Dispersive Fourier Transformation for Versatile Microwave Photonics Applications

Abstract

Dispersive Fourier transformation (DFT) maps the broadband spectrum of an ultrashort optical pulse into a time stretched waveform with its intensity profile mirroring the spectrum using chromatic dispersion. Owing to its capability of continuous pulse-by-pulse spectroscopic measurement and manipulation, DFT has become an emerging technique for ultrafast signal generation and processing, and high-throughput real-time measurements, where the speed of traditional optical instruments falls short. In this paper, the principle and implementation methods of DFT are first introduced and the recent development in employing DFT technique for widespread microwave photonics applications are presented, with emphasis on real-time spectroscopy, microwave arbitrary waveform generation, and microwave spectrum sensing. Finally, possible future research directions for DFT-based microwave photonics techniques are discussed as well.

Ultrafast interrogation of fully distributed chirped fibre Bragg grating strain sensor

“…A photonic time-stretch frequencydomain reflectometry is then formed when a coherent ultrashort pulsed laser and dispersive fibres are used [3]. A temporal interference pattern is obtained thanks to dispersioninduced wavelength-to-time mapping, also known as dispersive Fourier transform [5]. Therefore, fully distributed or local strain along the CFBG sensor can be measured from the instantaneous RF frequency of the temporal interference pattern due to the unique one-to-one mapping relation between spatial position, wavelength and time.…”

Advanced fiber Bragg gratings for microwave photonics applications

“…By properly designing the response of an optical spectral filter, a temporal pulse with the shape identical to the shaped-spectrum is obtained after the mapping process. The physics is also known as dispersive Fourier transform [10], as the intensity profile of the dispersed waveform is the Fourier transform of the original input optical pulse.…”

Temporal analog optical computing using an on-chip fully reconfigurable photonic signal processor

“…Still, the use of dispersive Fourier transformation in analog optical computing requires specific considerations. To make the structure implementable in an integrated photonic system, we implemented the dispersive Fourier transformation [35,36,37] with an on-chip structure with high group-delay-dispersion (GDD) benefiting from time lens for chirp modulation [38]. Moreover, time-domain modulation for multiplying the signal and arbitrary transfer function in frequency domain can be performed through a cascaded Mach-Zehnder modulator and optical modulator [39,40].…”