OPTICAL REFLECTIVITY OF MICROMACHINED (111)-ORIENTED SILICON MIRRORS FOR OPTICAL INPUT-OUTPUT COUPLERS

In this work, bulk-micromachined {111}-oriented silicon mirrors at 54. 7 degrees have been fabricated in 20 wt% KOH solution at various tempe ratures and characterized with single-mode fibers (10/125 and 5/125). In fabricating the mirrors, the etch rate of the (100) silicon surface was widely varied from 5.3 to 73 mu m hr(-1) as the-processing temper atures were varied from 40 to 80 degrees C. In spite of the tremendous variation of etch rate, the measured reflectivities of the mirrors sh owed fairly stable values of 63.7-58% at 1330 nm and 55.4-57.7% at 155 0 nm. This paper describes the silicon mirror processing conditions, m easured reflectivities, reflected beam profiles, and a prototype integ rated optical I-O coupler with the realized mirrors. The results obtai ned from this work show that optical I-O couplers with 54.7 degrees mi rrors on conventional (100)-oriented silicon wafers are feasible, enab ling us to envisage a synchronized optical clock distribution system a s well as a distributed remote optical sensing system with low manufac turing cost.