Wavelength-selective voltage-tunable photodetector made from multiple quantum wells

We show that a pin-doped multiple quantum well (MQW) diode can be used as a photodetector whose voltage of maximum photocurrent is wavelength dependent. The voltage of maximum photocurrent can be located accurately and related to the wavelength of the incident light, allowing measurements of the wavelength with a precision of 0.03 Å=1.2 GHz. This provides a simple, compact, solid-state device that can be simultaneously used to measure the intensity and wavelength of an optical beam. Furthermore, the device shows high responsivity, low dark current, and fast response.