Silicon-on-Insulator Photoconducting Mesas for High-Speed Detection of Laser Speckle Motion

Silicon-on-insulator (SOI) photoconductor structures show promise in making real-time laser speckle monitoring useful for high-speed applications, such as acoustic and ultrasonic surface vibration detection. For small detection areas below 10
³
¿m
²
and at low optical intensities, the internal gain mechanism of these mesa structures can provide better SNR ratios than similarly sized photodiodes while still operating in the megahertz regime. Small-area detectors, in turn, improve the sensitivity of speckle monitoring systems, suggesting that these simply constructed SOI photoconducting mesas are a good choice of detector element for high-speed speckle monitoring applications.