Considerations are presented for the design of GaAs traveling-wave electro-optic modulator arrays for space data-link applications. Central to the modulator design is a low loss folded optical configuration giving direct, straight-line radio frequency (RF) access at one end of the device, with all fiber-optical ports at the opposite end. This configuration is a critical enabler for the close-packed monolithic modulator arrays needed for multi-channel applications. It also leads to much more compact packaging, improved fiber handling and contributes to high modulation bandwidths with low ripple by eliminating directional change in the RF feed arrangements. Both single Mach-Zehnder (MZ) and monolithic dual-parallel (IQ) modulators have been assessed up to 70 GHz, with bandwidths around 50 GHz achieved with a low-frequency ON/OFF voltage swing (Vπ) of 4.6 V (a voltage. length product of 8.3 Vcm). The folded devices can be significantly more compact than conventional ‘straight in-line’ modulators, while a modest array of devices (e.g., ×4) can be accommodated in a package of similar dimensions to a single modulator. Design considerations for monolithic arrays of independently addressed MZ modulators (each with its own input fiber) are discussed and practical configurations proposed.

提出了用于空间数据链路应用的GaAs行波电光调制器阵列的设计注意事项。调制器设计的核心是低损耗的折叠式光学配置，可在设备的一端提供直接的直线射频（RF）访问，而所有光纤端口均在另一端。对于多通道应用所需的密排单片调制器阵列，此配置至关重要。它还消除了RF馈送装置的方向变化，从而带来了更加紧凑的包装，改进的光纤处理并有助于以低纹波实现高调制带宽。单马赫曾德尔（MZ）调制器和单片双并行（IQ）调制器均已评估到70 GHz，低频开/关电压摆幅（Vπ）为4.6 V（电压，长度乘积为8.3 Vcm）可实现约50 GHz的带宽。折叠后的器件可以比传统的“直列式”调制器更加紧凑，而适度的器件阵列（例如×4）可以容纳在尺寸与单个调制器相似的封装中。讨论了独立寻址的MZ调制器的单片阵列（每个都有其自己的输入光纤）的设计注意事项，并提出了实用的配置。