An 11-fs, 5-kHz optical parametric/Ti:sapphire hybrid chirped pulse amplification system

We developed a noncollinear optical parametric/Ti:sapphire hybrid chirped pulse amplification system, which consists of a two-pass optical parametric amplifier and multipass Ti:sapphire amplifiers with adaptive phase control. The use of the parametric amplifier instead of a regenerative amplifier broadened the final spectrum significantly, resulting in 11-fs pulses with a peak power of 18 GW at 5 kHz. PACS 42.55.-f; 42.65.Re; 42.65.Yj     

Development of a 100-kHz femtosecond high-power laser using down-chirped regenerative amplification

We have developed a 100-kHz high-power downchirped-pulse-amplification (DPA) Ti:sapphire laser. A regenerative amplifier, acoustooptically switched and pumped by a Q-switched green laser, is employed for the high-energy amplification with a high repetition rate. Dispersion control is achieved, based on the DPA technique, by use of a prism-grating stretcher and a SF10 glass compressor. We have obtained 28 μJ 45 fs laser pulses at 100 kHz with a compression efficiency of 95%, and further compression down to 20 fs is possible due to the broad amplified spectrum.     

0.85-PW, 33-fs Ti:sapphire laser

We have successfully produced a laser pulse with a peak power of 0.85 PW for a pulse duration of 33 fs in a four-stage Ti:sapphire amplifier chain based on chirped-pulse amplification. To our knowledge this result represents the highest peak power pulses yet produced in any Ti:sapphire chirped-pulse amplification system.     

High-average-power kilohertz-repetition-rate sub-100-fs Ti:sapphire amplifier system

We report on a femtosecond Ti:sapphire laser amplifier system that generates pulse energies >5 mJ at a 1-kHz repetition rate. The system consists of regenerative and multipass amplifiers and uses the technique of chirped-pulse amplification. When the system was seeded with 70-fs pulses at 800 nm from a self-mode-locked Ti:sapphire oscillator, amplified pulses of 94-fs duration at a repetition rate of 1 kHz and an average output power of 5.4 W were produced. The amplified pulse-repetition rate is variable from 250 Hz to 3 kHz. Pulse energies of >7.5 mJ were obtained at 500 and 250 Hz.     

Self-starting 6.5-fs pulses from a Ti:sapphire laser

We demonstrate self-starting 6.5-fs pulses from a Kerr-lens mode-locked Ti:sapphire laser with 200-mW average output power at a pulse repetition rate of ~86 M Hz. This is to our knowledge the shortest pulse ever generated directly from a laser. For dispersion compensation we used a prism pair in combination with double-chirped mirrors, which balances the higher-order dispersion of the prism pair and therefore flattens the average total group-delay dispersion in the laser cavity. For self-starting mode locking we used a broadband semiconductor saturable-absorber mirror.     

Sub-10-fs, terawatt-scale Ti:sapphire laser system

A three-stage, 1-kHz amplifier system delivering pulses shorter than 10 fs with a peak power in excess of 0.3 TW is reported. Passive and active spectral intensity and phase control allows the preservation of a bandwidth of 120 nm (FWHM) to as high as multimillijoule energy levels and temporal compression of the broadband pulses close to their Fourier limit. The system is scalable to peak powers well beyond 1 TW and holds promise for substantially advancing the state of the art of coherent laboratory soft-x-ray sources.     

Broadband spectral shaping in a Ti:sapphire regenerative amplifier

A birefringent crystal quartz plate of known thickness has been used as a spectral filter for spectral shaping in a Ti:sapphire regenerative amplifier. The spectral profile of the amplified pulse ejected from the regenerative amplifier was observed while adjusting the birefringent crystal plate in the cavity. By altering the gain spectrum, the bandwidth of the regeneratively amplified pulse was increased from 18 to 35 nm by using a 0.34-mm thick birefringent plate. The output pulse spectrum from the regenerative amplifier neared the bandwidth of the seed pulse. As a comparison, we used a coated filter outside the regenerative amplifier cavity, and the bandwidth of the regeneratively amplified pulse was stretched to 28 nm. When the bandwidth was stretched to 35 nm, the pulse was compressed to 35 fs.     

