Waveguide Dye Laser Research Articles

Solvent-free fluidic organic dye lasers

We report on the demonstration of liquid organic dye lasers based on 9-(2-ethylhexyl)carbazole (EHCz), so-called liquid carbazole, doped with green- and red-emitting laser dyes. Both waveguide and Fabry-Perot type microcavity fluidic organic dye lasers were prepared by capillary action under solvent-free conditions. Cascade Förster-type energy transfer processes from liquid carbazole to laser dyes were employed to achieve color-variable amplified spontaneous emission and lasing. Overall, this study provides the first step towards the development of solvent-free fluidic organic semiconducting lasers and demonstrates a new kind of optoelectronic applications for liquid organic semiconductors.

A tunable 3D optofluidic waveguide dye laser via two centrifugal Dean flow streams

This paper presents a tunable optofluidic waveguide dye laser utilizing two centrifugal Dean flows. The centrifugal Dean flow increases the light confinement of the dye laser by shaping a three-dimensional (3D) liquid waveguide from curved microchannels. The active medium with the laser dye is dissolved in the liquid core and pumped with an external pump laser to produce stimulated emission. The laser's Fabry-Pérot microcavity is formed with a pair of aligned gold-coated fiber facets to amplify the fluorescent emission. The advantage of the 3D optofluidic waveguide dye laser is its higher efficiency, thus to obtain lasing at a reduced threshold (60%) with higher output energy. The demonstrated slope efficiency is at least 3-fold higher than its traditional two-dimensional equivalent. In addition, the laser output energy can be varied on demand by tuning the flow rates of the two flows. This technique provides a versatile platform for high potential applications microfluidic biosensor and bioanalysis.

Organic dye lasers with distributed Bragg reflector grating and distributed feedback resonator

The paper presents polymeric waveguide dye laser with distributed Bragg reflector (DBR) grating or distributed feedback (DFB) resonator. DBR grating and DFB resonator were fabricated on a surface of SU-8 2002 photoresist polymer using interference of laser beams. Polystyrene (PS) and poly(vinyl butyral) (PVB) waveguides dispersed with laser dye of 3-(2-benzothiazolyl)-7-(diethylamino)-coumarin (Coumarin 6) and tris(8-quinolinolate)aluminum (Alq) as a host were used. Single mode of lasing with TE mode was measured from the polymeric waveguide with DBR grating and DFB resonator. Threshold of lasing with DBR grating is lower than that with DFB resonator. For PVB/Alq/Coumarin 6 waveguide, 0.1 mJ cm(-2) pulse(-1) of threshold was measured with DBR grating and 0.3 mJ cm(-2) pulse(-1) with DFB resonator. Slope efficiency between 0.06 and 0.09 % was measured for PS/Alq/Coumarin 6 waveguide and that between 0.07 and 0.15 for PVB /Alq/Coumarin 6 waveguide.

Highly Efficient Long-Lifetime Dual-Layered Waveguide Dye Laser Containing SiO2 Nanoparticle-Dispersed Random Scattering Active Media

We have demonstrated a highly efficient, long-lifetime waveguide dye laser using nanosized-particle-dispersed random scattering active media. An experimental laser slope efficiency of 38.6% and energy threshold of less than 1 µJ at a single longitudinal mode were measured. The operation lifetime of this laser device reached 6.5 million pump shots.

Experimental Realization of Monolithic Diffractive Broad-Area Polymeric Waveguide Dye Lasers

We discuss the first experimental realization of a polymeric waveguide dye laser with intracavity diffractive elements. Due to a special technology used the diffractive phase structures are directly integrated into the waveguide layer. Thus, there is no need for additional external optics or extensive alignment effort. The elements are used to support a Gaussian-like fundamental mode while at the same time suppresses the undesired higher order transverse laser modes. The technology has the potential to be used also for improving the beam quality of semiconductor broad area lasers.

Waveguide dye laser including a SiO2 nanoparticle-dispersed random scattering active layer

We presented a dual-layered waveguide dye laser including a random active layer with nanoparticle doping. A slope efficiency of 12.0% and an energy threshold of 0.34μJ were obtained in a single-longitudinal-mode operation.

