薄片式Yb:YAG激光器及其应用

介绍了薄片式固体激光器的原理,YbYAG晶体的特性及其与传统棒状NdYAG晶体固体激光器的对比.VersaDisk固体激光器是一个功能强大的光学平台,可以实现红外(基频)、绿光(倍频)或双波长(红外和绿光)同时输出,也可以在腔内插入标准具、布儒斯特窗片、双折射滤光片来实现单频、线偏振、波长可调谐等多项传统棒状固体激光器实现不了的功能.该激光器在科研领域可以用于中红外高分辨率光谱、玻色-爱因斯坦凝聚和光镊、材料微加工、泵浦高功率Tisapphire激光器和染料激光器和全息、干涉、光存储等需要激光器单频特性的应用领域.     

Dual wavelength dye laser incorporating distributed feedback

A dual wavelength dye laser has been constructed in which one wavelength is selected by distributed feedback and the other by a conventional external cavity tuned by a grazing incidence/Littrow grating pair. Both wavelengths are emitted collinearly and simultaneously, show the same temporal profile (10 ns pulse), have comparable linewidths (0.1/0.2 Å), are of comparable energies (0.5 mJ), and are independently tunable. The laser exhibits the low amplified spontaneous emission properties normally associated with distributed feedback lasers. Gain competition effects have been examined.     

Thermo-optical properties of polar dielectric laser dye solvents

This work is devoted to study the thermo-optical properties of three important pure polar dielectric laser dye solvents (aniline, pyridine and ethyl ether). Experimental measurements of the refractive index n and its thermo-optic coefficient dn/dT are carried out using dual laser Mach–Zehnder interferometric technique. The determined values of n and dn/dT are used to extract new data concerning the mentioned laser dye solvents. Applying the empirical relationship of Cauchy between the refractive index and the wavelength, the optical dispersion dn/dλ and dn/dT, as a function of wavelength are calculated and represented. Additionally, Cauchy's constants as a function of temperature has been calculated and a comparison between the studied solvents are considered.     

Lead-insensitive fiber optic pH sensor and performance under bending

We have designed and tested a lead-insensitive fiber optic pH sensor that is based on the absorption of an indicator dye immobilized in a polymer bead. The fiber optic pH sensor uses two wavelengths; one senses the change in absorption of the indicator dye and the other provides a reference signal. In a view to desired time modulation and the dual wavelength time division multiplexing, we used light emitting diodes for sources, a phototransistor for the detector, and electronics process the detected signal. The sensor has demonstrated fast response, repeatable calibration, reversibility, and stability. This inexpensive device may also be used during bending of the optical fiber for applications in the field.     

Full-automatic broad-band wavelength control of a pulsed dye laser

A full-automatic wavelength controled pulsed dye laser has been developed. With the control system, dye laser oscillations of nanosecond pulses are tuned to any wavelength in the visible or scanned in any sweep mode keeping the nearly transform-limited bandwidth of 0.45 GHz. A mechanical tuning of the wavelength is employed, such that the motion of three wavelength selectors is synchronized to give a smooth and precise wavelength control. The basic principle underlying the tuning scheme, various requirements to be met in system construction, and the practical performance of automatic wavelength control are described in this paper.     

Dual wavelength lasers

Dual wavelength lasers are discussed, covering fundamental aspects on the spectroscopy and laser dynamics of these systems. Results on Tm:Ho:Er:YAG dual wavelength laser action (Ho at 2.1 μm and Er at 2.9 μm) as well as Nd:YAG (1.06 and 1.3 μm) are presented as examples of such dual wavelength systems. Dual wavelength lasers are not common, but there are criteria that govern their behavior. Based on experimental studies demonstrating simultaneous dual wavelength lasing, some general conclusions regarding the successful operation of multi-wavelength lasers can be made.     

Experiment Study of Dual Wavelength and Dual Pulse Q-switched Intracavity Frequency Doubling of a Tunable Cr:LiSAF Laser

In this paper, a flashlamp-pumped Q-switched Cr: LiSAF laser system with intracavity frequency doubling is designed to obtain dual pulse and dual wavelength laser output. The behaviors of second harmonic output of dual pulse and dual wavelength are studied experimentally. Good results are obtained in experiments: the output energy of each second harmonic pulse a round 448.1 nm is 10.2 mJ, the dual pulse time interval can be tuned widely, and the tunable range of each second harmonic wavelength is 448.1 to 465 nm.     

