DCM Laser Research Articles

Spectral and emission characteristics of DCM and oxazine laser dyes in annealed silica xerogel

Spectral and emission characteristics of DCM and oxazine laser dyes in annealed silica xerogel

Observation and analysis of a new [14.26]0+ – X3Σ–0+ transition of WS, observed using intracavity laser spectroscopy with Fourier-transform detection

The (1,0), (0,1), and (1,2) bands of a new [14.26]0+ – X3Σ–0+ transition of WS are described. The WS molecules were produced in the plasma discharge formed when either a 0.15 A DC plasma current or a 0.80 A RF-pulsed DC plasma current was applied to a W-lined Cu hollow cathode in an atmosphere that was 0.1%CS2, ~30% H2 and ~70% Ar at a total pressure of 1–2 torr. The hollow cathode was located in the resonator cavity of either a Ti:Sapphire or dye laser (with DCM laser dye), causing molecular absorption to be superimposed upon the tunable broadband profile of the laser. This profile was detected using a Bruker IFS 125 M spectrometer with an instrument resolution set to 0.01 cm−1. Effective pathlengths for the ILS-FTS measurements were 170 m (Δv = +1) and 535 m (Δv = –1). The ILS-FTS spectra were rotationally analyzed using PGOPHER. Transitions of 182W32S, 183W32S, 184W32S, and 186W32S were identified for all three bands, and a mass-independent Dunham model was built in PGOPHER to fit the X3Σ–0+ ground state of WS. Experimental line positions from the laser induced fluorescence (LIF) spectrum of WS [Tsang et al., J. Mol. Spectrosc.359 (2019) 31] and our analysis of the (1,0) band of the [13.10]1–X3Σ–0+ transition [Harms et al., J. Mol. Spectrosc.372 (2020) 111349] were included in the PGOPHER fit. A correlation diagram between the experimentally observed states and those predicted ab initio [Tsang et al.] is used to shed light on the complex electronic spectrum of WS.

Theoretical study of multiwavelength dye amplifier

Gain extraction dynamics of co amplification of multi signal amplification in a pulsed dye amplifier is theoretically studied using four level rate equations. Generic multi signal amplification in dye gain media and gain competition among amplifying signals were studied for two gain media of rhodamine 6 G and DCM laser dyes. Wavelength and power depended gain competition of one signal on other co amplifying signals for dual and three wave amplifiers were evaluated. This study will be useful for implementing compact multi wavelength oscillator and amplifier system.

Fluorescence and lasing in an electric-field-induced periodic structure of a cholesteric liquid crystal

Fluorescence and lasing in a structure with an electric-field-induced spatially periodic director modulation in the plane of a planar-oriented layer of a cholesteric liquid crystal (CLC) is experimentally investigated. The thickness of the CLC layer is chosen close to the natural pitch of the cholesteric helix, which corresponds to the second Grandjean zone. The electric-field-induced periodic field of the CLC director leads to spatial modulation of the refractive index and the appearance of optical properties typical of 1D photonic crystals, when light propagating in the plane of the CLC layer experiences Bragg reflection. In polarised light, the induced spatial modulation of the refractive index manifests itself in the form of banded domains oriented in the plane of the CLC layer perpendicular to the original (unperturbed electric field) direction of the director in the centre of the layer. For the electric field strengths that correspond to fundamentally different distributions of the field of a CLC director, the fluorescence spectra of the DCM laser dye are studied both for different geometries (including the waveguide regime) and for different levels of optical pumping. In the range of electrical voltages corresponding to the induction of a spatially periodic photonic structure, multimode lasing in the waveguide regime is detected. It is shown that the mode composition of lasing depends on the electric field, which affects the properties of the distributed feedback.

