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

1. GaAs/AlGaAs非线性光器件的设计与优化我们设计了1.55 μm波段的DFG器件，并考虑到其在未来DWDM光网络中OXC的应用。AlGaAs QPM波导有望成为偏振无关的高性能器件，其转换效率高达700%/W/cm ^2。10 mm长器件的估计3 dB带宽（100 mW泵输入为30%）为40 nm，覆盖C波段。另一方面，GaAs QPM OPG/OPA/OPO在QPM周期为10 μ m时有望在指纹波长区域使用。GaAs/AlGaAs QPM器件的制作工艺我们开发了一种AlGaAs/GaAs QPM波长转换器件的制作工艺。该工艺包括GaAs/Ge/GaAs sablattice反转外延，通过化学刻蚀或CMP平坦化模板，以及使用MBE或MOVPE保持垂直畴壁的再生长技术. AlGaAs QPM差分光纤光栅器件的研制与性能研究我们研制了1.55 μm波段的AlGaAs三阶QPM波导差分光纤光栅器件。通过化学蚀刻实现平坦化。考虑到剩余的谐波和由此产生的传播损耗，QPM SHG以合理的效率实现。通过CMP平坦化工艺实现了具有低传输损耗的改进型一阶QPM器件，并且波长转换性能的表征正在进行中. GaAs QPM光参量器件已研制成功.利用Nd：YAG激光器作为泵浦源的参量荧光实验正在进行。

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.