Dye Laser Oscillator Research Articles

Co-amplification: An efficient spectral beam combination approach for high power, closely separated dual wavelength dye laser systems

Characteristics of an efficient spectral beam combination of two dye laser beams with wavelength difference of less than 10 nm are presented. Two dye laser oscillator beams were spatially and temporally combined with reduced losses before their co-amplification in a common power amplifier. Yellow and green beams of 9 kHz (pulse repetition rate) copper vapour laser (CVL) Master Oscillator Power Amplifier (MOPA) Chain were utilised to pump Rh 101 dye laser oscillators and DCM dye common amplifier respectively. The characteristics of green beam pumped DCM dye common amplifier were studied at various pump power and input power ratios. Combination losses for this configuration were 40% relative to individually amplified configuration. Input–output characteristics of the common amplifier were determined at various input power ratios. Composite dual wavelength dye laser beam having total power of 7.35W at 38.4 W pump power with extraction efficiency 16.5% was demonstrated.

Circularly polarized laser emission induced in isotropic and achiral dye systems.

The production of efficient, tunable, and switchable circularly polarized laser emission would have far reaching implications in optical communications or biophotonics. In this work, it is demonstrated the direct generation of circularly polarized (CP) laser emission in achiral and isotropic dye laser systems without the use of extracavity polarizing elements, and without resorting to chiral dyes, chiral liquid crystal matrices, or interferometric methods. The origin of this ellipticity arises from the dynamic birefringence induced by the strong and polarized laser pumping and the subsequent orientation anisotropy of the excited molecular dipoles. A complete polarimetric characterization of the polarization state of conventional dye laser oscillators as a function of different experimental parameters is performed and it is shown that the generated light always possesses a certain level of circularity that changes in a distinctive way with pump energy and polarization. These results demonstrate that it is possible to generate and modulate CP laser light from efficient and photostable conventional laser dyes.

Spectral characteristics of a ternary-mixture of dyes in a dye laser pumped by copper vapor laser

The spectral characteristics of a ternary-mixture, composed of Rhodamine 640, Rhodamine 6G and DCM in ethanol and excited by copper vapor laser, are reported. The concentration of each dye in the ternary-mixture was optimized to provide peak emission at 633nm and absorb both wavelengths of copper vapor laser, i.e. 510.6 and 578.2nm. A fluorescence range of 612–679nm with a relatively broad peak at 631–634nm was obtained when concentrations of Rhodamine 640, Rhodamine 6G and DCM in the ternary-mixture were 0.90mM, 0.30mM and 0.90mM respectively. This ternary-mixture of dyes in ethanol, when used as a gain medium in a narrowband, tunable dye laser oscillator, transversely pumped by both wavelengths of a copper vapor laser, provided a spectral tuning range of 620–665nm with an almost flat peak at 630–634nm.

An experimental study and theoretical analysis of the mode characteristics of a narrow line-width, pulsed dye laser oscillator at different pump powers

This paper presents an experimental study and theoretical analysis on the effect of pump power on the divergence, pointing, line-width and wavelength stability of a narrow line-width, high repetition rate dye laser oscillator. The dye laser oscillator, based on the hybrid multiple-prism grazing-incidence grating cavity, was pumped by copper vapor laser (CVL). The dye laser mode characteristics were studied at CVL average pump powers of 2, 4 and 8 W. The single pulse dye laser divergence/pointing stability was studied by far-field intensity distributions. The line-width and wavelength stability were studied using a high resolution wave-meter. The experimental results were theoretically analyzed in terms of dye laser mode structure drift induced by beam pointing instability, beam divergence and thermally induced optical path length fluctuation. A comprehensive theoretical treatment on pointing stability of dye laser beam and its influence in the dye laser wavelength stability is presented. The theoretical and experimental trends were found to be in good agreement.

