Visible laser sources based on frequency doubling in nonlinearwaveguides

This paper reviews nonlinear quasi-phase-matching (QPM) waveguides and laser diodes with application to conversion of infrared laser diode wavelengths to the visible. The discussion of nonlinear QPM waveguides includes Ti-diffusion poled and E-field poled LiNbO₃ and KTP waveguides. Up to 25 mW of blue output power has been demonstrated for 120-mW infrared power injected into a nonlinear waveguide. Semiconductor laser sources suitable for frequency doubling are discussed, including distributed Bragg reflection (DBR) lasers operating at up to 200 mW output power, master oscillator power amplifiers with over 1 W output power, and wavelength-tunable flared semiconductor lasers with over 0.5 W output. A compact blue laser with 1-4 mW output power at 425-nm wavelength has been demonstrated based on a DBR laser frequency doubled in a nonlinear waveguide     

High power output InGaAsP/InP buried heterostructure lasers

A novel InGaAsP/InP buried heterostructure (BH) laser was fabricated on a p-InP substrate. This laser can provide a peak pulse output of 0.8 W per facet with a stable lateral transverse mode oscillation and enables the fault location measurement of a single mode fibre cable over 20 km.     

High-Power and Widely Tunable All-Fiber Raman Laser

A high-power and widely tunable all-fiber Raman laser is demonstrated. The Raman fiber laser has been tuned over a range of 60 nm from 1075 to 1135 nm and delivers up to 5.0 W of Stokes output power for 6.5 W of launched pump power. Efficiencies ranging from 76.1 to 93.1% and laser thresholds from 0.78 to 2.59 W have been measured. The spectrum of the depolarized Raman gain coefficient of the germanosilicate fiber has also been inferred from our experimental measurements.     

Achieving broad-area laser diodes with high output power andsingle-lobed far-field patterns in the lateral direction by loading amodal reflector

A modal reflector, which consists of a high-reflectivity region surrounded by low-reflectivity regions, is added to the front facet of two types of broad-area laser diodes (LD's) to control the lateral modes. One type of LD is the self-aligned laser with a bent active layer (SBA LD) that has a real index-guiding mechanism. The other is a planar-stripe LD that consists of a Zn-diffused region to confine the current flow and has a gain-guiding mechanism. For the SBA LD's with a modal reflector, stable single-lobed far-field patterns (FFP's) are obtained at up to 0.3 and 0.4 W output powers in continuous wave (CW) operation and pulsed operation, respectively. In addition, for planar-stripe LD's with a modal reflector, stable single-lobed FFP's are obtained at up to 0.4 W in CW operation. The lateral modes inside the cavity are analyzed by utilizing a slit model and FFP's are calculated. Good agreement is found between experimental and calculated FFP's for a large Fresnel number     

梯度补偿法控温晶体的高功率绿光激光器

研究了平均功率超过30W的稳定高效全固态绿光激光器,分析得出影响全固态腔内倍频激光器倍频效率和输出稳定性的主要因素是倍频晶体局部温升造成的相位失配和热透镜效应,采用温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,降低激光器工作中倍频晶体内外温度梯度从而有效地克服因晶体局部温升造成的倍频相位匹配角失配和热透镜效应。采用三条60W的半导体激光二极管阵列板条侧面抽运Nd:YAG激光增益介质棒,采用声光调Q,平凹直腔和腔内倍频结构配合温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,得到了稳定高效的532nm绿光输出。在抽运电流25A,抽运功率174.6W时,得到了脉冲宽度110ns,重复频率10kHz,输出平均功率31.6W稳定高效的绿光输出,光-光转换效率为18.1%,功率稳定性为±0.66%,绿光输出光束质量因子M2=4.3。     

Improved coupling efficiency of a strained InGaAs-AlGaAs quantum-well laser into a fiber Bragg grating

We describe a highly efficient coupling of up to 78% into a single mode fiber (SMF) by utilizing a low-divergence-angle InGaAs-AlGaAs laser and a new high-NA aspheric lens, resulting in the coupled optical output of over 300 mW with a kink-free performance. The kink-free 300 mW of fiber-coupled power is the largest power reported from a diode laser wavelength stabilized using a fiber Bragg grating. A 3% fiber Bragg grating makes the optical output stabilize at a wavelength of 1.016 /spl mu/m for an optical output power up to 310 mW and without any distinct decrease of the optical output. The coupling tolerance for lateral offsets is improved by utilizing a thermal-diffused expanded-core technique even in the case of using a high-NA coupling aspheric lens. We have also achieved a 300-mW fiber-coupled wavelength-stabilized InGaAs-AlGaAs semiconductor laser butterfly module using a fiber Bragg grating.     

