钛宝石再生放大器实验研究

分析了啁啾脉冲在钛宝石再生放大器中的能量增益与泵浦光及信号光光束口径的关系。并用不同能量的调Ｑ倍频ＮｄＹＡＧ激光器的５３２ｎｍ光为泵浦光，测量了２ＴＷ钛宝石激光系统中钛宝石再生放大器在无注入信号脉冲时和有注入信号脉冲时的脉冲建立时间及相应的输出能量大小。再生放大器的增益为２×１０７。     

Integrated injection seeded terahertz source and amplifier for time-domain spectroscopy

We used a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier for THz time-domain spectroscopy. A THz input pulse is generated inside a QCL by illuminating the laser facet with a near-IR pulse from a femtosecond laser and amplified using gain switching. The THz output from the QCL is found to saturate upon increasing the amplitude of the THz input power, which indicates that the QCL is operating in an injection seeded regime.     

基于单个BBO晶体载波包络相位稳定的高效率光参量放大器

基于单个BBO非线性晶体,利用非共线光参量放大技术,研究了载波包络相位稳定的高效率可调谐近红外脉冲产生.以载波包络相位稳定的飞秒激光放大系统产生的白光作为种子光,注入一个二类匹配的二级光参量放大器,在1350 nm波段获得抽运-信号光34%的转换效率.利用f—2f光谱相干测量技术,放大脉冲载波包络相位的抖动30 min内小于137 mrad.该方法提供了一种简单高效的载波包络相位稳定的红外脉冲产生技术.     

Multikilohertz optical parametric chirped pulse amplification in periodically poled stoichiometric LiTaO3 at 1235 nm

We demonstrate, for the first time to our knowledge, multikilohertz operation of a double-stage optical parametric chirped pulse amplifier with periodically poled stoichiometric LiTaO3 crystals, seeded by a homemade Cr:forsterite oscillator operating at 1235 nm. The repetition rate of the amplifier could easily be tuned without the use of electro-optic modulators by using a repetition-rate-tunable kilohertz pump laser operating at 532 nm and a time-synchronization unit. Amplified total (signal+idler) energies of 55.9 and 36.2 microJ were achieved at 1 and 5 kHz, respectively. After recompression, the pulse width of amplified idler pulses at 1235 nm amounted to 530 fs.     

Millijoule pulse energy picosecond fiber chirped-pulse amplification system

The efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium (Yb)-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally.A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification (CPA) system and generates mode-locked pulses with hundreds of picosecond widths.Two kinds of large-mode-area (LMA) double-clad Yb-doped fibers are employed to construct the pre-amplifier and main amplifier.All of the adopted instruments help avoid severe nonlinearity in fibers to raise sub-nanosecond pulse energy with acceptable signal-to-noise ratio (SNR).The output spectrum of this fiber-based CPA system shows that amplified spontaneous emission (ASE) is suppressed to better than 30 dB,and the onset of stimulated Raman scattering is excluded.     

Carrier envelope phase stabilization of a Yb:KGW laser amplifier

In this paper we report on the active stabilization of the carrier envelope phase (CEP) of a Yb:KGW chirped pulse amplifier laser system seeded by a Yb-doped solid-state Kerr-lens mode-locked oscillator. The regenerative amplifier delivers 180 fs CEP stable pulses of 30 μJ-1 mJ energy at a repetition rate tunable from 1 to 200 kHz. The bandwidth of the feedback loop was extended by a factor of 5 using a specially designed high-pass filter, which resulted in a dramatic decrease of CEP jitter below 0.45 rad after the amplifier.     

Tunable mid-infrared MHz-rate picosecond pulses generated by optical parametric amplification of white-light continuum in GaSe

The output of a long-cavity 2 MHz all-solid-state Nd:YVO(4) picosecond oscillator with nonlinear optical mirror mode locking is used for direct pumping of an optical parametric amplifier seeded with white-light continuum generated in optical fiber by the same laser to generate tunable (5-12 microm) mid-IR radiation.     

