aXenic presents SIPHODIAS work on GaAs modulator at ICSO 2022

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Steve Clements presenting at ICSO 2022

Steve Clements (aXenic) presented the poster titled: “Space-grade gallium arsenide IQ and modulator arrays for VHTS photonic SatCom systems” at the International Conference on Space Optics – ICSO 2022, in Dubrovnik, Croatia.


We discuss the design and implementation of compact IQ modulators and modulator arrays to be monolithically integrated in the GaAs/AlGaAs material system. 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 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. Typically, the folded devices are half the length of conventional format modulators and a modest array of devices (e.g. x4) can be accommodated in a package of similar dimensions to a single modulator. Design considerations for arrays of independently addressed MZ modulators (each with its own input fiber) are discussed. Both single MZ and monolithic dual-parallel (IQ) modulators have been assessed up to 70GHz, with bandwidths of 40-50GHz achieved with a low-frequency Vp below 3V. A novel integrated RF termination, of especial benefit to a compact array configuration, is demonstrated with return loss better than 12dB to 70GHz.

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