Y-junction power divider in InGaAsP-InP photonic integrated circuits

A demonstration is presented of an InGaAsP-InP asymmetric waveguide Y junction with a power dividing ratio which is independent of the polarization of the input light. The Y junction is monolithically integrated with an active optical gain section by metalorganic chemical vapor deposition (MOCVD). The integrated chip represents a fundamental building block for photonic integrated circuits. Experimental results are in agreement with a theoretical analysis of the Y junction. The theory shows a low radiation loss (0.4 dB) and negligible power reflection (-63 dB) at the Y junction, which is ideal for monolithic integration with active devices. They also report on an integrated optical amplifier Y-junction-monitoring detector chip as an example of a photonic integrated circuit that employs the new Y-junction design. The estimated excess loss of the Y junction was 1.4 dB for the integrated chip, and the Y-junction reflectivity was found to be negligible.>