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October


Long Reach OFDM WDM-PON Delivering Downstream data 100Gbps and Upstream data 2 Gbps using CW Laser and RSOA

  • Sofien Mhatli, Mohammad Ghanbarisabagh, Laxman Tawade, Bechir nsiri, Mutsam Jarajreh, malèk channoufi, and Rabah Attia
  • received 07/18/2014; accepted 10/21/2014; posted 10/22/2014; Doc. ID 217200
  • [full text: PDF (718) KB)]
  • Abstract: This paper presents Long Reach Orthogonal frequency division multiplexing Wavelength Division Multiplexing Passive Optical Network (OFDM WDM-PON) system capable of delivering downstream 100 Gbit/s data and upstream 2 Gbit/s data on a single wavelength. The optical source for downstream data and upstream data is Continuous wave Laser at central office and reflective semiconductor optical amplifier (RSOA) at each optical network unit

Keywords (OCIS):

  • (060.0060) Fiber optics and optical communications : Fiber optics and optical communications
  • (060.1660) Fiber optics and optical communications : Coherent communications
  • (060.3735) Fiber optics and optical communications : Fiber Bragg gratings

Long period grating based fiber coupler to whispering gallery mode resonators

  • Gualtiero Nunzi Conti, Daniele Farnesi, Francesco Chiavaioli, Giancarlo Righini, Silvia Soria, Cosimo Trono, and Pedro Jorge
  • received 09/08/2014; accepted 10/21/2014; posted 10/22/2014; Doc. ID 222669
  • [full text: PDF (972) KB)]
  • Abstract: We present a new method for coupling light to high-Q silica whispering gallery mode resonators (WGMs) which is based on long period fiber gratings (LPGs) written in silica fibers. An LPG allows selective excitation of high order azimuthally symmetric cladding modes in a fiber. Coupling of these cladding modes to WGMs in silica resonators is possible when partial tapering of the fiber is also implemented in order to reduce the optical field size and increase its external evanescent portion. Importantly, the taper size is about one order of magnitude larger than that of a standard fiber taper coupler. The suggested approach is therefore much more robust and useful especially for practical applications. We demonstrate coupling to high-Q silica microspheres and microbubbles detecting the transmission dip at the fiber output when crossing a resonance. An additional feature of this approach is that by cascading LPGs with different periods a wavelength selective addressing of different resonators along the same fiber is also possible.

Keywords (OCIS):

  • (050.2770) Diffraction and gratings : Gratings
  • (060.2310) Fiber optics and optical communications : Fiber optics
  • (140.4780) Lasers and laser optics : Optical resonators
  • (230.5750) Optical devices : Resonators
  • (140.3945) Lasers and laser optics : Microcavities

Nonlinear optical magnetometry with accessible in situ optical squeezing

  • Benjamin Lawrie, Raphael Pooser, Nils Otterstrom, Raphael Pooser, and Nils Otterstrom
  • received 09/30/2014; accepted 10/21/2014; posted 10/22/2014; Doc. ID 222774
  • [full text: PDF (404) KB)]
  • Abstract: We demonstrate compact and accessible squeezed-light magnetometry using four-wave mixing in a single hot rubidium vapor cell. The strong intrinsic coherence of the four wave mixing process results in nonlinear magneto-optical rotation (NMOR) on each mode of a two mode relative-intensity squeezed state. This framework enables 4.7 dB of quantum noise reduction while the opposing polarization rotation signals of the probe and conjugate fields add to increase the total signal to noise ratio.

Keywords (OCIS):

  • (190.0190) Nonlinear optics : Nonlinear optics
  • (270.0270) Quantum optics : Quantum optics
  • (270.6570) Quantum optics : Squeezed states
  • (280.4788) Remote sensing and sensors : Optical sensing and sensors

Role of incoherent pumping in strongly coupled system of exchange-split excitons and pillar-microcavities

  • Sheng-Di Lin and Yi-Shan Lee
  • received 09/12/2014; accepted 10/21/2014; posted 10/22/2014; Doc. ID 222982
  • [full text: PDF (426) KB)]
  • Abstract: We present an experimental study of the influence of incoherent pumping upon the strong coupling between quantum dot excitons and micropillar-cavity. For two exchange-split excitons, the inherent difference in the detuning with respect to the cavity modes leads to an unequal reduction of Rabi splitting for two orthogonal polarizations as excitation power is increased, which could destroy the indistinguishable decay paths built by the coupled states. This work prompts a careful implementation of optical pumping for the pursuit of polarization-entangled photon pairs in the strong coupling regime.