Fluorescent probe based on proton transfer in 4′-(diethylamino)-3-hydroxyflavone: Spectral and luminescent characteristics upon selective excitation

The spectral characteristics of acetonitrile solutions of 4′-(diethylamino)-3-hydroxyflavone dye with dual fluorescence are studied under selective excitation. This dye is a structural analog of 3-hydroxyflavone and exhibits excited-state proton transfer, which, in contrast to 3-hydroxyflavone, has a thermodynamic rather than a kinetic character. The fluorescence spectra at different excitation photon energies and the excitation spectra of different fluorescence bands are studied. It is found that the intensity ratio of the normal and tautomeric fluorescence bands lying near 507 and 570 nm, respectively, depends on the excitation wavelength, namely, this ratio is 1.45 and almost does not change in the region of the main absorption band (370–420 nm), while, in the region of the second singlet band (near 280 nm), it decreases to 1.15. This can be explained by an increase in the probability of proton transfer with formation of a tautomeric form in the case of excitation into the second band. Another interesting feature is the existence of a latent third emission band peaked at 535 nm, which was found and reliably recorded upon excitation at wavelengths of 470–500 nm. Addition of water quenches this emission, which indicates that it belongs to the anionic form of the dye.     

Spectral properties of molecular charge-transfer probe QMOM

The spectral characteristics of solutions of a dye with dual fluorescence, 1-methyl-2-(4-methoxy)phenyl-3-hydroxy-4(1H)-quinolone, in acetonitrile are studied upon selective excitation. This dye is a structural analogue of 3-hydroxyflavone and also exhibits excited-state proton transfer, which, as well as in the case of 3-hydroxyflavone, has a kinetic nature. The fluorescence spectra are studied upon excitation by photons of various energies, and the excitation spectra are recorded at wavelengths of different fluorescence bands. It is found that the intensity ratio of the emission of the normal and tautomeric forms (at wavelength of 415 and 518 nm, respectively) is almost the same (0.23–0.25) for excitation in the regions of the main and the second absorption bands. At the same time, in the case of excitation between these bands, this ratio decreases to 0.19. The second interesting feature is the existence of a third latent emission band peaked at about 480 nm, which is reliably detected upon excitation at wavelengths in the region of 400–450 nm. This study shows that this emission belongs to the anionic form of the dye. This form is also responsible for a decrease in the intensity ratio of the emission of the two main forms in the case of excitation between the first and second absorption bands.     

感绿菁染料J-聚集体吸附在氯化银微晶表面的吸收光谱

染料J-聚集体对于现代彩色信息记录与存储材料、生物光电子器件、光合作用、太阳能转换与存储等方面具有十分重要的应用前景和理论意义。感绿菁染料在适当浓度时,对立方体氯化银微晶有增感效应,文章应用吸收光谱法对增感后的氯化银微晶样品进行了研究。研究表明, 增感染料浓度低于0.02 mL(染料浓度为5.0 mg·mL-1)/40 g乳剂时,感绿菁染料在立方体氯化银表面不形成J-聚集体,吸收光谱没有J-聚集体吸收峰出现;当染料浓度高于0.2 mL(染料浓度为5.0 mg·mL-1)/40 g乳剂时,染料开始在立方体氯化银微晶表面聚集并形成J-聚集体,吸收光谱有J-聚集体吸收峰出现。随染料浓度进一步增加,J-聚集体的吸收明显加强,吸收峰有微小的红移。     

Wavelength stabilization of a 980-nm semiconductor laser module stabilized with high-power uncooled dual FBG

An optimized dual fiber Bragg grating (FBG) is proposed for 980-nm semiconductor lasers without thermoelectric coolers to restrict temperature-induced wavelength shift.The mathematical model of the temperature-induced wavelength shift of the laser with the dual FBG is built using the external cavity feedback rate equations.The external cavity parameters are optimized for achieving the stability mode-locking laser output.The spectral characteristics of the dual FBG stabilized laser are measured to range from 0 to 70 °C.The side mode suppression ratio (SMSR) is more than 45 dB,while the full-width at half-maximum (FWHM) is less than 1 nm.The peak wavelength shift is less than 0.1 nm.The dual FBG wavelength shift proportional coefficient is between 0.1086 and 0.4342.     

超冷里德堡原子的产生以及探测

利用激光冷却与俘获技术获得冷原子,由双光子激发产生超冷里德堡原子,利用场电离法得到了里德堡原子ns和nd态的离子谱图;再将激光波长固定在6p3/2-34d态的共振跃迁线上,得到了离子和里德堡原子的TOF(Time of Flight)图,并对实验结果做了分析.     

Laser dye stability. Part 4

Changes in the absorption of a dye laser solution are examined after excitation with a xenon flashlamp. It is found that the rate of bleaching as a function of the total input energy of coumarin or quinolone dyes in ethanol increases in direct proportion to the dye concentration. This relationship suggests that the dye reacts with a photoproduct of the solvent rather than being directly decomposed by the xenon flash. We have measured the conversion of the dye to form products,P, absorbing at the lasing wavelength. Results correspond to the dye reacting with a precursor ofP to form either insoluble products or ones not absorbing at the lasing wavelength. Thus larger total amounts of bleached dye do not proportionately increaseP, and hence do not proportionately inhibit lasing. Furthermore, we find thatP increases with the total input energy fairly independent of the rate of bleaching for a given bicyclic dye in an alcohol solution.     

