Intracavity frequency-doubled and stabilized cw ring Nd:YAG laser with a pair of KTP crystals

Generation of an up to 1.5-W single-frequency and a 650-mW frequency-stabilized second harmonic at 1.06 μm has been demonstrated in a cw ring Nd:YAG laser with a pair of properly oriented KTP crystals in which the walk off between the intracavity modes has been eliminated. The frequency stability is better than 5 MHz for the second-harmonic output level of 650 mW. The fluctuation of power is less than 4%. PACS: 42.60. By. 42.65 Ky.     

Single-mode, tunable output from a midwave-infrared-seeded optical parametric oscillator system

We have built a coupled master oscillator and a slave oscillator optical parametric oscillator (OPO) system that provides single-frequency, pulsed radiation in the midwave infrared (MWIR). The direct-diode-pumped master OPO provided narrow-band (<6-MHz, instrument-limited), tunable MWIR cw radiation that was used to seed a higher-peak-power pulsed slave OPO. When seeded directly at the MWIR idler, the pulsed output of the slave OPO was constrained to oscillate on a single longitudinal mode even though the slave OPO is pumped by a multilongitudinal-mode laser source. The linewidth of the pulsed output has been measured to be <220 MHz (instrument limited), which is well suited for coherent differential absorption lidar applications.     

Tunable continuous-wave doubly resonant optical parametric oscillator by use of a semimonolithic KTP crystal

A temperature-tuned continuous-wave doubly resonant optical parametric oscillator (OPO) consisting of a semimonolithic KTP crystal and a concave mirror has been designed and built. Under single-axial-mode-pair operation, we obtained a combined output power of the signal and idler light fields up to 365 mW at a pump power of 680 mW. The output wavelength of the OPO can be temperature tuned by as much as 9 nm. We achieved 2.8-GHz continuous frequency tuning of the OPO by tuning the pump laser frequency.     

Multiple-wavelength quasi-phase-matching for efficient idler generation in MgO:LiNbO3 based nanosecond optical parametric oscillator

We present numerical results for optimization of the overall idler conversion efficiency of a nanosecond optical parametric oscillator (OPO), wherein the signal generated in the OPO process is also used as the pump for a difference frequency generation (DFG) process in a quasi-periodic MgO:LiNbO(3) crystal. The phase-matching conditions are considered such that the generated idler frequencies in both the processes (i.e., OPO and DFG) coincide. Optimization for the idler generation has been performed with respect to the different parameters, such as input pump power, pump pulse duration, and the output coupler reflectivity, for quasi-phase-matched interaction in MgO:LiNbO(3). Wavelength of the pump, signal, and idler waves considered in the optimization are 1.064 μm, 1.456 μm, and 3.95 μm, respectively. A maximum overall idler generation efficiency of ≈33% could be obtained in the simultaneous OPO+DFG process for a pump pulse duration of 72 ns and output coupler reflectivity (R(s)) of 90%, whereas for the stand-alone OPO process, the maximum idler generation efficiency was found to be ≈15%. The optimization has been illustrated for an average pump power of 8 W at a pulse repetition frequency (PRF) of 10 kHz. This approach of simultaneous OPO+DFG process can be employed to significantly enhance the idler generation efficiency of nanosecond OPOs.     

Long-pulse, amplitude-modulated optical parametric oscillator

A singly resonant optical parametric oscillator (OPO) based on periodically poled LiNbO(3) is pumped by a Nd:YAG-based oscillator-modulator-amplifier source. This pump source, operating at 1.064 μm, provides the ability to control the temporal characteristics of the OPO waveform. We illustrate pulse tailoring by demonstrating three pulse formats: a pulse with a sharply rising edge, a square pulse, and an amplitude-modulated square pulse. The OPO output is tuned over 1.45-1.67-μm (signal) and 2.9-4.0-μm (idler). We demonstrate a 7-μJ, 2-μs square pulse with 5-MHz sinusoidal amplitude modulation.     

Compact and efficient Nd:YVO 4 laser that generates a tunable single-frequency green output

We demonstrate 250 mW of single-frequency 532-nm output from a simple intracavity-doubled Nd:YVO(4) laser, pumped with 1.2 W from a fiber-coupled diode laser. The laser can be frequency chirped smoothly over ~17 GHz while maintaining a single-frequency green output of greater than 200 mW. A short Fabry-Perot cavity is used, and single-frequency operation is enforced by means of a birefringent filter that utilizes the birefringence of both the KTP doubling crystal and the Nd:YVO(4) laser crystal with polarization-dependent loss from a glass Brewster plate combined with polarization-dependent gain from the laser crystal.     

