abstract: Twin extra high photoluminescence (PL) in resonant quasi-periodic double-period quantum wells (DPQWs) for higher generation orders is demonstrated. In the DPQW, the number of maxima in the maximum values of the PL intensity is two, which is different from other quasi-periodic QWs and traditional periodic QWs. The maximum PL intensity in a DPQW is also stronger than that in a periodic QW under the anti-Bragg condition and that in a Fibonacci QW. Although the peaks of the squared electric field for the twin PL are both located near the QWs, their field profiles are distinct.

Keywords (OCIS):

  • (250.5230) Optoelectronics : Photoluminescence
  • (160.5293) Materials : Photonic bandgap materials
  • (250.5590) Optoelectronics : Quantum-well, -wire and -dot devices

800-fs, 330-µJ pulses from a 100-W regenerative Yb:YAG thin-disk amplifier at 300 kHz, and THz generation in LiNbO3

  • Peter Baum, Waldemar Schneider, Andrey Ryabov, Csaba Lombosi, Thomas Metzger, Zsuzsanna Major, and József Fülöp
  • received 09/05/2014; accepted 10/17/2014; posted 10/20/2014; Doc. ID 222516
  • [full text: PDF (443) KB)]
  • Abstract: Yb:YAG thin-disk lasers offer extraordinary output power, but systems delivering femtosecond pulses at a repetition rate of hundreds of kHz are scarce, even though this regime is ideal for ultrafast electron diffraction, coincidence imaging, attosecond science and THz spectroscopy. Here we describe a regenerative Yb:YAG amplifier based on thin-disk technology, producing 800-fs pulses at a tunable repetition rate between 50 and 400 kHz. The key design elements are a short regenerative cavity and fast-switching Pockels cell. The average output power is 130 W before the compressor and 100 W after compression, which at 300 kHz corresponds to pulse energies of 430 µJ and 330 µJ, respectively. This is sufficient for a wide range of nonlinear conversions and broadening/compression schemes. As a first application, we use optical rectification in LiNbO3 to produce 30-nJ single-cycle THz pulses with an electric field exceeding 10 kV/cm at a central frequency of 0.3 THz, suitable for driving structural dynamics or controlling electron beams.

Keywords (OCIS):

  • (140.3280) Lasers and laser optics : Laser amplifiers
  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (160.2100) Materials : Electro-optical materials
  • (190.7110) Nonlinear optics : Ultrafast nonlinear optics

Dual-pump vibrational/rotational femtosecond/picosecond coherent anti-Stokes Raman scattering temperature and species measurements

  • Terrence Meyer, Chloe Dedic, and Joseph Miller
  • received 09/19/2014; accepted 10/16/2014; posted 10/20/2014; Doc. ID 222788
  • [full text: PDF (650) KB)]
  • Abstract: A method for simultaneous ro-vibrational and pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is presented for multi-species detection and improved temperature sensitivity from room temperature to flame conditions. N₂/CH₄ vibrational and N₂/O₂/H₂ rotational Raman coherences are excited simultaneously using fs pump pulses at 660 nm and 798 nm, respectively, and a common fs Stokes pulse at 798 nm. A fourth narrowband 798 nm ps pulse probes all coherence states at a time delay that minimizes nonresonant background and effects of collisions. The transition strength is concentration dependent, while the distribution among observed transitions is related to temperature through the Boltzmann distribution. The broadband excitation pulses and multiplexed signal are demonstrated for accurate thermometry from 298–2400 K and concentration measurements of four key combustion species.

