Intensity stabilization of dye laser radiation by saturated amplification

A novel scheme is proposed for stabilizing the intensity of a fluctuating laser source, using a partly saturated high gain traveling wave laser amplifier with a nonsaturable absorber distributed in the amplifying medium. Calculations for homogeneously broadened laser gain band in an adiabatic approximation are presented, which indicate that the stabilization factor can be increased by several orders of magnitude with the help of the absorber. An experiment is reported in which a two-stage dye laser amplifier with inserted attenuator, pumped by a nitrogen laser, is used to amplify and stabilize the intensity of an ultra-narrowband repetitively pulsed dye laser. The output intensity changes by less than a factor of four when the input is changed over three orders of magnitude. Work supported by the U.S. Office of Naval Research, Contract No. N00014-67-A-0112-0071, and by a Grant from the Research Development Fund, Stanford University. On leave from the Laboratorio de Elettronica Quantistica del CNR di Milano, Milano, Italy.     

FLaser frequency stabilization and shifting by using modulation transfer spectroscopy

The stabilizing and shifting of laser frequency are very important for the interaction between the laser and atoms. The modulation transfer spectroscopy for the 87Rb atom with D2 line transition F = 2 →F＇ = 3 is used for stabilizing and shifting the frequency of the external cavity grating feedback diode laser. The resonant phase modulator with electro-optical effect is used to generate frequency sideband to lock the laser frequency. In the locking scheme, circularly polarized pump- and probe-beams are used. By optimizing the temperature of the vapor, the pump- and probe-beam intensity, the laser linewidth of 280 kHz is obtained. Furthermore, the magnetic field generated by a solenoid is added into the system. Therefore the system can achieve the frequency locking at any point in a range of hundreds of megahertz frequency shifting with very low power loss.     

Laser frequency stabilization and shifting by using modulation transfer spectroscopy

The stabilizing and shifting of laser frequency are very important for the interaction between the laser and atoms. The modulation transfer spectroscopy for the87 Rb atom with D2 line transition F = 2 → F = 3 is used for stabilizing and shifting the frequency of the external cavity grating feedback diode laser. The resonant phase modulator with electro–optical effect is used to generate frequency sideband to lock the laser frequency. In the locking scheme, circularly polarized pump- and probe-beams are used. By optimizing the temperature of the vapor, the pump- and probe-beam intensity, the laser linewidth of 280 kHz is obtained. Furthermore, the magnetic field generated by a solenoid is added into the system. Therefore the system can achieve the frequency locking at any point in a range of hundreds of megahertz frequency shifting with very low power loss.     

激光稳频中的高灵敏度光谱技术

高灵敏度谱分析技术是激光稳频系统的关键。通过系统的理论分析,结合国内外研究的稳频系统,详尽介绍了导数谱和ＦＭ 光谱激光稳频技术,并对其进行了分析、比较。两者的根本区别在于ＦＭ 光谱技术具有相对较大的调制频率,这是它们在应用中各具特点的根源：ＦＭ 光谱技术具有更高的灵敏度和噪声抑制能力,可以探测到０－００５ ％ 的微小吸收,而导数谱技术对未知的超精细谱线结构具有较好的兼容性。     

High-resolution laser spectroscopy of the potassium-argon molecule: The BΣ state

The absorption spectrum of the KAr molecule has been observed with high resolution between 13 032 and 13 077 cm⁻¹ using tunable laser diodes as light sources, a supersonic beam for production of the molecules, and laser-induced fluorescence for detection. In addition, optical-optical double resonance (OODR) experiments have been performed to simplify the spectrum and to get rotational assignment. Altogether, 670 lines due to the transition B²Σ⁺ ← X²Σ⁺ have successfully been assigned with vibrational levels of the B state ranging from v = 0 to v = 6. The corresponding energy values were fitted to the well-known Dunham expansion. In addition, we were able to analyse a local perturbation between the vibrational level v = 1 of the B state and v = 14 of the A²Π_3/2 state. Unexpected extra lines in the OODR spectra are most probably due to a collision-induced population of other levels. For the equilibrium distance and the well-depth of the B state we obtain from the Dunham expansion 7.03 (8) Å and 26.2 (8) cm⁻¹, respectively.     

A frequency stabilized,cw dye laser for high resolution spectroscopy

A single frequency, jet stream cw dye laser spectrometer locked to a stable high finesse optical reference cavity is described. This system is capable of maintaining a frequency stability of ± 1 MHz/min and a continuous scan of up to 6 GHz.     

碘吸收激光稳频中调制信号的理论计算

激光频率标准是将激光频率锁定于原子或分子的超精细能级间的跃迁频率,从而获得高精密度的激光频率输出。在激光稳频研究工作中,通常将碘分子的吸收谱线采用导数谱、FM光谱和调制转移光谱MTS(ModulationTransferSpectroscopy)进行频率的精密控制。为更好地消除吸收谱线的本底噪声,目前最好的稳频方案是采用调制转移光谱法。它具有高灵敏度、高分辨率和无多普勒背景等特点。从物理学的原理出发,分析了激光对介质的极化机理,导出介质对激光的吸收和色散作用的数学模型,用信号处理的技术从理论上推导了MTS谱线线型,分析了光谱线型的特性,讨论了提高激光频率稳定度的各种情况。     

Holographic contour mapping using a dye laser

Narrow depth contour lines with variable depth distance were generated, using a multiple-frequency cw-dye laser. The feasibility of extending contour mapping with dye lasers to very large objects is discussed.     