Coupled-cavity concept applied to a highly compact single-frequency laser operating in the 2 μm spectral region

We present a highly compact and cost-efficient Tm:YAP laser setup supporting single-frequency operation at a significantly high efficiency. The coupled-cavity concept was used to design a single-frequency laser operating at 1990 nm. Single-frequency output power of 784 mW was obtained when the absorbed pumping power was 2.4 W. The optical-to-optical efficiency was 33%, and the slope efficiency was 52%.     

Femtosecond optical parametric oscillators based on periodically poled lithium niobate

Abstract

We describe two configurations of collinearly pumped femtosecond optical parametric oscillator based on periodically poled lithium niobate and tunable in the infrared from 975 nm to 4.98 μm. Maximum output powers of 240 mW for the signal and 106 mW for the idler were recorded with 25 mW of average power measured at 4.88 μm. An overall conversion efficiency of 35% and slope efficiencies for the signal of 46% at a wavelength of 1.04 μm and 70% at 1.1 μm were measured. Interferometric autocorrelations of the signal and idler pulses at various wavelengths within the tuning range have been obtained and imply nearly transform-limited pulse durations of about 140fs for the signal and about 190fs for the idler.     

High-power single-mode laser diodes (λ = 1.1–1.2 μm) based on quantum-confined AlInGaAs/InP heterostructures

Quantum-confined AlInGaAs/InP laser heterostructures emitting at a wavelength of 1.18 μm have been grown by metalorganic vapor-phase epitaxy. An output radiation power of 40 mW in a single-mode CW regime has been obtained using a diode based in this structure with a mesastrip width of W = 4 μm. The total maximum CW emission power amounted to 75 mW.     

可调蓝光皮秒脉冲

利用３５１ｎｍ紫外光泵浦非临界相位匹配ＬｉＢ３Ｏ５光参量振荡器（ＬＢＯ－ＯＰＯ）,直接获得了在４７２￣４５３ｎｍ范围内波长连续可调的蓝图光皮秒脉冲序列。ＯＰＯ所用ＬＢＯ晶体的两端面切割成Ｂｒｅｗｓｔｅｒ角,避开了晶体表面增透膜的稳定性问题,保证了ＬＢＯ晶体端面低反射损耗和ＯＰＯ长期稳定工作。     

Intracavity frequency doubling and Q switching in diode-laser-pumped Nd:YVO(4) lasers

A highly efficient and compact Nd:YVO(4) laser is proposed. In cw operation, a single-longitudinal-mode output of 95 mW and a multilongitudinal-mode output of 435 mW have been observed at 1.06 μm with a 1-W diode laser. Using a KTP crystal in the short laser cavity, a green output of 105 mW was generated. A Q-switched pulse with a peak power of 230 W and a pulse width of 8 ns was obtained with the intracavity KTP crystal, which was used as both an electro-optic Q switch and a frequency doubler.     

All-fiber Q-switched operation of thulium-doped silica fiber laser by piezoelectric microbending

We demonstrate an all-fiber Q-switched laser operation in the 2 μm region on the basis of a dynamic periodic microbend and pulsed-pump configuration. A single-mode thulium-doped silica fiber is pumped by 1.6 μm-band laser diodes, and the dynamic loss is introduced in the fiber ring resonator by the periodic microbend that is electrically controlled with a piezoelectric actuator. When the voltage-off period of the piezoelectric actuator is set at 20 μs for the pump power of 120 mW, the output pulse power is measured by 420 mW with a pulse width of 1.3 μs.     

High-efficiency 1.06-µm output in a monolithic Nd:YVO(4) laser

A miniature 1.5-mm-long monolithic Nd:YVO(4) laser was end pumped with a Ti-sapphire laser. The Nd-doping density was 3 at. %. The maximum output power obtained with 885 mW of absorbed pump power was 495 mW at 1.064 μm. The maximum slope efficiency was 57%, and the output power was only slightly dependent on pump polarization. Laser diode pumping was also demonstrated. Thermal effects were observed to reduce the output power and required active cooling of the laser crystal.     

