Pure Temporal Dispersion for Aberration Free Ultrafast Time-Stretch Applications

Photonic time-stretch applications overcome the speed limitations of conventional digitizers and enable the observation of nonrepetitive and statistically rare phenomena that occur on short timescales. In most time-stretch applications, large temporal dispersion with large bandwidth is highly desired to satisfy the far-field diffraction regime. However, most conventional spatial dispersers or chirped fiber Bragg gratings are constrained by their spatial volume, which can be overcome by using ultra-low-loss dispersive fibers, an ideal medium for large temporal dispersion (β
₂
), but they suffer from third-order dispersion (β
₃
) and aberrations. In this paper, an optical phase conjugation-based, third-order dispersion compensation scheme was introduced, with accumulated β
₂
and eliminated β
₃
, and it achieved a ±3400-ps
²
pure temporal dispersion of over 30-nm bandwidth. Leveraging this pure temporal dispersion, up to 2% of temporal aberrations were eliminated. Furthermore, Fourier domain spectroscopy achieved a record 15000 optical effective resolvable points, with a nondegraded 2-pm resolution over a 30-nm range.