Keywords (OCIS):

  • (280.1740) Remote sensing and sensors : Combustion diagnostics
  • (300.6230) Spectroscopy : Spectroscopy, coherent anti-Stokes Raman scattering
  • (300.6290) Spectroscopy : Spectroscopy, four-wave mixing
  • (300.6530) Spectroscopy : Spectroscopy, ultrafast

Visible all-fiber frequency-doubled laser

  • Costantino Corbari, Alexey Gladyshev, Laure Lago, Morten Ibsen, Yves Hernandez, and Peter Kazansky
  • received 09/17/2014; accepted 10/16/2014; posted 10/17/2014; Doc. ID 223311
  • [full text: PDF (875) KB)]
  • Abstract: All-fibre ns-pulsed visible laser at λ =521 nm is realized by frequency doubling an Yb-doped fibre laser with a periodically poled silica fibre. A 50 mW second-harmonic output power is produced which is over 6-orders of magnitude greater than previous results obtained with poled fibres in the visible spectral range. The normalized conversion efficiency of 0.2 %/W is to date the largest demonstrated with poled fibre technology. Furthermore, 21% conversion efficiency is achieved for the doubling of 8 ps pulses from a neodymium-doped yttrium vanadate solid state laser. The advances are made possible by the precision and flexibility offered by using the continuous periodic UV erasure, as opposite to photolithographic methods, for the fabrication of over 20-cm-long χ(2)-gratings for quasi-phase matched second-harmonic generation.

Keywords (OCIS):

  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (140.7300) Lasers and laser optics : Visible lasers
  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4360) Nonlinear optics : Nonlinear optics, devices
  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (190.4400) Nonlinear optics : Nonlinear optics, materials

100-ps-Pulse-Duration, 100-Joule Burst-Mode Laser for kHz–MHz Flow Diagnostics

  • Sukesh Roy, Joseph Miller, Mikhail Slipchenko, Paul Hsu, Jason Mance, Terrence Meyer, and James Gord
  • received 09/30/2014; accepted 10/16/2014; posted 10/17/2014; Doc. ID 213514
  • [full text: PDF (705) KB)]
  • Abstract: A high-speed, master-oscillator power-amplifier burst-mode laser with ~100-ps pulse duration is demonstrated with output energy up to 110 J per burst at 1064 nm and second-harmonic conversion efficiency up to 67% in a KD*P crystal. The output energy is distributed across 100 to 10,000 sequential laser pulses, with 10-kHz to 1-MHz repetition rate, respectively, over 10-ms burst duration. The performance of the 100-ps burst-mode laser is evaluated and compares favorably with that of a similar design that employs a conventional ~8-ns pulse duration. The nearly transform-limited spectral bandwidth of 0.15 cm-1 at 532 nm is ideal for a wide range of linear and nonlinear spectroscopic techniques, and the 100-picosecond pulse duration is optimal for fiber-coupled spectroscopic measurements in harsh reacting-flow environments.

Keywords (OCIS):

  • (120.1740) Instrumentation, measurement, and metrology : Combustion diagnostics
  • (140.3280) Lasers and laser optics : Laser amplifiers
  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (140.3538) Lasers and laser optics : Lasers, pulsed

Broadband cavity-enhanced molecular spectra from Vernier filtering of a complete frequency comb

  • Morville Jérôme and Lucile Rutkowski
  • received 07/31/2014; accepted 10/16/2014; posted 10/17/2014; Doc. ID 220047
  • [full text: PDF (640) KB)]
  • Abstract: We present a new approach to Cavity Enhanced - Direct Frequency Comb Spectroscopy where the full emission bandwidth of a Titanium:Sapphire laser is exploited, currently at GHz resolution. The technique is based on low-resolution Vernier filtering obtained with an appreciable -actively stabilized- mismatch between the cavity Free Spectral Range and the laser repetition rate, using a diffraction grating and a Split-Photodiode. Spectra covering 1300 cm$^{-1}$ (40 THz) are acquired in less than 100\,ms and a baseline noise of 1.7$\times$10$^{-8}$\,cm$^{-1}$ is reached with a cavity finesse of only 300, providing an absorption figure of merit \emph{M}=6$\times$10$^{-11}$\,cm$^{-1}$.Hz$^{-1/2}$

Keywords (OCIS):

  • (120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
  • (120.4120) Instrumentation, measurement, and metrology : Moire' techniques
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (280.3420) Remote sensing and sensors : Laser sensors
  • (300.1030) Spectroscopy : Absorption
  • (300.6390) Spectroscopy : Spectroscopy, molecular

