CW Cr2+:CdSe laser pumped by semiconductor disk laser

An output power of 0.85 W with a differential efficiency with respect to absorbed pump power of 55.4% is achieved for a Cr²⁺:CdSe laser with a wavelength of 2.6 ??m under optical pumping with a semiconductor disk laser with a wavelength of 1.98 ??m.     

Extended-cavity grating-tuned operation of mid-infrared InAsSb diode lasers

2 cryostat that permits placement of both the collimation optics and the extended-cavity elements within a vacuum chamber. We have observed tuning of the laser frequency over a 1.44 THz (48 cm^-1) range by rotation of the external grating. This result was obtained without anti-reflection coating of the laser output facet. Received: 8 July 1997/Revised version: 31 July 1997     

Efficient laser operation of heavily doped Cr4+:forsterite

Pulsed laser operation of a new high Cr4+ concentration forsterite crystal is reported. Slope efficiencies of 13% and 5% have been obtained for 1064 and 532nm pumping. Results are compared with the performance of three other forsterite crystals. A threefold enhancement in operating efficiency is obtained over standard low dopant-level material. Tuning ranges have also been investigated. This revised version was published online in November 2006 with corrections to the Cover Date.     

Efficient laser operation and continuous-wave diode pumping of Cr2+:ZnSe single crystals

Efficient continuous-wave laser operation of Cr²⁺:ZnSe was demonstrated with an output power of 1400 mW at an absorbed pump power of 1900 mW from a Tm:YAG laser. Under continuous-wave diode pumping at 1.54 μm an output power of 15 mW was obtained from a Cr⁺²:ZnSe laser. Excited state absorption is shown to be negligible in the pump and laser spectral region. Received: 12 October 2000 / Published online: 30 November 2000     

Continuous-wave tunable Cr2+:ZnS laser

We report the first continuous-wave tunable over ∼280 nm around 2.3 μm room-temperature operation of a chemical vapor transport-grown and diffusion-doped Cr²⁺:ZnS laser, pumped by a Co:MgF₂ laser at 1.67 μm and generating over 100 mW of output power at 16% slope efficiency. The self-consistent results of the laser and spectroscopic analysis demonstrate a large potential of this crystal as an active medium for diode-pumped tunable mid-infrared sources. Received: 7 January 2002 / Revised: 14 March 2002 / Published online: 2 May 2002     

Efficient and low-threshold Cr4+:YAG double-clad crystal fiber laser

A significant advancement of cw lasing in Cr4+:Y3Al5O12 (Cr4+:YAG) double-clad crystal fiber grown by the codrawing laser-heated pedestal growth technique was demonstrated at RT. The optical-to-optical slope efficiency of 33.9% is the highest, to the best of our knowledge, among all Cr4+:YAG lasers, whether they are in bulk or fiber forms. The low-threshold lasing of 78.2?mW and high efficiency are in good agreement with the simulation. The keys to the high laser efficiency are twofold: one is the improved Cr4+ emission cross section and fluorescence lifetime due to release of the strain on the distorted Cr4+ tetrahedron, which also mitigates photobleaching in Cr4+:YAG; the other is the improved core uniformity at long fiber lengths. In addition, because of the low threshold, the impact of excited state absorption of the pump light is significantly reduced. The effects of crystal-orientation, self-selected, and pump-dependent linear polarization states were also addressed.     

Continuous-wave broadly tunable Cr2+:ZnSe laser

We report room-temperature operation of an all-solid-state broadly tunable continuous-wave Cr(2+):ZnSe laser. Output power of 250 mW, an absorbed power slope efficiency of 63%, and continuous tunability from 2138 to 2760 nm are demonstrated.     

Efficient Cr:ZnSe laser with a volume Bragg grating

An efficient and narrow linewidth Cr:ZnSe laser pumped by Tm,Ho:GdVO₄ laser with a volume Bragg grating (VBG) is reported. The Cr:ZnSe laser operated at 2580 nm with emitting linewidth (FWHM) about 0.8 nm. Using the volume Bragg grating, 3.57 W of output was achieved under total incident pump power of 13.1 W, corresponding to optical-to-optical conversion efficiency of 27.3%. By use of conventional mirror, 4.11 W of output was achieved the same incident pump power and the optical-to-optical conversion efficiency is 31.4%.     

Time-resolved Fourier transform intracavity spectroscopy with a Cr2+:ZnSe laser

Intracavity laser absorption spectroscopy (ICLAS) with an evacuated Cr2+:ZnSe laser is performed with a high-resolution time-resolved Fourier transform interferometer with a minimum detectable absorption coefficient equal to 4 x 10(-9) cm(-1) Hz(-1/2) in the 2.5 microm region. This represents the extreme limit currently reached in the infrared by ICLAS with Doppler-limited resolution. The broad gain band of the crystal allows a spectral coverage at most equal to 125 nm, wide enough to see entire vibration bands. Weak CO2 bands observed up to now only in the Venusian atmosphere are recorded for the first time, to our knowledge, in a laboratory. An H2O detection limit down to 0.9 parts per billion by volume is also demonstrated.     

Compact 2 W wavelength-tunable Er:ZBLAN mid-infrared fiber laser

We report a high-power diode-pumped wavelength-tunable (2.7-2.83 mum) erbium-doped ZBLAN mid-infrared fiber laser. Continuous-wave output of >2 W with a spectral linewidth of 1.27 GHz was obtained. Nevertheless, the wavelength-tunable range was found to shrink with increasing pump power. The gain bandwidth narrowing under strong pumping may be ascribed to the enhanced reabsorption process and the weakened population inversion associated with shorter-wavelength emissions.     