Efficient operation of a diode-bar-pumped Nd:YAG laser on the low-gain 1123-nm line

Efficient operation of a Nd:YAG laser on the low-gain 1123-nm transition by end pumping with the reshaped output from a 7-W diode bar is reported. Using a simple standing-wave laser configuration and pumping with 5.6 W of incident power yielded a laser output power of 1.7 W in a near-diffraction-limited TEM00 mode with a beam quality factor of M2 < or approximately equal to 1.1. A unidirectional single-frequency ring laser was also constructed, yielding 180 mW of single-frequency output. The prospects for further increase in power by optimization of the resonator design are discussed.     

Doubled single-frequency Nd:YLF ring laser coupled to a passive nonresonant cavity

We demonstrate an original solution to obtain a single-frequency ring laser coupled to an external passive nonresonant ring cavity, which plays the role of an optical diode. This system provides more output power than systems with an intracavity unidirectional device. To the best of our knowledge, this work marks the first demonstration of a unidirectional planar ring laser at 1.3 microm. Using 12 W at 797 nm to pump a Nd:YLF laser, combined with intracavity second-harmonic generation, we achieve yields of 440 mW at 661.3 nm and 340 mW at 656.0 nm.     

Imaging at 3.4 Thz with a quantum-cascade laser

We have assembled a single-frequency imaging system at 3.4 THz with a quantum-cascade laser. Images of electronic and biological applications are demonstrated. We operate the laser with a peak output power of 2.5 mW at a 7% duty cycle and a 22 K operating temperature. The minimum spot size is 340 microm. The signal is detected with a single-element deuterated triglycine sulfate detector, and images are captured by scanning of the sample.     

Nd:YLF laser at 1.3 microm for calcium atom optical clocks and precision spectroscopy of hydrogenic systems

We describe single-frequency operation of a diode-pumped Nd:YLF laser in the range 1311.9-1317.2 nm. It can be used for the interrogation of the clock transition in calcium (1314.0 nm) or spectroscopy in hydrogen and metastable singly ionized helium (1312.6 nm). By using a twisted-mode cavity, we have obtained output powers of 830 and 970 mW at 1312.6 and 1314.0 nm, respectively, in a single longitudinal mode.     

Broadband Tuning of a Continuous-Wave, Doubly Resonant, Lithium Triborate Optical Parametric Oscillator from 791 to 1620 nm

We report the use of extreme broadband, high reflectivity >99.5%, optical parametric oscillator (OPO) cavity mirrors. A continuous-wave, doubly resonant, OPO demonstrated tuning over a range of 791-1620 nm with a single mirror set. Wavelength tuning was performed by temperature tuning the nonlinear material of lithium triborate. Narrow linewidth oscillation was confirmed throughout the tuning range, and threshold pump power increased gradually from 50 mW near the degeneracy to 800 mW at the tuning band edge in a double-pass pumping configuration.     

Widely tunable fiber-coupled single-frequency Er-Yb:glass laser

A fiber-coupled tunable Er-Yb:glass minilaser is presented with output power of 40 mW. The laser can be stepwise tuned in single-frequency operation from 1530 to 1560 nm by compressing a fiber Bragg grating that provides selective feedback. Constant output power (fluctuation < 0.8 dB) over the full tuning range is demonstrated. The relative intensity noise spectrum was measured to be < 150 dB/Hz for frequencies > 2 MHz.     

Extra-cavity, widely tunable, continuous wave MgO-doped PPLN optical parametric oscillator pumped with a Nd:YVO4 laser

An extra-cavity, widely tunable, and continuous wave (CW) singly resonant optical parametric oscillator (SRO) based on MgO-doped periodically poled lithium niobate (PPMgLN) has been developed. A Nd:YVO₄ laser pumped by 808 nm laser diode array (LDA) is used as the pump source. The threshold value of the SRO system is only 1.86 W at 1064 nm. 1101.1 mW of idler output at 3.217 μm and 2004.3 mW of signal output at 1.590 μm have been achieved when the pump power is 8.76 W, and this corresponds to a total (idler + signal) optic–optic conversion efficiency of 35.5%. The periods of the domain structure on the PPMgLN wafer can be changed by shifting the PPMgLN crystal, thus enabling a widely tunable mid-infrared spectrum of 3.026–4.485 μm, and signal wavelengths widely tunable in range of 1.395–1.641 μm. Along with the signal and idler light, the visible and near-infrared spectrum (697.5–820.5 nm, 603.6–645.5 nm, 532 nm, 421.3–463.3 nm) is observed. This OPO system is compact, simple and operated at room temperature.