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Compressed sensing (CS) is a newly developed research in multimedia compression studies. A large portion of papers in this field focuses on compression performance. In this paper, we aim at transmitting CS signals over lossy channels. We employ wavelet transform, and then apply compressed sensing to original image to obtain CS signals. Channel errors may cause severe effects to CS signals, leading to degradation to the reconstruction. We use multiple description coding (MDC) to protect CS signals beforehand, transmit the protected signals, and recover the reconstruction with the calculations from the compensations of MDC. Simulations have presented the alleviation of reconstructed image quality with proposed algorithm.

We report the detection of $> 70 -$kW radiation power at about $52 \mu$ m from a KTP off-axis THz parametric oscillator, when pumping it with 11.9-mJ energy in a 450-ps pulse from a single-frequency Nd:YAG laser and seeding it with a 7-μJ, 40-GHz-linewidth Stokes pulse from a synchronously pumped KTP parametric generator. With 63% coupling efficiency of the silicon prism, the seeded off-axis THz parametric oscillator has emitted $> 111 -$kW peak power radiation into the silicon prism.

In previous studies, KTiOPO4 (KTP) shows higher laser damage resistance and larger figure of merit for THz parametric generation [1,2]. To generate high-power THz radiation, it is possible to perform pulsed difference frequency generation in a bulk KTP crystal [3]. Recently, we have also reported an off-axis THz parametric oscillator (OTPO) with unprecedented SPS gain in lithium niobate [4]. In this work, we employ a y-cut KTP slab crystal as an OTPO and seed it with a pulsed signal from a KTP THz parametric generator (TPG) to generate THz radiation with tens of kW power.

Using the superradiant Smith-Purcell radiation from a train of periodic electron-bunches interacting with a grating is an efficient way for generating terahertz radiation beyond the frequency region of traditional vacuum electron devices. The producing of a train of well-shaped electron bunches is essential for these radiation schemes. Here we design and simulate a photocathode DC-gun driven by train of laser pulses, aiming to generating train of sheet-shaped electron bunches for practices. The effects of main structural parameters and of laser properties on the performances of electron gun are investigated. It will set an important base for the development and improvement of practical electron guns in experiments.

We demonstrate a 40 W peak power terahertz (THz) wave from an off-axis parametric oscillator by pumping a y-cut monolithic lithium niobate slab crystal with a pulsed laser at 1064 nm. This is a demonstration that, for the first time, a THz parametric oscillator resonates a THz wave, having the advantages of compact size, easy alignment, and high efficiency. The experimental results show that the efficiency of such a monolithic parametric oscillator is significantly larger than of a THz parametric generator using the same crystal dimensions.

Thin film crystalline silicon (c-Si) solar cells have been a hot topic of photovoltaic research recently because its lower material consumption could potentially lead to lower capital expenditure. However, contact recombination is more prominent in thin-film c-Si solar cells compared with it in traditional c-Si solar cells due to higher carrier concentration. To address such a challenge, this work presents a design of metal-insulator-semiconductor (MIS) contact, based on thin TiOx layer that is grown by atomic layer deposition (ALD). Transmission line measurement (TLM) was conducted to study the conducting behavior of the TiOx MIS contact structure. Experimental results demonstrate that with the same doping density in silicon, the TiOx MIS contact forms an Ohmic contact to n-type silicon with good conductivity while cannot form Ohmic contact with p-silicon. This result demonstrates that the ALD TiOx layer can conduct electrons while blocking holes, thereby potentially reduce the contact recombination for thin-film c-Si solar cells, leading to an improvement of cell efficiency.

EGFET pH sensor based on metallic W sensing electrode with stable and superior performance (65.86 mV/pH, r2=0.9972) has been demonstrated. The enhanced proton-exchange process and/or the number of H+ ions amplified by transferred electrons related to the hydrolyzation of W could be responsible for the super-Nernstian response of the proposed pH sensors. Firm understanding of the interfacial electronic reactions would be necessary for further development of W-based pH sensors.

Various predesigned terahertz spectra can be generated via optical rectification of laser pulses in aperiodically poled crystals. The opportunity to manage the terahertz spectrum via the crystal domain structure is stored when the femtosecond transform-limited optical pulses are replaced by the non-transform-limited pulses of the same spectral bandwidth.

In this paper, we propose the low complexity transcoding methods from H.264/AVC IPPP prediction structure to SVC hierarchical B prediction structure. The macroblock coding mode and motion vector information are extracted from H.264/AVC bitstreams and transcoded to the SVC bitstreams. A mode decision approach is proposed to reduce the candidate coding modes and a motion vector decision approach is proposed to compose the forward and backward motion vectors in hierarchical B prediction structure. In the experimental results, the proposed methods can achieve a significant improvement in computational complexity with low video quality degradation.

We report electromagnetic radiation covering a spectral range between radio and THz frequencies from a thin metal wire excited by ns, ps, and fs laser pulses. The transient current induced by the pondermotive force of the laser and photoemission from the wire is responsible for the radiation from the thin wire.

