A narrow bandwidth,pulsed, ultra-violet dye laser

A simple, narrow bandwidth, dye laser using para-terphenyl and operating in the region 3350–3450 Å is described. The laser incorporates beam expansion at a grazing incidence diffraction grating and is pumped by a rare gas halide excimer laser. Output bandwidths as low as 0.012 Å have been obtained.     

Tunable,narrow bandwidth, 2 MW dye laser pumped by a KrF1 discharge laser

Characteristics of p-terphenyl and PBD, the most efficient uv dyes, have been investigated under high intensity pumping by a multi-atmosphere KrF¹ discharge laser at 248 nm wavelength. Energy conversion efficiencies, spectral features and temporal behaviour of the dyes were studied parametrically. A maximum powerof 2 MW uv emission with a bandwidth of ～2×10^-2 nm was obtained for PBD. It was found that a mixture of both dyes provided higher (by a factor of 1.3) output in the range 348–366 nm than either of the dyes alone. Significant pump intensity dependent conversion efficiency and pulse shape variations were observed for the most efficient uv dye, p-terphenyl and were related to triplet-triplet adsorption processes in the dye.     

腔内带圆形空心波导的可调谐窄带脉冲染料激光器

本文报道了一种腔内带圆形空心波导和掠入射光栅的可调谐窄带脉冲染料激光器;实验结果表明:该激光系统能获得基横模、窄频带和高效率的激光输出。文中对系统设计机理也进行了分析。     

Single mode operation of a narrow bandwidth dye laser using a single prism, grazing incidence grating long cavity

The single mode pulsed dye laser is an attractive tool for many spectroscopic applications. Long cavity tunable dye lasers generally operate in multi-longitudinal modes within the bandwidth of gain profile. Single longitudinal mode oscillation can be obtained by either making the cavity short enough or introducing an additional loss mechanism, in which all modes but one have a gain less than their loss. A new technique to achieve single mode operation in a long cavity dye laser, based on Rhodamine 6G dye in ethanol and ethylene glycol solution, pumped by a high repetition rate copper vapor laser, is reported. This laser, which operates in three modes in grazing incidence grating configuration (cavity length of 16 cm), has been made to lase in single mode by increasing the loss in the resonator through beam walk-off.     

Flashlamp pumped tunable dye laser of ultra-narrow bandwidth

A flash lamp pumped dye laser with a ring cavity is injected with the light beam coming from a stabilized singlemode c.w. dye laser. The light emitted by the pulsed laser is analysed either by a Fabry Perot etalon, or by producing a Doppler-free two-photon transition. The bandwidth of the pulsed laser is identical to the one of the c.w. laser; but the pulsed light is shifted to higher frequency by an amount of a few MHz.     

A 657-nm narrow bandwidth interference filter-stabilized diode laser

We present a 657-nm external cavity diode laser (ECDL) system,where the output frequency is stabilized by a narrow-band high transmission interference filter.This novel diode laser system emits laser with an instantaneous linewidth of 7 kHz and a broadened linewidth of 432 kHz.     

利用超短脉冲激光和光电子能量微分谱直接测量窄带飞秒超紫外线XUV脉冲的时间结构

介绍用亚皮秒超短激光脉冲直接测量窄带飞秒真空超紫外线(XUV)脉冲时间结构的方法. 可以由XUV激发惰性气体产生、并在与超短脉冲激光的线性极化方向成0°或90°的方向上测量 得到的光电子能量微分谱重建这种时间结构. 谱仪的能量分辨率和所选取的能量间隔大小是 测量及计算的两个重要参数. 上述方法有很宽的时间测量范围和很高的分辨率，可以用于飞 秒计量学和与原子运动有关的超快速动力学过程的研究. 关键词： 超快速测量 超短脉冲激光 超紫外线(XUV)时间结构 光电子能量微分谱     

Optical pumping experiments using a cw dye laser with a narrow spectral output

An optical pumping experiment on the Na atoms of an atomic beam by means of a continuous wave dye laser is described. The atoms interact at two different regions with the laser beam. In the first region the atoms are optically pumped so that a Zeeman coherence in their substates is produced. In the second light beam the coherence is probed. Any changes in the phase of the eigenfunction of the atom through interaction in a magnetic field, or through collisions, or other effects occuring in the light free section can thus be sensitively detected. The possible applications of the set-up are discussed.     

On the origin of laser coherence

It is shown that the light created in the process of the “emission of many photons by many atoms”, as treated recently by Ernst and Stehle, has extreme coherence properties. In particular, it leads to spatial interference effects between radiation from two distinct sources of this type. Under certain conditions this interference even can become optimal in the sense that the intensity minima vanish. Furthermore, in the sense of the definition of Glauber, the light field produced in this process is practically coherent to the ordern～N, whereN is the the number of emitted photons. One arrives at a natural and simple interpretation of two-laser interference experiments of Magyar and Mandel, and Pfleegor and Mandel, if one assumes that the mentioned process constitutes the primary creation mechanism of laser light. It is shown that and how the physically important features of laser activity can be understood on the base of this assumption.     

Broadly tunable,narrow linewidth dye laser emission in the near infrared

An efficient organic dye laser with a linewidth of less than 2 Å has been developed as a source of tunable high power radiation in the wavelength range 7500–9200 Å. Utilizing a 2 MW ruby laser pump, infrared output powers in excess of 200 kW have been attained for the range 7650–8900 Å with peak power levels above 400 kW. The tunning range for a single dye varies from 550 to 1030 Å.     

