Digital OPLL-based distributed Brillouin sensing system in optical fibers
Optics Express, May 10, 2022
A digital optical phase-locked loop (OPLL) has been implemented to develop a distributed Brilloui... more A digital optical phase-locked loop (OPLL) has been implemented to develop a distributed Brillouin sensing system in optical fibers. In our experiment, two commercial semiconductor lasers are phase-locked to each other with a highly flexible offset frequency using field programmable gate array (FPGA)-based electronics. Then, the difference frequency between the two lasers is highly stabilized and scanned by a desired step frequency in the vicinity of the Brillouin frequency of standard single-mode optical fibers. Consequently, the distribution of Brillouin frequency shift over a 50 km-long sensing fiber has been successfully measured by a very simple and low-cost Brillouin optical time-domain reflectometry (BOTDR) sensing system without any penalty in the sensing performance. The measurement repeatability at 50 km position of sensing fiber with a 5 m spatial resolution was measured be 4.5 MHz under fast measurement conditions: the number of trace averaging of 2000 and the frequency scan step of 12.8 MHz, showing the figure-of-merit of 3.0.
Complete characterization of multipass gas cell using a high sensitive optical frequency-domain reflectometry
Compact UAV compatible broadband 2D Spectrometer for multi-species atmospheric gas analysis
We present an UAV compatible spectrometer designed for sampling air pollutants in remote location... more We present an UAV compatible spectrometer designed for sampling air pollutants in remote locations. Relying on a custom-made Multi-Pass Cell and a 3-5 µm broadband supercontinuum light source, it takes advantage of an uncooled MWIR camera to record 2D cross-dispersed molecular absorption spectra.
Digital electronics platform-based supercontinuum light detection for mid-infrared trace gas sensing
Conference on Lasers and Electro-Optics, 2022
We present a digital platform-based lock-in detection scheme to improve the gas sensing performan... more We present a digital platform-based lock-in detection scheme to improve the gas sensing performance of a spectrometer. A numerically-controlled oscillator serves as reference clock to trigger the supercontinuum source and to demodulate the detector signal.
Compact, UAV compatible, broadband, uncooled Spectrometer for multi-species atmospheric gas analysis
OSA High-brightness Sources and Light-driven Interactions Congress 2020 (EUVXRAY, HILAS, MICS), 2020
Item does not contain fulltextMICS 202
Terahertz and Infrared Radiation from Femtosecond Light Filaments in Gases
Dual-frequency interaction and THz generation in the core of femtosecond filament in gasesNoncollinear and collinear spectroscopy of one-dimensionally inhomogeneous media with second-order susceptibility
acceptée sur proposition du jury: Prof. R. Salathé, président du jury Prof. L. Thévenaz, directeu... more acceptée sur proposition du jury: Prof. R. Salathé, président du jury Prof. L. Thévenaz, directeur de thèse
A multiplexed CW Brillouin system for precise interrogation of a sensor array made from short dis... more A multiplexed CW Brillouin system for precise interrogation of a sensor array made from short discrete sections of optical fibre
Airborne campaign results of a compact 2-4um broadband supercontinuum-based spectrometer system for multi-species atmospheric gas analysis at ppm level
A compact broadband atmospheric gas spectrometer has been developed in the framework of the EU-H2... more A compact broadband atmospheric gas spectrometer has been developed in the framework of the EU-H2020 FLAIR project. The system is composed of a mid-IR 2-4um broadband supercontinuum source, a temperature controlled 10- meter-long multipass-cell for light-gas interaction, a diffraction grating, and an uncooled PbSe-on-CMOS matrix detector recording absorption spectra. The detection limit has been measured at sub-ppm level on methane under laboratory conditions. We also present 2 successful field measurement campaigns aboard airborne platforms: a hot-air airship for controlled methane release experiments, and a helicopter tracking ship exhaust fumes abroad the coastline of Denmark, with special emphasis on methane detection.
Dual-frequency interaction and THz generation in the core of femtosecond filament of abstracts in gases
OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES), 2021
A compact and lightweight mid-infrared supercontinuum gas spectrometer has been developed and suc... more A compact and lightweight mid-infrared supercontinuum gas spectrometer has been developed and successfully tested in airborne campaigns to simultaneously monitor the methane and water vapor concentration in the exhaust fumes of ships.
A novel technique to produce large all-optically controlled tunable delays of 100 ps pulse train ... more A novel technique to produce large all-optically controlled tunable delays of 100 ps pulse train in optical fibers is demonstrated. The configuration of the delay line basically consists of two main stages: the wavelength conversion via semiconductor optical amplifiers and the group velocity delaying via a dispersive optical medium. The wavelength-converted signal was precisely delayed over a wide temporal range from picoseconds to nanoseconds using a dispersive fiber, preserving the wavelength and the bandwidth of the signal. 100 ps FWHM signal pulses were delayed continuously up to 14 ns with moderate pulse distortion, corresponding to a 140-bit delay.
A dynamically reconfigurable Microwave Photonic Filter based on True Time Delay generated by Stim... more A dynamically reconfigurable Microwave Photonic Filter based on True Time Delay generated by Stimulated Brillouin Scattering in optical fibers and separate phase shift of the optical carrier has been experimentally demonstrated, resulting in a flexible tunable Free Spectral Range.
The ubiquitous role of optical fibers in modern photonic systems has stimulated research to reali... more The ubiquitous role of optical fibers in modern photonic systems has stimulated research to realize slow and fast light devices directly in this close-to-perfect transmission line. Recent progress in developing optically-controlled delays in optical fibers, operating under normal environmental conditions and at telecommunications wavelengths, has paved the way towards real applications for slow and fast light. Advanced schemes can be realized thanks to the extremely flexible possibility to shape the gain spectrum to make it optimized for applications. Ultra wide bandwidth, delaying with flat amplitude response and lower distortion were successfully demonstrated this way.
The impact of pulse shape is studied in order to enhance time delaying in Brillouin slow-light. A... more The impact of pulse shape is studied in order to enhance time delaying in Brillouin slow-light. An exponential-like pulse with 14-ns FWHM duration is delayed up to 31-ns in a 27 MHz wide Brillouin resonance.
An optical comb consisting of 15 lines within 30 dB was generated with an extremely simple setup,... more An optical comb consisting of 15 lines within 30 dB was generated with an extremely simple setup, based on the combination of amplified spontaneous Brillouin scattering and 4-wave mixing in optical fibers.
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Papers by Sanghoon Chin