Proposal for nonlinear refractive index measurement using spectral ratio in modulated OFRR dynamics

A novel method for measuring the nonlinear refractive index of an optical fiber using a spectral ratio between the modulation frequency and a harmonic component in a modulated optical fiber ring resonator (OFRR) is proposed. The spectral ratio between the modulation frequency and the 2nd-harmonics generated by phase-modulation through the OFRR is increased with increasing the input light power and has peaks above 5 W input power, however, the peaks was shifted to the lower input power below 1 W by averaging taken into account of the phase distribution. A experimental setup consisted of an OFRR system and an Ar-laser as a pump light source was used to determine the nonlinear refractive index of an optical fiber. In the experimental results, the peaks of the spectral ratio as a function of the input power was found out at 0.8 W and 0.45 W of the input power corresponding to the input source line at 488.0 nm and 514.5 nm, respectively. The profile was similar to that obtained by the simulation and the nonlinear refractive index of a optical fiber was determined as 1.0 × 10⁻²² m²/V² by a relationship between the input power giving the peak and the nonlinear refractive index.     

Resonant optical nonlinearity measurement of Yb(3+) / Al(3+) codoped optical fibers by use of a long-period fiber grating pair

A new method of measuring optical nonlinearity for resonant nonlinear optical fibers is proposed. A long-period fiber grating (LPG) pair was used to measure the nonlinear refractive index n(2) of a Yb(3+)/Al (3+) codoped optical fiber, which was spliced between the two LPGs, as the fiber was pumped with a laser diode. The nonlinear refractive index of the Yb(3+)/Al (3+) codoped fiber near 1580 nm depended on the pump power. As the pump power increased, the nonlinear refractive index decreased. At launched pump powers of 2-8 mW, the nonlinear refractive index of the Yb(3+)/Al (3+) codoped fiber near 1580 nm was ~7.5x10(-15)m (2)/W .     

Continuous-wave mode-locked Ti:sapphire laser focusable to 5 x 10(13) W/cm(2)

Generation of sub-10-fs pulses with an average power of 1 W and a peak of 1.5 MW from a Kerr-lens mode-locked mirror-dispersion-controlled Ti:sapphire laser is demonstrated. A specially designed lens triplet focuses the output of this compact all-solid-state source to a peak intensity in excess of 5x10(13) W/cm (2) . Nonperturbative nonlinear optics is now becoming feasible by use of the output of a cw mode-locked laser.     

High Speed Demultiplexer Based on a Three-Wavelength SLA

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High Speed Demultiplexer Based on a Three-Wavelength SLA

By using a semiconductor laser amplifier (SLA) with a three-wavelength configuration, which works as a nonlinear element in an optical loop mirror, a demultiplexer device for ultra-fast processing is presented. The simulation shows that its switching time can be less than 10 ps at the holding beam power of 1 W, therefore it has the ability of demultiplexing one bit data from 100 Gb/s Optical Time Division Multiplexing (OTDM) pulse trains at the control power of 1 W.     

888nm LD泵浦Nd：LuV04倍频绿光激光器

报道了采用888nIn的激光二极管（LD）泵浦Nd：LuVO4晶体得到1066nm的激光输出,其对应能级跃迁为4F3／2→4I11/2。在注入的泵浦功率为18．2W时,获得了11．3W的近红外1066nm激光输出;然后采用非线性晶体LiB。O。（LBO）进行腔内倍频,获得了533nm的绿激光输出,输出功率为4．3W,其光-光转换效率为23．6％,光束质量因子为M2=1．3,4h功率稳定度优于3．7％。     

50.2W high stability and high compact all-solid-state green laser with extra-cavity frequency-doubling at 500 Hz

A 50.2W high pulse energy green laser system at 532 nm was demonstrated by extra-cavity second-harmonic generation (SHG). The fundamental laser was based on laser diode (LD) side-pumped MOPA Q-switched technology, producing 79W of average power at the repetition rate of 500 Hz, while the pulse width was 6 ns. Type-II angle phasematched KTiOPO₄ (KTP) crystal was used as the nonlinear crystal. The 50.2W average power of 532 nm laser was obtained with the divergence angle less than 0.6 mrad and the corresponding peak power of 16.7MW. The optical frequency conversion efficiency from fundamental to green laser was up to 63.5%. The measured output power fluctuation was less than 0.38% in one hour operation.     

