Accurate and precise wavelength controlling of narrowband excimer lasers is essential for the lithography of an integrated circuit. High-precision wavelength tuning and calibration of a line-narrowed ArF laser are presented in this work. The laser spectrum is narrowed to a sub-picometer with a line narrowing system. Absolute wavelength calibration of the line-narrowed laser is performed based on the optogalvanic (OG) effect using iron hollow cathode discharge (HCD). An sccuracy of better than 0.1 pm for wavelength tuning and calibration is achieved with our homemade wavemeter.

A Dammann grating is used as a spatial filter for a passive coherent beam combination (CBC) of three Yb-doped fiber amplifiers with an all-optical feedback loop. Using this diffractive-optics-based spatial filtering technique, we demonstrate CBC with 20 W output power, and the visibility of the far-field interference pattern is up to 88.7%. Measurements suggest that this approach is robust with respect to laboratory environment perturbations, and it can scale to high powers and large arrays.

A passive coherent beam combination of three nanosecond Yb-doped fiber amplifiers by an all-optical feedback loop is realized by a Dammann grating intracavity spatial filter. By using this diffractive-optics-based spatial filtering technique, three tile-aperture laser beams are phase-locked with a peak power of 1.02 kW. The width of the combined pulses is 9.6 ns, and the repetition frequency is 2.208 MHz. The visibility of the far-field interference pattern is up to 82.9%. The results show that this approach can scale to larger arrays and higher powers.

Theoretical simulation and experiments based on a prism beam expander and an echelle grating are conducted to study the dependence of linewidth and pulse energy on incidence angle and slit width. With a larger prism incident angle or narrower slit width, the linewidth becomes narrower while the laser pulse energy becomes lower. However, the pulse energy can be improved by optimally designing the prism beam expander. In addition, a subpicometer linewidth ArF laser is obtained with a double-prism beam expander and an echelle grating.

We report a high-peak-power, single-polarized master oscillator power amplification system employing polarization- maintaining Yb-doped rod-type photonic crystal fiber. The MOPA system comprises of a Q-switched microchip laser generating ~630ps pulses at 8.6 kHz repetition-rate and two amplification stages employing double cladding fiber and rod-type PCF respectively. The MOPA system obtains narrow spectral bandwidth, single-polarized pulses of 9W maximum output average power, corresponding to peak power of 1.7MW.

An injection-locked fiber laser is introduced to the passive fiber laser coherent beam combination with all-optical feedback loop. A coherent beam combining system with two-dimensional four Yb-doped fiber amplifier chains is established, and the injection-locked fiber laser works as a switchable seed source. The 1064 nm output laser of the injection-locked fiber laser is extinguished automatically as the feedback injection power is high enough, and the injection-locked fiber laser acts as an amplifier for the feedback laser with 7.4 dB gains. We find that the phase-locked far-field interference pattern of our system with seed laser extinguished is stable, and the visibility is up to 91.5%, which is slightly higher than the prevalent method with auxiliary seed laser (88.2%).

以被动调Q的小型Nd···YAG/Cr4+···YAG激光器为种子光源,以后向抽运的掺镱双包层光纤为功率放大介质,经过一级光纤功率放大,获得了平均功率5.5W,重复频率9kHz的激光输出,脉冲宽度为575ps,峰值功率达到1MW。采用非临界相位匹配的LBO晶体,对该亚纳秒脉宽光纤放大器进行了单通倍频实验研究。当晶体温度为150.5℃、基频光功率为2.7W时,获得了平均功率1.3W、峰值功率250kW的倍频绿光输出,倍频转换效率为48%。

以被动调Q的固体薄片激光器作为种子光源,以中心波长976nm的半导体激光器为抽运源,通过端面抽运耦合,搭建了窄脉宽双包层掺镱光纤放大器。实验研究了前向、后向端面抽运方式对窄脉宽双包层掺镱光纤放大器的输出平均功率、激光光谱、脉冲宽度等特性的影响,并进行分析讨论。结果表明,采用后向抽运方式,窄脉宽双包层掺镱光纤放大器,获得了平均功率为9.3W的放大激光输出,重复频率为10kHz,脉冲宽度为450ps,峰值功率大于2MW。

A passive coherent beam combination of two nanosecond amplifiers is realized by using an all-optical feedback loop. The width of the combined pulses is 9.7 ns, and the pulse repetition frequency is 2.023 MHz. With the least mismatch between pulse period and time of the cavity round trip in our loop, the visibility of far-field coherent patterns is more than 71%. The dynamics of passive phase locking is studied, and the established time of phase locking of two pulsed amplifiers is at least 10 cavity round trips in the all-optical feedback loop.

