Fiber-Based Programmable Picosecond Optical Pulse Shaper

Abstract

We experimentally demonstrate a fiber-optic programmable optical pulse shaper based on time-domain binary phase-only linear filtering, which is capable of switching picosecond pulse shapes at unprecedented sub-GHz rates by simply updating the binary signal driving an electro-optic phasemodulator (EO-PM). The required binary phase-filtering functions are computed using a genetic algorithm (GA). One limitation of the binary phase-filtering approach is the inherent symmetry of the output temporal shapes. To generate fully arbitrary time-domain intensity profiles (including asymmetric temporal waveforms) we must employ a multi-level phasefiltering function. However, the size of the solution-space and complexity of the computation multiplies to manifolds as the number of levels in the phase-filtering function increases. Here we numerically demonstrate a simple strategy, by combining the Gerchberg-Saxton algorithm (GSA) and GA, for the fast computation of multi-level phase-filtering functions. The performance of this approach is numerically proven by generating different asymmetric pulse shapes of practical interest, assuming experimentally feasible design parameters

Temporal self-imaging effect for periodically modulated trains of pulses

“…The realization of the Fourier transform by means of a dispersive medium in the optical domain has found several applications, such as the realization of temporal magnification systems, causing the waveform to be stretched in time and allowing thus the single-shot characterization of ultrafast waveforms [23][24][25][26]. In combination with electro-optic modulation, this setup can also perform the temporal and spectral shaping of optical pulses [27][28][29][30][31].…”

Fast arbitrary waveform generation by using digital micro-mirror arrays

“…Beating of different longitudinal laser modes of wavelength-division-demultiplexed mode-locked laser (MLL) pulses also enables phase or amplitude modulation to produce arbitrarily shaped beat signals [5]. In addition, many approaches based on all-fiber techniques such as optical spectral shaping [6], microwave photonic filtering combined with wavelength-to-time mapping [7], and temporal pulse shaping via programmable amplitude-only [8] and phase-only modulation [9] have been recently proposed for optical waveform generation. Pulse shaping based on the space-wavelength mapping followed by a spatial mask or programmable spatial light modulator (SLM) has been widely established for femtosecond pulse shaping and programmable RF waveform generation [10].…”

Dispersion requirements in coherent frequency-to-time mapping

“…The ability to measure or manipulate the spectral information in the temporal domain has enabled new metrology and signal processing schemes with a superior performance in terms of compactness and operation speed with respect to more conventional approaches. Some of the most recent applications reported that make use of this phenomenon include absorption spectroscopy [5]; radio-frequency arbitrary waveform generation (RF-AWG) [6]; spectral interferometry [7,8]; rapidly reconfigurable optical pulse shaping [9]; or 2D ultrafast imaging [10], for example.…”

“…Recently, Solli et al have shown that the spectral information can be alternatively recovered off-line using two temporal intensity measurements in the near-field region [11]. While being a certainly interesting technique for absorption spectroscopy, different applications such as the photonic RF-AWG [12,13] or temporal Fourier processors [9] require the spectral information mapped to the temporal domain in situ. Unfortunately, the temporal far-field or Fraunhofer condition is provided by a strong inequality [4], thus making it challenging to establish the precise amount of dispersion needed in a general case.…”