Nedavno, Russell Center za naprednu svjetsku nauku o optičkim i finim mehaničarima Vingzhou, Univerziteta i tehnologije Ujedinjenih nacija za napredne studije, i preciznu mehaniku Kineske akademije i IFIBO (NINGBO), LTD ., doo je objavio svoje najnovije rezultate istraživanja u međunarodnom vrhunskim optičkim časopisima "Optica", a prvi put su postigli visoku efikasnost, visoke vjernosti i visoki čistoću nalik na režim fleksibilan prijenos u blizini razine u blizini femtosekundi, 2 . 8 μm opseg srednje infracrvene impulse u šupljim jezgri PCF). Ovaj rezultat ne samo da pruža efikasno rješenje nedostataka srednje infracrvenog ultra tastera u prijenosu, ali postavlja i temelj za širenje srednje infracrvene laserske aplikacije
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%.
Eksperimentori su takođe uporedili shemu prenosa sa prostorne optičke staze iste dužine i solid-core fluoridne vlakne ., a nelinearni efekt je prejako, što rezultira razdvajanjem vremenskih domena i očigledno spektralni redroživi, koji provjerava jedinstvene prednosti šupljeg fotonije Kristalna vlakna u prenosu visokog vrhunskog napajanja ultra i eksperiment postigla je visoku efikasnost, visoku efikasnost čistoću i visoko-jednosmjernu čistoću srednje infracrvene laserske fleksibilne tehnologije, polaganje širokopojasnih srednjih infracrvenih izvora ultrafast u spektroskopiju, infracrvene kontramjere i daljinske senzing .
Relevantni rezultati istraživanja objavljeni su u gornjem časopisu Lasera i optoelektronike, s naslovom "Fleksibilna isporuka širokopojasnih impulsa u obliku apsorpcije u šupljim jezgrama, zajednički doktorski student Shanghai Instituta za optiku i tehnologiju Kineski Hangezhou Institute za naprednu tehnologiju i LI Zeqing, doktorski student Šangajskog instituta za optiku i finu mehaniku, su prvi autori, a Huang Jiapeng, Jiang Xin i Pang Meng iz Russell Centra su koarektivni autori .
Slika 1. eksperimentalni podešavanje i rezultati. (a) eksperimentalni optički staza . objektiv, obloženi CAF2 plano-konveksni objektiv; HWP, pola talasna ploča; QWP, ploča od četvrt talasa; FM, savijanje ogledala; FTIR, Fourierov transformirani infracrveni spektrometar; AC, autocorelator . (b) Slika vlakana . (c) Izlazna snaga za sjensku površinu (plava, desna osovina) . (d) izlazna snaga kroz . meter-dugi šupljina PCF . (E) koristeći 30 mm ZNSE i 5 mm GE materijali, ostvaren je pulsni izlaz sa širinom impulsa u blizini od 98 FS .
Slika 2. Usporedba različitih prenosnih režima . (a) normalizirani apsorpcioni spektar vodene pare . (b) izravni laserski izlaz (siva) i prenosni spektar u prostornoj optičkoj stazi u zraku (zeleno) i prenosni spektar šupljeg PCF-a u vakuumu (crveni). desna strana prikazuje prošireni spektar u rasponu od. μm . (c) Raman Solitona u čvrstom fluoridnom vlaku . FTIR spektar je s lijeve strane i trag autokorelacije je s desne strane .
