About Me
I am Denghui Pan, a first-year Ph.D. student at the ECE Department, University of California, Santa Cruz working with Prof. Holger Schmidt. My research interests mainly focus on Ultrafast Fiber Laser, Ultrafast Time-resolved Laser Spectroscopy, Integrated Optofluidics Ultrafast Spectrometer, and Spectral Analysis.
Education
News
Projects
Research on Linear Polarization-maintaining NPE Mode-locked Fiber Laser
- I designed and constructed an innovative ultrafast fiber laser utilizing the principle of Nonlinear Polarization Evolution (NPE) for mode-locking in a Polarization-Maintaining (PM) erbium-doped fiber laser. The novelty of this work lies in the incorporation of a novel wavelength-division multiplexer (WDM) collimator integrated device, contributing to a more compact laser architecture. The resultant laser demonstrates stable output of ultrashort pulses at a repetition rate of 60.9 MHz.
Research on Transient Dynamics of Dissipative Solitons in Mode-locked Fiber Lasers
- By employing Time-Stretch Dispersion Fourier Transform (TS-DFT) technique, I investigated the dynamic process of dissipative soliton formation within an anomalous dispersion fiber laser. The construction of dissipative solitons revealed five distinct transient stages: relaxation oscillations, modulation instability, spectral broadening, soliton explosion, and stable mode-locking state. Notably, during the soliton explosion phase, the existence of dissipative rogue waves was discovered. This finding significantly contributes to comprehending the evolutionary dynamics of dissipative soliton formation within nonlinear dissipative systems.
Research on Ultra-compact Femtosecond Fiber Laser Product
- This project aims to transition the research-oriented, dispersion-managed, polarization-maintaining, erbium-doped femtosecond fiber laser (referred to as the fiber laser) developed within our laboratory into an industrialized product. The goal is to create a compact, portable, stable, and adaptable fiber laser product suitable for various complex engineering environments. The fiber laser employs full-polarization-maintaining fiber with erbium-doped gain medium and features a nine-mirror cavity structure. By adjusting the lengths of positively and negatively dispersive fibers, the net dispersion within the cavity can be controlled, yielding pulses with different characteristics. When approaching near-zero dispersion, the laser generates femtosecond pulses. In an industrial setting, the fiber laser is pumped by butterfly-packaged laser diodes for energy supply. Mode-locking is achieved by rotating an internal polarizing waveplate to ensure stable pulse output. During the product design phase, the precise components of the laser were modeled using Solidworks. These components were fabricated by a precision machinery factory, followed by assembly and performance testing of the laser to meet industrial-grade standards. This prototype is capable of generating stable laser pulses at 97 MHz with an impressively narrow pulse width of only 293 femtoseconds. This product has been included in multiple research project and grant applications, including the Tsinghua SIGS Concept Verification Project (Fiber Lasers for Biomedical Imaging) and the Overseas Research Cooperation Fund (Coexistence and Evolution of Bright and Dark Solitons in Mode-Locked Fiber Lasers).
Research on Hybrid Mode-locked Fiber Laser Based on Nonlinear Multimodal Interference
- The project involved the design of a novel semi-polarization-maintaining erbium-doped fiber laser. A distinctive approach was employed, utilizing a reflective multi-mode interference saturable absorber (SA) for mode-locking. Within this specially designed SA, linearly polarized light was coupled into a 15 cm long gradient refractive index multi-mode fiber through polarization-maintaining fiber. The light was then reflected back into the polarization-maintaining structure via a mirror connected to a single-mode fiber. The measured modulation depth and saturation peak power were 1.5% and 0.6 watts, respectively. This laser generated mode-locked pulses of 409 femtoseconds at a repetition rate of 33.3 MHz. Compared to traditional nonlinear polarization evolution (NPE) mode-locking in non-polarization-maintaining fiber lasers, this laser exhibited superior optical performance metrics, including spectral bandwidth, pulse duration, and stability.
Publications
Appl. Opt. 62, 5946-5953 (2023)
Asia Communications and Photonics Conference 2021, Shanghai China, 24–27 October 2021
Optoelectronics and Communications Conference 2021, Hong Kong China, 3–7 July 2021
2023 Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, USA, 2023, pp. 1-2.
IEEE Photonics Technology Letters, vol. 33, no. 2, pp. 81-84, 15 Jan.15, 2021.
Optoelectronics and Communications Conference 2021, Hong Kong China, 3–7 July 2021.
Journal of Lightwave Technology, vol. 39, no. 23, pp. 7509-7516, Dec.1, 2021.
Optics & Laser Technology, Volume 159, April 2023, 108941.