实现了一种单端光纤耦合的高重复频率、窄脉冲、窄线宽及高效率的主动声光调Q全光纤脉冲光纤激光器.该光纤激光器基于光纤光栅与平面镜组合而成的线性法布里-珀罗(F-P)腔结构,采用激光二极管与(2+1)×1抽运耦合器形成后向抽运,并利用单端光纤耦合声光调制器(AOM)实现了全光纤化结构的脉冲掺镱双包层光纤激光器.调Q声光开关工作在一级方向,反向输出调Q脉冲,重复频率20～100 kHz可调.在重复频率50 kHz、抽运功率5.7 W下系统获得了输出激光功率2.64W、单脉冲能量528μJ、脉宽56 ns、峰值功率943 W的稳定的高效率、窄线宽的窄脉冲,中心波长在1080 nm左右,线宽为0.06 nm,光-光转换效率高达46％.

Polarization self-selection in passive phasing of four fiber amplifiers with an all-optical feedback loop is demonstrated. The polarization extinction ratio (PER) of the combined beam is increased, and the polarized direction is selected with the use of a polarization-maintaining (PM) isolator and some non-PM components. The best visibility of the interference patterns is observed at 95.2% and in the largest increment in the PER of the combined beam up to 7.4 dB. Results show that all PM components are unnecessary in the coherent beam combination with an all-optical feedback loop, whereas non-PM components have good potential to achieve high output power.

The maximum output power of fiber lasers limited by the thermal degradation of double-clad fiber coatings is theoretically simulated. We investigated the thermal effects on high-power continuous wave (CW) fiber lasers with a focus on heating at the splice joints as well as on the doped fiber caused by quantum defects. Whether thermal interface materials are used or not, the thermal contact resistances between the fiber and its heat sink are measured separately while using different cooling equipments. Though the thermal management of splices is more difficult than that of active fibers, a temperature increase of 0.019 K/W is obtained for a splice joint into which the pump light launches. The splice joint sustains 3 kW of total passing power.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text S. Du, J. He, Z. Wang, W. Wu, Q. Lou, J. Zhou, and Y. Wei, "Millijoule-class Pulse Energy, High Peak Power Q-switching Large-Mode-Area Photonic Crystal Fiber Laser at 978nm," in International Photonics and Optoelectronics Meetings, OSA Technical Digest (online) (Optica Publishing Group, 2012), paper MTh5A.5. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

In order to increase the power fraction of the central lobe in the coherent beam combination of lasers in an array, the effects of the distance factor of near-field distribution on far-field interference patterns are calculated and demonstrated experimentally. An improved beam array of interwoven distribution is demonstrated to enable the power in the central lobe to reach 41%. An optimized mirror array is carefully designed to obtain a high duty ratio, which is up to 53.3% at a high power level. By using these optimized methods and designs, the passive phase locking of eight Yb-doped fiber amplifiers with ring cavities are obtained, and a pleasing interference pattern with 87% visibility is observed. The maximum coherent output power of the system is up to 1066 W.

We demonstrate a controllable dual-wavelength fiber laser which contains a master laser and a slave laser. The master laser is a kind of ring cavity laser which can be injected into by the slave laser. The output laser wavelength is controlled by injected power of the slave laser; both single- and dual-wavelength operation can be achieved. Under free running, the master laser generates 1064nm laser output. Here the slave laser is a 1072nm fiber laser. The 1064nm and 1072nm laser coexist in output spectrum for relatively low injected power. Dual-wavelength and power-ratio-tunable operation can be achieved. If the injected power of the slave laser is high enough, the 1064nm laser is extinguished automatically and there is only 1072nm laser output.

We report an all-fiber high power, single frequency large-mode area (LMA) linearly polarized ytterbium-doped fiber amplifiers (YDFA) module, which is based on the master oscillator multi-stage power amplifiers (MOPA). The maximum output power is 43.8 W at a wavelength of 1064 nm when 60-W launched pump light is coupled, with high slope efficiency of 88%, polarization extinction rate (PER) > 17.2 dB and nearly diffraction-limited beam quality (M-2 < 1.1).

实验研究了单频单模保偏掺Yb光纤放大器中的受激布里渊散射（SBS）效应。采用前向抽运的两级级联掺Yb光纤放大器,研究了保偏光纤放大器中的受激布里渊散射的光谱变化特性。理论计算的单模光纤的布里渊频移和SBS阈值与实验测试的结果进行了比较。在光纤放大器前后两端观察到多级次的斯托克斯（Stokes）谱线和多级的反斯托克斯（anti-Stokes）谱线,这是由级联受激布里渊散射和四波混频过程产生的。