Content adaptive sparse illumination for Fourier ptychography

  • Qionghai Dai, Liheng Bian, Jinli Suo, Guo Situ, Guoan Zheng, and Feng Chen
  • received 08/01/2014; accepted 10/16/2014; posted 10/16/2014; Doc. ID 220199
  • [full text: PDF (3325) KB)]
  • Abstract: Fourier Ptychography (FP) is a recently proposed technique for large field of view and high resolution imaging. Specifically, FP captures a set of low resolution images under angularly varying illuminations and stitches them together in Fourier domain. One of FP's main disadvantages is its long capturing process due to the requisite large number of incident illumination angles. In this letter, utilizing the sparsity of natural images in Fourier domain, we propose a highly efficient method termed as AFP, which applies content adaptive sparse illumination for Fourier ptychography by capturing the most informative parts of the scene's spatial spectrum. We validate the effectiveness and efficiency of the reported framework with both simulations and real experiments. Results show that the proposed AFP could shorten the acquisition time of conventional FP by around 30%-60%.

Keywords (OCIS):

  • (100.3010) Image processing : Image reconstruction techniques
  • (180.0180) Microscopy : Microscopy
  • (110.1758) Imaging systems : Computational imaging

Highly precise stabilization of Er:fiber frequency comb using optical-microwave phase detector

  • Jy Zhao, Jiutao Wu, Shunnan Lai, Jianxiao Leng, and Shuangyou zhang
  • received 08/15/2014; accepted 10/15/2014; posted 10/16/2014; Doc. ID 221036
  • [full text: PDF (674) KB)]
  • Abstract: In this letter, we demonstrate a fully stabilized Er:fiber frequency comb by using a fiber-based, high-precision optical-microwave phase detector. To achieve high-precision and long-term phase locking of the repetition rate to a microwave reference, the frequency control techniques of tuning pump power and cavity length are combined together as its feedback. Besides, a novel method of carrier-envelop-offset frequency control technique should be developed for completely comb stabilization. Therefore, we introduce a pair of intracavity prisms as a regulator for carrier-envelope offset frequency, thereby phase locking one mode of the comb to rubidium saturated absorption transition line. The stabilized comb performs the same high stability as the reference for the repetition rate, and provides an frequency instability of 7.4×10-12 for each comb mode. The demonstrated stabilization scheme could provide high precision comb for optical communication, direct frequency comb spectroscopy.

Keywords (OCIS):

  • (140.3500) Lasers and laser optics : Lasers, erbium
  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (250.0250) Optoelectronics : Optoelectronics
  • (140.3425) Lasers and laser optics : Laser stabilization

Null-fifield radiationless sources

  • Elisa Hurwitz and Gregory Gbur
  • received 08/19/2014; accepted 10/15/2014; posted 10/16/2014; Doc. ID 221275
  • [full text: PDF (382) KB)]
  • Abstract: It is shown that it is in principle possible to produce combined sources of polarization and magnetization that are not only radiationless but which have any (and sometimes several) of the four microscopic or macroscopic electromagnetic fifields exactly zero. The conditions that such a "null-fifield radiationless source" must satisfy are derived, and examples are given for several cases. The implications for transformation optics and invisibility physics in general are discussed.

Keywords (OCIS):

  • (160.3820) Materials : Magneto-optical materials
  • (290.5839) Scattering : Scattering, invisibility

Fiber-optic magnetometry with randomly oriented spins

  • Aleksei Zheltikov, Nikolay Safronov, Ilya Fedotov, Lyubov Amitonova, Andrey Fedotov, Dmitry Sidorov-Biryukov, Marlan Scully, Vladimir Velichansky, Alexey Levchenko, Sergey Zibrov, Kazuaki Sakoda, Philip Hemmer, Alexey Akimov, Sean Blakley, and H Perez
  • received 08/19/2014; accepted 10/15/2014; posted 10/16/2014; Doc. ID 221280
  • [full text: PDF (954) KB)]
  • Abstract: We demonstrate fiber-optic magnetometry using a random ensemble of nitrogen--vacancy (NV) centers in nanodiamond coupled to a tapered optical fiber, which provides a waveguide delivery of optical fields for the initialization, polarization, and readout of the electron spin in NV centers.

