Dispersive temporal holography for single-shot recovering comprehensive ultrafast dynamics

Abstract

It is critical to characterize the carrier and instantaneous frequency distribution variation in ultrafast processes, all of which are determined by the optical phase. Nevertheless, there is no method that can single-shot record the intro-pulse phase evolution of pico/femtosecond signals, to date. By analogying holographic principle in space to the time domain and using the time-stretch method, we propose the dispersive temporal holography to single-shot recover the phase and amplitude of ultrafast signals. It is a general and comprehensive technology and can be applied to analyze ultrafast signals with highly complex dynamics. The method provides a new powerful tool for exploring ultrafast science, which may benefit many fields, including laser dynamics, ultrafast diagnostics, nonlinear optics, and so on. Main Text: Introduction One of the most fundamental and challenging problems throughout ultrafast science is to fully characterize the complex electric fields of the ultrashort optical pulses. Nowadays, in laboratories and industry, the techniques called FROG (Frequency-Resolved Optical Gating) (1, 2), SPIDER (Spectral Phase Interferometry for Direct Electric-field Reconstruction) (3), and IAC (Interferometric Autocorrelation) (4) are successfully used for pulse reconstruction. However, in some crucial explorations (such as how the ultrafast and nonlinear processes occur and evolve), the recordings must be genuine real-time and accurate. The above mainstream correlation-based methods require multi-point scanning to determine the phase and cannot track the ultrafast signals consecutively. Even if the single-shot detection is realized (5), the nonlinear-effect-dependent measurements must satisfy some certain conditions, such as phase matching or pretty high pulse peak power. That means such reconstructions, or to say a kind of estimation, are affected by the properties of the signals themselves. It may have considerable errors to reveal the irregular pulse waveforms has a single occurrence. Recently, a technique independent of nonlinear effects called dispersive Fourier transform (DFT) (6, 7) has made it possible to real-time detect spectral evolution in complex ultrafast systems (8, 9). Utilizing their spectral interferometry, the relative carrier phase and the time interval limited at optical soliton molecules can also be retrieved (10, 11). Fast dynamics such as the mode-locking buildup (8), breathers (9), supercontinuum (12), pulsating solitons (13) were intensely studied using DFT-based single-shot spectral measurement in recent years. However, the method cannot describe the panorama enough. It missed the complex waveform shapes and the temporal phase distribution, and failed to directly reveal the intrinsic physical mechanism by the observations. Submitted Manuscript: Confidential Template revised February 2021 2 The basic behavior of many vital nonlinear dynamics is still unknown because of lacking realtime time-domain measurements. A typical example is the optical rogue wave (14), which like ocean rogue wave (15), always appears and disappears suddenly. In theory, it was closely related to the breathers (16, 17). They have a strong connection with the Fermi-pasta-Ulam-Tsingou (FPUT) paradox (18), and the modulation instability (19). Previous researches only report the time-stretch spectroscopy or the oscilloscope traces, but the transient phase evolution is more significant for determining the origin of rogue waves. Therefore, it is urgent and essential to developing a singleshot phase and amplitude reconstruction technology for detect complex ultrafast dynamics. Fig. 1. The basic idea of dispersive temporal holography. (a) The signal and reference pulses are stretched by a large amount of dispersion, and the formed interference fringes are recorded by an oscilloscope. (b)The information in the fringes can be retrieved by the reference beam. Corresponding to (d) “intervene recording” and (e) “diffraction reappearance” in classical holography. (c) Holograms of signal pulses with different chirps. (F) The corresponding reconstructions.