Abstract

In earlier work [1] we proposed a novel phased array resonator based on the 1-to- N-way splitting properties of rectangular, step index, multimode waveguides [2]. A rectangular cross-section multimode waveguide splitter section was used along with phase plates to couple light from a single mode axial waveguide to a lateral array of N single mode waveguides (top of Fig. 1). The design was shown to have significant advantages over the Talbot resonator in many respects and could be partial larly relevant to phase locking semiconductor laser arrays. However, (he intracavity power density on the output facet of the single axial guide could, depending on the number of elements in the array, be very high resulting in catastrophic optical mirror damage. In this paper we describe a new design (bottom of Fig. 1) which overcomes these power density problems. In the new design the single axial guide and the associated plane mirror are omitted, the multimode guide length is reduced by an amount δ from the original value L = W²/Nλ, and is terminated by a phase conjugate mirror which returns the field from the N-element array, back to it. Here W is the width of the multimode guide, N is the number of elements in the array, and λ is the wavelength of a plane wave in the core of the multimode guide. The phase conjugate mirror was approximated by a convex mirror of radius of curvature R(δ) where $R(\delta )=\delta +{\left(\pi {\omega }_0^2/\lambda \right)}^2/\delta$. Here, ω₀, = 0.3516_ν, where ν is the width of the fundamental mode guides in the array.

© 2000 IEEE