The double and colliding pulse mode-locking (DCPM) of an Ar+ and dye laser in a ring cavity

We report the first double and colliding pulse mode-locking (DCPM) of an Ar⁺ and a dye laser in a ring cavity. An analytic solution for the stability of this ring cavity is presented, together with the experimental results on the DCPM laser.     

Travelling-wave operation of a tunable cw dye laser

A ring cavity configuration for a tunable cw dye laser is described. A substantial reduction of the output bandwidth of the ring laser with increase in power for unidirectional or traveling-wave operation has been demonstrated. The advantages of the ring configuration for single-frequency operation of cw dye lasers are explored.     

A mirror-free cavity configuration for a CW ring dye laser

A new cavity configuration without mirrors is described for a CW ring dye laser. The cavity design is based on a new type of focusing prism which uses the Brewster angle of incidence and total internal reflection. Special roof prisms allow wavelength tuning. All of these elements are made from uncoated quartz thus allowing dye laser operation over a large range of wavelengths. CW operation as well as synchronously pumped mode locked operation with intracavity doubling is reported using the Rhodamine 6G dye.     

Generation of 49 fs pulses in a CPM laser pumped by a small-frame Ar+ laser

A colliding pulse mode-locked ring dye laser, pumped by an all-line small frame Ar⁺ laser has been used to generate stable pulses as short as 49 fs with pulse duration and stability similar to those obtained with the usual configuration where a single line of the pump is used. The effects of cavity alignment on the absorber saturation are presented and explained in terms of an analysis of stability of the ring cavity.     

Design of ring cavities for c.w. passively mode-locked dye lasers

A simple approach for the analysis and design of ring cavities for c.w. passively mode-locked dye lasers is suggested. The approach is based on the representation of the intracavity beam as a series of two matched beams, each considered to be formed in a linear cavity configuration. Useful expressions are obtained for the cavity parameters in terms of the intracavity beam properties of interest for two different beam configurations. The expressions can be used for the correct design of ring resonators.     

Subpicosecond pulse generation in synchronously pumped and hybrid ring dye lasers

Subpicosecond pulse generation has been examined in synchronously pumped mode-locked ring dye laser systems. These include hybrid and composite absorber/gain media arrangements as well as a simple synchronous cavity. The shortest pulses recorded were 0.3 ps for the hybrid system, and this has been shown to be critically dependent on the positioning of the absorber jet in the centre of the cavity to better than 50 m. Stable operation for subpicosecond pulse generation has been achieved in the ring configuration with greater wavelength tunability and higher average power conversion efficiency than with conventional cavity arrangements.     

Efficient single mode operation of a CW ring dye laser with a Mach-Zehnder interferometer

Stable single mode operation of a ring dye laser is obtained with the combination of a Mach-Zehnder interferometer (MZI), three plate birefringent filter, a single thin etalon and a unidirectional diode. The MZI eliminates the fractional insertion loss due to beam walk-off and distortion which an intracavity etalon must introduce in order to select single frequency operation. We experimentally demonstrate the low insertion loss, single mode stability and frequency tuning of a ring dye laser using a specially designed, compact MZI. Finally, we propose MZIs with no coatings, which should permit extremely low loss broadband operation.     

利用带模型探讨染料环形腔系统的光学双稳特性

利用染料分子带模型，探讨了染料环形腔系统的光学双稳特性，得到光学双稳可在一个比较大的频率范围内实现；其双稳区域是染料分子带结构参数（带宽及偶极分布的Ｌｏｒｅｎｔｚｉａｎ宽度等）的函数． 关键词：     

Intracavity spectrometer with a ring travelling-wave dye laser: Reduction of detection limit

In a ring travelling-wave dye laser a parasitic structure in the intracavity absorption spectrum is fully eliminated and a detection limit as low as 10^-10 cm^-1 is obtained. The sensitivity dependence of the intracavity laser spectrometer with travelling-wave cavity on the pumping level is also investigated.     

A high-power single-mode cw dye ring laser

Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.     

Generation of continuous-wave 243-nm radiation by sum-frequency mixing

We have generated tunable cw radiation near 243 nm with a linewidth of less than 4 MHz by sum-frequency mixing the 351 nm radiation from an argon-ion laser with the 789 nm radiation from a ring dye laser in a crystal of ammonium dihydrogen phosphate held at moderate temperature. An external ring cavity, resonant with the dye laser, gives a power enhancement of about 12 in the sum-frequency generated radiation. Thermal lensing due to laser heating of the nonlinear crystal, distorded the 351 nm mode structure. This effect could limit the efficiency of the sum frequency mixing process.     

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.     

