SOI Ridge Waveguide Incorporating a Photonic Crystal Microcavity Multi-Channel Filter

Abstract

A one-dimensional photonic crystal microcavity filter that transmits light simultaneously at several wavelengths has been designed and fabricated. Transmission peaks occurred at 1168, 1321 and 1562 nm wavelengths, meeting the design specification. OCIS codes: 230.3990, 230.4000, 250.3500, 310.2790 Microcavity filters based on photonic crystal PhC) structures have received considerable attention recently [1][2][3]. In principle, one-dimensional 1-D) PhC structures can be readily incorporated into ridge waveguides conventionally used in photonic integrated circuits to increase component densities. This paper describes the design and fabrication of a multi-wavelength transmission 1D PhC microcavity integrated into silicon-on-insulator SOI) ridge waveguides, with the aim of realising compact photonic integrated circuit filters capable of transmitting light simultaneously in the telecommunications bands centred on 1310 and 1550 nm wavelength. Fig. 1 shows schematically device structure, which comprises, from left to right, a two period reflector of period Λ A , a cavity section formed by another 1D PhC of period Λ B ≠Λ A ) followed by a second two period reflector period Λ A ). The period, refractive index contrast and air fraction of the inner 1D PhC are tuned until its pass band lies within the first band gap of the 1D PhCs of period Λ A used to form the reflectors [2]. Consequently, the transmission wavelengths are adjustable with several degrees of freedom, for which a rapid design optimisation procedure is ideally required. It is shown here that the wave vector approach [3] can be applied to achieve this. Fig.1 Schematic 1D PhC micro-cavity structure etched into a planar SOI ridge waveguide. Fig. 2 Illustration of a plane wave and its component wave vectors propagating via total internal reflection through a slab waveguide of permittivity εav, equivalent to the 1D PhC.If the width of a ridge waveguide is significantly greater than its height, then the Bloch modes can be approximated by slab waveguide modes propagating in an equivalent dielectric slab. Fig. 2 illustrates the simple wave vector model for this situation, for which the following dispersion relationship holds ( )

Recent advances in silicon-based passive and active optical interconnects

“…Optical filters are extensively used in optical interconnect systems, and find useful applications in signal processing, signal routing, signal monitoring, and wavelength division multiplexing (WDM). The most common types of filters demonstrated are resonance type, such as Arrayed waveguide gratings (AWG) [82][83][84][85][86], Fabry-Perot [87][88][89], ring resonators [90][91][92][93][94][95][96][97][98][99], photonic crystal microcavity [100][101][102], multimode interference (MMI) [103,104]. AWGs can provide a very large channel count and have been very popular.…”