An asymmetric twin waveguide eight-channel polarization-independent arrayed waveguide grating with an integrated photodiode array

We demonstrate the regrowth-free integration of an InP-based arrayed waveguide grating (AWG) with a 1 × 8 In_0.53Ga_0.47As p-i-n photodiode array. Low-loss polarization-independent adiabatic tapers transfer light from a passive waveguide optimized for external fiber coupling into a higher index waveguide for absorption in the In_0.53Ga_0.47As layer. The AWG and individual photodiodes have an external responsivity of 0.46 A/W and a polarization-dependent loss of ≤0.76 dB. The integrated device shows a worst-case crosstalk of -12.9 dB and a best-case crosstalk of -16.2 dB between channels, 9-dB total loss (including coupling losses), and -1.5-dB channel nonuniformity. The photodiode 3-dB electrical bandwidth is (25 ± 5) GHz.