Microlens arrays with integrated thin film power monitors

VCSEL 1D or 2D arrays for parallel optical interconnect links require monitor photodiodes, but conventional discrete detectors as used in single lasers are not feasible for arrays. Aegis Semiconductor is developing 1D and 2D 'smart' microlens arrays with integrated power monitor sensors in the form of semi-transparent thin film silicon and silicon-germanium based photodiodes direct deposited by PECVD. The developmental 12 channel 820-860 nm VCSEL array monitor described here incorporates Adaptive Optics Associates' process for molding epoxy-on-glass microlens arrays directly onto glass substrates bearing thin-film sensors. Transmission of the sensor / microlens package exceeds 75% at 850 nm, with responsivity 0.07 A/W (based on total incident optical power) and bandwidth >50 kHz. Experimental measurements of antireflection properties and wavelength dependence are reported. Integration of thin film sensors (and potentially transistors and other circuit elements) with microlenses combines optoelectronic and passive optical functions in one compact element.