We report a watt-level, single-frequency, mid-infrared, continuous-wave singly resonant OPO with a thermal-induced waveguide in its gain crystal. The waveguide, with a NA of 0.0062, doubled the parametric efficiency and made the OPO insensitive to alignment.

When the idler absorption loss exceeds parametric gain in THz DFG, the THz wave can still grow monotonically versus crystal length for forward DFG but saturates within a few absorption lengths for backward DFG.

A novel memory repair architecture based on redundant hypercube is proposed, which mainly consists of a modified ternary CAM with an address bubble-shifter. Generally for an acceptable repair rate about 3% of spare sub cubes and no more than 5% of hardware overhead are required. A modified Quine-McCluskey algorithm and the Essential Cube Pivoting algorithm are also developed for redundancy analysis. Almost 100% of repair rate can be obtained using only 32 equivalent rows under reasonable situations. Under less spare memory the repair rates of proposed approaches can be much higher than most results of previous work.

Thin-film transistors were fabricated using amorphous indium gallium zinc oxide (α-IGZO) as channels and high-к material HfSiO as gate dielectric by RF sputtering. The influence of high-к PDA temperature variation on device characteristics was investigated. The bottom-gate low voltage driven (≤ 2 V) TFTs operated in n-type enhancement mode with a field-effect mobility of 12.7cm2/V-s, on-off current ratio of 3×105, threshold voltage of 0.005V, and subthreshold voltage swing of 0.11V/dec.

We report the thermal-induced optical guiding and bistability in a mid-infrared continuous-wave, SRO at ~3.2 µm. When the pump power reaches the guiding threshold at 16.5 W, the parametric efficiency shows an increase of 2.5.

We demonstrate difference frequency generation of backward THz waves from collinearly phase-matched, periodically poled lithium niobate. Coherent THz waves between 457~507 mum were generated by using kW pump power at a kHz repetition rate.

We show in simulation and experiment the generation of comb-like sidebands and compressed pulses from a beat-wave-seeded optical parametric amplifier. Under suitable group-velocity mismatch, 50-fold pulse compression can be achieved for the output laser pulse.

We report a periodically poled lithium niobate (PPLN) crystal for both temperature-insensitive laser Q-switching and temperature-tuned wavelength conversion. The PPLN crystal consists of two sections, a 20.3-mum period section functioning as an electro-optic Bragg grating for Qswitching a diode-pumped Nd:YVO4 laser at 1064 nm and a 31-mum-period section functioning as an optical parametric generator for down converting the generated 1064-nm laser. When driving the PPLN Bragg grating with 170-V voltage pulses, we measured 181 muJ pulse energy at 1064 nm from the Nd:YVO4 laser pumped by 20.4 W diode power. The 181-muJ pulsed laser was further converted into mid-infrared radiation in the monolithic PPLN crystal with 35% parametric efficiency. The wavelengths were broadly tunable in the range of 1.75-1.88 mum (signal) and 2.7-2.44 mum (idler) via temperature without affecting the performance of the PPLN Bragg Qswitch.

Reduction of multimode interference in 300-nm broadband Cr-doped fibers (CDFs) using mode-field matched center launching technique is demonstrated. With a matched CDF core diameter around 15.5 μm, the measured broadband coupling efficiencies are 60.3%~ 87.5%. This study may open the possibility for utilizing the CDFs as a new broadband fiber amplifier to cover 300 nm bandwidths.

We demonstrate the PPLN crystal as a laser Q-switch by using electro-optic Bragg modulator effect and generate 200-muJ/pulse with 10 kHz switching rate at 19-W diode pump power.

We report the first experimentally demonstrated active Sole-type optical wavelength filters based on Ti:PPLN waveguides. A peak spectral transmittance of ~99% at a bandwidth of ~2.6 nm in telecom bands was obtained in this device.

We report the first experimental demonstration of active narrowband multiple wavelength filters in aperiodically poled lithium niobate (APLN) crystals. Simultaneous transmission of >90% (~100% in design) of 8 telecom wavelengths was achieved in this device.

We report difference frequency generation of THz waves from collinearly phase-matched, periodically poled lithium niobate crystals. Transform-limited THz-wave pulses with a wavelength range between 190~210 mum were generated at a kHz repetition rate.

We report a compact, narrow-line intracavity OPO with a grazing-incidence grating. This kHz pulsed OPO fits into a 25 times 25 cm area, generating 30 muJ/pulse at 1560 nm with a linewidth of 0.8 cm-1.

A distributed-feedback optical parametric amplifier allows idler-seeding without concerning Bragg-reflection loss. An oscillator of this type has both wavelength and mode selectivities. We have developed a coupled-wave theory for the gain and resonance of this new class of laser devices.

We have developed the theory of a distributed-feedback optical-parametric oscillator pumped by a laser pulse length shorter than the round-trip length of the nonlinear gain material. We also demonstrated distributed-feedback optical-parametric oscillation in a 5-cm PPLN crystal pumped by a 430-ps passively Q-switched Nd:YAG laser.