| Summary: | 碩士 === 國立中山大學 === 光電工程研究所 === 93 === The purpose of this paper is to fabricate optical waveguide reflectors to reflect the incident optical mode of multi-mode interference coupler by the etched vertical mirror surfaces. We used the design of etched vertical mirror surfaces to bend the incident optical mode, and changed the length of multi-mode interference coupler for the power splitting ratio. By the simulation and design, we could use the multi-mode interference coupler to fabricate optical waveguide reflectors.
A 1.52µm symmetric quantum well InGaAlAs/InGaAs epitaxial wafer is used to fabricate the devices. In the device design, we designed a optical waveguide reflector of two inputs and outputs with 90° angle. We fabricated a Fabry-Perot laser by two optical waveguide reflectors with 90° angle, a 1x2 multi-mode interference coupler and a ring cavity. In addition, we designed optical waveguide reflectors of one input and two inputs, and utilized them to fabricate a Fabry-Perot laser. We also utilized an optical waveguide reflector of one input or two inputs directly to fabricate Fabry-Perot lasers.
In fabrication process, firstly, we etched the waveguide to the depth of about 1.81µm by multi-step wet etching. In order to reduce bending loss, we made deep etching for the outside of curve waveguide. Then, we etched the mirror to the depth of about 6µm by multi-step wet etching to have a greater variation of refractive index to reflect the mode of optical waveguide reflectors. Finally, we used polyimide to flatten the sides of the ridge waveguides and evaporated metal pad over the polyimide.
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