Fast frequency control of a cw dye jet laser

For frequency stabilization of a cw dye laser a very fast reacting piezo mirror translator with 350 kHz lowest resonance frequency has been developed. If it is driven by appropriate control electronics it allows to suppress efficiently fast frequency changes of the jet stream dye laser. The remaining frequency jitter is 270 kHz rms for full-bandwidth detection; it drops to a few kHz if a filter time constant of 100 μs is used.     

Experimental determination of cw dye laser parameters by loss variation

The behavior of a cw dye laser under variation of the output coupling has been investigated. By studying the dependence of laser threshold, output power and slope efficiency on the degree of outcoupling, numerical values for macroscopic and microscopic laser parameters have been obtained. The macroscopic data comprise values for internal cavity losses and mode matching conditions, the microscopic data refer to molecular parameters of the dye used, such as cross-sections for stimulated emission and triplet-triplet absorption.     

High-resolution spectroscopy based on optical phase modulator and optical frequency comb

A phase modulation of an optical frequency comb has been applied to measure a fine spectrum in the 1.5 μm wavelength range by the optical heterodyne-detection method. The measurement frequency range covered 25 GHz, which satisfies the frequency interval of the optical frequency comb, with a spectral resolution of 1 MHz.     

Frequency stabilization of a 399-nm laser by modulation transfer spectroscopy in an ytterbium hollow cathode lamp

The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.     

Automatic laser frequency stabilization to iodine absorption line

The measurement accuracy of a Doppler lidar and other laser spectra research is very sensitive to the frequency drift of the laser transmitter. Because currently used frequency locking methods usually involve complicated optics and are sensitive to the working conditions, we present a simple and robust locking method—locking the laser to iodine absorption lines with a software-based PID controller. The locking strategy was successfully applied to three kinds of cw single-frequency Nd: YAG lasers with different tuning actuators. The disadvantage of a slow tuning response is eliminated by using a parameter-adjustable PID algorithm. The frequency stability is better than 200 kHz for 3 h which, to our knowledge is one of the best long-period locking result achieved for this kind of laser.     

Difference frequency generation with a synchronously mode-locked cw dye laser system

The generation of continuous trains of tunable infra-red pulses by the nonlinear mixing of the wave-lengths available from a self-contained synchronously mode-locked cw dye laser is described. The factors determining the optimization of the process are identified and their roles demonstrated.     

环行染料激光器用于内腔吸收光谱的研究

本文报告了利用新型连续波环行染料激光器,即使行波工作于超过阈值两倍以上,仍在大气中获得了近10~5的内腔吸收灵敏放大;并首次利用单频扫描方法,在不降低灵敏放大的同时,得到了10~(-2)的光谱分辨率。实验结果与经改进后的Brunner-Paul理论分析一致。     

Uniphase1007型He—Ne激光管的纵向塞曼稳频研究

本文介绍采用拍频曲线晶振基准法首次在Uniphase 1007型长寿命商品He-Ne激光管上实现了无压电陶瓷调谐元件的塞曼双频稳频,采用可调永磁供磁,达到光频长期漂移5×10~(-9);双频双线偏振分离度1/60;双线偏振正交度89.5°;入锁及锁定情况良好.给出了塞曼双频激光器的调试技术.描述了输出光束偏振状态和纵模数关系的一个物理现象.     

Efficient frequency doubling of cw dye laser radiation

An efficient conversion of the tunable cw dye laser radiation to the UV region was achieved by intracavity SHG. The conversion efficiency depends strongly on the total cavity loss. This paper gives a survey on conventional and thermally induced loss mechanisms and discusses ways of loss reduction. A system is described that yields 50 mW and 4 mW of tunable UV radiation in multimode and single mode operation, respectively, where the wavelength can be varied from 285–315 nm.     

High-resolution spectroscopy with a femtosecond laser frequency comb

The output of a mode-locked femtosecond laser is used for precision single-photon spectroscopy of 133Cs in an atomic beam. By changing the laser's repetition rate, the cesium D1 (6s 2S(1/2)-->6p 2P(1/2)) and D2 (6s 2S(1/2)-->6p 2P(3/2)) transitions are detected and the optical frequencies are measured with accuracy similar to that obtained with a cw laser. Control of the femtosecond laser repetition rate by use of the atomic fluorescence is also implemented, thus realizing a simple cesium optical clock.     

Efficient frequency doubling of cw dye laser radiation

An efficient conversion of the tunable cw dye laser radiation to the UV region was achieved by intracavity SHG. The conversion efficiency depends strongly on the total cavity loss. This paper gives a survey on conventional and thermally induced loss mechanisms and discusses ways of loss reduction. A system is described that yields 50 mW and 4 mW of tunable UV radiation in multimode and single mode operation, respectively, where the wavelength can be varied from 285–315 nm.     

A narrowband single-mode dye laser

The linewidth of a cw-single-mode tunable dye laser has been investigated. It was found that the linewidth is determined by microscopic velocity fluctuations of the turbulent flow within the dye cell of the laser and by fluctuations of the pump power. The linewidth is further influenced by mechanical disturbances and by temperature fluctuations of the dye solution. The results of the investigations made it possible to achieve a reduction of the velocity fluctuations. It is shown that under adequate operating conditions the free-running dye laser has a linewidth of 2 MHz.