Spectral line-by-line pulse shaping for optical arbitrary pulse-train generation

ulse-shaping techniques, in which user-specified ulrashort pulse fields are synthesized via parallel manipuation of optical Fourier components, are now widely dopted [1]. Among the almost arbitrary waveforms enbled by pulse shaping, one subset with particular appeal nvolves generation and manipulation of optical pulse rains. Discrete pulse train packets (or bursts) have been enerated by both Fourier transform pulse shapers [2–4] nd direct space-to-time pulse shapers [5,6]. In these exeriments the pulse train bursts were isolated in time nd occupied a short time window compared to the laser epetition rate. Manipulation of continuous trains of ulses has attracted interest for many applications, inluding high-speed optical fiber communications, ulrafast optical signal processing, and photonically asisted generation of arbitrary millimeter-wave and icrowave electromagnetic waveforms. Continuous ulse-train manipulation is usually implemented by all ptical processing of pulses from high-repetition-rate 10 GHz mode-locked lasers [7–19]. The simplest exmple for continuous pulse-train operation is repetition ate multiplication (RRM) [7–15], which is usually impleented by spectral intensity or spectral phase filtering. n addition to simple RRM, continuous pulse trains with ontrollable patterns and envelopes have also been proosed and demonstrated [16–19]. In these demonstraions, high-repetition-rate mode-locked lasers 10 GHz re essential. In the frequency domain the output of such ode-locked lasers are characterized by an evenly spaced eries of discrete spectral lines, with the frequency spacng equal to the pulse repetition rate. Recently we have emonstrated spectral line-by-line pulse shaping [20], in hich we are able to resolve and manipulate individual pectral lines from mode-locked lasers at 10 GHz. The apability of line-by-line pulse shaping immediately leads o efforts in pursuing optical arbitrary waveform generaion [21]. In this paper we demonstrate optical arbitrary ulse-train generation (OAPTG) using spectral line-byine pulse shaping, in which a pulse train spanning the ntire period can be generated, and individual pulses can