Multichannel AM video transmission using a high-power Nd:YAG laserand linearized external modulator

A high-power Nd:YAG laser with a linearized external modulator-based system is demonstrated for a transmission of 50 channels of vestigal sideband amplitude modulated (VSM AM) video. The 1320-nm diode-pumped Nd:YAG laser is an attractive source for AM video transmission due to the high output power (~200 mW) and low relative intensity noise (<-170 dB/Hz). However, the required external modulator generates third-order distortion products, which limit the performance of such a system. A predistortion linearization technique is described. It reduces the modulator generated third-order distortion products by 16.4 dB, allowing a modulation index of 3.37% per channel. When combined with the Nd:YAG laser, this yields a 50-channel video transmission system with a 12 dB optical power budget for video carrier-to-noise ratios of 52 dB and composite distortion products (CSO and CTB) of less than -60 dBc. The demonstrated power budget is sufficient to allow four-way power splitting, with the remaining margin comparable to the test results obtained with DFB (distributed-feedback) laser-based AM transmission systems     

Ar+激光器用于电阻微调的研究

本文讨论并研究了Ar+激光器用于电阻微调的优越性。结果表明,在比常用的Nd:YAG激光功率小得多的情况下,可得到与之相当的刻线宽度和阻值稳定性。     

Continuous wave, Q-switched and mode-locked operation of alaser-pumped Nd:LNA laser

A linear cavity Nd:LNA laser pumped by a Ti:sapphire laser was investigated in a continuous wave (CW), Q-switched and mode-locked regime. A parallel study using a Nd:YAG crystal was also conducted using the same optics and intercavity elements. The slope efficiencies obtained with a 5% output coupler in CW operation are 41 and 55% for Nd:LNA (λ~1.054 nm) and Nd:YAG (λ~1.065 nm), respectively. Mode locking was achieved with a 360-MHz intracavity phase modulator and led to a relative improvement of the Nd:LNA versus the Nd:YAG device. In the Q-switched mode with an intracavity acoustooptic modulator, the performance of the two lasers is almost identical. With 300 mW of absorbed pump power at λ~800 nm, peak powers ~130 W were achieved in a 65-ns pulse with a 5% output coupler     

Improved-dynamic-range single-mode OTDR at 1.3 ?m

A high-performance single-mode optical time-domain reflector (OTDR) incorporating a new low-noise receiver design utilising a PIN diode detector and a transimpedance amplifier is described. With a 1.3 ?m laser diode source a dynamic range of 30 dB one way is achieved, and using an Nd: YAG laser source the dynamic range is 41 dB one way.     

FM-laser operation of the Nd:YAG laser

The FM-laser or frequency-sweeping mode of laser oscillation has been demonstrated in a Nd :YAG 1.06-μ laser with an intracavity LiNbO3phase modulator. The experimental results are in excellent agreement with the theoretical expressionDelta= (DeltaOmega/Deltanu) (delta/pi)where δ= peak single-pass phase retardation in the modulator,DeltaOmega= axial mode spacing,Deltanu=modulator detuning, and Δ=resulting FM index of the laser output. Modulation indices as large asDelta approx 230rad have been obtained, in which case the instantaneous laser frequency is sweeping over a full spectral range of2Delta cdot f_{m} approx 120GHz (≈ 4 cm^-1) at a repetition frequencyf_{m} approx 260MHz, with a time-bandwidth product per periodapprox 2Delta approx 460. The coherently mode-locked spectral bandwidth thus obtained in the FM-laser case is very much wider than can be achieved in the pulsed mode-locked case with the same Nd:YAG laser. Some possible ways of using this broad-band coherent FM spectrum are suggested.     

