Photovoltaic Modulating Retroreflectors for Low Power Consumption Free Space Optical Communication Systems

An InGaAs-InAsP-GaInP asymmetric stepped quantum well structure is proposed for unbiased detection and subsequent modulation of an incident continuous wave optical signal for application in compact, retroreflective, free-space optical communication platforms. Such operation drastically reduces onboard power consumption in large-area, pixelated arrays by driving only optically activated pixels. A modelling routine involving calculations of band structure, fraction of light absorbed, and responsivity have been used to analyse structures exhibiting an asymmetric quantum confined Stark effect. The proposed structure, compared with devices following similar modeling approaches, is predicted to exhibit an unbiased responsivity of 0.004 A/W enabling single pixel detection prior to triggering modulation. The calculated photocurrent of 4 mu A offers adequate signal to noise against dark current when operated in a photovoltaic mode. Furthermore, the strong blueshift in the ground state transition energy calculated for the applied field results in extinction ratios in excess of 4dB for the modulated signal. These findings suggest performance enhancements at a fraction of current onboard power consumption in modulating retroreflectors for compact, free-space optical communication platforms.