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1.
A simple cavity ring-down technique employing a cw broadband diode laser is described for the reflectivity measurements of
highly reflective mirrors. Due to the broad line width of the diode laser, the laser beam can be continuously injected into
the ring-down cavity without tuning the cavity length or the laser frequency. Both Fourier- and time-domain data-processing
approaches are developed to determine the reflectivity. In the Fourier domain, the amplitudes and phase shifts of the first
and third harmonics of a periodic ring-down signal are measured as a function of the modulation frequency covering an appropriate
range. The cavity decay time and the reflectivity of the cavity mirror are determined by minimizing a mean square variance
containing both the amplitude and phase-shift error terms. On the other hand, in the time domain, the cavity decay time and
the instrumental response time are determined simultaneously by fitting the measured waveforms of the cavity ring-down signals
to a rigorous time-domain model via a multi-parameter fitting procedure. The reflectivity measurements are repeated at four
cavity lengths and all the results obtained with both data-processing approaches are in excellent agreement. The reflectivity
of cavity mirrors near 830 nm is statistically determined to be 0.99797 with an uncertainty less than 3×10-5.
PACS 07.60.Hv; 42.60.Da; 42.55.Px 相似文献
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A simple, accurate and reliable method for measuring the reflectivity of lasergrade mirrors (R > 99.5%) based on cavity ring-down (CRD) technique has been successfully demonstrated in our laboratory using a pulsed Nd:YAG
laser. A fast photomultiplier tube with an oscilloscope was used to detect and analyse the CRD signal. The cavity decay times
were measured for three cavities formed by a combination of three mirror pairs. The absolute reflectivities R
1, R
2, R
3 were determined to be 99.94%, 99.63%, 99.52% at normal incidence. The reflectivity of mirrors is measured to an accuracy
of 0.01%. 相似文献
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We present the noise suppression of an amplified diode laser by using an optical filter and resonant optical feedback. The
intensity noise of the amplified diode laser has been significantly decreased by using the optical filter cavity. It was further
suppressed and reached the shot noise limit at 15 MHz by introducing resonant optical feedback from the transmission of the
filter cavity. The filter cavity transmits 53% of injection power, and the output power of the filter cavity is more than
200 mW. The observed frequency fluctuations were less than 100 kHz in one minute. This level of noise suppression and output
power may allow diode lasers to be utilized in many quantum-optics experiments.
PACS 42.55-f; 42.55-Px; 42.50.-p 相似文献
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基于通讯波段的分布式反馈半导体激光器(DFB),搭建了一套光腔衰荡光谱仪(CRDS)。衰荡光腔由一对反射率高于99.997%的高反镜组成,衰荡腔长约为130 cm,空腔衰荡时间约为150 μs。当光谱平均次数达到1 000次时,光谱仪灵敏度(最小可探测吸收系数)达到5×10-12 cm-1。利用热隔绝的方式稳定衰荡腔长,并使用衰荡光腔自身作为光学标准具,来标定光谱的频率:利用反馈式光谱扫描程序步进改变激光器频率,使之与衰荡腔的纵模频率逐一匹配,从而实现所测得光谱的自动标定。通过测量一氧化碳分子在1.565 μm附近的吸收光谱,测定气体中一氧化碳的含量。将光谱测量结果和标准样品中的一氧化碳含量进行对比,对装置的定量精度进行了检验,表明其对一氧化碳的探测极限达4 ppbv。利用该装置对实际大气中一氧化碳的含量进行了实时监测。 相似文献
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光腔衰荡方法是目前测量光学元件超高反射率(反射率>99.9%)的唯一方法。介绍了一种对光腔衰荡法中激光信号强度与时间关系的优化提取方法。设计了基于光腔衰荡法的光学元件超高反射比的测试系统,通过对采集的光腔衰荡曲线数据进行分段指数拟合,将光腔衰荡曲线数据分为5段,对每段指数拟合结果对应的R2 (R-square)和RMSE(root mean squared error)值进行对比分析,计算每段指数拟合的衰荡时间。实验结果表明:截取光腔衰荡曲线数据40%~60%部分拟合得到的结果最接近真实值,求得对应的腔镜的反射率为99.988 977%。最后通过与腔镜的自身反射率进行比较,表明该种数据拟合方法能有效地测量腔镜的反射率,并能减小实验数据本身带来的误差。 相似文献
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CO2的腔增强吸收与高灵敏吸收光谱研究 总被引:6,自引:2,他引:4
腔增强吸收光谱(CEAS)是在衰荡吸收光谱的基础上发展起来的一种新型的直接吸收光谱技术.文章报道了用中心输出波长为1.573μm的窄线宽连续可调谐半导体激光器(DFB封装)作光源,用两块高反射率平凹透镜(在1.573μm附近,凹面反射率R~99.4%,曲率半径r~1 m)组成对称共焦腔作吸收池的腔增强吸收光谱系统.采用扫描腔长的方法改变谐振腔的模式,当激光器的输出频率与谐振腔的某一腔模之间满足共振匹配关系时,激光被耦合到谐振腔内,用探测器接收透过谐振腔的光信号,同时用波长计精确测量激光器的输出波长.在33.5 cm长的吸收池内测量了吸收强度为1.816×10-23cm-1·(molecule·cm-2)-1的二氧化碳分子的弱吸收谱线,探测灵敏度达到了6.78×10-7 cm-1.实验结果表明,腔增强吸收光谱具有灵敏度高,装置简单,易于操作等优点. 相似文献
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利用光腔衰荡光谱技术,建立了氧碘化学激光器腔镜高反射率的精密测量系统。对用直型衰荡光腔时可能影响测量系统精度的各种因素进行了系统的实验研究。采用直型和折叠型衰荡光腔,检测了氧碘化学激光器高反腔镜在1.315μm的反射率。实验测得COIL凹面高反腔镜反射率为99.770%;平面高反镜反射率为99.917%,测量精度约为10-5。结果表明,该系统可以精密测量氧碘化学激光器腔镜的高反射率,测量结果精确可靠。 相似文献
