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Nonlinear-optical conversion and light absorption effects in KTP-family Pockels cells employed in picosecond lasersтезисы доклада
- Авторы: Morozov V.B., Olenin A.N., Rusov V.A., Tunkin V.G., Yakovlev D.V.
- Сборник: IV Int. Conf. on Ultrafast Optical Science (Ultrafast Light-2020) Book of abstracts, September 28 - October 2, 2020
- Тезисы
- Год издания: 2020
- Место издания: Lebedev Physical Institute Moscow Moscow Lebedev Physical Institute, Moscow
- Первая страница: 295
- Последняя страница: 296
- Аннотация: Practical and reliable, highly stable, compact and easy maintaining laser sources generating picosecond pulses of mJ and multi-mJ energy levels at repetition rates within kHz are subjects of multiple requests nowadays. Key elements underlying high-speed schemes of picosecond pulses gating and beams redirecting are electro-optical modulators (EOMs), i.e. Pockels cell (PC) plus polarizer that are utilized for operational control of generation since the early laser era. Demands for better energy and temporal stability, effective shortening of picosecond pulses seed and it further amplifying are stimulating development of electro-optically governed combined schemes based on active-passive modelocking, cavity Q-factor control, negative feedback (NFB), switching and dumping cavities. Crystals of KTP-family (KTP and RTP) meet basic requirements for advanced electro-optical materials and are characterized by a unique combination of physical parameters that are needed for high EOM performance: low absorptivity at the laser wavelength, high damage threshold, low piezoelectric coupling of electric field to acoustics and relatively large electro-optical coefficients. In fact, they outperform most of other crystals by combination of its characteristics. PCs based on KTP/RTP are assembled as a rule by the thermal compensated scheme with two equal lengths crystals. There are two variants of PC assembling that characterized by largest electro-optical coefficients values with corresponding light propagation along X (X-cut) or Y (Y-cut) axes. High-peak power picosecond pulses propagation through PCs based on KTP/RTP crystals may be accompanied by noticeable nonlinear conversion to second (SH) and third harmonics (TH) despite the lack of synchronism conditions. TH for Nd:YAG fundamental is out of KTP/RTP crystals transparency ranges then its conversion efficiencies may be rather high due to resonance vicinity. Since KTP/RTP crystals effectively absorb TH radiation this may cause additional heat loading. When influence was increasing on EOMs due to repetition rate growing it leaded to unwanted depolarization, disturbance of the operating mode and also to crystal degradation. SH and TH conversions efficiencies for KTP and RTP crystals were estimated based on literature data and were compared with measured ones. Generation efficiencies of SH and TH in PCs based on KTP and RTP crystals was evaluated using output of an independent supplementary Nd:YAG picosecond laser as a pump.
- Добавил в систему: Морозов Вячеслав Борисович