Compact two-element transmission trap detector for 1550 nm wavelength

We have developed and characterized a new kind of trap detector based on InGaAs photodiodes. The detector contains only two 10 mm diameter InGaAs photodiodes arranged in a transmission trap configuration with non-coaxial beam orientation. The detector has large active area, more than 9 mm in diameter, and a built-in linearity monitoring feature. One of the key advantages of the developed detector is polarization insensitivity - the difference in responsivity between two orthogonal incident polarization states is zero within the standard uncertainty of 0.3%. The spatial non-uniformity of the responsivity is less than 0.5% across the active area.