Dependence of Er:Yb-codoped 1.5 μm amplifier on wavelength-tuned auxiliary seed signal at 1 μm wavelength

We report on experiments performed with a cladding-pumped single-mode Er:Yb-codoped single-frequency fiber amplifier simultaneously seeded by a distributed-feedback diode at 1556 nm and a tunable external-cavity diode laser emitting at a wavelength of about 1 μm wavelength. The influence of the output wavelength of the external-cavity laser on amplification and reabsorption behavior of the Yb emission as well as the amplifier performance at a wavelength of 1556 nm is examined experimentally.     

Picosecond laser system with 30-W average power via cavity dumping and amplifying

We present a picosecond laser system with high energy by technologies of cavity dumping and amplifying. Firstly, pulses with 10 ps and ～520 nJ were obtained by cavity-dumped mode-locked laser at 10 kHz repetition rate. Secondly those pulses were seeded into a side-pumped regenerative amplifier (RA). Then pulses output from the regenerative amplifier were amplified by two four-pass post amplifiers. From the laser system pulses with an average power of 30 W corresponding to 3 mJ pulse energy were achieved with the pulse-width of 25.4 ps at repetition rate of 10 kHz.     

Generation of fs laser pulses from a ps pulse-pumped optical parametric amplifier with a beat-wave seed signal

We describe a method of ultrashort-pulse and ultrafast-pulse-train generation through optical parametric amplification of a laser beat wave. Numerical simulation shows that 250-fs laser pulses at 1.55 μm are generated from a beat-wave seeded optical parametric amplifier pumped by a 30-ps laser at 1064 nm. The pulse compression is attributable to sideband generation and parametric amplification under group velocity mismatch. Our experimental result confirms efficient generation of comb-like sidebands for the mixing waves from such an optical parametric amplifier.     

Narrow-band, tunable, semiconductor-laser-based source for deep-UV absorption spectroscopy

Tunable, narrow-bandwidth (<200-MHz), ~215-nm radiation was produced by frequency quadrupling the ~860-nm output of a high-power, pulsed GaAlAs tapered amplifier seeded by an external-cavity diode laser. Pulsing the amplifier increased the 860 nm?215 nm conversion efficiency by 2 orders of magnitude with respect to cw operation. Detection of nitric oxide and sulfur dioxide by high-resolution absorption spectroscopy was demonstrated.     

High power tunable picosecond green laser pulse generation by frequency doubling of an Yb-doped fiber power amplifier seeded by a gain switch laser diode

A compact tunable high power picosecond green laser pulse source based on frequency doubling of an Yb-doped fiber amplifier seeded by a gain switch laser diode has been developed. The fiber amplifier generates the picosecond infrared pulses with average power of 10.3 W, repetition rate of 1 MHz, pulse duration of 150 ps, and tunable range of 20 nm around 1064 nm. For underwater use, the tunable output infrared pulses are frequency doubled into picosecond green laser pulses, which can be tuned from 527 to 537 nm with average power of more than 1.1 W, corresponding to an overall conversion efficiency of 10.7% by a BBO nonlinear crystal. This kind of laser source will have potential application for underwater optical communication.     

Carrier-envelope phase offset for pulses from a tunable optical parametric amplifier

The carrier-envelope phase (CEP) characteristics of the tunable infrared laser pulses from a noncollinear optical parametric amplifier (OPA) with passively stabilized CEP are investigated experimentally. We compare the CEP fluctuation of different wavelength outputs from the OPA which is seeded by the idler pulse of a difference frequency generation (DFG) process. It is found that when the OPA output is tuned to a longer wavelength, the CEP fluctuation becomes less sensitive to the jitter of laser intensity and the phase mismatch, and therefore more stable CEP for the longer wavelength output pulses is realized.     

