Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.     

信号光的调制对基于光纤光参量放大光脉冲源的改善

在理论上从四波混频的强度耦合方程出发,给出了基于光纤光参量放大(FOPA)光脉冲的光场表达式,并进一步分析了信号光被相位调制或强度调制后,光脉冲的频率啁啾和强度演化.结论指出：若信号光被强度调制,对所生成脉冲宽度无明显的影响,但可以提高消光比;若信号光被相位调制,所生成的脉冲具有更大的线性正啁啾,可以在相同的抽运功率条件下得到比无相位调制时更窄的脉冲.实验上给出了10 GHz工作速率下的结果,其结果与理论分析符合得很好.通过信号光的相位调制,在05 W平均抽运功率条件下得到了消光比22 dB,脉宽为5 关键词： 光纤参量放大 四波混频 光脉冲源 频率啁啾     

光纤参量放大增益谱边带快慢光特性研究

针对窄带光纤参量放大(FOPA),区别于以往增益谱的大增益斜率区域,研究了FOPA增益谱边带脉冲信号的快慢光特性.首先从理论上推导出了小信号增益条件下信号延时量的解析表达式;其次,在低抽运功率条件下(1 W),实验研究了10 Gb/s伪随机二进制序列脉冲信号在FOPA增益谱边带的延时特性,实验结果与理论计算基本符合;最后,通过分析研究抽运光功率、光纤色散及非线性系数等参数对信号延时量的影响规律,可以为FOPA增益谱边带的快慢光延迟线的设计提供参考.     

Efficient Tm:YLF laser with a volume Bragg grating recycle pumped by laser diode

By using a pump recycling configuration, we presented a high efficient diode-pumped Tm:YLF laser with a volume Bragg grating. When the incident pump power was 33.1 W, a maximum output power of 11.1 W at 1907.8 nm with full width at half maximum of 0.6 nm was obtained. The slope efficiency with respect to the incident pump power was 44.8%, and the optical-to-optical efficiency was 33.5%. In addition, the VBG-based Tm:YLF laser was employed as a pumping source of Ho:YAG laser, the maximum output power of 4.7 W with a slope efficiency of 67.0% was obtained, corresponding to Tm-to-Ho conversion efficiency of 51.6%.     

A 15.1 W continuous wave TEM00 mode laser using a YVO4/Nd:YVO4 composite crystal

A effective continuous-wave (CW), high power laser generated using a YVO₄/Nd:YVO₄ composite crystal is presented. 18.8 W output power in multi-mode has been achieved with a maximum absorbed pump power of 31.2 W, corresponding to an optical-to-optical efficiency of 60.26%. In TEM₀₀ mode operation, 15.1 W output power also has been achieved with the maximum absorbed pump power of 31.2 W, corresponding to an optical-to-optical efficiency of 47.69%. With a 200 mm focal-length positive lens and using the moving knife-edge method, the beam quality factor is measured to be M² = 1.2 for TEM₀₀ mode beam.     

Diodes-double-end-pumped high efficiency continuous wave 36 W TEM00 mode Nd:GdVO4 laser

A effective continuous-wave (CW), high power laser generated using a YVO₄/Nd:YVO₄ composite crystal is presented. 18.8 W output power in multi-mode has been achieved with a maximum absorbed pump power of 31.2 W, corresponding to an optical-to-optical efficiency of 60.26%. In TEM₀₀ mode operation, 15.1 W output power also has been achieved with the maximum absorbed pump power of 31.2 W, corresponding to an optical-to-optical efficiency of 47.69%. With a 200 mm focal-length positive lens and using the moving knife-edge method, the beam quality factor is measured to be M² = 1.2 for TEM₀₀ mode beam.     

High-efficiency composite Tm:YAG laser

A high-efficiency continuous-wave Tm:YAG laser end-diode pumped at room temperature is presented in this letter. The highest output power reaches 6.37 W when the incident pump power is 18.9 W. The optical conversion efficiency is 33.7% and the slope efficiency is 42.8%. The wavelength of the output laser is shifted to the short wavelength with an increase in the transmission of the output couplers. At a fixed cavity length, the composite Tm:YAG shows its dominance for its higher efficiency and higher quantum efficiency compared with the noncomposite Tm:YAG.     

