Highly linear InP phase modulator for high dynamic range RF/photonic links

The optical phase locked loop (OPLL) photonic integrated circuit (PIC) is a key element for the emerging linear coherent RF-photonic links. One of the main challenges for the OPLL-PIC is the nonlinearity of the Indium Phosphide (InP)-based phase modulator. In this paper, we report the experimental results from a multi-quantum well phase modulator fabricated on an InP substrate that is specially designed for the OPLL-PIC. The phase modulator shows low optical loss and good linearity performance. In particular, at a reverse bias voltage of 5.6 V, its phase IP3 and insertion loss per unit length are ∼2.8p/mm and 1.2 dB/mm, respectively.