LD端面抽运Nd:YAG 1319/1338nm双波长激光器研究

从LD端面抽运固体激光器的激光阈值公式出发,建立了双波长激光同时振荡的阈值条件,理论计算了腔镜对于两个波长的透过率关系,实现了LD端面抽运Nd:YAG 1319nm/1338nm双波长激光连续和准连续输出.双波长激光连续输出功率可达6W,斜效率为30%;准连续输出功率在重复频率50kHz时可达4.75W,斜效率为24.73%,脉冲宽度为55.05ns;腔内插入布儒斯特片,在重复频率为50kHz时,双波长激光准连续线偏振输出功率可达2.22W,不稳定性小于0.52%,M² 关键词： 端泵Nd:YAG激光器 1319nm/1338nm双波长 声光调Q 太赫兹波     

LD端面抽运Nd:YAG 1319nm/1338nm双波长激光器研究

从LD端面抽运固体激光器的激光阈值公式出发，建立了双波长激光同时振荡的阈值条件，理论计算了腔镜对于两个波长的透过率关系，实现了LD端面抽运Nd:YAG 1319nm/1338nm双波长激光连续和准连续输出.双波长激光连续输出功率可达6W，斜效率为30%；准连续输出功率在重复频率50kHz时可达4.75W，斜效率为24.73%，脉冲宽度为55.05ns；腔内插入布儒斯特片，在重复频率为50kHz时，双波长激光准连续线偏振输出功率可达2.22W，不稳定性小于0.52%，M²     

83 W yellow-green laser at 556 nm from frequency-doubling of a Q-Switched Nd:YAG laser at 1112 nm in LBO

We demonstrate a high power 556 nm yellow-green laser by intracavity frequency doubled of the diode-pumped 1112 nm Nd:YAG laser in a symmetrical L-shaped flat-flat cavity. The coatings of the resonator mirrors were carefully designed to achieve efficient operation of fundamental wavelength of the laser at 1112 nm. By using a type-II phase matching LBO nonlinear crystal as the frequency-doubler, the maximum output power of the 556 nm laser was measured to be as high as 83 W with a pulse repetition frequency (PRF) of 10 kHz under incident pump power of 1150 W, corresponding to an optical-to-optical conversion efficiency of about 7.2%. The fluctuation of output power was less than 2% over 30 min.     

被动谐波锁模Er3+/Yb3+共掺双包层光纤环形腔激光器

 为了实现高重复频率和高功率的光脉冲,实验采用Er³⁺/Yb³⁺共掺双包层光纤作为增益介质,稳定的中心波长为976 nm的高功率半导体激光器作为泵浦源,利用非线性偏振旋转锁模技术,得到稳定的自起振锁模光脉冲。当泵浦功率为2.4 W时,激光器输出重复频率为8.829 MHz的连续锁模光脉冲,平均输出功率为52.5 mW,自起振锁模泵浦阈值功率为0.6 W,并观测到了稳定的高阶谐波锁模、调Q和调Q-锁模光脉冲输出。     

高稳定LD端面泵浦腔内倍频Nd∶YVO4/LBO连续红光激光器

设计出一种能够较好地补偿激光晶体热效应的激光谐振腔,实现了高稳定LD单端泵浦LBO腔内倍频Nd∶YVO4连续红光激光器.当晶体吸收的泵浦功率为24.56 W时,671 nm激光功率达到1.203 W,光-光转换效率4.9%,激光模式为TEM00模.在输出功率为1.08 W时,激光器1 h功率不稳定度为0.52%.     

Nonlinear femtosecond pulse compression at high average power levels by use of a large-mode-area holey fiber

We demonstrate that nonlinear fiber compression is possible at unprecedented average power levels by use of a large-mode-area holey (microstructured) fiber and a passively mode-locked thin disk Yb:YAG laser operating at 1030 nm. We broaden the optical spectrum of the 810-fs pump pulses by nonlinear propagation in the fiber and remove the resultant chirp with a dispersive prism pair to achieve 18 W of average power in 33-fs pulses with a peak power of 12 MW and a repetition rate of 34 MHz. The output beam is nearly diffraction limited and is linearly polarized.     

