InGaAsP/InP Waveguide Grating Filters for λ=1.5μm

Abstract

With the achievement of single longitudinal mode semiconductor lasers, the prospect of multiplexing several closely spaced wavelength channels appears quite attractive. Waveguide reflection grating filters are potential candidates for such narrowband multiplexing/demultiplexing applications. In addition, such narrowband filters may be used for FSK detection schemes. Glass waveguide grating filters for visible,1 and recently for long wavelength operation,2 have been demonstrated. However, grating filters based on InGaAsP/InP waveguides offer several advantages including the potential for electrical tunability and monolithic integration with detectors. While gratings have been incorporated into DFB lasers, their fabrication in passive InGaAsP/InP waveguides and filter response evaluation has not been previously reported. Here we report InGaAsP/InP waveguide grating filters for λ≅1.5μm with peak reflectivity >99 percent and filter bandwidths as narrow as 6Å and as broad an 80Å.