Author Affiliations
Abstract
1 Key Laboratory for Laser Plasma, Shanghai Jiao Tong University, Shanghai 200240, China
2 Key Laboratory of Micro and Nano Photonic Structures, Fudan University, Shanghai 200433, China
3 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
We propose a spatially chirped quasi-phase-matching (QPM) scheme that enables ultrabroadband second-harmonic-generation (SHG) by using a fan-out QPM grating to frequency-convert a spatially chirped fundamental wave. A “zero-dispersion” 4f system maps the spectral contents of ultrabroadband fundamental onto different spatial coordinates in the Fourier plane, where the fundamental is quasi-monochromatic locally in picosecond duration, fundamentally canceling high-order phase mismatch. A fan-out QPM grating characterized by a linear variation of the poling period along the transverse direction exactly supports the QPM of the spatially chirped beam. We theoretically demonstrate the SHG of an 810-nm, 12.1-fs pulse into a 405-nm, 10.2-fs pulse with a conversion efficiency of 77%.
nonlinear optics second-harmonic generation few-cycle pulse Chinese Optics Letters
2024, 22(1): 011901
强激光与粒子束
2023, 35(9): 091005
Author Affiliations
Abstract
School of Physics and Astronomy, Key Laboratory for Laser Plasmas (Ministry of Education), Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai, China
Spatiotemporal mode-locking creates great opportunity for pulse energy scaling and nonlinear optics research in fiber. Until now, spatiotemporal mode-locking has only been realized in normal-dispersion dissipative soliton and similariton fiber lasers. In this paper, we demonstrated the first experimental realization of a spatiotemporally mode-locked soliton laser in mid-infrared fluoride fiber with anomalous dispersion. The mode-locked fluoride fiber oscillator directly generated a record pulse energy of 16.1 nJ and peak power of 74.6 kW at 2.8 μm wavelength. This work extends the spatiotemporal mode-locking to soliton fiber lasers and should have a wide interest for the laser community.
mid-infrared soliton fiber laser spatiotemporal mode-locking High Power Laser Science and Engineering
2023, 11(5): 05000e59
Author Affiliations
Abstract
1 School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
2 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
Parametric interaction allows both forward and backward energy transfers among the three interacting waves. The back-conversion effect is usually detrimental when unidirectional energy transfer is desired. In this theoretical work, we manifest that the back-conversion effect underpins the direct generation of the picosecond pulse train without the need for a laser resonator. The research scenario is an optical parametric amplification (OPA) that consists of a second-order nonlinear medium, a quasi-continuous pump laser and a sinusoidal amplitude-modulated seed signal. The back-conversion of OPA can transfer the modulation peaks (valleys) of the incident signal into output valleys (peaks), which inherently induces spectral sidebands. The generation of each sideband is naturally accompanied with a phase shift of ±π. In the regime of full-back-conversion, the amount and amplitude of the sidebands reach the maximum simultaneously, and their phase constitutes an arithmetic sequence, leading to the production of a picosecond pulse train. The generated picosecond pulse train can have an ultrahigh repetition rate of 40 GHz or higher, which may facilitate ultrafast applications with ultrahigh speed.
picosecond pulse train quadratic parametric process sideband generation High Power Laser Science and Engineering
2023, 11(2): 02000e21
Author Affiliations
Abstract
1 Key Laboratory for Laser Plasmas (MOE), Collaborative Innovation Center of IFSA, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
2 Joint Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China
3 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
In strong-field physics experiments with ultraintense lasers, a single-shot cross-correlator (SSCC) is essential for fast optimization of the pulse contrast and meaningful comparison with theory for each pulse shot. To simultaneously characterize an ultrashort pulse and its long pedestal, the SSCC device must have both a high resolution and a large temporal window. However, the resolution and window in all kinds of single-shot measurement contradict each other in principle. Here we propose and demonstrate a novel SSCC device with two separate measurement channels: channel-1 for the large-window pedestal measurement has a moderate resolution but a large window, while channel-2 for the ultrashort pulse measurement has a small window but a high resolution; this allows the accurate characterization of the pulse contrast in a single shot. A two-channel SSCC device with a 200-fs resolution and 114-ps window has been developed and tested for its application in ultraintense lasers at 800 nm.