"Synthesis and Optical Properties of Polystyrene Doped with DCM Thin Films "

"In the present work Polystyrene (PS) polymer doped with DCM laser dye thin films have been prepared on glass substrate using casting method. The final samples of PS doped with DCM thin films were treated with different annealing temperatures at (30, 40, 50, 60) oC. Optical absorption and transmission spectra of the prepared thin films were recorded using UV-VIS double beam spectrometer in the wavelength range from 190 to 1100 nm. The results shown that the allowed direct electronic transitions energy gap increased from 2.08 up to 2.25e.V as the temperature increasing from 30 to 60oC, whereas the allowed indirect electronic transition energy gap increase from 2.02 up to 2.17 eV as the temperature increase from 30 to 60oC. The effect of temperature on the optical properties such as Urbach’s energy, Refractive index, Extinction coefficient, Critical angle, Brewster angle, and Finesse coefficient of PS doped with DCM thin films also studied in this work.

Optical Study on Deposed Polystyrene Doped DCM Laser Dye Thin Films at Different Temperature

Polystyrene (PS) polymer doped with DCM laser dye thin films have prepared on glass substrate using casting method. The obtained PS doped with DCM thin films were treated at different annealing temperatures such (30, 40, 50, 60, 70) °C. It was observed from result that the allowed direct electronic transitions energy gap was increased from 2.21 up to 2.3e.V as the temperature increasing from 30-70°C. And the allowed indirect electronic transition energy gap rose from 0.06 to 0.15e.V as the temperature increasing. The allowed indirect phonon energy also was decreased at the same range of temperature. The different effect of temperature variation was observed on the optical properties of PS doped with DCM thin films.

Optical Study on Deposed Polystyrene Doped DCM Laser Dye Thin Films at Different Temperature

Polystyrene (PS) polymer doped with DCM laser dye thin films have prepared on glass substrate using casting method. The obtained PS doped with DCM thin films were treated at different annealing temperatures such (30, 40, 50, 60, 70) °C. It was observed from result that the allowed direct electronic transitions energy gap was increased from 2.21 up to 2.3e.V as the temperature increasing from 30-70°C. And the allowed indirect electronic transition energy gap rose from 0.06 to 0.15e.V as the temperature increasing. The allowed indirect phonon energy also was decreased at the same range of temperature. The different effect of temperature variation was observed on the optical properties of PS doped with DCM thin films.

Studying the Optical Properties of Thin Films Prepared from Polystyrene Doped with DCM Dye

Polymeric thin films of Polystyrene (PS) doped with DCM laser dye have been prepared using casting method and pure thin films of PS. Optical properties for deposed thin films on glass substrate with 0.237μm was prepared using casting method involved absorptions spectra measurement using UV mate SP-8001 double-beam spectrophotometer covering the wavelengths range 190-1100nm, where the absorption coefficient was calculated and the direct energy gap was 3.9eV for PS thin film, energy gap for PS-DCM thin film was 2.2eV. While for indirect transitions the energy gap for PS thin film was 2.25eV and phonon energy was 0.55eV, but the energy gap for PS-DCM film was 1.4eV and phonon energy was 0.5eV.

Studying the Optical Properties of Thin Films Prepared from Polystyrene Doped with DCM Dye

Polymeric thin films of Polystyrene (PS) doped with DCM laser dye have been prepared using casting method and pure thin films of PS. Optical properties for deposed thin films on glass substrate with 0.237μm was prepared using casting method involved absorptions spectra measurement using UV mate SP-8001 double-beam spectrophotometer covering the wavelengths range 190-1100nm, where the absorption coefficient was calculated and the direct energy gap was 3.9eV for PS thin film, energy gap for PS-DCM thin film was 2.2eV. While for indirect transitions the energy gap for PS thin film was 2.25eV and phonon energy was 0.55eV, but the energy gap for PS-DCM film was 1.4eV and phonon energy was 0.5eV.

