Temporal SU(1,1) Interferometer with Broadband Squeezed Light Injection

Abstract

Temporal optics has attracted much attention due to its ability for lossless stretching of ultrafast temporal pulses. At the same time, spatial SU(1,1) interferometers have been widely used because of their high sensitivity to phase changes. On this basis, we studied a temporal SU(1,1) interferometer based on a temporal Fourier transform system and injected broadband squeezing light into the interferometer for research. The results show that the output spectral characteristics of the interferometer depend on the ratio of the focal group velocity dispersion (GDD) of the two temporal lenses (this ratio is defined as the scaling factor $M$) and the phase derivative of the applied phase. The scaling factor $M$ significantly affects the bandwidth and squeezing degree of the output spectrum. The phase derivative induces a frequency-shift effect, and the magnitude of the shift exhibits a linear relationship to the phase derivative. Furthermore, in the output squeezed-state spectrum, the distribution of squeezing degree concentrates at the center frequency and at positions where frequency shifts occur. As the value of scaling factor $M$ increases, the proportion of squeezing degree allocated at the center frequency correspondingly increases. This temporal SU(1,1) interferometer architecture opens new avenues for the control of non-classical fields in the time-frequency domain and quantum information processing applications.