Keywords (OCIS):

  • (020.5580) Atomic and molecular physics : Quantum electrodynamics
  • (030.1670) Coherence and statistical optics : Coherent optical effects
  • (140.3945) Lasers and laser optics : Microcavities

Alignment-Stabilized Interference Filter-Tuned External-Cavity Quantum Cascade Laser

  • Jan Kischkat, Mykhaylo Semtsiv, Mikeala Elagin, Grygorii Monastyrskyi, Yuri Flores, Sergii Kurlov, Sven Peters, and W. Masselink
  • received 09/30/2014; accepted 10/20/2014; posted 10/22/2014; Doc. ID 223897
  • [full text: PDF (368) KB)]
  • Abstract: A passively alignment-stabilized External Cavity Quantum Cascade Laser (EC-QCL) employing a ``cat's eye'-type retroreflector and an ultra-narrowband transmissive interference filter for wavelength selection is demonstrated and experimentally investigated. Compared with conventional grating-tuned ECQCLs, the setup is nearly two orders of magnitude more stable against misalignment of the components and spectral fluctuation is reduced by one order of magnitude, allowing for a simultaneously light-weight and fail-safe construction, suitable for applications outdoors and in space. It also allows for a substantially greater level of miniaturization and cost reduction. These advantages fit in well with the general properties of modern QCLs in the promise to deliver useful and affordable mid-infrared light sources for a variety of spectroscopic and imaging applications.

Keywords (OCIS):

  • (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
  • (300.6340) Spectroscopy : Spectroscopy, infrared
  • (350.2460) Other areas of optics : Filters, interference
  • (140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade

Vertical external cavity surface emitting PbTe/CdTe quantum dot lasers for the mid-infrared spectral region

  • Amir Khiar, Martin Eibelhuber, Valentine Volobuev, Michael Witzan, Astrid Hochreiner, Heiko Groiss, and Gunther Springholz
  • received 09/04/2014; accepted 10/20/2014; posted 10/22/2014; Doc. ID 222444
  • [full text: PDF (791) KB)]
  • Abstract: Optically pumped vertical external cavity surface emitting lasers (VECSELS) emitting in the mid-infrared range are demonstrated with an active structure based on PbTe quantum dots embedded in CdTe. In contrast to Stranski-Krastanow quantum dots, the PbTe quantum dots are fabricated by a strain-free synthesis method consisting of a molecular beam epitaxy growth step followed by a post-growth-annealing step. The laser emission of the VECSELs covers a wavelength range between 3.5 – 4.3 µm by changing the temperature from 85 K to 240 K. The threshold power is lower than 100 mWp and the output power more than 50 mWp at low temperature.

Keywords (OCIS):

  • (140.0140) Lasers and laser optics : Lasers and laser optics
  • (140.3070) Lasers and laser optics : Infrared and far-infrared lasers
  • (140.3380) Lasers and laser optics : Laser materials
  • (140.5960) Lasers and laser optics : Semiconductor lasers
  • (230.5590) Optical devices : Quantum-well, -wire and -dot devices
  • (140.7270) Lasers and laser optics : Vertical emitting lasers

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

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

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

Up-Scalable Method to Amplify the Diffraction Efficiency of Simple Gratings

  • Fabian Luetolf, Olivier Martin, and Martin Stalder
  • received 09/10/2014; accepted 10/19/2014; posted 10/22/2014; Doc. ID 217616
  • [full text: PDF (1132) KB)]
  • Abstract: An innovative class of coupling gratings for efficiently redirecting light beams is described. They are based on symmetric binary gratings equipped with an asymmetric high refractive index coating. This kind of structure exhibits a grating blaze effect and produces high diffraction efficiencies. Coupling gratings based on the described principle have been fabricated by UV casting and subsequent deposition of coatings by oblique ZnS evaporation. The gratings were characterized by measuring their diffraction efficiencies. For unpolarized light, efficiencies of around 70% have been measured. Simulations revealed that diffraction efficiencies of up to 90% can be obtained for polarized light

