Abstract
We report a type of programmable pulse shaping method based on cascaded frequency-detuned optical differentiators. By properly adjusting the central wavelength of each differentiator, a large variety of symmetric pulses can be generated from a transform-limited Gaussian-like pulse. We numerically and experimentally demonstrate the generation of flat-top, parabolic and triangular pulses with tunable pulse widths from a 20-ps Gaussian-like pulse, using no more than three cascaded differentiators. It can be found that as more differentiators are used, higher synthesized accuracy and larger tuning range of pulse widths can be obtained in general. Additionally, in our experiment, we design and fabricate thermally tunable delay interferometers on the silicon-on-insulator (SOI) platform to work as optical differentiators, which can help us realize the shaping system with small footprint (943μm × 395μm) and high stability.
Highlights
Optical pulse shaping is an important signal processing technique which has been widely studied in optical communications, coherent control, ultra-broadband radio-frequency (RF) waveform generation and some nonlinear optical applications [1,2,3,4]
We theoretically demonstrate that when we concatenate a series of optical differentiators, many symmetric pulses can be generated from a transform-limited Gaussianlike pulse by adjusting the central wavelength of each differentiator
In order to simplify the tests, the metal electrodes were connected to larger pads on a film circuit through wire bonding technology
Summary
Optical pulse shaping is an important signal processing technique which has been widely studied in optical communications, coherent control, ultra-broadband radio-frequency (RF) waveform generation and some nonlinear optical applications [1,2,3,4]. It is always hard to control the shaping system when we need to deal with the frequency comb line by line or obtain very high accuracy limited by the resolution of shaping devices Apart from these proposals, generation of some special pulses such as flat-top pulse, triangular pulse and parabolic pulse are especially interesting since their wide range of applications in nonlinear optical signal processing [10,11,12,13,14]. Optical differentiator (OD) is one of the basic building blocks of optical signal processing, which has been studied extensively and can be fabricated utilizing fiber-based devices [21,22,23,24] or integrated devices [25,26,27,28,29,30] It has a large variety of applications [31,32,33], and among which the optical pulse shaping is rather attractive. The pulse shaper has the advantages of compactness, stability and compatible with electronic integrated circuit technology
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