Dye laser transverse mode control using capillaries

We propose and demonstrate the use of a hollow circular dielectric waveguide for laser transverse mode control. A capillary inserted in a conventional transversely pumped pulse dye laser is shown to effectively promote the fundamental gaussian beam oscillation. It is shown by direct comparison that capillary dye lasers are superior to pinhole dye lasers in that the beam far-field divergence is small, the power conversion of the pump to TEM 00 mode output is high. Capillary dye lasers are also superior to waveguide dye lasers in that the design is simple and flexible. It is suggested that the use of capillaries for transverse mode control be applicable to other types of lasers.

Thin‐film energy‐transfer dye lasers in spectral region of near ultraviolet to violet

AbstractThe development of the thin‐film waveguide dye lasers has created extensive applications in laser technology and fiber optics. This paper reports the laser properties of two types of thin‐film energy‐transfer dye lasers (thin‐film ETDL). One is the mixture‐type doped with a donor‐acceptor dye pair in the polymer thin‐film waveguide, which operates largely by nonradiative resonance transfer; the other is two‐layer type with the active core (layer of acceptor dye) and clad (layer of donor dye), which operates only by radiative transfer. These ETDLs are pumped by an N2 laser and operate efficiently as practical compact laser sources in the spectral region of near ultraviolet to violet. Furthermore, the measurement of the energy transfer rate constants in these ETDLs is also presented.

Energy transfer in slab dye lasers

A simple model of the energy transfer between a booster dye and the active dye in a flashlamp pumped planar waveguide dye laser is described.

A 200 W average power, narrow bandwidth, tunable waveguide dye laser

A planar waveguide dye laser, driven by commercial xenon flashlamps with an average power output of 200 W at 50 pulse per second (pps) is described. Due to the planar structure, a narrow bandwidth operation down to 10 GHz has been obtained with a single grating arranged at grazing incidence. With this configuration, high overall efficiency up to 0.6 percent has been obtained, partially due to energy conversion of the broad-band emission spectrum of the flash-lamps by circulating an appropriate dye solution between flashlamps and reflectors.

Transverse mode control in high gain, millimeter bore, waveguide lasers

A technique is presented for assuring TEM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</inf> transverse mode operation in visible wavelength lasers with bore diameters of 0.1- 1.0 mm. This then is a solution to the problem of obtaining TEM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</inf> mode output from pulse pumped dye lasers which have high and non-uniform gain. The desired mode control is achieved by confining the lasing medium in a waveguide and placing each resonator mirror so that its focal plane, rather than its center of curvature, lies at the nearest waveguide opening. Thus, the far-field pattern of the field distribution emerging from the waveguide opening is focused by the mirror back into the waveguide. For the proper choice of mirror curvature, the width of the central lobe of the far-field pattern is such that over 99 percent of the energy couples into the two lowest order modes of the waveguide. The waveguide transmits this bell-shaped field distribution to the opposite end where the process of propagating to the mirror and being reimaged is repeated. The end result is that a pulsed, laser pumped, waveguide dye laser has been made to produce a mode of the same quality as a TEM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</inf> mode, CW, HeNe laser. This technique has also improved the output mode distribution of flashlamp pumped dye lasers. Analysis of the resonator shows that a TEM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</inf> mode having a curved wavefront at the waveguide opening couples primarily to both the EH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> and EH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> waveguide modes. The amplitudes of the EH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> and EH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> modes, however, have a complex phase difference which results in a refocusing of the field distribution when both propagate in a hollow waveguide. The refocusing is shown to be a periodic function of the length of the waveguide. In addition, it is shown that as a result of gain or propagation loss differences for the two waveguide modes, the phase radius of curvature of the TEM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</inf> mode of a waveguide resonator does not in general match the mirror curvatures. This model of TEM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</inf> mode coupling to the EH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> plus EH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> modes results in a clearer physical insight into the interaction between the waveguide and free space portions of the resonator.

Spectral narrowing of a flashlamp-pumped, waveguide dye laser by amplification of tunable narrow-band cw radiation

Spectral narrowing of the broad-band emission from a flashlamp-pumped dye laser, which consisted of a slab waveguide high-gain amplifier in conjunction with a high-loss resonator, is reported. The pulsed laser oscillator was driven by a cw dye laser oscillating in several longitudinal modes. An energy output up to 10 mJ per pulse has been obtained with a driving power of 10 mW, showing the possibility of substantial power amplification of the narrow-band emission from a cw dye laser.

