Planar optical waveguide core
The waveguide consists of a semi-infinite slab of dielectric materials with thickness d and refractive index n 1 (the core) that is sandwiched between two regions (the cladding) both of refractive index n 2, and where n 1>n 2. One essential el-ement is the guiding of the optical radiation in waveguides for integrated optical devices and optical fibers for long distance transmission. The same mathematical ideas can be applied (with minor modifications) to circular waveguides. The waveguide core size of the fundamental mode in the waveguide direction (y axis) can be enlarged to 400 μm by introducing the refractive index matching and mode competition, to increase single-pass gain of the waveguide while ensuring good beam quality in the y -axis direction.
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