Keywords (OCIS):

  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (230.0230) Optical devices : Optical devices

Heterogeneously integrated III-V/silicon dual-mode distributed feedback laser array for THz generation

  • Haifeng Shao, Shahram Keyvaninia, Mathias Vanwolleghem, Guillaume Ducournau, Xiaoqing Jiang, Geert Morthier, Jean-Francois Lampin, and Gunther Roelkens
  • received 07/08/2014; accepted 10/15/2014; posted 10/16/2014; Doc. ID 216511
  • [full text: PDF (2252) KB)]
  • Abstract: We demonstrate an integrated distributed feedback (DFB) laser array as a dual-wavelength source for narrowband terahertz (THz) generation. The laser array is composed of four heterogeneously integrated III-V-on-silicon DFB lasers with different lengths enabling dual-mode lasing tolerant to process variations, bias fluctuations and ambient temperature variations. By optical heterodyning the two modes emitted by the dual-wavelength DFB laser in the laser array using a THz photomixer composed of an uni-traveling carrier photodiode (UTC-PD), a narrow and stable carrier signal with a frequency of 0.357 THz is generated. The central operating frequency and the emitted terahertz wave linewidth are analyzed, along with their dependency on the bias current applied to the laser diode and ambient temperature.

Keywords (OCIS):

  • (130.3120) Integrated optics : Integrated optics devices
  • (140.3490) Lasers and laser optics : Lasers, distributed-feedback
  • (060.5625) Fiber optics and optical communications : Radio frequency photonics
  • (060.2840) Fiber optics and optical communications : Heterodyne

Breathing laser as inertia-free swept source for high-quality ultrafast optical bioimaging

  • Kenneth Kin-Yip Wong, Jingjiang XU, Xiaoming Wei, Yiqing Xu, Luoqin Yu, Jianbing xu, Bowen Li, Andy K. S. Lau, Chi Zhang, Kevin Tsia, and Xie Wang
  • received 07/23/2014; accepted 10/15/2014; posted 10/16/2014; Doc. ID 217619
  • [full text: PDF (5303) KB)]
  • Abstract: We demonstrate an all-fiber breathing laser as inertia-free swept source (BLISS), with an ultra-compact design, for the emerging ultrafast bioimaging modalities. BLISS is built upon an all-fiber ring cavity consisting of only a 0.55×5.5-cm optical integrated module and an in-line polarization controller, which performs the stretched-pulse additive pulse mode-locking, and a dispersive fiber, which performs all-optical broadband wavelength-sweep by optical time-stretch. The unique feature of BLISS is its broadband wavelength-swept operation (~60 nm) with superior temporal stability in terms of both long term (0.08 dB over 27 hours) and shot-to-shot power variations (2.1%). More importantly, it enables a wavelength sweep rate of >10 MHz (~700000000 nm/s) – orders-of-magnitude faster than the existing swept sources based on mechanical or electrical tuning techniques. BLISS thus represents a practical and new generation of swept source operating in the unmet megahertz swept-rate regime which aligns with the pressing need for scaling the optical bioimaging speed in ultrafast phenomena study or high-throughput screening applications. To showcase its utility in high-speed optical bioimaging, we here employ BLISS for ultrafast time-stretch microscopy and multi-MHz optical coherence tomography (OCT) of the biological specimen at a single-shot line-scan rate or A-scan rate of 11.5 MHz. The stable and robust operation of BLISS requires no averaging of the wavelength-swept waveforms to attain high image quality in time-stretch imaging and OCT. With its compact configuration and stable performance, BLISS can also be applied to other applications, such as ultrafast spectroscopy, real-time single-shot digitizer, and hyperspectral imaging.

