Engineering the Frequency Spectrum of Bright Squeezed Vacuum via Group   Velocity Dispersion in an SU(1,1) Interferometer
  Bright squeezed vacuum, a promising tool for quantum information, can be generated by high-gain parametric down-conversion. However, its frequency and angular spectra are typically quite broad, which is undesirable for applications requiring single-mode radiation. We tailor the frequency spectrum of high-gain parametric down-conversion using an SU(1,1) interferometer consisting of two nonlinear crystals with a dispersive medium separating them. The dispersive medium allows us to select a narrow band of the frequency spectrum to be exponentially amplified by high-gain parametric amplification. The frequency spectrum is thereby narrowed from (56.5 +- 0.1) to (1.22 +- 0.02) THz and, in doing so, the number of frequency modes is reduced from approximately 50 to 1.82 +- 0.02. Moreover, this method provides control and flexibility over the spectrum of the generated light through the timing of the pump. 
Samuel Lemieux, Mathieu Manceau, Polina R. Sharapova, Olga V.   Tikhonova, Robert W. Boyd, Gerd Leuchs, Maria V. Chekhova
quant-ph