Photosensitivity of composite heavily erbium-doped phosphosilicate fibers

Rybaltovsky A. A., Egorova O., Vasiliev S., Zhuravlev S., Butov O.V., Semjonov S., Galagan B., Sverchkov S., Denker B. Photosensitivity of composite heavily erbium-doped phosphosilicate fibers. In: International Conference Advanced Laser Technologies (ALT'19), 15-20 September 2019, Prague, Czech Republic

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Аннотация

Single frequency fiber lasers are attractive for many photonic applications. Narrowband emission of this laser type is usually provided by a relatively short (10-20 mm) Fabry-Perot structure (or phase-shifted fiber Bragg grating (FBG)) created in the fiber core. Two factors have key importance for short-length laser structures: high pump absorption (emission gain) per unit length and sufficient photosensitivity of the active fiber. A novel composite heavily erbium-doped phosphosilicate (24 mol. % of phosphorus oxide, 3 mol. % of aluminium oxide and 0.39 mol. % of erbium oxide) single-mode fiber has been recently developed using a rod-in-tube technique. It was shown that the fiber has good lasing properties as well as rather high photosensitivity to 193-nm radiation, which allowed achieving a stable single frequency lasing using optical pump at 980 nm. In this work the photosensitivity of this composite fiber was further investigated. Particularly, dose dependencies of modulation amplitude and mean index change have been measured for both pristine and hydrogen-loaded fiber samples. Thermal stability (temperature annealing) of the induced index change has been also analyzed. It was shown that the UV-induced index gradually decreases with temperature increase, nevertheless some magnitude of induced index remains unerased until the core material melts (600-650°C). A composite fiber with a core diameter of 5 µm (cut-off wavelength - 1.43 µm) has been used for investigation. An ArF excimer laser (Coherent COMPexPro) emitting 20-ns pulses at 193 nm (repetition rate - 10 Hz) was used for fiber side irradiation with the energy density of about 200 mJ/cm2 per pulse. Low temperature hydrogen loading of fiber samples has been performed in gas chamber (H2 pressure - 120 atm) at 90°C during 24 hours. FBGs were written via the 10-mmlong phase mask having a period of 1064 nm. Dose dependences of UV-induced index modulation amplitude and average index change measured for both as prepared and H2-loaded fibers are shown in Fig.1. Similar to germane-silicate glass, molecular hydrogen dissolved in the phosphosilicate glass increases its photosensitivity greatly. The observed photosensitivity is enough to fabricate highly reflecting FBGs, necessary to create single-frequency laser cavities. Other results obtained in our experiments on induction and erasure of refractive index in the core of the composite Er-doped phosphosilicate fiber will be presented at the Conference.

Тип объекта: Доклад на конференции или семинаре (Доклад)
Авторы на русском. ОБЯЗАТЕЛЬНО ДЛЯ АНГЛОЯЗЫЧНЫХ ПУБЛИКАЦИЙ!: Рыбалтовский А.А., Егорова О., Васильев С., Журавлев С., Бутов О.В., Семёнов С., Галаган Б., Сверчков В., Денкер Б.
Подразделения (можно выбрать несколько, удерживая Ctrl): 195 лаб. волоконно-оптических технологий
URI: http://cplire.ru:8080/id/eprint/7662
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