イベント（シンポジウム・講演会）

概要: Laser frequency combs can provide new capabilities across a range of precision measurements. I will discuss their unique properties and two applications currently pursued in our group. In both applications, frequency comb light is transmitted over long open air paths. In the first application, we exploit the femtosecond timing noise of frequency comb light to synchronize the time and frequency at two remote sites. This technique should enable future distributed optical clock networks. In the second application, we exploit the broad spectrum of frequency comb light to probe the atmospheric infrared absorption and thereby measure important atmospheric gases, such as carbon dioxide and methane, with high precision.

概要： A short introduction for the mode-locking and a brief review of recent work on high power femtosecond fiber laser are demonstrated, which shows that few cycle laser pulse can be obtained by optimization of nonlinear process in fiber laser system. Pulse dynamics optimization also bring great impact on the time jitter of the pulse train. These new laser resources provide convenience for novel applications in the fields of high precision fabrication and measurement, experimental quantum physics, functional materials, etc.

概要: A laser frequency comb provides a vast array of absolutely known and precisely controlled spectral lines that can be used for direct spectroscopy as well as spectral calibration. In this talk, we present recent laser and nonlinear optics advances that extend laser frequency comb spectral coverage from 350 nm to beyond 20,000 nm. This is accomplished with robust erbium-fiber laser technology in the 1550 nm region that pumps nonlinear photonic platforms such as lithium niobate, gallium phosphide, and silicon nitride. Of particular interest is a simple and robust method for generating frequency combs spanning the 6-20 micron fingerprint region through intra-pulse difference frequency generation in an orientation-patterned gallium phosphide crystal. This frequency comb is orders of magnitude brighter than thermal light sources and comparable to infrared beam lines at synchrotron user facilities. We demonstrate the utility of our unique, coherent light source for high-resolution (100 MHz), dual-comb spectroscopy of molecular compounds.

概要： Precision is a common aspect that governs most of today’s leading-edge technologies including IT, BT, NT and aerospace technology. In response to ever-growing demands on precision, various laser sources have been used to attain sub-wavelength precision in many fields of fabrication and metrology by means of photons. This precision-directed laser-based photonics will continue to advance to the direction of ultraprecision to achieve better resolutions, larger functional ranges, higher throughputs, and more improved stability. Nonetheless, the light sources available today are limited in the wavelength bandwidth, photon energy, spatial and temporal coherence, and peak power, which consequently hinders breakthroughs toward the realm of ultraprecision. The research objective of the Precision Engineering & Metrology Group at KAIST is to investigate the technological possibilities of ultrashort mode-locked lasers with the aim of establishing the new foundations for ultraprecision that will enable nano-fabrication and distance and dimensional metrology over extensive ranges as demanded in the next generation of precision engineering. To the end, a systematic approach will be pursued to generate noble coherent light sources covering the broad optical spectrum spanning from THz waves, infrared, visible to extreme violet light radiation by making the most of ultrafast femtosecond laser pulses.