A highly damage-resistant Zn:LiNbO/sub 3/ ridge waveguide and its application to a polarization-independent wavelength converter

We have fabricated a periodically poled ridge waveguide using a liquid phase epitaxy (LPE)-grown Zn:LiNbO/sub 3/ substrate. The waveguide can confine both the transverse electric and transverse magnetic mode. Its strong resistance to photorefractive damage enables stable parametric amplification. We demonstrate polarization-independent wavelength conversion using polarization diversity in a single waveguide.     

Parametric wavelength conversion and amplification usingdamage-resistant Zn:LiNbO3 waveguide

Wavelength conversion with a 12 dB parametric gain is demonstrated using a picosecond pulse-to-pulse interaction in a periodically poled Zn:LiNbO₃ waveguide. The reduced photorefractive damage enabled intense pumping at a relatively low temperature (~50°C)     

MgO:LiNbO3与KTiOAsO4超短中红外光参量放大

比较分析了MgO:LiNbO3(MLN)与KTiOAsO4(KTA)晶体中超短中红外光参量放大的角度调谐、有效非线性系数、群速度失配、晶体长度以及参量放大的转换效率等。结果表明，MgO:LiNbO3晶体的有效非线性系数较大，可用非共线相位匹配方式补偿三波群速度失配，在一定泵浦光强下有利于转换效率的提高。而KTA晶体的有效非线性系数较小，群速度失配严重且不能用非共线相位匹配方式补偿，达到饱和放大所需要的泵浦光功率密度高。在超短中红外光参量放大上，MgO:LiNbO3晶体具有较优的参量耦合性能。     

Zn indiffusion waveguide polarizer on a Y-cut LiNbO3 at1.32-μm wavelength

A polarization-dependent loss measurement of Zn indiffusion (ZI) waveguide on a Y-cut LiNbO₃ substrate is firstly reported. The measured results show that the waveguides support either a single extraordinary polarization or both extraordinary and ordinary polarizations depending on the fabrication process parameters. For the single extraordinary polarization waveguide, the measured propagation loss at 1.32-μm wavelength is 0.9 dB/cm and the best measured polarization extinction ratio is 44 dB at a distance of 1.5 cm from the input end, which are quite good for being a waveguide polarizer. Moreover, the voltage-length product measured for the ZI Mach-Zehnder modulator shows that the substrate electrooptic coefficient is not degraded     

Widely tunable multichannel wavelength conversion using multiple wavelength quasi-phase-matched LiNbO/sub 3/ waveguide

Widely tunable multichannel wavelength conversion using a multiple wavelength quasi-phase-matched LiNbO/sub 3/ waveguide is proposed. Simultaneous conversion of four-channel signals with a tunable range of more than 35 nm is successfully demonstrate for the first time.     

Low crosstalk and variable wavelength conversion using multiple QPM LiNbO3 waveguide module

A multiple quasi-phase matched LiNbO₃ device in a four-port fibre-pigtail module for variable difference frequency generation (DFG) is described. The module structure realises DFG pumped by second-harmonic light that results in wavelength conversion with low crosstalk. The module is also used to demonstrate polarisationinsensitive conversion. This device technology will be useful for future photonic networks that employ a grouped wavelength path.     

Blue-light generation by frequency doubling of a laser diode in aperiodically domain-inverted LiTaO3 waveguide

The authors report quasi-phase matched second-harmonic generation by frequency doubling of a laser diode in LiTaO₃ having a first-order periodically domain-inverted region and proton-exchanged channel waveguide. A deep domain-inverted region and a low-loss channel waveguide with strong confinement are formed by using proton-exchange and quick heat treatment techniques. Utilizing this structure, a high normalized conversion efficiency of 157%/W is obtained with a Ti:Al₂O₃ laser. Using a temperature-controlled laser diode and AR coating on the input and output facet of the waveguide, the laser diode maintains single-mode oscillation without any mode hopping. Consequently, 1.1 mW of blue light is obtained at a wavelength of 436.5 nm     

Efficient multikilowatt mid infrared difference frequency generation in CdGeAs2

Multikilowatt mid infrared emission with high pump photon conversion efficiency (∼ 15 percent) has been obtained by difference frequency generation in CdGeAs2utilizing the double wavelength output from a grating tuned twin-cavity TEA CO2system, one signal of which is frequency doubled to provide efficient synchronized sources for both pump and idler. Tuning over a spectral range8-14 mum can be achieved and further extended to 17 μm using 12.8 μm emission from an efficient TEA CO2pumped NH3laser.     

Quasi-phase-matched second harmonic generation in a LiTaO3 waveguide

The authors report third-order quasi-matched (QPM) second harmonic generation (SHG) in a LiTaO₃ channel waveguide. A deep domain-inverted region is first fabricated by a proton-exchange and heat treatment technique. Then a uniform and low-pass channel waveguide is fabricated by pyrophosphoric acid proton exchange. Consequently, 12 mW of blue light is obtained at 424 nm wavelength with a conversion efficiency of 6%. The observed FWHM (full-width half maximum) temperature acceptance width for SHG power is 3.2°C and FWHM wavelength acceptance bandwidth for that is 0.2 nm. It is also shown that diffraction limited focusing of the generated blue light may be obtained     

Noncritical quasi-phase-matched second harmonic generation in anannealed proton-exchanged LiNbO3 waveguide

