Zejiang Deng

East China Normal University

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Daping Luo

East China Normal University

Chenglin Gu

East China Normal University

Wenxue Li

East China Normal University

Gehui Xie

East China Normal University

Lian Zhou

Guangxi University of Finance and Economics

Zhiwei Zhu

Chinese University of Hong Kong

Wenxue Li

Guilin University of Electronic Technology

Yang Liu

Shenzhen Children's Hospital

Yang Liu

Chongqing University of Science and Technology

Haipeng Lou

East China Normal University

Cooperative Institutions

East China Normal University

Chinese Academy of Sciences

Huazhong University of Science and Technology

University of Chinese Academy of Sciences

Peking University

East China University of Science and Technology

Fudan University

National University of Defense Technology

Tianjin University

Sun Yat-sen University

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Achieving Precise Spectral Analysis and Imaging Simultaneously with a Mode-Resolved Dual-Comb Interferometer

Sensors (2021)

Zejiang Deng Yang Liu Zhiwei Zhu Daping Luo Chenglin Gu

In this paper, we report a scheme providing precise spectral analysis and surface imaging, simultaneously, based on a high-coherence dual-comb interferometer. With two tightly phase-locking frequency combs, we demonstrate a high-coherence dual-comb interferometer (DCI) covering 188 to 195 THz (1538.5 to 1595.7 nm) with comb-tooth resolution and a max spectral signal-to-noise ratio (SNR) of 159.7. The combination of the high-coherence dual-comb spectrometer and a reference arm simultaneously enables gas absorption spectroscopy and for the absolute distance information to be obtained in one measurement. As a demonstration, we measure the spectrum of CO2 and CO. From the same interferograms, we demonstrate that distance measurement, by time-of-flight (TOF), can be resolved with an rms precision of 0.53 μm after averaging 140 images and a measurement time of 1 s. Finally, we demonstrate that non-contact surface imaging, using 2D mechanical scanning, reaches lateral resolution of 40 μm. The longitudinal precision is 0.68 μm with a measurement time of 0.5 s. It verifies that DCS has the potential to be applied in standoff detection, environmental pollution monitors, and remote sensing.

Spectral resolution

Imaging Spectroscopy

10.3390/s21093166

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Citations (4)

Passive coherent dual-comb spectroscopy based on optical-optical modulation with free running lasers

PhotoniX (2020)

Chenglin Gu Zhong Zuo Daping Luo Zejiang Deng Yang Liu

Abstract Dual-comb spectroscopy is a powerful spectroscopic tool with ultrahigh-resolution, high-sensitivity properties, which opens up opportunities for the parallel detection of multi-species molecules. However, in its conventional form, highly stable laser combs with sophisticated control systems are required to perform dual-comb spectroscopy. Here, a passive mutually coherent dual-comb spectroscopy system via an optical-optical modulation method is addressed, where all fast phase-locking electronics are retired. Without post computer-based phase-correction, a high degree of mutual coherence between the two combs with a relative comb-tooth linewidth of 10 mHz is achieved, corresponding to a coherent time of 100 s. To demonstrate the performance and versatility of the system, the dual comb spectrometer is applied to record the mode-resolved single molecular spectra as well as parallel detected spectra of mixed gases including CO 2 , CO and C 2 H 2 that well agree with the established spectral parameters. Our technique exhibits flexible wavelength tuning capability in the near-infrared region and can be potentially extended to the mid-infrared region for more applications.

Laser linewidth

Modulation (music)

Molecular spectroscopy

10.1186/s43074-020-0005-2

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Tunable compact asynchronous optical sampling system using Er-doped fiber laser

High Power Laser Science and Engineering (2023)

Zilin Zhao Daping Luo Yang Liu Zejiang Deng Lian Zhou

Abstract We report a compact, tunable, self-starting, all-fiber laser-based asynchronous optical sampling (ASOPS) system. Two Er-doped fiber oscillators were used as the pulsed-laser source, whose repetition rate could be set at 100 MHz with a tuning range of 1.25 MHz through a fiber delay line. By employing phase-locked and temperature control loops, the repetition rate offset of the two lasers was stabilized with 7.13 × 10 −11 fractional instability at an average time of 1 s. Its capabilities in the terahertz regime were demonstrated by terahertz time-domain spectroscopy, achieving a spectral bandwidth of 3 THz with a dynamic range of 30 dB. The large range of repetition rate adjustment in our ASOPS system has the potential to be a powerful tool in the terahertz regime.

10.1017/hpl.2023.21

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Low-Noise, Robust, All-Polarization-Maintaining Mode-Locked Er-Doped Fiber Ring Laser

IEEE Photonics Technology Letters (2018)

Zhiwei Zhu Yang Liu Wenchao Zhang Daping Luo Chao Wang

We report on a low-noise, robust, all-polarization-maintaining (PM) mode-locked Er-doped fiber ring laser, indicating an effective method to further optimize the phase noise by adjusting the pump power. Integrated from 10 Hz to 10 MHz, the optimized timing jitter is as low as 269 fs with an amplitude noise of 0.028%. The experimental results agree well with the prediction in a series of simulations and numerical analyses, revealing that the phase noise performance is improved by rebalancing the interactions between the gain, dispersion, and nonlinearity, and the high pulse energy and short pulse duration contribute to a reduction in the phase noise until the nonlinearities begin to neutralize the benefit. Consisting of a packaged semiconductor saturable absorber mirror and an all-PM-fiber ring structure, the laser performs well with reliable output pulses in vibrational environments, and most of the technical noise from external disturbances is also suppressed.

