Reflection gratings as THz local oscillator multiplexer

We present a new type of phase grating, the Fourier grating, to be used as local oscillator beam multiplexer in heterodyne receivers. The device has been developed for the SOFIA Terahertz Array Receiver (STAR). In contrast to the binary phase gratings (Dammann gratings), which are being used in many array receivers, our gratings have a smooth surface structure without any sharp edges.