Tunable single-frequency CW Cr<Superscript>2+</Superscript>:CdSe laser

Continuous tuning of the lasing wavelength from 2350 to 3450 nm in the cw Cr²⁺:CdSe laser is demonstrated. It is shown that the laser efficiently operates at a wavelength of 3.28 μm, which is promising for the methane optical frequency standard. The single-frequency mode of the laser with a lasing linewidth not exceeding 60 MHz is implemented in this spectral range.     

Diode-pumped 10-fs Cr3+:LiCAF laser

We demonstrate 10-fs pulses from a diode-pumped, soft-aperture Kerr lens mode-locked Cr3+:LiCAF laser with a spectral bandwidth of 150 nm and 40 mW of output power at a repetition rate of 110 MHz. For dispersion compensation, double-chirped mirrors and prisms are used. The pulses are characterized by use of spectral shearing interferometry.     

Efficient, kHz repetition rate, gain-switched Cr:forsterite laser

We have developed a gain-switched room-temperature Cr:forsterite laser operating at repetition rates of between 1 and 34 kHz, and pumped by a continuous wave, Q-switched Nd:YAG laser. With optimised output coupling, an output pulse energy of 52 μJ was measured at 1.5 kHz repetition rate, corresponding to 11% efficiency and 13% slope efficiency. Threshold pulse energy was 53 μJ. Output power of 370 mW was obtained at 10 kHz repetition rate and 4.4 W pump power. Water cooling was not required for repetition rates up to 10 kHz. In a tunable, folded resonator, the Cr:forsterite wavelength tuned between 1173 and 1338 nm. This laser operated with maximum pulse energy of 34 μJ, efficiency of 13%, and power of 307 mW. The laser output was close to diffraction-limited with M² of 1.2. Received: 6 January 1999 / Published online: 29 July 1999     

多光束泵浦中红外激光器

为了获得高功率高效率3 m～5 m中红外激光输出,利用双声光调Q晶体,通过高重复频率驱动调Q同步技术和LD侧面泵浦双棒串接技术,获得高功率高光束质量1.06 m激光双端输出,外置起偏器获得4束激光输出,利用波片偏振旋光原理,实现4束偏振态一致的激光输出,泵浦非线性晶体PPLT进行频率变换,实现高功率3 m～5 m中红外激光输出。在电源输入电流30 A、调Q驱动频率10 kHz的条件下,获得最高功率10.6 W的3.9 m中红外激光,1.06 m～3.9 m转化效率为9.5%。实验结果表明:通过双声光调Q技术和LD侧面泵浦双棒串接技术,可以实现4束高重复频率窄脉宽1.06 m偏振激光输出,泵浦PPLT可获得高功率3.9 m中红外激光输出。     

Efficient up-conversion in CdSe

In this work up-conversion in CdSe with a HF laser as a pump and an experimental quantum efficiency higher than 40% is reported. With this device, it is possible to obtain up-conversion in the 8–25 μ wavelength range.     

Diode-pumped, high-average-power femtosecond Cr3+ :LiCAF laser

We demonstrate a high-average-power continuous wave (cw) and cw mode-locked Cr3+ :LiCAF laser pumped by broad-area laser diodes. In cw lasing experiments, up to 580 mW of output was obtained with 4.35 W of incident pump. A semiconductor saturable absorber mirror was used to initiate stable, self-starting, mode locking. In the cw mode-locked regime, the Cr3+ :LiCAF laser produced nearly transform-limited, 67 fs long pulses near 800 nm with an average output power of 300 mW. The pulse repetition rate was 120 MHz, with a pulse energy of 2.5 nJ.     

Broadly tunable continuous-wave diode-pumped Cr4+:YAG laser

We describe a widely tunable, continuous-wave, room temperature Cr⁴⁺:YAG laser with direct pumping by two high brightness 4 W InGaAs laser diodes. In a tunable configuration, the output wavelength covered a span of 197 nm (1356–1553 nm) and provided a maximum power of 195 mW. A maximum non-tunable output power of 260 mW was obtained with a 0.6% transmission output coupler (OC) and 6.6 W of incident pump power. Pumping at two different wavelengths, 911 and 968 nm, was investigated.     

Directly diode-pumped Kerr-lens mode-locked Cr4+:YAG laser

A directly diode-pumped Kerr-lens mode-locked Cr4+:YAG laser is demonstrated for what is to our knowledge the first time. Pulses as short as 65 fs with up to 30 mW of average output power, at a central wavelength of 1569 nm, were obtained at a repetition rate of 100 MHz. Low-loss chirped mirrors have been used for dispersion compensation up to the third order. Comparison with an Yb-fiber-pumped configuration shows good prospects for improvement.     

Flashlamp-pumped laser performance of LiCaAIF6:Cr3+

The results of flashlamp pumping of the LiCaAIF₆:Cr³⁺ (Cr:LiCAF) laser crystal are reported. We have so far obtained slope efficiencies as high as 1.55% in a close-coupled, diffusely reflecting cavity. Based on the measured insertion loss of the presently available material, we predict that an efficiency of about 4% will be obtained when low-loss material becomes available. This extrapolated efficiency is comparable with the performance of a high-quality alexandrite laser rod in the same apparatus.