We report the demonstration of dimensional noncritical phase matching, a phase-matched interaction length exceeding 10 mm, and an internal conversion efficiency of 204%/W for second harmonic generation of 976 nm radiation in a periodically poled, annealed proton-exchanged LiNbO₃ waveguide. Using models for the linear and nonlinear optical properties of annealed proton-exchanged LiNbO₃ waveguides and the observed ferroelectric domain grating, the phase-matching wavelength was predicted to within several nm and the conversion efficiency to within ≈20% of the measured values. Optimization of waveguide second harmonic generation devices is discussed     

LiIO_3晶体中双波长Nd:YAP激光的和频作用

基于LiIO_3晶体的Sellmeier方程,计算了晶体中1.0795μm和1.3414μm双波长Nd:YAP激光和频的相位匹配条件。计算结果与实验结果相当一致。并得到连续和脉冲的0.5981μm和频相干辐射。     

Third harmonic generation of Nd:YAG laser light in periodicallypoled LiNbO3 waveguide

The authors propose and first demonstrate an LiNbO₃ waveguide device with cascading quasi-phase-matched second harmonic generation and quasi-phase-matched sum-frequency generation for generation of a third harmonic wave. Ultraviolet light of 355 nm wavelength, which was the shortest value ever reported for LiNbO₃ waveguide wavelength-convertors, was obtained with Nd:YAG laser light     

中频溅射技术制备镱铒共掺Al2O3光波导

在硅单晶(100)衬底上用热氧化法氧化一层SiO₂做缓冲层,在高纯铝靶上镶嵌金属Yb,Er,然后用中频磁控溅射法制备了镱铒共掺杂氧化铝薄膜。讨论了靶电压及沉积速率随氧流量的变化的磁滞回线效应,分析得出了沉积氧化物薄膜的最佳氧流量。在室温下检测到了薄膜的位于1535nm的很强的光致发光光谱(PL),并在光学掩模下用BCl₃离子束对薄膜样品进行刻蚀,得到条形光波导。     

Ortho-deuterium Raman laser using the S0(2) rotationaltransition in the mid-infrared region

Based on a calculation for the Raman gain coefficient of the S₀(2) transition in ortho-D₂, we have demonstrated the generation of first Stokes waves in the 15-16-μm spectral region. Use of ortho-D enriched by a catalytic converter enabled us to realize efficient conversion at room temperature. Stokes energies as high as 400 mJ were obtained     

High-power difference-frequency generation at 4.4-5.7 µm in LiIO3

Efficient generation of high-power difference-frequency radiation, continuously tunable over the range of4.4-5.7 mum, has been achieved by mixing the Nd :YAG laser and Nd :YAG pumped infrared dye-laser outputs in LiIO3. Peak pulse powers as high as 550 kW with an average power output of 45 mW were obtained around 4.9μm.     

160 Gbit/s wavelength shifting and phase conjugation usingperiodically poled LiNbO3 waveguide parametric converter

High efficiency 160 Gbit/s wavelength conversion and optical phase conjugation using cascaded nonlinearities in periodically poled LiNbO ₃ waveguides is reported. The authors also report on use of this device as a dispersion compensator for transmission of 100 Gbit/s OTDM data through 160 km of singlemode fibre     

Ti:LiNbO3光波导在中红外波段的有效折射率研究

应用变分法修正计算表面折射率增量的计算公式 ,并计算Z切Ti:LiNbO3光波导在中红外波长 3 .0、3 .3 9μm导模的有效折射率 ,给出了单模、截止、多模的制备参数。     

Low-loss proton-exchanged waveguide in MgO-doped LiNbO3fabricated with pyrophosphoric acid using Ta2O5protective mask

The authors describe low-loss proton-exchanged channel waveguides in MgO-doped LiNbO₃. The authors demonstrate the application of a Ta₂O₅ film for the protective mask material in proton-exchanging instead of a Ta film in order to reduce the propagation loss. A Ta₂O₅ sputtered film was applied as a protective mask with pyrophosphoric acid. The propagation loss of the waveguide, measured with laser diode light (λ=0.83 μm) was 0.5 dB/cm. It is shown that the use of a Ta₂O₅ mask reduces the propagation loss compared with the use of a Ta mask (1.5 dB/cm)     

Pulse train generation by soliton fission in highly nonlinear chalcogenide (As2S3) waveguide Bragg grating

The conversion of a 3.9 ps optical pulse into a train of six 450 fs pulses within a 37 mm length of a highly nonlinear chalcogenide (As₂S₃) waveguide Bragg grating is reported. Here, the initial pulse develops into a sixth-order soliton and is split into its six fundamental solitons through soliton fission. The very large optical nonlinearity and strong photosensitivity of As₂S₃ enables the use of pulses that are 25 x shorter than in previous experiments, and have 500 x less energy. The results are compared to numerical modelling using the nonlinear coupled mode equations and find satisfactory agreement between experiment and theory after accounting for imperfections observed in the grating.     

Reflective waveguide array demultiplexer in LiNbO3

Wavelength demultiplexer fabricated on electrooptic LiNbO₃ is demonstrated. Reflection structure was employed to halve the device length. The full width at half maximum of the transmission peak was around 1 nm. The crosstalk was -12 to -25 dB. Polarization independence was attained using a reflective quarter-wave plate