Rate equation simulation of temporal characteristics of a pulsed dye laser oscillator

A time-dependent, two-dimensional (in space) rate equation model of a transversely-pumped pulsed dye laser oscillator, which incorporates transverse pump intensity variation in the presence of intracavity dye laser radiation, is proposed to understand and predict its temporal behaviour. The model yields output pulses which agree well with experimental results using rhodamine 6G and kiton red dyes. The shape, amplitude and temporal position of the simulated pulse within the pump pulse vary dramatically across the tuning range of each dye depending on the relative gain and loss values.

High Efficiency Amplifier for Single-Mode CW Dye Laser

A high power, tunable dye laser system composed of a master oscillator and power amplifiers is demonstrated. A single-mode cw dye laser oscillator of simple composition generates a narrow-bandwidth spectrum of less than 20 MHz compared with that of a pulse dye laser oscillator; however, the output power from the cw dye laser is low. Therefore, a high efficiency pre-amplifier for the pulse dye laser is needed. We developed a simulation code to amplify spontaneous emission and also designed a pulse dye laser amplifier to increase efficiency. In experiments, we obtained a power output pulse with a narrow-bandwidth spectrum with a very high power gain greater than 10,000 by using a four-pass pre-amplifier. Good agreement is obtained between the calculated and measured amplifier characteristics.

A hybrid laser system consisting of a frequency-doubled, narrow-line-width, distributed-feedback dye laser oscillator and a high saturation-fluence Ce:LiCaAlF6 crystal amplifier

A tunable narrow-band picosecond dye laser emitting in the ultraviolet region was amplified using a Ce:LiCaAlF6 crystal pumped by the fourth-harmonic emission of a Nd:Y3Al5O12 laser. The single-pass gain obtained exceeded 2 in the spectral range of 288 to 297 nm.

Single Longitudinal Mode Operation of a Solid-State Dye Laser Oscillator

Single Longitudinal Mode Operation of a Solid-State Dye Laser Oscillator

Multiple-prism grating solid-state dye laser oscillator: optimized architecture

A multiple-prism grating solid-state dye laser oscillator was demonstrated with its grating, deployed in a Littrow configuration, under total illumination at reduced intracavity beam expansion. This compact cavity yields laser linewidths in the 350-MHz range and smooth temporal pulses with a near-Gaussian profile.

Long-pulse narrow-linewidth dispersive solid-state dye-laser oscillator

We report on narrow-linewidth long-pulse laser emission from a dispersive solid-state dye-laser oscillator. Output energy was ~0.4 mJ/pulse at laser linewidths of 650 MHz and pulse lengths of 105 ns FWHM. The solid-state gain medium utilized was Rhodamine 6G dye-doped 2-hydroxyethyl methacrylate:methyl methacrylate.

Multiple-prism near-grazing-incidence grating solid-state dye-laser oscillator

Solid-state multiple-prism near grazing-incidence grating dye lasers have been configured in cavities as short as 73 mm using dye-doped modified PMMA gain media. Single-longitudinal-mode emission, in near-Gaussian temporal pulses of 6–7 ns (FWHM) duration, has been achieved. Measured laser linewidths are in the 375 MHz range, and beam divergence is ∼2.3 mrad, at 3%–4% conversion efficiencies.

Dispersive solid-state dye laser oscillators

Narrow-linewidth multiple-prism grating solid-state dye laser oscillators are analysed using ray transfer matrices. Attention is given to beam divergence measurements and the effect on them of thermal lensing, at the solid-state gain medium. It is found that although thermal lensing leads to an increment of beam divergence, it induces oscillation in the unstable resonator regime, thus contributing to the attainment of TEM00 beam profiles. In addition, narrow-linewidth emission in dispersive oscillators, incorporating rhodamine 6 G doped HEMA:MMA gain media, is reported for the first time. Laser efficiency is 4–5% at a laser linewidth ≤1.8 GHz for double-longitudinal-mode emission. Beam divergence is measured in the 2–2.3 mrad range, in good agreement with theory.