Mode coherence measurements across a 1.5 THz spectral bandwidth of a passively mode-locked quantum dash laser

The mode coherence of adjacent and non-adjacent spectral modes of a passively mode locked quantum dash (QDash) semiconductor laser are deduced through radio frequency beat-tone linewidth measurements. A wavelength conversion scheme that uses degenerate four wave mixing in a semiconductor optical amplifier is proposed which considerably extends the mode spacing beyond the limit imposed by conventional fast-photodetection and electrical spectrum analysis of around 100 GHz. Using this scheme, the mode coherence of the QDash laser was measured out to the thirty-first harmonic, or a mode separation of 1.5 THz.     

Bistable operation of a GaAs-AlGaAs diode laser coupled to an external resonator of narrow spectral bandwidth

The influence of an external dispersive resonator on the emission properties of a double heterostructure semiconductor laser operating at room temperature has been investigated. The proper design of the external resonator (frequency selectivity and efficient back-coupling of the radiation leaving the diode) demonstrates that a laser with optical feedback can show bistability and hysteresis phenomena. The dispersive bistability has its origin in the dependence of the refractive index on carrier density, temperature and optical power. Hysteresis curves have been measured by changing the injection current or by tuning the dispersive element. We have found a threshold in the injection current for the onset of the hysteretic behaviour. Moreover, a theoretical model has been established to explain the essential features of the experimental results. Hysteresis cycles for different experiments have been calculated.     

窄线宽、高光束质量的外腔双反馈激光二极管阵列

设计了一种离轴双反馈外腔能够有效地改善激光二极管阵列的线宽和光束质量。闪耀光栅和高反镜之间形成了一个共振腔。通过调整光栅和高反镜之间的倾角可以选定一个空间模在共振腔中放大。将一个半波片插入外腔中的光栅反馈支路,来控制反馈光的数量,激光从光栅反馈支路输出。运用这项技术,在工作电流16 A,可以把激光二极管阵列的输出线宽压缩到0.15 nm,光束束宽积减小到283 mm·mrad。由于光栅的锁定作用,中心波长几乎不随温度的变化而改变。在工作电流17 A时,输出激光的功率为2.44 W,斜率效率为0.5 W/A。     

Grating-assisted coupler used as a narrow bandwidth channel-dropping filter

A theoretical analysis of a modified grating-assisted coupler involving an additional long period grating in the input channel is presented. We show that the second grating allows for improved performance of the device, especially in terms of spectral selectivity: the presented technique leads to a decrease in the spectral bandwidth of the coupler.     

Electronic improvement of interferometric measurement of dye laser wavelengths

The wavelength of a dye laser beam has been determined with a Michelson interferometer with one moving mirror. The addition and design of a phase locked loop (PLL) to multiply the fringe frequency is discussed. Experimentally it appeared that the addition of a PLL has two main advantages: an improvement in the resolution of the system by a factor of ten, and an improvement in reproducibility due to the flywheel effect of the PLL.     

Delay self-heterodyne measurement of narrow linewidth laser frequency drift characteristic

Resonator integrated optic gyro (RIOG), which employs narrow linewidth laser, is a high-accuracy inertial rotation sensor based on the Sagnac effect. The performance of RIOG is greatly affected by the frequency drift of narrow linewidth laser. A simple, effective method to measure the relative frequency drift of narrow linewidth laser based on delayed self-heterodyne technique is proposed in this paper. The measurement range and sensitivity can easily be satisfied by setting the length difference of the fiber segments between two interferometer arms. The relationship between the length difference and the frequency drift is derived based on the given principle of measuring the relative frequency drift. Then the laser frequency drift measuring setup is established and the experiment results demonstrate that a center frequency drift rate is less than 2 MHz/6.7 s under the room-temperature. Moreover, the measuring setup is applied to test the modulation coefficient of piezoelectric-transducer (PZT), and the modulation coefficient of 9.62 MHz/V is obtained, which satisfies the requirements of RIOG closed-loop operation.     

Broad bandwidth interference filter-stabilized external cavity diode laser with narrow linewidth below 100kHz

Interference filter-stabilized external cavity diode lasers(ECDLs) have properties of simple configurations, high stabilities, and narrow linewidths. However, the interference filter used in common ECDL designs requires an ultra-narrow bandwidth(about 0.3 nm) to achieve mode selection, that is considerably expensive and not yet available for a wide range of wavelengths. In this paper, a robust ECDL using an available broad bandwidth(about 4 nm) interference filter as the wavelength discriminator is constructed and tested. The ECDL demonstrated a narrow Lorentzian fitted linewidth of 95 kHz and a spectral purity of 2.9 MHz. The long-term frequency stability of the ECDL reaches 5.59×10~(-12).     

On the possibility of mode-locking a dye laser by a fast saturable absorber

The problem of mode-locking a fully relaxing saturable (dye) laser medium by an instantaneously saturating (fast) absorber is theoretically considered when group velocity dispersion and Kerr-type nonlinearity are present. Off-resonant chirped solutions are found whose minimum duration is determined by the relative losses (saturable and nonsaturable) and by the saturation depth of the absorber. The addition of nonlinear elements can only broaden the stability range of the solution with respect to the group velocity dispersion.     

On the dispersion of a prism used as a beam expander in a nitrogen laser pumped dye laser

It is shown that the dispersion of a prism beam expander used at very high angles of incidence has a large effect on the laser linewidth.     

窄带集成声光可调谐滤波器的研制

利用模式耦合理论分析了声光模式转换,并对声光可调谐滤波器的滤波带宽、调谐范围、驱动功率等性能参数进行分析计算。设计并制作出窄带集成声光可调谐滤波器(IAOTF)样品,搭建相应的IAOTF测试平台,得到中心波长在1.55μm,滤波带宽达到0.85 nm,波长调谐范围达到80 nm,驱动功率低于40mW的IAOTF。并对进一步压缩滤波带宽和旁瓣效应提出了解决途径。