3 db couplers 1 Cnc machining 1 Coupling ratios 1 Device modeling Device structures 1 Equipment 1 Excess loss 1 Fabricated device 1 Fiber optic sensors 1 Fibers 1 High-index contrast waveguides 1 Lateral displacements 1 Machining 1 Numerical analysis 1 Optical fiber coupling 1 Optical fiber fabrication 1 Output fibers 1 Output ports 1 Plastic optical fibers 1 Ray-tracing technique 1 Variable coupling 1 Waveguide tapers 1 Waveguides 1 Y-branch 1