Laser dye stability. Part 4

Changes in the absorption of a dye laser solution are examined after excitation with a xenon flashlamp. It is found that the rate of bleaching as a function of the total input energy of coumarin or quinolone dyes in ethanol increases in direct proportion to the dye concentration. This relationship suggests that the dye reacts with a photoproduct of the solvent rather than being directly decomposed by the xenon flash. We have measured the conversion of the dye to form products,P, absorbing at the lasing wavelength. Results correspond to the dye reacting with a precursor ofP to form either insoluble products or ones not absorbing at the lasing wavelength. Thus larger total amounts of bleached dye do not proportionately increaseP, and hence do not proportionately inhibit lasing. Furthermore, we find thatP increases with the total input energy fairly independent of the rate of bleaching for a given bicyclic dye in an alcohol solution.     

双波长高精度红外测温仪

利用双波长红外测温方法,通过黑体红外辐射曲线中双波长等比吸收的原理消除了由于辐射环境中水蒸气等外界吸收原因造成的单波长红外测温仪中的测量误差,实现更稳定的高精度红外测温.该方法绕开了传统红外测温方法中"辐射率修正困难"的问题.同时利用此红外测温仪器改进了金属钨电子逸出功测量实验.     

轴向隐失波激励的回音壁模式光纤激光器

采用轴向隐失波激励增益的方式,使激光增益区域局限在光纤回音壁模式的模场区域内,显著地降低了回音壁模式光纤激光辐射的抽运阈值,由此形成一种低阈值的回音壁模式光纤激光器.在微焦耳量级的低抽运能量条件下,用回音壁模式光纤激光器研究了激光染料的浓度效应.实验结果表明,随着激光染料浓度的增加,回音壁模式激光辐射的波长向长波方向移动,激光波长范围变宽.用回音壁模式染料激光的四能级模型得到激光上能级和所有能级上的分子数比值γ(λ)曲线后,很好地解释了实验结果.低抽运阈值的回音壁模式光纤激光器,为研究液体激光现象提供了极为便利的手段.     

Dye laser pumped, continuous-wave KTP optical parametric oscillators

4 (KTP) optical parametric oscillators (OPOs) with pump and idler resonant cavities. With a linear two-mirror cavity the pump power at threshold was 70 mW. The single-frequency signal and idler output wavelengths were tuned in the range of 1025 to 1040 nm and 1250 to 1380 nm by tuning the dye laser in the range of 565 to 588 nm. With a dual three-mirror cavity the threshold was 135 mW. Pumped by 500 mW of 578 nm radiation the 1040 nm single-frequency signal wave output power was 84 mW. Power and frequency stable operation with a spectral bandwidth of less than 9 MHz was obtained by piezo-electrically locking the length of the pump resonant cavity to the dye laser wavelength. Similar performance was achieved by placing the idler resonant OPO inside the resonator of the dye laser. With this system power stable and single-frequency operation was achieved with a spectral bandwidth of less than 11 MHz for the idler wave. Received: 3 February 1998/Revised version: 9 March 1998     

偏斜光线抽运下的回音壁模式光纤激光辐射特性

研究了偏斜光线抽运下的回音壁模式光纤激光辐射特性.实验发现,在抽运光以偏斜光线方式沿光纤的近轴向抽运时,回音壁模式的光纤激光辐射中,既存在光电矢量和光纤径向垂直的横电波(TE),也存在光电矢量和光纤径向平行的横磁波(TM);随增益包层染料溶液折射率的增加,径向模式数和角模式数相同的TE波和TM波之间的波长差单调减小,回音壁模式激光辐射的中心波长向短波方向移动,辐射的波长范围变窄.用回音壁模式激光的辐射理论结合激光染料的四能级模型,满意地解释了实验结果.     

Influence of dye gain medium flow on the wavelength jitter and the drift of high repetition rate—Single mode dye lasers

This paper presents the effect of the flow of the dye gain medium on the wavelength jitter (<30 s) and drift (≈10 min) of a single axial mode dye laser pumped by a copper vapor laser (5.5 kHz). The study was carried out using a wave-meter. The dye solution temperature was maintained to within ±0.1 °C to allow the influence of dye flow rate on the wavelength stability. For the investigated dye flow rate, varying from 1.4 to 2.8 lpm (with corresponding Reynolds number varying from 1975 to 3950), the dye laser wavelength jitter reduced from ±0.15 pm (±130 MHz) to ±0.08 pm (±70 MHz) and drift rate reduced from 1.0 to 0. 2 MHz/s. However for flows beyond 1.7 lpm, random fluctuations in dye laser wavelength were observed. The observed behavior was linked to the flow related variation of angular spread and angular drift of the dye laser beam circulating in the cavity. This was revealed by an exhaustive study of the long term (≈10 min) divergence and pointing stability of the single mode dye laser output beams for different dye media flows.     

双波长光纤光栅的矩阵分析

本文在分析双波长光栅特征的基础上,结合耦合模理论和矩阵分析方法,提出了分析双波长光栅的一种数学模型,并在此基础上,采用矩阵分析方法对双波光栅进行了理论分析,得到的结果与实验结果基本吻合。