A wavelength and polarization detector using monolithically integrated subwavelength MSM photodetectors

We report an innovative detector based on subwavelength MSM photodetectors that contains no moving parts and can directly and instantaneously measure both the wavelength and polarization angle of light. The wavelength-polarization detector consists of a monolithically integrated metal-semiconductor-metal (MSM) photodetector pair with subwavelength finger spacings and widths. When the finger spacing of the MSM photodetector is smaller than the wavelength of light, the transmission of TE and TM waves through the detector fingers becomes strongly dependent on the wavelength and polarization of the incident light. As a result, the photodetector current also becomes dependent on the wavelength and polarization. However, since the photocurrent is also a function of the incident optical intensity, a pair of integrated MSM photodetectors with two different finger spacings must be used so that the photocurrent ratio will be independent of the optical power, but still be a function of the wavelength and polarization.