Integration of low-pass filter with optical receiver using quantum well intermixing

We report on monolithic integration of a low-pass optical filter with an optical receiver composed of a semiconductor optical amplifier (SOA) and p-i-n photodiode (PD) using quantum well intermixing on an AlInGaAs-based multiple quantum well structure. The bandgap energy of the low-pass optical filter has been increased deliberately relative to the SOA and PD sections. The amplified spontaneous emission for photon energy higher than the filter bandgap is then absorbed prior to entering to PD and the optical noise can thus be reduced. By adjusting the reverse bias applied to optical filter and PD, a coarse tuning on the detection wavelength range can be obtained.