Vertical input transverse resonant cavity device structure for surface refractive index variation sensor

Abstract

A resonant cavity waveguide device structure is reported which uses a grating structure to couple the vertical incident light into the waveguide. A thin, high-refractive-index waveguide is used to attain high sensor sensitivity for the surface refractive index variation measurement. © 2009Society of Photo-Optical Instrumentation Engineers.

Optical waveguide resonator for refractive index change sensor using arrayed waveguide with grating to couple light beam

“…We have proposed a Si waveguide optical sensor using normal incidence and resonant cavity structure [2][3][4]. In the previous study we used a wide waveguide and the TM mode.…”

Vertical input transverse resonant cavity optical device for refractive index variation sensor

“…The fabrication process becomes simple as both types of gratings can be fabricated simultaneously. To attain strong resonance, the grating depth should be shallow enough to achieve weak coupling between the I/O light and the waveguide light [5]. To attain sufficient reflection by shallow Bragg grating, long grating is required and its length is optimised to achieve both high reflection and a wide reflection wavelength range, as these are in a trade-off relation.…”

“…We have been studying a new type of device structure [4,5] without gold for cost reduction and disposability required in clinical applications. A high refractive index optical waveguide [6] is used instead of a gold film to generate a light with high surface refractive index sensitivity.…”

“…The waveguide thickness is adjusted to around l/(2n w ) to avoid the back ground reflection caused by the high refractive index waveguide layer [5], where n w is the refractive index of the Si waveguide layer.…”