Yb∶Y_2O_3陶瓷薄片激光器获得10.5 W连续激光输出

室温下采用中心波长约970 nm准直输出的大功率激光二极管模块作为抽运源,端面抽运双程吸收的腔型结构,抽运原子数分数为8%的Yb:Y2O3多晶透明陶瓷片获得连续激光输出。抽运阈值功率为7 W,当抽运功率达到35 W时,获得优化连续激光输出功率为10.5 W,光光转换效率为30%,斜率效率为37.5%。激光输出功率随抽运功率基本呈线性增长。采用更高功率抽运源、优化谐振腔结构和减小热效应的影响,Yb∶Y2O3陶瓷激光器的输出功率和效率将会得到进一步提高。     

采用国产大模场面积双包层光纤的714W连续光纤激光器

采用两个中心波长约976 nm准直输出的高功率半导体激光模块为抽运源,通过空间滤波和非球面透镜耦合技术,双端抽运长度为21 m的大模场面积国产掺镱双包层光纤,获得了714.5 W的高功率连续激光输出。采用反向抽运,当入纤抽运功率为760 W时,激光输出功率达到501 W;采用双端抽运,当入纤抽运功率为1137 W时,获得了714.5 W的高功率连续输出,光光转换效率为62.8%,斜率效率为67%。     

Diode-pumped passively Q-switched yellow laser with SrWO4 Raman crystal and ceramic Nd:YAG gain medium

A diode-pumped passively Q-switched Nd:YAG/SrWO₄/KTP yellow laser is presented for the first time. As high as 1.02 W average output power was obtained at a pump power of 14.0 W with a pulse repetition frequency of 21.9 kHz and the corresponding diode-to-yellow conversion efficiency was 7.29%. The highest pulse energy of 56.2 μJ was obtained at a pump power of 7.2 W.     

Laser diode pumped actively Q-switched Nd:GdVO4 self-Raman laser operating at 1173 nm

A laser diode pumped actively Q-switched Nd:GdVO₄ self-Raman laser operating at 1173 nm is presented. The maximum output power was 2.26 W at an incident pump power of 18 W, with the corresponding optical conversion efficiency of 12.6%. Two different resonator configurations were investigated in order to achieve high output power and efficiency.     

A diode side-pumped YAG/Nd:YAG/YAG composite crystal laser

A diode-bar side-pumped YAG/Nd:YAG/YAG composite crystal laser is presented. A maximum output power of 18.4 W at 1.064 μm with a slop efficiency of 57% and an optical-optical conversion efficiency of 46% was obtained for a pump power of 40 W. Compared with a side-pumped conventional crystal laser in the same experimental conditions, the side-pumped composite crystal laser improved the optical-to-optical conversion efficiency by 12%. Experimental results indicate that a composite crystal can depress the thermal effects effectively and improve the optical-to-optical conversion efficiency easily in the diode side-pumped lasers. The composite crystal has great potential in high-power diode side-pumped lasers.     

A Low-Pump-Threshold Photonic Crystal Fibre Raman Laser

We investigate a photonic crystal fibre Raman laser using fibre Bragg grating pairs as cavity mirrors. The threshold pump power is up to 0.65 W by decreasing the cavity loss and using a photonic crystal fibre with high Raman gain coefficient. A maximum continuous-wave output power of 2. 7 W is obtained at the maximum incident pump power of 5.6 W. The corresponding optical conversion efficiency and the slope efficiency are about 48% and 56%, respectively.     

Study of LD pumped Q-switched Nd:Y<Subscript>0.5</Subscript>Lu<Subscript>0.5</Subscript>VO<Subscript>4</Subscript> laser with acousto-optic modulator

A laser-diode (LD) pumped Q-switched Nd:Y_0.5Lu_0.5VO₄ crystal laser with an acousto-optic (AO) modulator is presented in this paper. The maximum continuous wave (CW) output power of 5.53 W is achieved at the incident pump power of 14.09 W with the transmission of 10% for the output coupler, resulting in an optical-to-optical conversion efficiency of 39.2%. For Q-switching operation, the shortest pulse width of 8.3 ns and the highest peak power of 259 kW are generated under the incident pump power of 14.09 W at 1 kHz.     