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以半导体激光器中的复合腔模型和实测的分布反馈光纤激光器的外腔端面反射率为基础,对不同反射率条件下分布反馈光纤激光器的输出功率进行了仿真,同时搭建了二基元分布反馈光纤激光器阵列实验平台,对仿真结果进行了验证.仿真与实验结果表明:外腔反馈光重新注入分布反馈光纤激光器会增加激光器的输出功率,降低了阵列的输出功率平坦性.并且外腔端面反射率越大,这种平坦性降低的效果越明显.在构建分布反馈光纤激光器阵列时,应考虑外腔反馈对阵列输出功率平坦性造成的影响,尽量选择外腔端面反射率较小的激光器进行组阵. 相似文献
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2 laser. After excitation, the laser power is turned off for a short time and the subsequent decay of the radiation stored
in the cavity is observed via detection of the light leaking out through one of the cavity mirrors. Measurement of the decay
time allows one to determine the photon losses und thus to detect weakly absorbing species inside the cavity. Since the cavity
is frequency-locked to the laser the decay time can be probed with a high repetition rate, basically limited by the sampling
rate of the analog-to-digital converter. This approach is closely related to cavity ring-down spectroscopy with pulsed lasers,
but exhibits several advantages concerning spectral resolution and detection sensitivity. As a practical example we demonstrate
monitoring of trace amounts of ethylene. Using R=99.5% mirrors we achieve a detection limit of 1 ppb ethylene (integration
time: 100 s) corresponding to absorption losses of 3×10-8 /cm. Further improvement is feasible when mirrors with higher reflectivity become available.
Received: 2 July 1998 相似文献
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NewApproachtoInvestigationofTunableExternalCavitySemiconductorLasers¥LUHongchang;LUOBin(SouthwestJiaotongUniversity,Chengdu61... 相似文献
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We report a cw optical parametric oscillator (OPO) in a novel architecture comprising two nonlinear crystals in a single cavity, providing two independently tunable pairs of signal and idler wavelengths. Based on a singly resonant oscillator design, the device permits access to arbitrary signal and idler wavelength combinations within the parametric gain bandwidth and reflectivity of the OPO cavity mirrors. Using two identical 30 mm long MgO:sPPLT crystals in a compact four-mirror ring resonator pumped at 532 nm, we generate two pairs of signal and idler wavelengths with arbitrary tuning across 850-1430 nm, and demonstrate a frequency separation in the resonant signal waves down to 0.55 THz. Moreover, near wavelength-matched condition, coherent energy coupling between the resonant signal waves, results in reduced operation threshold and increased output power. A total output power >2.8 W with peak-to-peak power stability of 16% over 2 h is obtained. 相似文献
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为测量高能激光传输系统中大口径高反射率光学元件的反射率,设计了一种大口径光学元件二维扫描的精密测量系统。介绍了该系统的结构及其工作原理,分析了影响系统测量精度的因素,从理论上分析了扫描系统的系统误差对测量精度的影响,结果表明在垂直于光束传播方向上,水平偏差在0.29 mm时,测量误差在10-6量级;腔长的变化量较小时,可通过对衰荡腔腔镜的调节,实现对旋转轴偏差的补偿及对系统的精细调节。通过拟合处理光强与时间的数据得到对应的一次指数函数拟合曲线,并通过计算得到衰荡时间和反射率,经过对比分析可知,该误差分析方法能比较有效地测量腔镜的反射率,并能减小实验数据本身带来的误差。 相似文献
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M Britzger A Khalaidovski B Hemb EB Kley F Brückner RH Rinkleff K Danzmann R Schnabel 《Optics letters》2012,37(15):3117-3119
In this Letter, we propose and demonstrate an external-cavity diode laser in second-order Littrow configuration. This topology utilizes a low-efficiency diffraction grating to establish a high-finesse external cavity, strong optical feedback, a high polarization discrimination, and a circular TEM00 output mode. In our proof-of-concept experiment, we realized a cavity with a finesse of 1855, being, to the best of our knowledge, the highest value ever reported for a three-port-grating-coupled cavity. With optical feedback, the laser threshold of the laser diode employed was reduced by a factor of 4. 相似文献
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We describe effective suppression of beam divergence for a high-power laser diode bar by use of an external-cavity technique. Nineteen off-axis external-cavity laser diodes of the high-power laser diode are formed by feedback with a stripe mirror. At three times the threshold current, the diverging angle (1/e2) of the external-cavity laser diode bar is reduced to 1.5 degrees from 6.6 degrees (free running) with 14.1-W peak output power and 70.4% of the radiated power of the free-running state without the external cavity. This technique effectively improves the beam quality of the high-power laser diode bar. 相似文献