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Novel Visible-NIR Ultrafast Sources

Posted on:2017-02-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:W L TianFull Text:PDF
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In recent years, ultrashort pulse lasers are widely applied in various of fields, such as precision matching, biomedical, physics, chemistry, information communication and military. Aiming at different demands for ultrafast lasers at different wavelengths, this dissertation focuses on the development of novel ultrafast sources in the visible and near-infrared region including all solid-state ultrafast lasers based on novel laser media (Yb doped orthosilicates) and synchronously pumped femtosecond optical parametric oscillators.The main research works in this dissertation are summarized as follows:1. Taking the multi-peaks structure on the emission spectra of the two crystals, the dual-wavelength synchronously mode-locked Yb:YSO and Yb:LSO lasers are firstly implemented. With a 3-mm long,5 at.% doped Yb:YSO crystal, mode-locked pulses at both 1059.2 nm and 1081.2 nm are obtained, the average output power is 164 mW. Periodic pulse train with 169 fs pulse duration at 1.4 THz repetition rate is generated by beating between the two mode-locked pulses at different wavelength; Dual-wavelength synchronously mode-locked at 1060.3 nm and 1084.2 nm with 225 mW average power is also realized using a 3-mm long,5 at.% doped Yb:LSO crystal. Ultrafast THz beatings with 590 fs pulse duration at 0.85 THz repetition rate can be distinctly observed from the measured autocorrelation trace. In addition, the dissipative soliton mode-locking operation in either Yb:LSO or Yb:YSO lasers is also observed with an all normal dispersion cavity for the first time.2. The femtosecond kerr-lens mode-locking operations of Yb:LYSO、Yb:LSO and Yb:GSO oscillators are firstly demonstrated. With reasonable dispersion compensation, as short as 61、54 and 72 fs pulses are produced using 3-mm long,5 at.% doped Yb:LYSO、 Yb:LSO and Yb:GSO crystals, respectively. Compared with the results from previous SESAM passively mode-locking operation, the generated pulses have been shorten by 10、5 and 5 times, respectively, which proves that Yb doped orthosilicates have great potential on ultrashort pulses generation. Moreover, stable mode-locked pulses with 3 W average power at 1035 nm and 1042 nm, respectively, are also obtained from the SESAM passively mode-locked Yb:LYSO laser. the pulses at 1035nm and 1042 nm have the pulse durations of 297 fs and 214 fs, respectively. The sub-100 femtosecond pulses generated in our experiment as well as the stable passively mode-locking operation with high output power certify that Yb doped orthosilicates are excellent ultrafast laser media with the potential generating ultrashort pulses with high average power.3. Using the home-made SESAM passively mode-locked Yb:LYSO oscillator as pumping source, we demonstrate a Yb-solid-state-laser pumped femtosecond OPO, which is believe to be the first time in domestic. Using a MgO:PPLN as nonlinear crystal, tunable signals from 1428nm to 1763nm are obtained. The wavelength of signal pulses is extended to 768-874 nm range by further intracavity doubling.4. With a 2.5-mm long LBO crystal,4.1 W femtosecond green pulses with high beam quality is produced by frequency doubling the commercial Yb:KGW oscillator, corresponding to as large as 57.7% conversion efficiency. Then, we demonstrate a green pumped femtosecond BIBO-OPO, to be our best knowledge, for the first time. Tunable signals from 660 nm to 1057 nm are achieved with the maximum output power of 1.09 W. The shortest pulse duration of the signals is only 71 fs after compression outside the cavity. Whilst, idlers in the range of 1150-1900 nm are also generated with the maximum output power of 414 mW and pulse durations between 94-223 fs.5. We demonstrate a green pumped femtosecond LBO-OPO, generating tunable signals from 660-1030 nm with the maximum output power of 1.9 W, which corresponding to an optical-optical conversion efficiency of 52.7%. This is, to our best knowledge, the highest conversion efficiency from a femtosecond OPO.6. Based on harmonic pumping method, green pumped femtosecond OPO operating at high repetition rate is realized for the first time. By designing a very compact ring cavity, green pump femtosecond OPO at 755 MHz repetition rate with a 2.4-mm long BIBO is demonstrated, generating 581 mW signal at 712 nm with 166 fs pulse duration.7. Using linear cavity, high-power Yb:KGW oscillator pumped femtosecond OPO at repetition rates from 7.7 GHz to 37.3 GHz are demonstrated, respectively, with a MgO:PPLN as nonlinear crystal. The generated signal is centered at 1515 nm, which belongs to the communication band. It is believed that the 37.3 GHz repetition rate is the highest one up to day, when the OPO generates 90 mW signal with 163 fs pulse duration.
Keywords/Search Tags:Yb doped orthosilicates, all solid-state ultrafast lasers, dual-wavelength synchronously mode-locking, synchronously pumped optical parametric oscillator, high repetition rate operation
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