A random laser made of nematic liquid crystal doped with a laser dye

We report on random laser emission obtained in 5CB and E7 nematic liquid crystal (LC) mixtures doped with 1% weight to weight ratio of DCM laser dye. The LC cell was used as asymmetric planar waveguide were emission was collected from the edge of the sample. Variable stripe length method was utilized to estimate the gain and the losses coefficients. Both systems have shown the threshold energy fluence in order of several mJ/cm2. In both cases above Fredericks potential, significant increase of emission intensity was observed due to the increase of light scattering on liquid crystalline domains. Moreover the use of fifth order of diffraction grating covered with thin alumina film resulted in strong multimode and directional laser emission.

Blue shift of spontaneous emission in hyperbolic metamaterial.

Spontaneous emission is one of the most fundamental quantum phenomena in optics. Following the seminal work of Purcell and in agreement with the Fermi's Golden Rule, its rate can be controlled with the photonic density of states (PDOS). In recent years, this effect has been demonstrated in metamaterials with hyperbolic dispersion – highly anisotropic composite materials, which have a broad-band singularity of the density of photonic states. At this time, we show that hyperbolic metamaterials can control spontaneous emission spectra as well. Experimentally, DCM laser dye has been embedded into lamellar metal/dielectric metamaterial. The observed 18 nm blue shift of emission is explained by strong dispersion of the density of photonic states. On the other hand, practically no spectral shift has been observed in the excitation spectra of the same dye. This suggests that the effect of PDOS on spontaneous emission is very different from its effect on excitation and absorption.

Coherent–incoherent random lasing based on nano-rubbing induced cavities

In this letter we present the results of studies carried out on poly(n-vinylcarbazole) doped with the well-known DCM laser dye. We show that the simple incorporation of highly luminescent dye into a polymeric matrix can form an efficient solid state laser material. Naturally occurring inhomogeneities of a polymeric layer prepared by a drop casting process can scatter out light emitted in the process of photoluminescence in such a way that feedback is introduced to the system and coherent and incoherent random lasing can be observed. Moreover we show that after a nano-scale rubbing process the random lasing phenomenon occurs for a lower energy density of pumping light as compared to the virgin sample, and changes the light amplification nature from incoherent to coherent.

Preparation and nonlinear optical properties of hybrid films containing dicyanomethylenepyran-based chromophores

A new nonlinear optical (NLO) chromophore 4-dicyanomethylene-2-methyl-6- {4-[4-( N-ethyl- N-hydroxyethylamino)phenylazo]}styryl-4 H-pyran (AZP), which features extended conjugated chain based on DCM laser dye, was synthesized and functionalized with alkoxysilane for materials processing. Hybrid films containing chromophore AZP and DCM were prepared via a sol–gel processing. The d 33 values of films containing AZP are 39-48 pm/V varying with concentration of chromophores, which is similar to that containing DCM. By tuning the organic content, the thermal stability of d 33 values can be significantly improved by about 30 °C, about 15 °C higher than those containing DCM. The residual rotational stress, along with cavity between chromophores and matrix, is proposed to contribute to the stability of NLO activity of hybrid films.

Nile Red and DCM Fluorescence Anisotropy Studies in C12E7/DPPC Mixed Systems

The lipid/surfactant mixed interactions between the lipid dipalmitoylphosphatydilcholine (DPPC) and the nonionic surfactant C12E7 (C12H25(OCH2CH2)7OH) were studied by the use of fluorescence anisotropy of nile red and DCM laser dye. Three different regions consisting of mixed micelles, mixed vesicles, and both aggregates were identified. Nile red fluorescence anisotropy is wavelength-dependent, the spectra being decomposed into two log-normal functions. These results are consistent with a solvent relaxation process, with distinct anisotropies for the relaxed and unrelaxed states. The spectral properties (anisotropy and maximum emission wavelength) of the relaxed state show higher sensitivity to the environment than those of the unrelaxed state. DCM fluorescence anisotropy shows similar trends. This was interpreted as a result of a trans−cis photoisomerization process. The observed anisotropy spectrum was decomposed in two Gaussian functions reflecting a distinct anisotropy for each isomer.