Ring laser

10.1109/lpt.2018.2836178

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Mode-resolved dual-comb spectroscopy with a free-running polarization-maintain fiber laser cavity

Zejiang Deng Chao Wang Yangcheng Ou Zhiwei Zhu Chenglin Gu

A simple and robust dual-comb scheme with different repetition rates is demonstrated from a passively mode-locked polarization-maintain fiber cavity. With mutual coherent properties in a single cavity, mode-resolved spectroscopy is obtained with free-running state.

10.1364/cleopr.2018.f2a.5

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Investigation of stable pulse mode-locking regimes in a NALM figure-9 Er-doped fiber laser

Optics Express (2022)

Shiping Xiong Daping Luo Yang Liu Wenchao Wang Zejiang Deng

We demonstrate three typical mode-locking processes of a nonlinear amplifying loop mirror (NALM) fiber laser via a general nonlinear Schrödinger equation-based (GNLSE) simulation model. First, the pulse evolutions in the NALM cavity were separately simulated under asymmetric and weakly asymmetric conditions. We found that the splitting ratio and positions of the gain fiber can result in a suitable phase bias between clockwise and counter-clockwise beams, enabling the realization of a self-starting low-threshold operating condition. To assess the roles of the splitting ratio and gain in the mode-locking process, we simulated three pulse formation processes: in the soliton, stretched-pulse, and dissipative soliton mode-locking regimes. The simulation results show that the splitting ratio, gain, and dispersion directly influence the mode-locking condition and pulse characteristics, thereby providing effective quantified guidance for high-quality pulse generation. Finally, an experimental NALM oscillation operating under stretched pulse conditions was established to investigate the impact of the splitting ratio and pump power on the pulse characteristics. The experimental results prove that the splitting ratio, gain, and dispersion can be used to manipulate the mode-locking threshold, self-starting threshold, nonlinear effects, and pulse characteristics.

Mode-Locking

10.1364/oe.476630

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Nonlinear dynamics of relative intensity noise transfer at fiber amplification and supercontinuum generation

Optics Communications (2023)

Zhenqiang Tang Daping Luo Gehui Xie Zejiang Deng Haipeng Lou

Supercontinuum

Relative intensity noise

10.1016/j.optcom.2023.130131

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132 W 132 μJ Femtosecond Pulses from a Coherently Combined System of Two Rod-Type Photonic Crystal Fibers

Photonics (2023)

Gehui Xie Daping Luo Zhenqiang Tang Zejiang Deng Lian Zhou

A coherent beam combination has the potential to revolutionize high-peak-power laser systems. However, achieving a high-average-power ultrashort pulse is difficult due to the accumulation of a nonlinear phase and gain narrowing. In this article, we demonstrate a coherent beam combination system that does not require pulse shaping or a spectral modulator. By optimizing the gain of each amplifier and using highly integrated optical components, we reduce the limitations caused by the accumulation of a nonlinear phase and gain narrowing. In our study, we used a polarization beam splitter to combine the pulses from two rod-type photonic crystal fibers (PCFs) in a Mach–Zehnder-type interferometer. A piezo-mounted mirror controlled with a Hänsch–Couillaud polarization detecting system was used to stabilize active phase locking. The system produces 165 W with a 91.6% combining efficiency compared to 90 W per amplifier. Compressed pulses with an energy of 132 µJ and Gaussian fitting pulse duration of 330 fs were achieved.

Beam splitter

Nonlinear photonic crystal

10.3390/photonics10101138

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Self-referenced frequency comb from a polarization-maintaining Er: Fiber laser based nonlinear polarization evolution

Results in Physics (2021)

Gehui Xie Yang Liu Lian Zhou Zhiwei Zhu Zejiang Deng

To the best of our knowledge, this paper presents the first self-referenced polarization-maintaining (PM) Er: nonlinear polarization evolution-based fiber frequency comb. A short PM fiber section segment acts as an artificial saturable absorber and compensates for the group velocity mismatch. A conventional f-2f interferometer allows detecting carrier-envelope offsetting frequency (fceo) after an octave-spanning spectrum generation. A complete description of the PM Er: fiber comb combining a noise study of the repetition rate (fr) and fceo is presented. Accordingly, the in-loop residual phase noise of fceo and fr are 468 mrad and 0.336 mrad from 1 Hz to 3 MHz, respectively. Further, we verify the long-term performance of the comb system by recording the fluctuation of fr and fceo for more than 10 h. We observed that combining fast actuators for phase noise suppression would potentially enable a compact and robust frequency comb system for a range of applications such as comb-based liars, optical clock, and gas sensing.

Carrier-envelope phase

Comb generator

10.1016/j.rinp.2021.103886

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Citations (9)

Line-scan spectrum-encoded imaging by dual-comb interferometry

Optics Letters (2018)

Chao Wang Zejiang Deng Chenglin Gu Yang Liu Daping Luo

Herein, the method of spectrum-encoded dual-comb interferometry is introduced to measure a three-dimensional (3-D) profile with absolute distance information. By combining spectral encoding for wavelength-to-space mapping, dual-comb interferometry for decoding and optical reference for calibration, this system can obtain a 3-D profile of an object at a stand-off distance of 114 mm with a depth precision of 12 μm. With the help of the reference arm, the absolute distance, reflectivity distribution, and depth information are simultaneously measured at a 5 kHz line-scan rate with free-running carrier-envelope offset frequencies. To verify the concept, experiments are conducted with multiple objects, including a resolution test chart, a three-stair structure, and a designed "ECNU" letter chain. The results show a horizontal resolution of ∼22 μm and a measurement range of 1.93 mm.

10.1364/ol.43.001606

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Citations (38)