Frequency-resolved optical mode decomposition of multimode quantum fields

Abstract

The measurement of multimode quantum fields is a relatively unexplored research area in quantum optics. In this paper, a mode-decomposition scheme termed the frequency-resolved optical mode decomposition (FROMD) is proposed to simultaneously decompose multimode quantum fields into parallel single modes. The mode basis is loaded onto the multifrequency components of the classical local oscillating (LO) field, where one pair of the frequencies that are symmetric with respect to the central frequency of the signal field is modulated by one temporal mode function. Thus, the balanced heterodyne detection using this LO is free of LO excess noise and 3 dB quantum noise penalty. The subsequent multichannel receiver resolves every beat note into the baseband of the signal field. Overall, the output of every channel is in one-to-one correspondence with the measurement outcome of every modal annihilation operator. This is similar to the traditional single-mode homodyne detection.