Laser dye DCM: CW,synchronously pumped,cavity pumped and single-frequency performance

Laser dye DCM exhibits a tuning range of 605 to 725 nm with a lasing efficiency as high as 34% when pumped by the 488 nm line of the argon ion laser, placing it among the most efficient and broadly tunable dyes known. Performance of the dye is characterized for four laser systems: 1) continuous wave, 2) synchronously pumped (SP), 3) cavity dumped synchrompously pumped (SPCD) and 4) single-frequency ring dye laser. Pulse peak powers were as high as 520 W and 2.8 kW for SP and SPCD systems respectively.     

环形腔被动锁模掺饵光纤激光器

通过在非线性偏振旋转环形腔内引入一种可旋转的在线起偏器,在保证装置的全光纤化结构的前提下,简化了被动锁模光纤激光器的结构.通过联合调节可旋转的在线起偏器、1/2波片和1/4波片的角度实现了掺饵光纤锁模脉冲20 nm间隔的双波长调谐输出,调谐过程中观察到了锁模脉冲双波长状态.另外,从装置中去掉1/2波片后,仅调谐可旋转的在线起偏器和1/4波片也能够实现锁模脉冲的单波长稳定输出.     

环形腔被动锁模掺饵光纤激光器

通过在非线性偏振旋转环形腔内引入一种可旋转的在线起偏器,在保证装置的全光纤化结构的前提下,简化了被动锁模光纤激光器的结构.通过联合调节可旋转的在线起偏器、1/2波片和1/4波片的角度实现了掺饵光纤锁模脉冲20nm间隔的双波长调谐输出,调谐过程中观察到了锁模脉冲双波长状态.另外,从装置中去掉1/2波片后,仅调谐可旋转的在线起偏器和1/4波片也能够实现锁模脉冲的单波长稳定输出.     

Comparison of FM dye lasers in standing-wave and ring configuration

We have compared the operation of a frequency-modulated dye laser (FML) in a standing-wave and ring configuration. As expected, for a given frequency detuning (difference between the drive frequency for the phase modulator and the cavity mode spacing) the enhanced modulation index is twice as large for the standing-wave configuration as for the ring configuration. In addition, we have demonstrated that application of small amounts of phase modulation in the ring configuration leads to improved mode stability. The fine structure of the rf beats for both FM lasers, have been studied and the results suggest that spatial hole burning complicates the detailed structure.     

Ultrasonics: (Wykeham Science Series No. 55) 1980, by A. P. Cracknell. London: Wykeham Publications (London) Ltd. (New York: Crane Russak & Company,Inc.) 200 pp.

A flat plate containing a two-dimensional rectangular cut-out was exposed to laminar grazing flow of water and a small oscillatory flow through the orifice of the cavity was applied resulting in a wave-like oscillation of the interface between the fluid at rest inside the cavity and the external flow. The interface was visualized by a thin filament of colour dye and the oscillation was recorded by means of a cine-camera. The experimental results are compared to the predictions of a model which had been developed in order to explain the effect of grazing flow on the acoustic impedance of small orifices.     

Temporal dynamics of high repetition rate pulsed single longitudinal mode dye laser

Theoretical and experimental studies of temporal dynamics of grazing incidence grating (GIG) cavity, single-mode dye laser pumped by high repetition rate copper vapour laser (CVL) are presented. Spectral chirp of the dye laser as they evolve in the cavity due to transient phase dynamics of the amplifier gain medium is studied. Effect of grating efficiency, focal spot size, pump power and other cavity parameters on the temporal behaviour of narrow band dye laser such as build-up time, pulse shape and pulse width is studied using the four level dye laser rate equation and photon evolution equation. These results are compared with experimental observations of GIG single-mode dye laser cavity. The effect of pulse stretching of CVL pump pulse on the temporal dynamics of the dye laser is studied.     

A narrowband unidirectional pulsed ring dye laser

A simple unidirectional optically stable ring laser cavity has been developed for short pulse excitation. Using only one grazing incidence grating as a selective element a N₂-laser pumped dye laser has been constructed having a single mode spectrum of 420 MHz, clockwise to counterclockwise wave ratio 166:1 and a conversion efficiency of 4.6%.     

Bi-directional dual-wavelength Brillouin lasing in a hybrid fiber ring cavity

In this paper, a novel Brillouin fiber laser (BFL) is proposed based on the hybrid fiber ring cavity composed of two types of fibers with different Brillouin shifts. Single mode fiber (SMF) and truewave fiber (TWF) are used in our experiments. Bi-directional dual-wavelength Brillouin lasing is achieved in the hybrid fiber ring cavity. The lasing lights along the two directions come from the Stokes waves generated in the two fibers, respectively, with different Brillouin shifts, however, they share the same fiber ring cavity. The BFL based on the hybrid fiber ring cavity provides a simple possible way to realize Brillouin fiber optical gyroscopes (BFOGs) without lock-in effect.