High-power ultraviolet 278 nm laser from fourth-harmonic generation of a Nd:YAG laser in CsB3O5

We demonstrate a high-power UV 278 nm laser by fourth-harmonic generation (FHG) of a 1112 nm Nd:YAG laser in a nonlinear optical (NLO) crystal CsB3O5 (CBO) for the first time, to our best knowledge. A 30 W level diode-pumped Q-switched Nd:YAG laser at 1112 nm with beam quality factor M2=1.2 was used as the fundamental light source at a pulse width of 500 ns. With an LiB3O5 crystal, the 1112 nm laser was first frequency-doubled to 556 nm with an average output power of 13.5 W. It was then frequency doubled again in a CBO crystal to obtain the FHG output at 278 nm. The maximum average output power of the 278 nm laser is up to 1.5 W. The results demonstrated that CBO crystal is a promising NLO material for UV high-power lasers below 300 nm.     

A Compact-Intracavity Frequency-Doubling Nd:YAG Laser with 1.3 W Dual-Wavelength (659.6 nm/669.4 nm) Light Output

Terahertz wave radiation has important applications in medical instrumentation, optical communication, and so on. In this paper, we demonstrate a dual-wavelength (659.6 nm/669.4 nm) light output of a compact intracavity frequency-doubling Nd:YAG laser. We achieve a maximum output power of 1.3 W at central wavelengths of 659.6 and 669.4 nm with linewidths of 57 and 74 pm, respectively. The power instability at the maximum output power is less than 1%, and the beam quality is 1.5. This dual-wavelength laser provides a potential source for generating a coherent terahertz wave radiation of 6.46 THz by the nonlinear optical difference frequency method.     

Wavelength tunable ultra-short pulses based on a flat broadband spectrum generated in a nonlinear ytterbium-doped fiber amplifier

We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum(center wavelength and linewidth) are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.     

Diode-pumped high-power cw blue laser at 473 nm with a compact three-element cavity

We report on a diode-pumped cw Nd:YAG laser operating at 946 nm with a maximum output power of 3.3 W and a slope efficiency of 22% with respect to the incident pump power of 17.5 W. Intracavity frequency doubling with nonlinear crystal LBO yielded a single-ended blue output power of 590 mW with optical conversion efficiency of 3.4%. A very simple, compact three-element cavity of 35 mm long was used. The power fluctuation of the blue laser was 4.3% (rms) at output power level of 400 mW. Transverse mode hopping was observed at higher output power.     

High power Yb-fiber laser amplifier based on nonlinear chirped-pulse amplification at a repetition rate of 1 MHz

We report a high power fiber amplifier based on nonlinear chirped-pulse amplification(NCPA). To manage the nonlinearity,pulse shaping is introduced by self-phase modulation in the fiber stretcher with the help of spectral filtering. The third-order dispersion is compensated for by the nonlinear phase shift in the NCPA. With optimization, the system can output 382 fs pulse duration with 20 W average power at 1 MHz repetition rate. The long-term average power fluctuation is measured to be0.5% in 24 h, and the beam quality factor(M~2) is 1.25.     

高稳定LD泵浦腔内倍频Nd∶YVO4/KTP连续绿光激光器

设计出一种能够较好地补偿激光晶体热效应的激光谐振腔，实现了高稳定LD单端泵浦KTP腔内倍频Nd∶YVO₄连续绿光激光器.当晶体吸收的泵浦功率为24.56 W时，532 nm激光功率达到5.3 W，光-光转换效率达到21.6％，激光模式为TEM00模.在输出功率5W左右时，激光器1 h功率不稳定度优于0.6％     

光子晶体光纤飞秒激光非线性放大系统的耦合动力学过程研究

构建了掺镱大模场面积单偏振光子晶体光纤飞秒激光非线性放大系统. 讨论了腔内净色散量和抽运功率对振荡级输出参数的影响和振荡级参数对放大级输出参数的影响. 在本实验条件下, 当腔内净色散量取较大负色散时, 振荡级直接输出的脉冲更宽, 且携带更少的啁啾. 当振荡级抽运4.53 W时, 选择最接近变换极限的脉冲作为种子脉冲, 放大级在60 W抽运时输出压缩后无基底的短脉冲, 宽度为45.7 fs, 平均功率28 W. 振荡级抽运功率增加到5.08 W, 放大级抽运70 W时, 获得最高输出功率34.5 W, 对应脉宽53.5 fs.