We demonstrate two novel and complementary techniques that allow the single-shot recordings of amplitude and phase of irregular waves with a high temporal resolution (~200 fs ) over a long time window (~40 ps) [1].
The key point is a completely new combination of the so-called time lens strategy [2,3] and of heterodyne detection [4,5]. We superimpose the input signal to a CW reference so that fringes of interference are produced in a c(2) crystal. As in the time microscope geometry published in [2], the temporal information is first encoded onto the spectrum of field by using sum frequency generation (SFG) between the signal and a chirped pump pulse. Then we design an original imaging time-lens system, which finally encodes the temporal evolution of the fringe line onto the horizontal axis and the fringes themselves onto the vertical axis of an sCMOS camera.
We first demonstrate the use of this technique by recording partially coherent waves emitted by an amplified spontaneous source having a spectral width of 1THz. We secondly demonstrate the formal analog of digital holography used here as an ultrafast measurement technique (that we call SEAHORSE). As an important application, our results open the way to novel fundamental investigations of nonlinear propagation of random waves in optical fibers. In particular, our system unveiled the special evolution of the phase (and amplitude) of rogue waves in integrable turbulence, and the compatibility with the expected Peregrine solitons [2].
REFERENCES
[1] A. Tikan et al, arxiv/1707.07567, (2017)
[2] B.H. Kolner and M. Nazarathy, Opt. Lett. 14, 12, (1989)
[3] P. Suret et al., Nat. Commun., 7, 13136 (2016)
[4] D.H. Broaddus et al., CLEO/QELS Laser Science to Photonic Applications, San Jose, CA, (2010)
[5] C. Dorrer, Opt. Lett., 31, 4, pp 540-542, (2006)
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