Spectral line‐by‐line shaping for optical and microwave arbitrary waveform generations

Abstract

Spectral line-by-line shaping is a key enabler towards optical arbitrary waveform generation, which promises broad impact both in optical science and technology. In this paper, generation of optical and microwave arbitrary waveforms using the spectral line-by-line shaping technique is reviewed. Compared to conventional pulse shaping, significant new physics arises in the line-by-line regime, where the shaped pulse fields generated from one laser pulse now overlap with those generated from adjacent pulses. This leads to coherent interference effects related to the properties of optical frequency combs which serve as the source in these experiments. We explore such effects in a series of experiments using several different high-repetitionrate optical combs, including harmonically mode-locked lasers and continuous-wave lasers that are externally phase modulated either with or without the help of an optical cavity. As an application of line-by-line pulse shaping, we describe generation of microwave electrical arbitrary waveforms that can be reprogrammed at rates approaching 10 GHz.Significance of line-by-line shaping: combining optical frequency combs with spectral pulse shaping

Periodic Time-Domain Modulation for the Electrically Tunable Control of Optical Pulse Train Envelope and Repetition Rate Multiplication

“…However, if only the temporal intensity profile is to be controlled leaving the phase unconstrained, as in [18] or in [25], it has been found that with only phase modulation many interesting envelopes can still be synthesized [4], [18], including the RRM at the output of the system. Phase-only shaping is preferred in these cases because of its greater energetic efficiency and also because it only requires the use of one electrooptic phase modulator to perform the shaping.…”

“…Optical pulse shaping techniques have, consequently, received an increasing attention in the last few years [4]- [6]. Of specific interest are techniques for pulse repetition rate multiplication (RRM), which are used to generate ultrafast optical pulse trains from a low repetition rate input pulse train [7]- [14].…”

“…One of the most applied schemes for optical pulse control and pulse RRM is based on the manipulation of the input spectrum by properly altering the amplitude and phase of its frequency components [4]. In particular, RRM can be achieved with a linear filtering of the periodic comb that a mode-locked laser produces [17].…”

“…However, this phase filtering technique results in output pulse trains with only uniform envelopes (constant amplitude of the pulses). Another popular implementation, that is also usable for amplitude filtering, uses bulk diffraction gratings to resolve the individual lines of the spectrum of incoming pulses in the space where spatial light modulators, based on liquid crystals, acoustooptic modulators, or deformable mirrors, perform the complex Fourier-domain filtering [4], [13], [18]. A similar setup can be configured to work as a direct space-to-time optical shaper [16].…”

Generation of sub‐terahertz repetition rates from a monolithic self‐mode‐locked laser coupled with an external Fabry‐Perot cavity

“…Nowadays, repetition-rate scale up of periodic pulse sources is significantly important for the increasing demand in ultrahigh-speed optical communications. One of the most appealing methods for scaling up the pulse rate is to multiply the repetition rate of a lower rate source [21][22][23][24][25][26][27][28]. Therefore, discovering a technique to multiply the repetition rate of a compact self-mode-locked laser will be greatly prospective for generating ultrahighrepetition-rate sources.…”