Pred kratkim so Russell Center za napredno Lightwave Science of Hangzhou Inštitut za optiko in fino mehaniko, Univerza za znanost in tehnologijo Združenih narodov Inštitut za napredne študije Hangzhou, Šanghajski inštitut za optiko in natančnost Mehanike kitajske akademije in IFBO (Ningbo) optoelectronics Technology ", ki so v najnovejših raziskavah objavili svoje najnovejše raziskave, ki so objavili svoje najnovejše raziskave, ki so objavili svoje najnovejše raziskave, ki so objavili svoje najnovejše raziskave, ki so objavili svoje najnovejše rezultate, ki so objavili svoje najnovejše raziskave, LTD. Dosegli so visoko učinkovitosti, visoke zveze in visoko eno mode čistost fleksibilnega prenosa na ravni na ravni na stotine femtosekund, 2,8 μm pasu srednjega infrardečega impulzov v votlih fotonskih kristalnih vlaknih (votlo-jedrni PCF). Ta rezultat ne zagotavlja samo učinkovite rešitve za pomanjkljivosti srednje infrardečega ultrafaznega impulzov pri prenosu, ampak tudi postavlja temelje za širitev srednjega infrardečega laserskega 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%.
Eksperimentatorji so primerjali tudi shemo prenosa s prostorsko optično potjo iste dolžine in trdno jedrnimi fluoridnimi vlakni. Rezultati kažejo, da je med prenosom ultra hitrih impulzov v trdo-jednih fluoridnih vlaknih nelinearni učinek premočan, kar ima za posledico cepljenje časovnih domenov in očitno spektralno rdečo premikanje, ki preverja edinstvene prednosti fotonskih kristalnih vlaken v Hollod-Core Conic. Poskus je dosegel visoko učinkovitost, visokozmogljivo in čistosti na načinu srednjega infrardečega laserskega fleksibilnega prenosa, ki je postavil dober temelj za uporabo širokopasovnih srednjih infrardečih virov svetlobe v spektroskopiji, infrardečih protiukrepih in občutljivosti na daljavo.
Ustrezni rezultati raziskav so bili objavljeni v Top Journal of Lasers in Optoelectronics, Optica, z naslovom "Prilagodljiva dostava širokopasovnih povezav, 100 FS srednjega infrardečega impulzov v vodnem absorpcijskem pasu z uporabo votlih fotonskih kristalnih vlaken". Lin Wei, skupni doktorski študent Šanghajskega inštituta za optiko in fino mehaniko ter Univerze za znanost in tehnologijo Kitajske Inštitut za napredno tehnologijo Hangzhou, in Li Zeqing, doktorski študent Shanghai Institute of Optics and Fine Mechanics, so avtorji soustanovitve, in Huang Jiapg, Jiang Xin in Pang Meng Meng Meng Meng Meng Meng Meng Meng Meng Meng Meng Meng Meng Meng Meng-a Meng Meng-a Meng Meng-a Meng Meng-a.
Slika 1. Eksperimentalna nastavitev in rezultati. (a) Eksperimentalna optična pot. Leča, prevlečena s kaf2 plano-konveksna leča; HWP, pol valovni krožnik; QWP, četrt-valovni krožnik; FM, upogibno ogledalo; FTIR, Fourier Transform infrardeči spektrometer; AC, avtokorelator. (b) SEM slika strukture vlaken. (c) Spekter izgube, izmerjen z metodo okrnic, senčno območje predstavlja merilno negotovost (oranžna, leva os) in izračunano disperzijsko krivuljo (modra, desna os). (d) Izhodna moč skozi 5- meter-dolgega votlega jedra PCF. (E) Z uporabo 30 mM Znse in 5 mm GE materialov je bil dosežen impulzni izhod s skoraj transformacijsko omejeno širino impulza 98 FS.
Slika 2. Primerjava različnih načinov prenosa. (a) Normaliziran absorpcijski spekter vodne pare. (b) Neposredni laserski izhod (sivi) in prenosnem spektru na prostorski optični poti (vijolična), spekter prenosa votlega jedra PCF v zraku (zelena) in spekter prenosa votlega jedra PCF v vakuumu (rdeča). Na desni strani je prikazan povečan spekter v območju 2. 7-2. 8 μm. (c) Generacija Raman Soliton v trdnem jednem fluoridnem vlaknu. FTIR spekter je na levi, sled avtokorelacije pa je na desni.