100-TW sub-20-fs Ti:sapphire laser system operating at a 10-Hz repetition rate

We developed a compact three-stage Ti:sapphire amplifier laser system that produced peak power in excess of 100 TW for a pulse duration of less than 19 fs and an average power of 19 W at a 10-Hz repetition rate. A final 40-mm-diameter Ti:sapphire amplifier is pumped by a Nd:YAG master-oscillator-power-amplifier system that produces ~7-J output of 532-nm radiation. The spatial beam quality is approximately 2 times diffraction limited for the full amplified compressed output pulse. With f/3 optics, this system should therefore be capable of producing a focused intensity of ~3x10(20) W/cm(2) .     

Noise characterization of an all-solid-state mirror-dispersion-controlled 10-fs Ti:sapphire laser

We characterized the phase and amplitude noise of a mirror-dispersion-controlled 10-fs Ti:sapphire laser pumped by a frequency-doubled cw diode-pumped Nd:YVO₄ laser and compared with these of the Ti:sapphire laser pumped by an Ar-ion laser. The rms timing jitters and rms amplitude noise for the all-solid-state and Ar-ion laser pumped Ti:sapphire lasers are calculated to be 0.31 ps rms and 0.71 ps rms and 0.15% rms and 0.32% rms, in the frequency range from 20 kHz to 400 kHz, respectively. The phase and amplitude noise characteristics of the Ti:sapphire laser were greatly improved by using the diode-pumped solid state laser as a pump source.     

All-solid-state high-peak-power Ti:sapphire laser system above 5-kHz repetition rate

We have developed an all-solid-state Ti:sapphire laser system, which produces 22-fs, 0.2-TW pulses at 5-kHz repetition rate. An average power of 22.2 W is the highest ever obtained in ultrashort laser sources. The serious thermal lensing due to high power pumping in a small area of Ti:sapphire crystal is controlled successfully by a stable quasi-cavity with two concave mirrors. The attempt to increase the repetition rate to 10 kHz is also described.     

Two-color chirped-pulse amplification in an ultrabroadband Ti:sapphire ring regenerative amplifier

We have developed a high-energy, ultrabroadband Ti:sapphire ring regenerative amplifier capable of producing in excess of 20-mJ output at a 10-Hz repetition rate. The technique of chirped-pulse amplification is used to generate two-color, time-synchronized pulses with central wavelength separations of up to approximately 120 nm and with a total energy of 10 mJ by use of a regenerative pulse-shaping technique. Mid-infrared pulses tunable from 6 to 11 microm are generated by difference frequency mixing the two-color outputs.     

High-power sub-10-fs Ti:sapphire oscillators

Received: 10 March 1997/Revised version: 16 April 1997     

Generation of 7-fs laser pulse directly from a compact Ti:sapphire laser with chirped mirrors

A compact femtosecond Ti:sapphire laser resonator consisting of three chirped mirrors and one output coupler was designed. By accurately balancing the intra- cavity dispersions between Ti:sapphire crystal, air and chirped mirrors, we directly generated the laser pulse shorter than 7 fs at the average power of 340 mW with 3.1 W pump. The repetition rate of the laser oscillator is 173 MHz at the centre wavelength of 791 nm, and the ultrabroaden spectrum covers from 600 nm to 1000 nm. To the best of our knowledge, this is the simplest laser resonator capable of generating sub-10 fs laser pulse.     

High-repetition-rate 12 fs pulse amplification by a Ti:sapphire regenerative amplifier system

We demonstrate the direct generation of 12 fs pulses from a Ti:sapphire regenerative amplifier system at a 1 kHz repetition rate utilizing properly designed broadband components for chirped-pulse amplification. Optimized designs of a regenerative amplifier with a multilayer gain-narrowing compensator and an adaptive dispersion compensator with a spatial light modulator contribute to the shorter pulse amplification.     