Optical phase-locked PSK heterodyne experiment at 4 Gb/s

A 4 Gb/s phase-locked optical PSK (phase shift keying) heterodyne communication system is demonstrated. The receiver was implemented with a single 100-Ω loaded p-i-n photodiode and a 1320-nm diode-pumped miniature Nd:YAG laser as a local oscillator. For a 2⁷-1 PRBS (pseudorandom bit sequence), the receiver sensitivity was -34.2 dBm or 631 photons/bit. The corresponding power on the surface of the detector was -37.3 dBm or 309 photons/bit. With a 2¹⁵-1 PRBS, a 2.6 dB additional sensitivity degradation was observed due to the nonideal frequency response of the phase modulator and the receiver amplifiers     

Coherent FMCW reflectometry using a temperature tuned Nd:YAG ringlaser

A long-coherence-length, diode-pumped, monolithic Nd:YAG laser operating at 1.32 μm is used to perform coherent FMCW (frequency-modulated continuous wave) reflectometry measurements. Compared with semiconductor-based lasers, the low phase noise of the Nd:YAG source offers greatly increased distance range combined with increased sensitivity to optical reflections. Measurement of Rayleigh backscatter from 50 km of fiber is demonstrated with over 60 dB of two-way optical dynamic range. Two-point spatial resolution is demonstrated to be better than 10 cm. This source and coherent measurement technique may have potential for both short and long-haul reflectometry applications     

LD泵浦Nd:YVO4倍频调Q激光器的输出特性

根据四能级非线性速率方程,对连续LD泵浦Nd:YVO4/Cr4+:YAG/KTP腔内倍频被动调Q绿光激光器的输出特性进行了数值模拟.理论分析与实验相一致,所得结果对该类器件参数优化具有参考价值.     

LD泵浦的Nd:YAG陶瓷激光器

介绍了一种新型的固体激光材料——Nd：Y3Al5O12(Nd：YAG)陶瓷的光学特性,设计并研制成LD泵浦的Nd：YAG陶瓷微型激光器件。阈值泵浦功率为48mW,在泵浦功率为1．5W时获得了516mW的1064nm连续激光输出,光-光转换效率为34．41%。     

低能耗YAG激光器的研究与实现

在研究小功率Nd：YAG激光电源的基础上,设计出RLC新型节能电路,经实验及各参数测试证明,应用了RLC节能电路的新型Nd：YAG激光电源待机电能耗散功率明显下降,且激光泵浦氪灯的使用寿命也相应延长,这一研究结果表明,新型RLC节能电路,在小功率Nd：YAG激光电源领域具有广泛的应用前景。     

A high-gain, high-output saturation power erbium-doped fiberamplifier pumped at 532 nm

An erbium-doped fiber amplifier with a high small-signal gain of 42 dB at the gain peak of 1536.4 nm, a pumping efficiency of 1.6 dB/mW, and an output saturation power of 10 dBm is obtained with a pump power of 60 mW at 532 nm using the second harmonic of a Nd:YAG laser as the pump source. These experimental results indicate that diode-laser-pumped mini-Nd:YAG lasers with intracavity frequency-doubling have an output power at 532 nm of 100-150 mW that can be of great interest for practical system applications using high-gain, high-output-power erbium-doped fiber amplifiers     

Fabrication of narrow pulse passively Q-switched self- stimulated Raman laser with c-cut Nd:GdVO4

Combining the self-stimulated Raman scattering technology and saturable absorber of Cr4+:YAG, a 1.17 μm c-cut Nd:GdVO4 picosecond Q-switched laser is demonstrated in this paper. With an incident pump power of 10 W, the Q-switched laser with average power of 430 mW for 1.17 μm, pulse width of 270 ps, repetition rate of 13 kHz and the first order Stokes conversion efficiency of 4.3% is obtained. The Q-switched pulse width can be the narrowest in our research. In addition, the yellow laser at 0.58 μm is also achieved by using the LiB3O5 frequency doubling crystal.     

高输出能量Cr4+:MSO激光器的实验研究

本文报道掺铬镁橄榄石激光器的最新研究结果.用1.06μmNd:YAG脉冲激光室温纵向泵浦,已获得135mJ的脉冲激光输出.     

