Photonically assisted generation of arbitrary millimeter-wave and microwave electromagnetic waveforms via direct space-to-time optical pulse shaping

Abstract

We present our work in optical generation of arbitrarily shaped millimeter-wave electromagnetic waveforms. Through a novel technique, which utilizes tailored optical pulse sequences from a direct space-to-time pulse shaper to drive a high-speed optical-to-electrical converter, we generate amplitude-equalized, arbitrarily phase-and frequency-modulated waveforms at center frequencies approaching 50 GHz. In addition, we demonstrate the extension of this technique to generation of arbitrary electromagnetic waveforms in the low-gigahertz range, through dispersive stretching of the pulse shaper output. In the dispersively stretched configuration, the duration of our electrical waveforms is tuned through simple alignment changes in our pulse-shaping apparatus.

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

“…The simplest examples for continuous pulse train operation are repetition rate multiplication (RRM), as we demonstrated in the earlier subsection, which are usually implemented by spectral intensity or spectral phase filtering. In addition to simple RRM, continuous pulse trains with controllable patterns and envelopes have also been proposed and demonstrated [28][29][30]. In these demonstrations, high repetition rate mode-locked lasers (∼ 10 GHz) are essential.…”

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

“…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]. These last two approaches require the use of bulk optics with the typical shortcomings such as significant insertion losses, limited integration capabilities with fiber or waveguide optics systems, and the need of accurate alignment and stability.…”

High-speed pulse train generation by spectral filtering of a mode-locked laser output

“…Without changing anything inside the laser cavity, high-speed pulse trains could also be generated by simply passing a mode-locked laser output through a device or apparatus for repetition rate multiplication, such as a dispersive fibre [5], fibre Bragg grating [6], a time-to-space pulse shaper [7], etc. Those methods also suffer from some drawbacks, such as pulse-to-pulse spectrum change [4,5] and/or relatively large amplitude variation [6][7][8].…”

“…Those methods also suffer from some drawbacks, such as pulse-to-pulse spectrum change [4,5] and/or relatively large amplitude variation [6][7][8]. An arrayed waveguide grating with a relatively narrow free spectral range (FSR) has been used as an extra-cavity repetition rate multiplier by periodic spectral filtering of ultrashort pulses in its FSR [8].…”