Spectroscopy and lasing of cryogenically cooled Yb, Na:CaF2
Spectroscopy and lasing of cryogenically cooled Yb, Na:CaF2
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DOI：
10.1007/s00340-009-3740-4
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发表时间：
2008-12
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通讯作者：
A. Pugžlys;G. Andriukaitis;D. Sidorov;A. Irshad;A. Baltuska;W. Lai;P. Phua;L. Su;J. Xu;H. Li;R. Li;S. Alisauskas;A. Marcinkevičius;M. Fermann;L. Giniu̅nas;R. Danielius
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作者：
A. Pugžlys;G. Andriukaitis;D. Sidorov;A. Irshad;A. Baltuska;W. Lai;P. Phua;L. Su;J. Xu;H. Li;R. Li;S. Alisauskas;A. Marcinkevičius;M. Fermann;L. Giniu̅nas;R. Danielius
研究了一种新型的Na+共掺Yb3+：CaF2激光晶体在10~290℃温度范围内的吸收、光致发光和连续激光特性，低温冷却导致1000 nm以上光谱区域基态吸收消失，发射截面和吸收截面显著增加。Yb3+，Na+共掺CaF2晶体的一个特殊优点在于可以在零声子线附近直接泵浦，同时几乎完美地避免了与受激辐射的重叠。在输出耦合器为28%的连续激光运转中，获得了接近92%的理论极限斜率效率，从而进一步证明了低温运转的优势。通过将来自飞秒Yb光纤振荡器的展宽脉冲注入低温DPSS Yb3+， Na+：CaF2再生放大器中，我们获得了重复频率为1 kHz，光谱带宽超过12 nm的>；3-mJ脉冲。经倍频FROG验证，用单个光栅压缩器将脉冲压缩到173fS。种子谱幅度的整形和高阶位相的主动控制是获得多毫焦耳能量下的亚200飞秒脉冲的关键。
Absorption, photoluminescence and cw-lasing properties of a novel Na+-codoped Yb3+:CaF2laser crystal are investigated in the temperature range from 10 K to 290 K. Cryogenic cooling leads to the disappearance of the ground-state absorption in the spectral region above 1000 nm and a substantial increase of emission and absorption cross-sections. A particular advantage of the Yb3+, Na+-codoped CaF2crystal lies in the possibility of a direct pumping in the vicinity of the zero phonon line while nearly perfectly avoiding an overlap with the stimulated emission. Further advantages of the low-temperature operation are demonstrated by achieving a close to the theoretical limit slope efficiency of 92% in a cw-laser operation with an output coupler of 28%. By seeding stretched pulses from a femtosecond Yb fiber oscillator into a cryogenically cooled DPSS Yb3+, Na+:CaF2regenerative amplifier, we obtain >3-mJ pulses at a 1-kHz repetition rate with a spectral bandwidth exceeding 12 nm. The pulses are compressed with a single grating compressor to 173 fs as verified by SHG FROG. Shaping of the spectral amplitude of the seed and active control of the higher-order phase is shown to be crucial for obtaining sub-200-fs pulses at multi-mJ energies.