采用振荡-放大结构的声光调Q Nd:YAG激光器及光纤传输聚焦系统

研究了一种氪灯抽运的双Nd:YAG棒和声光调制器构成一级振荡加一级放大的声光调QNd:YAG激光器.动态激光平均输出功率最大达到169W,在重复频率1kHz时,测得脉宽70ns,峰值功率达到594kW.用芯径0.6mm的全石英光纤传输激光,并设计了一套聚焦光学系统,实现了大幅面的激光雕刻工作.     

A radio-over-fiber network for microcellular system application

This paper investigates the feasibility of a radio-over-fiber network, which employs a single high-power Nd:YAG laser shared among many microcells. External amplitude modulators are employed at both base station (BS) and radio ports (RPs) to form an optical fiber distribution network. The distortions induced by the uplink remodulation are analyzed. The optimal preamplifier gain in the uplink is estimated for given sensitivity and dynamic range (DR). Appropriate modulator linearization and thermal-noise suppression schemes are utilized together to improve the DR. The clipping distortion for the predistortion-linearized modulator is also considered. The result shows that the effects of clipping and higher order distortions have little impact on the estimation of the system performance. A numerical example shows that a 100-mW Nd:YAG laser can provide for a macrocell of 5-km radius up to 16 microcells and 1600 channels when a 20-dB modulator linearization and 10-dB thermal-noise suppression are employed. The experiment setup uses a two-tone test to verify the theoretical calculation. The measurement agrees with the theoretical estimation very well     

周期极化近化学计量掺镁铌酸锂晶体倍频研究

采用气相输运平衡技术,对不同掺镁浓度的铌酸锂进行了近化学计量处理,并检验了其抗光折变性能。实验结果表明,掺摩尔分数为2%的镁的近化学计量铌酸锂晶体,光折变阈值比同成分晶体提高了4个量级。通过施加4.5kV/mm的脉冲电场,在上述1.0mm厚z切晶体上制备出了周期为6.8μm的均匀畴结构。采用声光调Q Nd:YAG激光器作抽运光源,基频光波波长为1.064μm,平均输入功率为230mW,在室温条件下,得到波长为0.532μm,输出功率为2.8mW的倍频绿光输出,倍频转换效率为1.22%。。     

KTP倍频Nd:YAG激光和Ho:YAG激光心肌打孔组织学变化的对比研究

目的 :比较国产 KTP倍频 Nd:YAG激光和 Ho:YAG激光对离体猪心激光打孔的组织学效应 ,探讨国产 KTP倍频 Nd:YAG激光用于激光心肌血运重建术的可能性。方法 :分别用 KTP倍频 Nd:YAG激光和 Ho:YAG激光以多种级别的工作参数对离体猪心左心室心内膜面进行照射 ,行病理组织学检查 ,测量激光孔道直径、深度及坏死层厚度。结果 :KTP倍频 Nd:YAG激光和 Ho:YAG激光均能有效形成激光孔道 ,随能量增加 ,孔道深度增加。KTP倍频 Nd:YAG激光具有孔道直、热损伤小的优点。结论 :KTP倍频 Nd:YAG激光是激光心肌血运重建术可供选择的激光源。     

二极管象散光束端面泵浦Nd:YAG激光器

研究了用象散二极管激光光束端面泵浦的TEM0m,TEMn0多模Nd:YAG激光器。文中报导了不同泵浦功率下的激光模式情况和稳定性情况,最大CW输出功率320mW,斜效率28%,最高稳定CW输出功率232mW,斜效率20%,为进一步研究二极管泵浦的列阵器件奠定了基础。     

Tunable fibre Raman oscillator in the 1.32?1.41 ?m spectral region using a low-loss, low OH? single-mode fibre

We report the first tunable fibre Raman oscillator in the 1.32?1.41 ?m spectral region using a 1 km-long low-loss (0.32 dB/km at 1.32 ?m) and low OH? (1 dB/km at 1.39 ?m) single-mode fibre as the nonlinear medium, and a CW mode-locked Nd: YAG laser at 1.32 ?m as the pump source.