High-gain harmonic-generation free-electron laser seeded by harmonics generated in gas

The injection of a seed in a free-electron laser (FEL) amplifier reduces the saturation length and improves the longitudinal coherence. A cascaded FEL, operating in the high-gain harmonic-generation regime, allows us to extend the beneficial effects of the seed to shorter wavelengths. We report on the first operation of a high-gain harmonic-generation free-electron laser, seeded with harmonics generated in gas. The third harmonics of a Ti:sapphire laser, generated in a gas cell, has been amplified and up-converted to its second harmonic (λ(rad)=133 nm) in a FEL cascaded configuration based on a variable number of modulators and radiators. We studied the transition between coherent harmonic generation and superradiant regime, optimizing the laser performances with respect to the number of modulators and radiators.     

High-peak-power nanosecond pulse generation by stimulated Brillouin scattering pulse compression in a seeded Yb-doped fiber amplifier

We demonstrate the generation of nanosecond and multikilowatt peak-power pulses in a double-clad Yb-doped fiber amplifier seeded by a spectrally narrowed gain-switched laser diode. Injected pulses with 100 ns duration were simultaneously compressed and amplified by the combination of high amplifier gain and stimulated Brillouin scattering. A maximum peak power of 20 kW has been obtained, corresponding to a single-pass gain of +57 dB in terms of peak power. Part of this output signal was also converted into IR continuum light by splicing a length of single-mode fiber at the end of the fiber amplifier.     

A CW seeded femtosecond optical parametric amplifier

1 Introduction Optical parametric amplification (OPA) based on femtosecond Ti:sapphire regen-erative amplifiers has been widely adopted in wavelength extension of ultrashort opticalpulses[1]. While BBO-based femtosecond optical parametric amplifiers have alreadycommercialized, the tuning range of such an 800 nm-pumped OPA is typically between1.15 μm and 2.6 μm due to the limited transparent range of BBO. From application’spoint of view, ultrashort pulses near 1 μm and between 3 and 4 …     

Diode-pumped Cr:LiCAF fs regenerative amplifier system seeded by an Er-doped mode-locked fiber laser

A fs regenerative amplifier based on Cr:LiCAF is demonstrated for the first time. With direct diode pumping, 8 μJ of pulse energy are obtained directly from the amplifier. When seeded by an Er-doped fiber laser, the amplified seed pulses are compressed down to 252 fs, limited by residual net third-order dispersion of the compression gratings and intracavity elements. Pulse broadening due to second- and third-order dispersion is theoretically investigated and compared to experimental results. Dispersion generated by the geometrical cavity arrangement is measured experimentally. Received: 19 November 2001 / Revised version: 28 January 2002 / Published online: 14 March 2002     

PPLT倍频宽线宽掺镱双包层光纤放大激光

分别通过理论和实验研究了周期性极化的钽酸锂（PPLT）倍频宽线宽准连续掺镱双包层光纤放大激光.PPLT样品长为40 mm,极化周期为7.67 μm.基频光的中心波长为1064 nm,线宽约为6 nm.从基频光的光谱特性出发,利用超晶格倍频理论,解释了实验中获得的倍频温度与二次谐波功率之间的关系.在基频光的功率为2.2 W时,获得的宽线宽光纤激光倍频效率为1.8%.     

Pump-limited, 203 W, single-frequency monolithic fiber amplifier based on laser gain competition

We present high power results of a Yb-doped fiber amplifier seeded with a combination of broad and single-frequency laser signals. This two-tone concept was used in conjunction with externally applied or intrinsically formed thermal gradients to demonstrate combined stimulated Brillouin scattering suppression in a copumped monolithic, polarization-maintaining (PM) fiber. Depending on the input parameters and the thermal gradient, the output power of the single-frequency signal ranged from 80 to 203?W with slope efficiencies from 70% to 80%. The 203?W amplifier was pump limited and is, to the best of our knowledge, the highest reported in the literature for monolithic, PM single-frequency fiber amplifiers.     

Controlling the carrier-envelope phase of ultrashort light pulses with optical parametric amplifiers

The phase link between signal, idler, and pump waves in a parametric interaction allows generation of an idler pulse with a phase independent of that of the input pulse. We suggest the use of a white-light seeded optical parametric amplifier as a self-stabilized source of few-cycle pulses, in which the phase of the electric field is exactly reproduced in each laser shot.