Abstract

We propose a novel optical 90$^{\circ}$ hybrid consisting of a paired-interference based 2$\,\times\,$4 multimode interference (MMI) coupler, a phase shifter and a 2$\,\times\,$2 MMI coupler. We theoretically clarified that the proposed device shows superior performances to a conventional 4$\,\times\,$4 multimode interference coupler from the viewpoint of a wavelength sensitive loss and an operating bandwidth. We fabricated the proposed 90$^{\circ}$ hybrid using a deep-ridge waveguide with a GaInAsP/InP material system, and experimentally demonstrated quadrature phase response with a low interchannel imbalance, a high common-mode rejection ratio ($> 20$ dB) and a low phase deviation $(<5^{\circ})$ over 94-nm-wide spectral range.

© 2010 IEEE

Compact optical 90° hybrid employing a tapered 2×4 MMI coupler serially connected by a 2×2 MMI coupler

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J. Opt. Soc. Am. B 28(1) 159-164 (2011)