J. Opt. 19, 054001 (2017)

Optical temporal imaging is a technique that involves stretching or compressing an optical waveform in time, while fully preserving its temporal structure. Usually, the technique is used to manipulate classical light, but now Giuseppe Patera and co-workers from France, China and Belarus have theoretically investigated its application to a non-classical, squeezed optical temporal waveform. The development is important for temporal stretching and compressing of squeezed fields, which are used in quantum-enhanced metrology and quantum communications. The scientists made a temporal imaging system based on sum-frequency generation in a nonlinear β-barium borate crystal, where the squeezed state to be temporally magnified is the signal beam and a strong coherent beam serves as the pump. Pump, signal and idler beams were propagated nearly parallel to each other and fulfilled the type-I phase-matching condition at the central frequencies. The obtained field of view (FOV) in the quantum regime was different from that in the classical regime. The main limiting factor for the FOV was the group velocity in the crystal. The quantum FOV was much narrower than the classical FOV for the same temporal imaging system.