Xiaohong Hu

Bio: Xiaohong Hu is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Fiber laser & Laser. The author has an hindex of 19, co-authored 56 publications receiving 1145 citations. Previous affiliations of Xiaohong Hu include Shanxi University.

Long-cavity passively mode-locked fiber ring laser with high-energy rectangular-shape pulses in anomalous dispersion regime

Abstract: We report on a long-cavity passively mode-locked fiber laser in the anomalous dispersion regime. The nonlinear polarization rotation technique is employed to achieve mode locking. The output pulse from the fiber laser has a rectangular shape and a corresponding Gaussian-shape spectral profile. Stable mode-locked pulses at a repetition rate of 278 kHz with single pulse energy as high as 715 nJ are obtained under equal bidirectional pumping power of 500 mW in cavity. The experimental results demonstrate that the passively mode-locked fiber laser operating in the anomalous regime can also realize a high-energy pulse, which is different from the conventional low-energy soliton pulse. (C) 2010 Optical Society of America

Partially polarized wave‐breaking‐free dissipative soliton with super‐broad spectrum in a mode‐locked fiber laser

Abstract: We have reported a novel type of partially polarized dissipative soliton in a mode-locked erbium-doped all-fiber laser with strong net normal dispersion. The output pulses exhibit as quasi-trapezoid spectral profiles with 3-dB width as large as 83 nm. The maximum pulse energy and peak power approach 75 nJ and 6 kW at the available pump power of 1 W, respectively. Experimental observations show that the polarization state of the broadband dissipative soliton changes along the cavity position from totally to partially polarized, which is distinct from the typical dissipative soliton that is completely polarized throughout the cavity. It is found that the polarization state of mode-locked dissipative solitons strongly depends on the peak power of pulses, and the partially polarized state results from nonlinear phase shift accumulated in laser cavity.

Broad-bandgap and low-sidelobe surface plasmon polariton reflector with Bragg-grating-based MIM waveguide

Abstract: Surface plasmon polariton reflector (SPPR) based on metal-insulator-metal (MIM) Bragg grating waveguide is numerically studied. A quasi-chirped technique is applied to the engraved grooves in the surface of the MIM waveguide, and a new kind of broad-bandgap SPPR is achieved. Meanwhile, by optimizing the profile of gap width between the metal and dielectric, the spectral sidelobe of SPPR is effectively suppressed and thus the performance of the SPPR is further improved.

Wavelength-Switchable and Wavelength-Tunable All-Normal-Dispersion Mode-Locked Yb-Doped Fiber Laser Based on Single-Walled Carbon Nanotube Wall Paper Absorber

Abstract: We demonstrate a compact wavelength-tunable and -switchable mode-locked Yb-doped fiber (YDF) laser based on single-walled carbon nanotube (SWCNT) wall paper absorber Two mechanisms coexist in the fiber cavity The switchable mode-locked state can be obtained between two wavelengths depending on the fiber-loop-induced cavity birefringence Because of the intensity-dependent transmission distribution, the proposed fiber laser can be operated in the tunable wavelength mode-locked state from 1025 to 1037 nm The spectral bandwidth varied from 11 to 24 nm depending on the operating wavelength and the pump power with pulse duration of hundreds of picoseconds The average wavelength spacing is 36 nm, which can be changed, corresponding to the birefringence of the fiber cavity Moreover, stable wavelength-tunable mode locking is obtained at room temperature

Hundred Micro-Joules Level High Power Chirped Pulse Amplification of Femtosecond Laser Based on Single Crystal Fiber

Abstract: We demonstrate a hundred micro-Joules level femtosecond laser system based on a compact and simple two-stage Yb:YAG single crystal fiber chirped pulse amplification system which delivers compressed power of 15.57 W, pulse width of 715 fs. The different amplification performance with different input seed power is experimentally studied. A maximum direct amplified power output of 44 W at 100 kHz is obtained for an input seed power of 12 W. To the best of our knowledge, this is the highest average power of femtosecond laser based on single crystal fiber at hundred micro-Joules energy level.

Supercontinuum generation, photonic crystal fiber

Abstract: A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Recent progress of study on optical solitons in fiber lasers

Abstract: Solitons are stable localized wave packets that can propagate long distance in dispersive media without changing their shapes. As particle-like nonlinear localized waves, solitons have been investigated in different physical systems. Owing to potential applications in optical communication and optical signal processing systems, optical solitons have attracted intense interest in the past three decades. To experimentally study the formation and dynamics of temporal optical solitons, fiber lasers are considered as a wonderful nonlinear system. During the last decade, several kinds of theoretically predicted solitons were observed experimentally in fiber lasers. In this review, we present a detailed overview of the experimentally verified optical solitons in fiber lasers, including bright solitons, dark solitons, vector solitons, dissipative solitons, dispersion-managed solitons, polarization domain wall solitons, and so on. An outlook for the development on the solitons in fiber lasers is also provided and discussed.

RF Photonics: An Optical Microcombs’ Perspective

Abstract: Over the past decade, optical frequency combs generated by high-Q microresonators, or optical microcombs, which feature compact device footprints, low power consumption, and high repetition rates in broad optical bandwidths, have led to a revolution in a wide range of fields including metrology, telecommunications, radio frequency (RF) photonics, spectroscopy, sensing, and quantum optics. Among these, an application that has attracted great interest is the use of optical microcombs for RF photonics, where they offer enhanced functionalities as well as reduced size and power consumption over other approaches. This paper reviews the recent advances in this emerging field. We provide an overview of the main achievements that have been obtained to date, and highlight the strong potential of optical microcombs for RF photonics applications. We also discuss some of the open challenges and limitations that need to be addressed for practical applications.

Tunable band-pass plasmonic waveguide filters with nanodisk resonators

Abstract: A novel and simple plasmonic filter based on metal-insulator-metal plasmonic waveguides with a nanodisk resonator is proposed and investigated numerically. By the resonant theory of disk-shaped nanocavity, we find that the resonance wavelengths can be easily manipulated by adjusting the radius and refractive index of the nanocavity, which is in good agreement with the results obtained by finite-difference time-domain (FDTD) simulations. In addition, the bandwidths of resonance spectra are tunable by changing the coupling distance between the nanocavity and waveguides. This result achieved by FDTD simulations can be accurately analyzed by temporal coupled mode theory. Our filters have important potential applications in high-density plasmonic integration circuits.

Nonlinear and quantum optics with whispering gallery resonators

Abstract: Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.