Compact TEM<Subscript>00</Subscript> grazing-incidence Nd:GdVO<Subscript>4</Subscript> laser using a folded cavity

A compact diode-side-pumped Nd:GdVO₄ laser system using a folded cavity and grazing-incidence configuration is presented. The highest multimode output power obtained was 21.8 W at 36 W of effective diode pump power. Highest optical-to-optical conversion efficiency of 61.5% was achieved at 33 W of effective diode pump power with 20.3 W of multimode output power. For single-mode TEM₀₀ operation, an intracavity telescope was adopted for mode matching in the horizontal direction. Because of the folded cavity and the intracavity telescope, this laser head was the most compact to our knowledge of the TEM₀₀ grazing-incidence laser geometry. At last, an output power of 15 W was produced at 36 W of effective diode pump power. The stable Q-switching operation was also obtained. PACS 42.55.-f; 42.55.Xi; 42.60.Gd     

6.2 W diode-end-pumped 1313 nm Nd:YLF laser

We presented a compact and efficient diode-end-pumped 1313 nm Nd:YLF laser with an effective pump system and no additional insertion loss. The different thermal lensing effects along the ?? and ?? polarizations in an a-cut Nd:YLF crystal were investigated. 6.2 W output power of the polarized 1313 nm laser was obtained at the absorbed pump power of 17.5 W, corresponding to the optical-optical efficiency of 35% and the slope efficiency of 41%.     

An efficient continuous-wave YVO_4/Nd:YVO_4/YVO_4 self-Raman laser pumped by a wavelength-locked 878.9 nm laser diode

We report an efficient continuous-wave self-Raman laser at 1176 nm based on a 20-mm-long composite YVO_4/Nd:YVO_4/YVO_4 crystal and pumped by a wavelength-locked 878.9 nm diode laser.A maximum output power of 5.3 W is achieved at a pump power of 26 W,corresponding to an optical conversion efficiency of 20%and a slope efficiency of 21%.The Raman threshold for the diode pump power was only 0.92 W.The results reveal that in-band pumping by a wavelength-locked diode laser significantly enhances output power and efficiency of self-Raman lasers by virtue of improved pump absorption and relieved thermal loading.     

60-W green output by frequency doubling of a polarized Yb-doped fiber laser

The frequency doubling of a 110-W linearly polarized diffraction-limited Yb-doped fiber oscillator power amplifier (FOPA) has generated 60-W near-diffraction-limited (M2 < or = 1.33) linearly polarized green output. The FOPA produces as much as 2.4 kW of peak power and less than 20-pm linewidth at a 10-MHz repetition rate and 5-ns pulse duration without the onset of nonlinear effects. With two lithium triborate crystals at noncritical phase matching, a maximum of 54.5% doubling efficiency has been demonstrated. The overall electrical efficiency to the green portion of the spectrum is 10%.     

Highly efficient diode-pumped actively Q-switched Nd:YAG-SrWO(4) intracavity Raman laser

A highly efficient diode-pumped actively Q-switched intracavity Raman laser with SrWO(4) as the Raman-active medium is presented. As high as 23.8% diode-to-Stokes optical conversion efficiency is obtained with an incident pump power of 7.17 W and a pulse repetition rate of 15 kHz.     

Highly efficient high-power thulium-doped germanate glass fiber laser

A 64 W fiber laser at 1.9 microm with a slope efficiency of 68% with respect to the launching pump power at 800 nm was demonstrated in a one-end pump configuration using a piece of 20 cm long newly developed thulium-doped germanate glass double-cladding single-mode fiber. A quantum efficiency of 1.8 was achieved. An output laser power of 104 W at 1.9 microm was demonstrated from a piece of 40 cm long fiber with a dual-end pump configuration.