For nylig var Russell Center for Advanced Lightwave Science fra Hangzhou Institute of Optics and Fine Mechanics, De Forenede Nationers University of Science and Technology Hangzhou Institute for Advanced Studies, Shanghai Institute of Optics and Precision Mechanics of the Chinese Academy of Sciences, og Ifibo (Ningbo) Optoelectronics Technology Co .}, ltdd .} publicerede deres senestresultater I International Top Optical Journal "Optica" og opnåede for første gang den højeffektive, højfidenskab og høje enkelt-mode renhed fleksibel transmission af næsten watt-niveau, hundreder af femtosekunder, 2 . 8 μm bånd midt-infrarøde impulser i hul-core fotonisk krystalfiber (Hollow-Core PCF). Dette resultat giver ikke kun en effektiv løsning på manglerne ved midt-infrarøde ultrahastiske impulser i transmission, men lægger også grundlaget for udvidelse af midtinfrarøde laserapplikationer
High-power mid-infrared ultrafast broadband light sources have important applications in advanced spectroscopy, material fine processing, medical surgery, and remote sensing. The limitations of laser transmission have hindered the further expansion of mid-infrared laser applications. In traditional transmission methods, the absorption of various gas molecules in the spatial optical path causes deformation of the output light spot and deterioration of pulse quality. Solid mid-infrared optical fiber has serious nonlinear accumulation, which causes serious distortion of the output time-frequency signal. To solve this problem, the research team used a self-made single-hole eight-ring structure Hollow-core PCF (length 5 m) to transmit mid-infrared ultrafast pulses. Thanks to the advantages of low transmission loss, low nonlinear effect accumulation and support for rapid vacuum extraction of Hollow-core PCF, the team not only solved the problems caused by traditional transmission methods, but also successfully achieved efficient transmission with an overall efficiency of >70%.
During the experiment, the experimenters used a self-built mid-infrared pulse fiber laser as the light source and a 5 m long Hollow-core PCF as the transmission medium. The two ends of the Hollow-core PCF were fixed in the air chamber so that the Hollow-core PCF could be evacuated using a vacuum pump. After the vacuum was drawn (the entire extraction process took less than 1 minute, and the gas pressure was drawn to ~10 mbar), the team successfully achieved an overall laser efficiency of > 70%, a Gaussian spot output that was close to the diffraction limit, and the entire system showed excellent stability. In addition, the spectral shape of the output in the frequency domain was basically consistent with the input. In the time domain, due to the small amount of waveguide dispersion of the hollow-core PCF (-2.04 fs2/mm @ 2.8 μm), the pulse width was widened from the input 117 fs to 404 fs. Subsequently, the experimenters added Ge and ZnSe positive dispersion materials to compensate for the negative dispersion introduced by the hollow-core PCF, coupling lens and air chamber window, and obtained an output with a pulse width of 98 fs (close to the transformation limit pulse width of 96 fs), with a peak power of 170 kW. In addition, the experimenters also used the autocorrelation trace to estimate that the output fundamental mode energy accounted for >95%.
Eksperimenterne sammenlignede også transmissionsskemaet med den rumlige optiske sti i samme længde og fast-core fluorfiber . Resultaterne viser, at under transmission af ultrahastiske pulser i fast-core fluoridfibre, er den ikke-lineære virkning for stærk, hvilket resulterer i tidsdomæne-opdeling af pulserer og en åbenlys spektral rødhift, som verificerer den unikke fordel, der resulterer i tidsdomæne-fotoniske fotoniske pulser og en åbenlys spektrale rødlige rødskab Krystalfibre i transmission af høj-spids kraft midt-infrarøde ultrahastiske impulser . Eksperimentet opnåede højeffektiv, høj-tro sensing .
The relevant research results were published in the top journal of lasers and optoelectronics, Optica, with the title "Flexible delivery of broadband, 100 fs mid-infrared pulses in the water-absorption band using hollow-core photonic crystal fiber". Lin Wei, a joint doctoral student of Shanghai Institute of Optics and Fine Mechanics and University of Science and Technology of China Hangzhou Institute of Avanceret teknologi og Li Zeqing, en doktorand ved Shanghai Institute of Optics and Fine Mechanics, er de co-første forfattere, og Huang Jiapeng, Jiang Xin og Pang Meng fra Russell Center er de med-korresponderende forfattere .
Figur 1. Eksperimentel opsætning og resultater . (a) Eksperimentel optisk sti . objektiv, coated caf2 plano-konveks objektiv; HWP, halvbølgeplade; QWP, kvartbølgeplade; FM, Bend Mirror; FTIR, Fourier transform infrarød spektrometer; Ac, autokorrelator . (b) SEM-billede af fiberstrukturen . (c) tabsspektret målt ved hjælp af trunkeringsmetoden, det skraverede område repræsenterer målingens usikkerhed (orange, venstre akse) og den beregnede dispersionskurve (blå, højre akse) . (D) udgangsstrøm gennem en 5- måle (blå, tors) {.} (D) output Power gennem en {5-}} måle. Hollow-core pcf . (e) ved hjælp af 30 mm ZnSE og 5 mm GE-materialer blev en pulsudgang med en næsten transformationsbegrænset pulsbredde på 98 fs opnået .
Figur 2. Sammenligning af forskellige transmissionstilstande . (a) Normaliseret absorptionsspektrum af vanddamp . (b) Direkte laserudgang (gråt) og transmissionsspektrum i det spatiale optiske sti (lilla), transmissionsspektrum af hollow-core pcf i luft (grøn) og transmissionsspektrum i det spatiale optiske sti (lilla) (rød) . Højre side viser det forstørrede spektrum i området 2.7-2.8 μm . (c) Raman Soliton-generation i en fast-core fluorfiber . ftir spektret er til venstre, og autokorrelationssporet er på højre {{{10 {.}}
