Ultrashort Flat-Top Pulse Generation Using On-Chip CMOS-Compatible Mach–Zehnder Interferometers

Abstract

Reshaping of an ultrashort Gaussian-like pulse into a flat-top pulse is demonstrated using an integrated Mach-Zehnder interferometer (MZI). The 7.8-ps Gaussian-like pulses are reshaped into nearly chirp-free 17.1-ps and 20.0-ps flat-top-pulses based on two different linear filtering schemes. In addition, the capability of this integrated MZI to generate a Hermite-Gaussian pulse with duration of a few picoseconds is demonstrated. Index Terms-Complementary metal-oxide semiconductor (CMOS)-compatible optical components, flat-top pulse generation, linear filtering.

Recent progresses on optical arbitrary waveform generation

“…Optical differentiator and integrator as two fundamental optical processors have been investigated in the past few years [71][72][73][74][75][76][77][78][79][80][81]. Thanks to the intrinsic advantages of broad bandwidth based on an optical implementation, optical differentiator and integrator have an extremely large bandwidth comparing to the electronics based signal processors.…”

“…Recently, an on-chip complemeritary metal-oxide semiconductor (CMOS)-compatible MZI is used for flat-top pulse generation by linearly re-shaping an input Gaussianlike optical pulse [75]. As shown in Fig.…”

“…When the wavelength shift between the pulse carrier wavelength and the directional coupler's central notch wavelength is tuned to~8 nm, as shown in Fig. 18(c1), a 2) time-domain intensity profiles of the input pulse, the measured output pulse and the numerical ideal output [75] nearly chirp-free flat-top pulse with a full width at half maximum (FWHM) of 540-fs is generated at the directional coupler's output, as shown in Fig. 18(c2).…”

“…As mentioned above, although a programmable optical processor can be used to generate arbitrary waveform with broad bandwidth [71][72][73][74][75][76][77][78][79][80][81], its cost is very high. In some applications, only one or a few specific waveforms are needed, e.g., only a flat-top waveform is required as an optical gating signal for a time-division multiplex (TDM) system.…”

Reconfigurable symmetric pulses generation using on-chip cascaded optical differentiators

“…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]. Many different schemes have been investigated to synthesize these waveforms [15][16][17][18][19][20], which usually show small errors. Whereas, only fixed pulse shape with fixed pulse width may limit their applications to some extent.…”