Keywords (OCIS):

  • (060.2350) Fiber optics and optical communications : Fiber optics imaging
  • (110.4500) Imaging systems : Optical coherence tomography
  • (140.3560) Lasers and laser optics : Lasers, ring
  • (140.4050) Lasers and laser optics : Mode-locked lasers

Focusing by a high numerical aperture lens of distributions generated by conical diffraction.

  • Clément Fallet, Gabriel Sirat, and Sybille Rosset
  • received 09/12/2014; accepted 10/15/2014; posted 10/17/2014; Doc. ID 222744
  • [full text: PDF (343) KB)]
  • Abstract: We study here the diffraction by a high numerical aperture of a vortex beam of topological charge ±1 generated by conical diffraction and show the behavior of such a vortex beam is similar to the one already observed for Laguerre-Gauss beams and Bessel beams. We also highlight a similarity between the phase singularity created by a lens and the one created by conical diffraction through a thin crystal. More precisely, if the input beam is homogeneously polarized, we show the electric fifield in the image plane of a thin crystal caught between two orthogonal polarizers has the same expression as Ez, the component of the electric fifield along the propagation axis, in the focal plane of a lens.

Keywords (OCIS):

  • (260.1180) Physical optics : Crystal optics
  • (260.1960) Physical optics : Diffraction theory
  • (260.5430) Physical optics : Polarization
  • (080.4865) Geometric optics : Optical vortices
  • (260.6042) Physical optics : Singular optics

Effect of oxygen vacancies on the laser-induced damage resistance of Y₀.₂₆Hf₀.₇₄Ox thin films

  • Xiaoying Chen, Lili Zhao, Lixin Song, Olaf Stenzel, Helena Kämmer, Felix Dreisow, Lijun You, Xinjie Fu, and Stefan Nolte
  • received 09/12/2014; accepted 10/14/2014; posted 10/16/2014; Doc. ID 221941
  • [full text: PDF (536) KB)]
  • Abstract: The influence of sub-stoichiometry of oxygen on the femtosecond laser-induced damage resistance of Y₀.₂₆Hf₀.₇₄Ox films was investigated in this work. Photoluminescence (PL) spectroscopy was applied to analyze the various states of oxygen vacancies (VO), and laser-induced damage measurement was performed using single 500 femtosecond pulse laser at the wavelength of 1030 nm. Based on the PL spectra, a probable band gap structure with different defect energy levels was obtained, which is significant to explain an observed inverse correlation between the laser-induced damage threshold (LIDT) and concentration of VO. The crystallization and the refractive index which were previously found to be a crucial factor in laser damage resistance of optical thin films, are also closely depending on the amount of induced oxygen vacancies.

Keywords (OCIS):

  • (140.3330) Lasers and laser optics : Laser damage
  • (310.0310) Thin films : Thin films
  • (320.0320) Ultrafast optics : Ultrafast optics

Ultrafast Saturable Absorption of Self-assembled WS2 Nanoplate Array

  • Zhijian Peng, Xiu-Li Fu, Jingwen Qian, Xiaofen Qiao, and ping-Heng Tan
  • received 08/13/2014; accepted 10/14/2014; posted 10/15/2014; Doc. ID 220864
  • [full text: PDF (1495) KB)]
  • Abstract: We report the nonlinear optical properties of vertically-stood WS2 nanoplate array excited by 532 nm picosecond laser light The nanoplates were synthesized by a no-catalyst thermal evaporation process. Raman spectroscopy and X ray diffraction pattern indicate that the nanoplates are with high crystal quality. The nanoplates exhibit large nonlinear saturable absorption but negligible nonlinear refraction. Mechanisms of the nonlinear optical response are proposed.

Keywords (OCIS):

  • (160.4330) Materials : Nonlinear optical materials
  • (190.4720) Nonlinear optics : Optical nonlinearities of condensed matter
  • (160.4236) Materials : Nanomaterials

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