Characteristics of a far-infrared molecular laser optically pumped by a high-power CO2 laser

A molecular far-infrared (FIR) laser optically pumped by a high-power CO₂ laser, which is a powerful source for testing detectors and mixers and for FIR spectroscopy, is constructed and the performance is examined through experiments. At frequencies between 580GHz and 4.25THz, FIR output power is more than 20～30m W by pumping power of 35～81W. Amplitude stability of ±3% is obtained at 100m W output at 2.52THz for over 30 minutes when the FIR tube is cooled at 5°C by a chiller. As an application to testing mixers, FIR laser lines up to 4.25 THz are detected by Schottky barrier diodes (SBD). Further, using a SBD, performance of absolute frequency stability at 693GHz of HCOOH oscillation is measured by harmonic mixing with a 115.5GHz millimeter wave from a phase-locked Gunn oscillator. The resultant center-frequency stability is 100kHz per 10 minutes.     

掺镱脉冲光纤激光器抽运的高功率PPMgLN光参变振荡器

报道了研制主振-放大（MOPA）结构的高功率保偏掺镱脉冲光纤激光器并用其抽运光参变振荡器（OPO）的研究工作。掺镱脉冲光纤激光器以声光调Q的Nd∶YVO4激光器作为种子源, Liekki的大直径双包层保偏光纤作为放大介质, 得到接近基模的1064 nm波长激光输出, 最大线偏振输出功率17 W, 偏振消光比优于10 dB, 重复频率50 kHz, 脉冲宽度60 ns。利用该光纤激光作为抽运光, 抽运基于周期性畴极化反转掺镁铌酸锂（PPMgLN）晶体的宽带可调谐OPO, 实现了高效参量转换。在信号光1518 nm通道, 以16.2 W功率抽运, 获得最大参变输出功率9 W, 其中3.5 μm波长功率为2.4 W。OPO的能量转换效率为58%, 斜效率为68％。在信号光1491 nm通道, 以14 W功率抽运, 获得最大参变输出6.6 W, 其中3.7 μm波长功率超过2 W。     

Fast axial flow CO2 laser excited by silent discharge

A fast axial flow CO₂ laser excited by silent discharge has been developed. With a new electrode system applied to the laser, homogeneous discharge of power density of up to 80 W/cm³ is obtained without applying any stabilization techniques on the discharge. An output laser power of 920 W in stable TEM₀₀ mode operation is attained with an efficiency of over 14%. Beam fluctuation common to fast axial flow lasers is suppressed by the combination of smooth gas flow and low CO₂ molar fraction     

多功能CO2激光器及其应用

研制成功多功能CO2激光器。该激光器输出TEM00高斯基模,输出波长在9.2-10.8μm范围内能够调谐,可以输出9P、9R和10P、10R支跃迁谱带的谱线共计30余条;能够以连续放电方式运转输出连续激光,输出功率5W左右（腔内不加声光调制器时输出25W）,也可以运转在脉冲放电方式输出＂长＂脉冲激光,还可以在连续放电运转条件下经过腔内Q突变方式输出＂短＂脉冲激光;在以脉冲方式工作时,可以选择单脉冲方式输出,也可以选择最高频率为10kHz的重复脉冲,激光脉宽（FWHM）可以在百纳秒至几十毫秒量级范围内变化,最高峰值功率超过数千瓦。该激光器在科研、教学以及激光医学等很多领域都具有实际应用价值。     

Single frequency 1550-nm AlGaInAs-InP tapered high-power laser witha distributed Bragg reflector

A strained-layer multiple-quantum-well tapered laser with single-frequency operation near 1550 nm and with 20-dB sidemode suppression, for continuous-wave power levels up to 0.6 W is reported. At a power level of 0.5 W, 80% of the power from this device remains in the central lobe of the far-field. Increased lateral mode stabilization was observed in devices having both a Gaussian-patterned contact and a distributed Bragg reflector (DBR) compared to those without a DBR. An increase by a factor of five in the power level obtainable, with at least 80% of that power in the central lobe of the far-field pattern, was obtained using the DBR reflector     

Broad-stripe near-diffraction-limited mid-infrared laser with a second-order photonic-crystal distributed feedback grating

Electron-beam lithography was used to pattern a second-order photonic-crystal distributed feedback grating onto an antimonide type-II "W" laser emitting at /spl lambda//spl ap/3.7 /spl mu/m. For pulsed optical pumping, the output beam was essentially diffraction-limited up to a stripe width of 150 /spl mu/m, and remained no worse than eight times the diffraction limit for stripes as wide as 600 /spl mu/m. This represents a considerable improvement over all previous mid-infrared semiconductor lasers with such broad stripes.     