Keywords (OCIS):

  • (050.1950) Diffraction and gratings : Diffraction gratings
  • (230.1950) Optical devices : Diffraction gratings
  • (310.1860) Thin films : Deposition and fabrication
  • (220.4241) Optical design and fabrication : Nanostructure fabrication

Reconfigurable 2-D optical tapped-delay-line to perform correlation on images

  • Mohammad Reza Chitgarha, Morteza Ziyadi, Salman Khaleghi, Amirhossein Mohajerin Ariaei, ahmed almaiman, Joseph Touch, Moshe Tur, Carsten Langrock, Martin Fejer, and Alan Willner
  • received 07/23/2014; accepted 10/19/2014; posted 10/22/2014; Doc. ID 217645
  • [full text: PDF (821) KB)]
  • Abstract: We demonstrate a reconfigurable 2-D optical tapped-delay-line (OTDL) to correlate quadrature-phase-shift-keying (QPSK) 20Gbaud data. By implementing two independent tapped-delay-lines which performs correlation over rows (inner sum), along with a coherent multiplexing of the correlated rows which performs correlation over columns (outer sum), a 2-D correlator is achieved with average error vector magnitude (EVM) of ~ 7.8%. Here we also search different 2×2 patterns in a 31×31 image and successfully recognize the target patterns in the image.

Keywords (OCIS):

  • (060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
  • (190.0190) Nonlinear optics : Nonlinear optics
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

Optical voice recorder by off-axis digital holography

  • Osamu Matoba, Hiroki Inokuchi, Kouichi Nitta, and Yasuhiro Awatsuji
  • received 09/04/2014; accepted 10/17/2014; posted 10/22/2014; Doc. ID 221487
  • [full text: PDF (7056) KB)]
  • Abstract: An optical voice recorder capable of recording and reproducing propagating sound waves by using off-axis digital holography, as well as quantitative visualization, is presented. Propagating sound waves temporally modulate the phase distribution of an impinging light wave via refractive index changes. This temporally modulated phase distribution is recorded in the form of digital holograms by a high-speed image sensor. After inverse propagation using Fresnel diffraction of a series of the recorded holograms, the temporal phase profile of the reconstructed object wave at each three-dimensional position can be used to reproduce the original sound wave. Experimental results using a tuning fork vibrating at 440 Hz and a human voice are presented to show the feasibility of the proposed method.

Keywords (OCIS):

  • (070.1060) Fourier optics and signal processing : Acousto-optical signal processing
  • (120.2880) Instrumentation, measurement, and metrology : Holographic interferometry
  • (090.1995) Holography : Digital holography
  • (110.6915) Imaging systems : Time imaging

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

Robust coupled-waveguide devices using shortcuts to adiabaticity

  • Shuo-Yen Tseng
  • received 09/01/2014; accepted 10/17/2014; posted 10/22/2014; Doc. ID 222254
  • [full text: PDF (552) KB)]
  • Abstract: Shortcuts to adiabaticity, originally developed in the context of quantum system control, is a powerful tool for the design of high coupling efficiency, robust, and short coupled-waveguide devices. The counterdiabatic protocol cancels the unwanted coupling in system evolution by the addition of a counterdiabatic term. The invariant-based inverse engineering approach designs system evolution using the decoupled eigenstates of the Lewis-Riesenfeld invariant. The single-shot shaped pulse technique directly parameterizes the solution of the coupled-mode equation. Starting from the counterdiabatic protocol, we show that these seemingly very different shortcut to adiabaticity techniques are equivalent in the framework of coupled-waveguide systems. When combined with perturbation treatment of the coupled-mode equation, robust coupled-waveguide devices against errors can be obtained.

Keywords (OCIS):

  • (000.1600) General : Classical and quantum physics
  • (060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
  • (130.2790) Integrated optics : Guided waves
  • (130.3120) Integrated optics : Integrated optics devices

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

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

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

Articles 1 to 20 of 97 Next Page >>





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