Highly coherent supercontinuum generation with picosecond pulses by using self-similar compression

Abstract

The low coherence of the supercontinuum (SC) generated using picosecond pump pulses is a major drawback of such SC generation scheme. In this paper, we propose to first self-similarly compress a high power picosecond pump pulse by injecting it into a nonlinearity increasing fiber. The compressed pulse is then injected into a non-zero dispersion-shifted fiber (NZ-DSF) for SC generation. The nonlinearity increasing fiber can be obtained by tapering a large mode area photonic crystal fiber. The fiber nonlinearity is varied by varying the pitch sizes of the air holes. By using the generalized nonlinear Schrödinger equation, we show that a 1 ps pump pulse with random noise can be compressed self-similarly down to a pulse width of 53.6 fs with negligible pedestal. The noise level of the compressed pulse is reduced at the same time. The 53.6 fs pulse can then be used to generate highly coherent SC in an NZ-DSF. By using the proposed scheme, the tolerance of noise level for highly coherent SC generation with picosecond pump pulses can be improved by 5 order of magnitude.

High Degree Picosecond Pulse Compression in Chalcogenide-Silicon Slot Waveguide Taper

“…The pulse compression factor, which is the ratio of the full width at half maximum (FWHM) of the pulses before and after compression, only depends on the product σz. It should be pointed out that if γ(z) is not a constant but varies significantly along the taper length, self-similar pulse compression can still be realized by using either nonlinearity increasing [7] or a combination of dispersion and nonlinearity management schemes [20].…”

“…In comparison, adiabatic [16]- [18] and self-similar [7], [19]- [23] pulse compression can achieve high degree of compression factor with small pedestal. While adiabatic pulse compression requires a long length of fiber, self-similar compression supports high degree pulse compression in a short fiber.…”

“…While adiabatic pulse compression requires a long length of fiber, self-similar compression supports high degree pulse compression in a short fiber. Recently, nonlinearity increasing photonic crystal fiber (PCF) tapers were proposed to realize the self-similar pulse compression [7], but the required peak power of the input pulse is more than kilowatt. Moreover, the fabrication of such PCF tapers is still challenging because of the difficulties in controlling the fiber profile during the drawing process.…”

Mid-infrared self-similar compression of picosecond pulse in an inversely tapered silicon ridge waveguide

“…Optical pulse compression technique is important for many applications, including optical communication, nonlinear microscopy, supercontinuum and frequency comb generations [1][2][3][4][5][6], etc. In laser systems, prism or grating-based compressors are typically used to compensate the linear chirp of pulses to compress them [7][8][9].…”

“…But the long fiber length required is undesirable in most systems because of compactness and cost [16][17][18]. Compared with the adiabatic compression, self-similar pulse compression can achieve large compression factor without pedestal generation in much shorter nonlinear media [3,[19][20][21][22][23]. In a 6.4 m nonlinearity increasing photonic crystal fiber (PCF) taper, a 1 ps pulse is self-similarly compressed to 53.6 fs with low pedestal [3].…”