GHz tuning of a planar dye laser with single dispersive element

A new scheme for tuning a planar waveguide dye laser is presented. Because of the high gain produced in the waveguide structure, a high-dispersion slit-grating arrangement can be used as a feedback element of the laser. Output energy of a few tens of mJ, which corresponded to the saturated output of the amplifier, was obtained within a 2-GHz bandwidth. A very stable and repeatable output frequency was observed. The device demonstrates that, as long as the waveguide overcomes gain and refractive index inhomogeneities, a much higher energy output can be expected from scaled-up devices.

Waveguide dye laser with Gaussian mode output

The successful operation of a high gain, laser pumped, dye laser in the TEM 00 mode is described. This was achieved by confining the active medium in a waveguide and designing the mirror configuration for optimum coupling of the EH 11 mode of the waveguide to the free space TEM 00 mode. An improvement was noted in the stability of the output beam axis and in the ease of alignment compared to that of a conventional, apertured, dye laser.

A simple, reliable waveguide dye laser for ophthalmological applications.

The principle of operation, construction, and performance of a compact waveguide dye laser, especially designed as a source of retinal photocoagulators, are described, The guiding effects produced by the thermal gradients induced by the pumping pulse and the use of closed resonator make the laser very reliable, simple, and with good pulse repeatibility. The construction is very simple and inexpensive. Except for flashlamps, which are commercial, no part of the laser requires sophisticated technology to be built or assembled; neither optical components have critical flatness and need careful alignment. The system does not need cooling, and slow recirculation of the solution, necessary to replace the degraded dye in the waveguide, is provided by a magnetically coupled 0.1 W electric motor. The dye cell, pump, and dye reservoir form a single component of the laser which can be easily extracted for inspection and replacement of the dye solution. The single, regular pulse emitted by the laser, its time duration (a few microseconds), the possibility to operate the laser at the absorption peaks of the ocular tissues make the laser better than the random spiking ’’passive’’ ruby laser or than the ’’explosive’’ Q−switched ruby laser for ophthalmological applications. If connected with a slit lamp, the laser should compete with the much more expensive ion gas lasers. Good retinal photocoagulations have been made in rabbits using a solution of Rhodamine 6G in ethanol. Retinal spots of rectangular shape of variable dimension but of constant energy density have veen produced by simply masking the exit window of the laser.

Tunable lasers in ophthalmology.

The present status of laser application in clinical ophthalmology is breifly reviewed. The potentials of tunable dye lasers as retinal photocoagulators are discussed. Selective irradiation of ocular tissues over the full visible spectrum and the simplicity and reliability of recently developed waveguide lasers are the most attractive features of these lasers. Waveguide dye lasers have permitted to set up very compact and simple retinal photocoagulators, with improved output intensity stability and nearfield distribution uniformity. Preliminary results obtained with pulsed Rhodamine 6G laser show that good retinal photocoagulations are obtained at very low output energies.

Laser oscillation in simple corrugated optical waveguide

The gain characteristics in a simple corrugated optical waveguide dye laser of Rhodamine 6G were observed. A new tuning method of lasing the wavelength of a DFB structure was examined.

Infrared dye laser excited by a diode laser

A waveguide dye laser with an inner diameter of 30 μm and a length of 1.0 nm has been excited with a pulsed GaAlAs diode laser. The infrared-absorbing dye 5,5′-dichloro-11-diphenylamino-3,3′-diethyl-10,12-ethylenethiatri- carbocyanine perchlorate was used in tetramethylene sulfoxide solution. By changing dye concentration, laser wavelengths from 950 to 1005 nm were obtained.

High-efficiency coaxial waveguide dye laser with internal excitation

A new configuration for flash-pumped dye lasers is presented. A coaxial dye cell with internal excitation is used and 2% efficiency is feasible. Optical cavity deterioration produced by thermally induced refractive index gradients is compensated by the coaxial geometry, and low-loss guided propagation results without any recirculation of the dye solution.

Waveguide dye laser amplifier

A single-stage flash-lamp-pumped waveguide dye laser amplifier is presented. A Pyrex cylindrical dye cell filled with a rhodamine 6G solution in ethanol acts as an active hollow dielectric waveguide for the light to be amplified. Over-all efficiency and absolute energy gain are about one order of magnitude larger than for a conventional single-pass dye laser amplifier. Such a device can be conveniently used when inserted, with suitable couplers, in an optical waveguide system.