Threshold current analysis of distributed feed-back organic semiconductor lasers

The relationship between the exciton density and material gain in an Alq3:DCM organic semiconductor laser material is estimated by a comparison between published experimental data and the results of a static analysis of organic semiconductor distributed feedback lasers. The gain coefficient for an Alq3:DCM laser material operating at 640 nm is estimated to be of order 1×10−18 cm2. This value is used to perform a threshold current optimisation of a double heterostructure (DH) organic semiconductor laser utilising a substrate grating for distributed feedback. It is found that the threshold current density can be reduced by approximately 35% by such an optimisation. The minimum threshold current density for a 2 cm long device is estimated to be about 50A cm−2.

Polymer thin-film distributed feedback tunable lasers

We report on measurements of laser emission from poly-methylmethacrylate and poly-vinyl carbazole polymer films doped with rhodamine-6G, DCM and coumarin laser dyes in an optically pumped distributed feedback scheme. We obtain tunability on a broad spectral range for all samples. We show the impact of waveguiding in the polymer film on reducing the laser threshold. We also show that the number of laser modes increases with the polymer film thickness, following the guided mode dispersion.

Transform-limited, narrow-linewidth lasing action in organic semiconductor microcavities

Lasing action in organic vertical-cavity surface-emitting laser (OVCSEL) structures is demonstrated. Optically pumped OVCSELs with an active layer composed of a thin-film organic semiconductor tris-(8-hydroxyquinoline) aluminum (Alq3) doped with DCM laser dye produced very narrow linewidth (0.2 +/- 0.1 angstrom), high-power (3 watts) emission that could be varied in different devices from orange to red. The efficient energy transfer from Alq3 to DCM results in a threshold input energy of 300 microjoules per square centimeter. An operational lifetime >10(6) laser pulses was achieved for a device operated well above threshold in atmosphere. The linewidths above threshold are Fourier transform-limited and could potentially be narrowed further.

Temperature independent performance of organic semiconductor lasers

Characteristics of lasing in optically pumped, vacuum deposited organic semiconductor thin films of tris-(8-hydroxyquinoline) aluminum doped with DCM laser dye are studied as a function of DCM concentration and ambient temperature. In contrast to inorganic laser diodes, the lasing wavelength, output power, differential quantum efficiency, and threshold pump energy of organic lasers are found to be independent of temperature in the range from 0 to 140 °C. In addition, no degradation in laser performance was observed at temperatures approaching 160 °C.

Femtosecond transform-limited Kerr-lens mode-locked dye lasers

Using SF6 glass plates as intracavity Kerr lenses and double-prism pairs for dispersion compensation, we achieve tunable femtosecond passive mode locking in rhodamine 590 (R6G) and 4-dicyanomethylene-2-methyl-16-p-dimethylaminostyryl-4H-pyran (DCM) dye lasers. The R6G laser produces transform limited 240–500 fs pulses between 577 and 606 nm, and the DCM laser produces 150 fs transform-limited pulses between 650 and 671 nm. We use dilute intracavity saturable-absorber jets to make the mode locking self-starting. Characteristics of the pulses and the stability regions of the lasers agree with general theories of passive mode locking.

(Dicyanomethylene)pyran Derivatives with C2v Symmetry: An Unusual Class of Nonlinear Optical Chromophores

A series of symmetric derivatives of 4-(dicyanomethylene)-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran (DCM laser dye) has been synthesized, and the nonlinear optical properties and thermal decomposition temperatures of each of the chromophores has been measured. The symmetric chromophores all have larger hyperpolarizabilities than one would expect based on their absorption maxima. Estimations of their oscillator strengths based upon UV/vis spectra are all well above 1.0. It is proposed that these compounds possess two excited electronic states close to each other in energy, both contributing to the hyperpolarizability in an additive fashion. Electro-optical absorption spectroscopy data and semiempirical calculations on a model compound support this hypothesis. The implications of these results with regard to the tradeoff between nonlinearity and transparency are discussed. The large dipole moments and high decomposition temperatures of these chromophores make them attractive candidates for use in electr...