SBIR-STTR Award

At frequencies above 10 ghz, conventional photodiodes must sacrifice quantum efficiency for speed since the thin active layers required do not absorb all of the light passing through them. A waveguide photodiode structure allows absorption over a much greater length along the active layer thus promising both speed and efficiency. Such a photodiode requires a more sophisticated approach for efficient coupling to an optical fiber. We propose to demonstrate a fiber-coupled packaged waveguide photodiode with an efficiency of >80% and a 3 db flat response to >20 ghz.

In order to improve system performance, many fiber optic transmission applications are turning to using high optical power (10 MW and more) to reduce noise. High speed photodiodes are rarely used with these powers and usually suffer strong nonlinearity or catastrophic failure if they are. We propose a program to study the mechanisms of failure for three photodiode structures (mesa, planar and waveguide) in order to elucidate design improvements which will permit operation at high power. The goal objective of this program is a packaged photodiode suitable for use up to 20 GHz and for optical powers >40 mW with a quantum efficiency >9O%.

Keywords:
High Efficiency Photodiode High Power Millimeter Wave Fiber Optic Microwave