RELATIVE ETCHING RATES OF VERTICAL DOWN TAPER-RIDGE WAVEGUIDE BY DIFFUSION-LIMITED ETCHING

Relative etching rates of vertical down taper-ridge waveguide used silicon dioxide (SiO 2 ) masks in bromine-nitride acid solutions were performed by the diffusion-limited etching method. Different gap widths and mask widths of the patterns are used to control the etching rate. Depending on the gap widths of the taper region samples, the fastest etching rate almost reaches up to a factor of three as compared to the unmasked areas. It is believed that this method is one good approach to produce a vertical taper that can be used to improve the light coupling efficiency between the Fabry-Perot laser diode and single-mode fiber in optical communications systems.