Development of Compound-Semiconductor-Based Nonlinear Optical Devices Using Sublattice Reversal Epitaxy

1.砷化镓/铝砷化镓非线性光学器件的设计与优化考虑到未来密集波分复用光网络中光交叉连接的应用，我们设计了适用于1.55μm波段波长转换的DFG器件。AlGaAsQPM光波导有望成为与偏振无关的高性能器件，其转换效率可达700%/W/cm^2。10 mm长器件(100 mW PUP输入为30%)的3分贝带宽估计为40 nm，覆盖C波段。另一方面，当制备的准PM周期为~10μM时，GaAsQPM OPG/OPA/OPOS有望用于指纹波长区。GaAsAlGaAsQPM器件的制作工艺我们研制了一种AlGaAsAlGaAsQPM波长转换器件的制作工艺。该工艺包括：GaAs/Ge/GaAsSABLATE反向外延，通过化学刻蚀或化学机械抛光使模板扁平化，以及使用分子束外延或MOVPE技术进行再生长，以保持垂直磁畴壁。制作了1.55μm波段三阶准相位调制AlGaAsDFG器件作为第一个原型器件。平坦化是通过化学腐蚀实现的。考虑到残余波纹和由此产生的传输损耗，以合理的效率实现了准PM倍频。利用化学机械抛光平坦化工艺制作了具有低传输损耗的一阶QPM器件，并对其波长转换性能进行了表征。制作了GaAsQPM光参量器件。目前正在进行一项使用Nd：YAG激光器作为PUP源的参数荧光实验。

1. Design and optimization of GaAs/AlGaAs nonlinear optical devicesWe have designed DFG devices for 1.55 μm band wavelength conversion bearing in mind the application to OXCs on future DWDM photonic network. AlGaAs QPM waveguids are expected to be polarization-independent and high-performance devices with conversion efficiencies as large as 700 %/W/cm^2. Estimated 3 dB bandwidth for 10-mm-long devices (30 % for 100 mW punp input) is 40 nm which covers the C band. On the other hand, GaAs QPM OPG/OPA/OPOs are expected to be usable in the finger-print wavelength region when fabricated with QPM periods of 〜 10 μm.2. Fabrication process of GaAs/AlGaAs QPM devicesWe have developed a device fabrication process for the AlGaAs/GaAs QPM wavelength conversion devices. The process consists of the GaAs/Ge/GaAs sablattice reversal epitaxy, flattening of the template by chemical etching or CMP, and regrowth techniques using MBE or MOVPE which maintain the vertical domain wall.3. Fabrication and characterization of AlGaAs QPM DFG devicesWe have fabricated 3rd-order QPM AlGaAs waveguiding DFG device for 1.55 μm band as a first prototype device. The flattening was achieved by the chemical etching. QPM SHG was achieved with a reasonable efficiency taking into account of the residual corrugation and the resulting propagation loss. Improved 1st order QPM devices with low propagation losses achieved by the CMP flattening process have been fabricated and the characterization of the wavelength conversion performance is now in progress.4. GaAs QPM optical parametric devicesGaAs QPM waveguiding parametric devices have been fabricated. A parametric fluorescence experiment using a Nd : YAG laser as a punp source is now underway.