采用环形再生腔结构的飞秒激光啁啾脉冲放大研究

采用环形再生腔结构的啁啾脉冲放大技术方案, 在重复频率100 Hz,单脉冲能量33.1 mJ的532 nm激光抽运下, 从钛宝石激光中获得了单脉冲能量9.84 mJ的放大输出, 对应的斜效率达33.1%.在重复频率10 Hz的情况下, 同样获得了单脉冲能量为9.64 mJ, 对应斜效率达36.8%的高效率放大结果. 通过色散补偿压缩该啁啾激光脉冲后的单脉冲能量为6.36 mJ, 脉冲宽度为59.7 fs. 测量结果表明典型的能量不稳定度为1.85%. 关键词： 啁啾脉冲放大 再生放大 飞秒激光 环形腔     

全固态kHz啁啾脉冲飞秒激光放大器

要建造大功率超强激光系统,必须将nJ量级的种子进行放大,以得到mJ量级以及更高能量的激光输出.为达到这个目的,必须使种子能量指数增加,再生腔放大器是实现这一目的的良好途径;同时,为了得到更稳定的激光输出,须采用高重复频率的泵浦源.为此,设计了一种kHz重复频率激光泵浦的再生放大器,使用15 mJ的527 nm的绿光泵浦,得到了约2.3 mJ的800 nm放大激光输出,同时,对其输出激光的光谱特性进行了测量,将带宽为40 nm的种子注入后,得到了光谱带宽约为30 nm激光输出.     

Generation of 5-fs pulses and octave-spanning spectra directly from a Ti:sapphire laser

Spectra extending from 600 to 1200 nm have been generated from a Kerr-lens mode-locked Ti:sapphire laser producing 5-fs pulses. Specially designed double-chirped mirror pairs provide broadband controlled dispersion, and a second intracavity focus in a glass plate provides additional spectral broadening. These spectra are to our knowledge the broadest ever generated directly from a laser oscillator.     

Sub-10-fs Ti:sapphire Kerr-lens Mode Locked Oscillator

Assembly of a sub-10-fs Ti:sapphire oscillator using only optical components commercially available in catalogues is reported. It was demonstrated that stable sub-10-fs optical pulses near 800 nm can be generated from a Kerr-lens mode locked oscillator equipped with a pair of prisms to compensate group delay dispersions (GDD) in the cavity. For the GDD control in a 10fs-pulse oscillator it was concluded that chirped mirrors are not always necessary, and a pair of prisms is still available.     

Birefringent plate design for broadband spectral shaping in a Ti:sapphire regenerative amplifier

A method to design a birefringent plate (BP) for broadening spectrum in a regenerative amplifier is presented. Using this method, we design a quartz BP with thickness of 761μm inserted into a Ti:sapphire regenerative amplifier. The gain narrowing effect is reduced efficiently, and the experimental results agree with the calculation well. The bandwidth is broadened from 28 to 62 nm using the designed quartz BP and the pulses are compressed to ～ 23 fs.     

High-power parametric amplification of 11.8-fs laser pulses with carrier-envelope phase control

Phase-stable parametric chirped-pulse amplification of ultrashort pulses from a carrier-envelope phase-stabilized mode-locked Ti:sapphire oscillator (11.0 fs) to 0.25 mJ/pulse at 1 kHz is demonstrated. Compression with a grating compressor and a LCD shaper yields near-Fourier-limited 11.8-fs pulses with an energy of 0.12 mJ. The amplifier is pumped by 532-nm pulses from a synchronized mode-locked laser, Nd:YAG amplifier system. This approach is shown to be promising for the next generation of ultrafast amplifiers aimed at producing terawatt-level phase-controlled few-cycle laser pulses.