Low-loss one-dimensional photonic bandgap filter in (110) silicon

Abstract

A free-space silicon one-dimensional photonic bandgap optical filter is designed and fabricated. A two-stage (110) wafer etching process is employed to form the extremely vertical, smooth, and high-aspect-ratio features that are essential for good optical properties. The (111) oriented planes of the wafer form <0.01 degrees off-vertical trenches that make up the Fabry-Perot filter. A simulation model is presented that analyzes the effect of verticality and predicts the measured spectrum well.

Micromachined Fabry–Perot resonator combining submillimeter cavity length and high quality factor

“…2, 3, 8, and 9͒ or by etching using aqueous potassium hydroxide. 10 In all these cases, Bragg mirrors were planar and the cavity length was in the order of tens of micrometers only, probably for the purpose of reducing the dominant loss mechanism, which relates to expansion of the Gaussian beam inside the cavity after several round trips. Nevertheless, these planar FP cavities are considered as "unstable resonators" 11 with Q-factor mostly limited to a few hundreds, except in Ref.…”

Low Loss Tunable Optical Filter using Silicon Photonic Band Gap Mirrors

“…Mirror fabrication was done by a two-step etch process which we have previously demonstrated for static filters [3]. First, deep reactive ion etching (DRIE) is used to define all the structures of the device.…”

Individually Tunable Silicon Bragg Reflectors

“…As many of the tunable optical filters that are being developed lately [3][4][5], it aims to be very compact, highly reproducible, and controllable; but more than that it is intended to be tuned in a faster and more precise way and to allow a larger tunable range of bandwidths. It also presents the unique feature of moving each individual reflector.…”

“…Contrarily to fiber gratings that are directly "written" in the optical fiber, microfabricated gratings are external devices that offer a more flexible and easy to integrate alternative. More recently, in-plane designs with mirrors vertically etched in the substrate have attracted more attention, despite the challenge they represents in terms of microfabrication [3]. In addition to permitting the integration of an increased variety of tuning mechanisms, these designs facilitate optical fiber alignment.…”