pulse contrast single-shot cross-correlator ultrashort ultraintense laser High Power Laser Science and Engineering
2022, 10(6): 06000e43
Author Affiliations
Abstract
1 School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
2 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai200240, China
Optical parametric chirped-pulse amplification is inevitably subject to high-order spatial chirp, particularly under the condition of saturated amplification and a Gaussian pump; this corresponds to an irreversible spatiotemporal distortion and consequently degrades the maximum attainable focused intensity. In this paper, we reveal that such spatial chirp distortion can be significantly mitigated in quasi-parametric chirped-pulse amplification (QPCPA) with idler absorption. Simulation results show that the quality of focused intensity in saturated QPCPA is nearly ideal, with a spatiotemporal Strehl ratio higher than 0.98. As the seed bandwidth increases, the idler absorption spectrum may not be uniform, but the Strehl ratio in QPCPA can be still high enough due to stronger idler absorption.
gain saturation quasi-parametric chirped-pulse amplification spatiotemporal distortions High Power Laser Science and Engineering
2022, 10(3): 03000e20
Author Affiliations
Abstract
1 School of Physics and Astronomy, Key Laboratory for Laser Plasmas (Ministry of Education), Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai200240, China
2 School of Information and Electrical Engineering, Hebei University of Engineering, Handan056038, China
Dissipative solitons have been realized in mode-locked fiber lasers in the theoretical framework of the Ginzburg–Landau equation and have significantly improved the pulse energy and peak power levels of such lasers. It is interesting to explore whether dissipative solitons exist in optical parametric oscillators in the framework of three-wave coupling equations in order to substantially increase the performance of optical parametric oscillators. Here, we demonstrate a temporal-filtering dissipative soliton in a synchronously pumped optical parametric oscillator. The temporal-gain filtering of the pump pulse combined with strong cascading nonlinearity and dispersion in the optical parametric oscillator enables the generation of a broad spectrum with a nearly linear chirp; consequently, a significantly compressed pulse and high peak power can be realized after dechirping outside the cavity. Furthermore, we realized, for the first time, dissipative solitons in an optical system with a negative nonlinear phase shift and anomalous dispersion, extending the parameter region of dissipative solitons. The findings may open a new research block for dissipative solitons and provide new opportunities for mid-infrared ultrafast science.
cascading nonlinearity dissipative solitons optical parametric oscillators temporal filtering High Power Laser Science and Engineering
2022, 10(2): 02000e16
Author Affiliations
Abstract
1 School of Physics and Astronomy, Key Laboratory for Laser Plasmas (Ministry of Education), Collaborative Innovation center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240, China
2 Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
3 SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
Optical vortex is a promising candidate for capacity scaling in next-generation optical communications. The generation of multi-vortex beams is of great importance for vortex-based optical communications. Traditional approaches for generating multi-vortex beams are passive, unscalable and cumbersome. Here, we propose and demonstrate a multi-vortex laser, an active approach for creating multi-vortex beams directly at the source. By printing a specially-designed concentric-rings pattern on the cavity mirror, multi-vortex beams are generated directly from the laser. Spatially, the generated multi-vortex beams are decomposable and coaxial. Temporally, the multi-vortex beams can be simultaneously self-mode-locked, and each vortex component carries pulses with GHz-level repetition rate. Utilizing these distinct spatial-temporal characteristics, we demonstrate that the multi-vortex laser can be spatially and temporally encoded for data transmission, showing the potential of the developed multi-vortex laser in optical communications. The demonstrations may open up new perspectives for diverse applications enabled by the multi-vortex laser.
红外与激光工程
2020, 49(12): 20201060