Munetaka Kurokawa

High-responsivity L-band micro intradyne coherent receiver using InP-based photodetector integrated with 90-degree hybrid

We demonstrate a high responsivity of 64 GBaud micro intradyne coherent receivers (Micro-ICR) operating at the wavelength range from 1565 nm to 1612 nm (L-band). The package body size is 12.0 mm × 22.7 mm × 4.5 mm, which is fully compliant with OIF implementation agreement. A newly developed InP-based photonic integrated circuit (InPPIC) for the L-band High-Bandwidth Micro-ICR is composed of the high-speed p-i-n-photodiode array (f3dB > 40GHz) and a 90° hybrid waveguide consisting of MMIs which is designed to obtain high transmittance over the L-band. They are monolithically integrated through butt-joint regrowth in which a GaInAs absorption layer of the photodiode is directly connected with a GaInAsP core layer of the 90° hybrid in order to achieve the high responsivity with high optical coupling efficiency. Furthermore, the optical couplings between optical fibers and InP-PICs are realized by low optical loss micro optics. Receiver responsivities of more than 65 mA/W for signal input and local input are achieved within the L-band at 25°C. The wide 3-dB bandwidth of 40 GHz is also confirmed using high-bandwidth TIA. These values are comparable to the coherent receiver for 64 GBaud C-band applications. This receiver module is very promising for the increase of transmission capacity through expansion of operation wavelength (C-band and L-band).