Vertical Cavity Devices as Wavelength Selective Waveguides

Abstract

We show that novel wavelength-sensitive devices can be fabricated by coupling a semiconductor vertical cavity resonator to a low index waveguide. The optical mode in the resonator propagates at an angle, and the resonator resembles a high index waveguide. A taper in the thickness of the resonator allows different parts of the waveguide to operate at different wavelengths. These structures are analyzed using both thin film equations and waveguide formalism. Concentrating on a waveguide demultiplexer, simple design equations are derived, and a demonstration device is fabricated for TE mode at 0.75 µm operation. Using AIGaAs/AIAs multilayers and a polymer top waveguide, the spectrometer exhibited a dispersion of 29 nm/cm a wavelength resolution of better than 1 nm, and an intrinsic device efficiency of about 90%. A similar structure containing a light-emitting quantum well operated as a multiwavelength light source by modifying the spontaneous emission into the polymer waveguide. 0733-8724/94#04.00 © 1994 IEEE