大功率XeCl准分子激光器放电开关的实验研究

本文报道了一台输出功率大于100W、重复频率达300Hz的XeCl准分子激光器的放电开关系统进行实验结果，比较了激励电路放电开关系统中带磁开关和无磁开关两种情况下闸流管的动态放电参数，证明了带磁开关的开关系统有利于激光器高重复频率工作和大功率输出。     

激光二极管抽运Tm:YAP晶体实验研究

简要阐述2 μm激光光源的广泛应用需求,分析掺铥铝酸钇(Tm:YAP)晶体的能级结构和吸收光谱特性,报道了采用激光二极管(LD)端面抽运Tm:YAP晶体的方式,实现室温下2 μm激光的高效输出。在激光二极管输出功率为19 W时, 2 μm连续激光输出功率为6.5 W,光光转换效率达34％,斜率效率为47.5％。经过声光(AO)Q开关进行调制后,在重复频率10 kHz下,获得5.4 W的动态激光输出,激光单脉冲宽度为70 ns,激光二极管输出功率到2 μm激光动态输出功率的转换效率为28％,斜率效率为42％。通过实验验证了激光二极管端面抽运Tm:YAP晶体在室温下高效输出的特性。     

输出功率50 W的脉冲染料激光放大器

推导了准稳态下横向抽运的脉冲染料激光放大器的简化速率方程,提出了双侧横向抽运方式的脉冲染料激光放大器的设计原则和设计方法.应用高功率脉冲染料激光放大器的物理设计结果,研制了输出功率为50 W的脉冲染料激光放大器的实验装置.采用铜蒸气激光(CVL)作为抽运光,在此染料激光放大器上进行了实验研究,获得染料激光输出功率为52 W,抽运激光功率提取效率为41%.给出了染料激光波长、注入染料激光功率以及抽运激光的时间和空间匹配特性与染料激光放大器输出激光功率和抽运激光功率提取效率的相互关系,讨论了染料溶液浓度对双侧横向抽运方式的脉冲染料激光放大器的输出光束质量的影响.     

192W的1319nm Nd:YAG激光器

采用国产激光二极管泵浦Nd:YAG晶体,双聚光腔串联,对称直通腔型结构,在LD总泵浦功率1220W时,实现1319nm连续激光输出192W.采用声光调Q,10kHz下,获得调Q输出平均功率155W,脉冲宽度205ns,光-光转换效率达15.7%.     

基于光纤光栅谐振腔的双包层光纤激光器

理论分析了线型腔双包层光纤激光器的输出特性,包括光纤长度、光纤损耗及后腔镜反射率对激光输出功率和阈值泵浦功率的影响.设计了基于光纤光栅谐振腔的双包层光纤激光器,采用锥度光纤实现了泵浦模块与双包层光纤之间的低损耗连接,实现了全光纤化的掺Yb3 双包层光纤激光器,其阈值泵浦功率为300 mW,在泵浦入纤功率为17 W时达到了10.5 W的最大激光输出功率,斜率效率为62%.     

1 W single-transverse-mode Yb-doped double-clad fibre laser at 978nm

A novel all-glass Yb-doped double-clad fibre laser that emits over 1 W of single-transverse-mode output at 978 nm is described. This device is efficiently pumped with 2.5 W of launched power from a single 200 μm broad-area laser diode at 915 nm     

紧凑型长寿命射频激励波导CO2激光器的研制

为了使Co2激光器在工业加工及军事上有更广泛的应用,采用铝合金拉制型材作为激光器壳体、盘装电感代替传统线绕电感的结构以及全金属封接工艺等,研制出一种紧凑型长寿命射频激励波导CO2激光器.可连续输出或在不高于20kHz调制频率下脉冲输出,最大输出功率30W,实测工作寿命超过1500h,存储寿命超过1.5a.结果表明,这种激光器具有结构紧凑、输出功率稳定、工作寿命长、可连续及脉冲调制工作等特点,除了能满足各种材料的加工,也可在军事上应用.     

High power GaInP/AlGaInP visible lasers (/spl lambda/=646 nm) with narrow circular shaped far-field pattern

GaInP/AlGaInP visible lasers based on a longitudinal photonic bandgap crystal waveguide emitting at 646 nm show narrow circular shaped far field pattern. Vertical and lateral beam divergence of about 8/spl deg/ (full width at half maximum) that is independent of injection current is demonstrated. Differential quantum efficiency is up to 85%. Pulsed total optical output power is as high as 20 W for 100 /spl mu/m-wide stripe lasers and 6 W for 20 /spl mu/m-wide stripe lasers. Such values of output optical power are 2.5 higher with respect to ones obtained for the lasers fabricated from the state-of-the-art epiwafers for commercial 650 nm range DVD lasers.