Dual-wavelength operation of a self-seeded dye laser oscillator

We demonstrate simultaneous dual-wavelength operation of a self-seeded dye laser. The laser cavity consists of one dye cell, two pairs of grating and tuning mirrors, and two reflecting mirrors. This configuration can be decomposed with two grazing-incidence cavities and a standing-wave cavity. The self-seeded dual-wavelength output beams are collinear and independently tunable. We were able to vary the output powers at the two wavelengths smoothly by changing the cavity length of a master oscillator.

Characteristics of a pressure‐tuned single‐mode dye laser oscillator pumped by a copper vapor laser

Frequency tuning based on pressure control is demonstrated on an etalon-narrowed Littrow-type single-mode dye laser oscillator pumped by a copper vapor laser. The oscillator is installed in a pressure vessel and the frequency is scanned by controlling the refractive index of the air inside the vessel. To scan the dye laser frequency continuously without mode hopping, the cavity length is also controlled in addition to the pressure change. The frequency stability of the oscillator in a pressure vessel is within 100 MHz/1.5 hr and the oscillator can be scanned with a frequency range of 29 GHz at a scan rate of around 2.5 GHz/min.

Solid-state dispersive dye laser oscillator: very compact cavity

A solid-state multiple-prism grating dye laser oscillator configured in a very compact cavity has been demonstrated. The cavity length can be as short as 55 mm and the oscillator yields single-longitudinal-mode emission ( Δν≤700 MHz) in a near-gaussian temporal pulse of 3–4 ns duration (fwhm). Conversion efficiency is in the 5–7% range.

Solid-state multiple-prism grating dye-laser oscillators

Compact solid-state multiple-prism grating dye-laser oscillators are shown to yield in excess of 9% conversion efficiency at Δv ≈ 1.12 GHz and a tuning range of 47 nm.

High-power high-repetition-rate copper-vapor-pumped dye laser

The design and development of an efficient high average power dye laser oscillator-amplifier system developed at the Laser & Plasma Technology Division, Bhabha Atomic Research Centre, is reported. The dye laser is pumped by a 6.5-kHz repetition rate copper vapor laser. The signal beam to the dye amplifier is obtained from an efficient narrow-band grazing incidence grating (GIG) dye laser oscillator incorporating a multiple prism beam expander. Amplifier extraction efficiency up to 40% was obtained in a single amplifier stage, using rhodamine 6G (Rh6G) in ethanol. We have also demonstrated simultaneous amplification of two laser beams at different wavelengths in the same dye amplifier cell.

Efficient high repetition rate synchronous amplification of a passively mode-locked femtosecond dye laser

We demonstrate reliable operation of a stable synchronously pumped dye amplifier for femtosecond pulses from a passively mode-locked dye laser. Conversion efficiencies of 8% are obtained with output powers of 40 mW and 50-fs pulse widths at repetition rates of up to 10 kHz with pulse energy stability of 3% rms. Synchronization is achieved by driving the frequency-modulated mode-locked seed oscillator for the regenerative amplifier pump laser directly from the dye laser oscillator. Low timing jitter between the dye oscillator and seed laser of less than 1 ps leads to efficient amplification and low amplified spontaneous emission (1%) from the amplifier.

Spectral characteristics of CVL pumped dye lasers

We have investigated the effect of changing the resonator length on the time-averaged and single pulse spectrum of a copper vapour laser pumped GIG dye laser oscillator. The time-averaged spectrum showed a well defined spectral profile and mode structure. However the single pulse spectrum was found to vary from pulse to pulse and showed strong gain competition and spatial hole burning effects. In addition it has been shown that there is an optimum position of the output mirror for which the laser linewidth is a minimum.

Pump and signal cross saturation in cw dye lasers

It is well known that the signal output intensity from a dye laser oscillator depends directly on the pump intensity. The opposite effect, the dependence of the transmitted pump intensity on the signal intensity, is studied in detail. The theoretical results are compared with experimental data obtained using an argon-laser-pumped rhodamine 6G dye laser.