ULTRACOMPACT, ALL-PASSIVE OPTICAL 90-DEGREES-HYBRID ON INP USING SELF-IMAGING

Self-imaging in multimode waveguides has been used to realize a miniat ure (300 x 1750 mum2), all-passive 90-degrees-hybrid in GaInAsP/InP. W e demonstrate excellent performance (splitting ratio of 97:99:104:99, low on-chip insertion losses less-than-or-equal-to 1 dB, only +/-3-deg rees deviation from phase quadrature) and polarization-insensitive beh avior at lambda0 = 1.523 mum. Experiments confirm simulations which pr edict that the splitting ratio and the IF phase relationships are much less sensitive to the coupler length than the insertion loss, thereby adding to the robustness of multimode interference devices.