Common Laser Dyes Research Articles

Two-dimensional coherent electronic spectrometer with switchable multi-color configurations.

Broadband implementation of two-dimensional electronic spectroscopy (2DES) is a desirable goal for numerous research groups, yet achieving it presents considerable challenges. An effective strategy to mitigate these challenges is the utilization of two-color approaches, effectively broadening the spectral bandwidth accessible with 2DES. Here, we present a simple approach to include multi-color configurations based on adjustable mirror mounts. This enables seamless toggling between single-color, two-color, and transient 2DES within the same spectroscopic apparatus, which is benchmarked on two common laser dyes, Rhodamine 6G and Nile blue. Upon mixing the dyes, single-color 2DES shows overlapping signals, whereas a high selectivity toward Nile blue responses is maintained in two-color and transient 2DES, owing to the fully resonant excitation that is spectrally shifted relative to the detection window. This method is readily implemented in other setups with similar experimental layouts and can be used as a simple solution to overcome existing bandwidth limitations. With the inclusion of transient 2DES, additional insights into excited-state processes can be gained due to its increased sensitivity toward excited-state coherences.

Non-degenerate two photon absorption enhancement for laser dyes by precise lock-in detection

This study demonstrates a measurement system for a non-degenerate two-photon absorption (NDTPA) spectrum. The NDTPA light sources are a white light super continuum beam (WLSC, 500 ∼ 720 nm) and a fundamental beam (798 nm) from a Ti:Sapphire laser. A reliable broadband NDTPA spectrum is acquired in a single-shot detection procedure using a 128-channel lock-in amplifier. The NDTPA spectra for several common laser dyes are measured. Two photon absorption cross section enhancements are found in the experiment and validated by theoretical calculation for all of the chromophores.

Efficient laser emission from organic semiconductor activated holographic polymer dispersed liquid crystal transmission gratings

Performances of organic distributed feedback (DFB) lasers made from holographic polymer dispersed liquid crystal (HPDLC) transmission gratings were greatly improved by replacing common laser dye with organic semiconductor poly(2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV) as the gain medium. The MEH-PPV layer was laminated between the glass substrate and the HPDLC grating layer. Light interaction for feedback is provided by an evanescent wave spread into the grating layer. The device showed single-mode, TE polarized laser emission with a threshold of only 0.17 μJ per pulse (17 μJ cm−2). Slope efficiencies as high as 4.7% and 6.5% were measured for optical pumping of the device with P polarization and S polarization, respectively. Lasing was also coupled by the grating out of the waveguide and into free space. Furthermore, the output laser wavelength was systematically tuned over a range of 43 nm by varying the grating period. The laser thresholds at different wavelengths trace well with the amplified spontaneous emission spectrum of the MEH-PPV film. In terms of the HPDLC technique, our results show there is still plenty of potential to be exploited for fabricating organic DFB lasers.

Low threshold amplified spontaneous emission from dye-doped DNA biopolymer

In this study, we investigate the amplified spontaneous emission (ASE) properties and conduct a comparative study for two kinds of dye-doped deoxyribonucleic acid (DNA) biopolymers. The system consists of optical films made of DNA modified by two types of surfactants and doped with a common laser dye rhodamine 6G (Rh6G). The ASE properties of the optical films were characterized by a pulsed Nd:YAG laser. The results show that low threshold of DNA biopolymer can be achieved by the employment of suitable surfactant in the system, resulting from an efficient energy transfer process. Coupled with the fluorescence enhancement exhibited in DNA, this effect can further advance biopolymers toward highly efficient media for lasing applications and organic solid-state lasers.

Strong Polarized Enhanced Raman Scattering via Optical Tunneling through Random Parallel Nanostructures in Au Thin Films

Random parallel nanostructures (ridges and channels) were created by scratching gold thin films deposited on glass slides. Atomic force microscope (AFM) images showed that the width of the substructures within the scratches were of the order of a few hundred nanometers. These nanometric gold features can then support localized surface plasmon resonances in the direction perpendicular to the propagation of the scratches. This surface plasmon excitation led to a remarkable dependence of the intensity of the surface-enhanced resonance Raman scattering (SERRS) on the polarization direction of the incident light relative to the orientation of the scratch. The maximum SERRS intensities for oxazine 720 (a common laser dye) adsorbed on these nanostructures were obtained when the polarization of the light field was perpendicular to the direction of the substructures. The SERRS intensities followed a squared dependence on the polarization direction of the incident field.

Lasing action and photodegradation of Disperse Orange 11 dye in liquid solution

We report optically pumped lasing action near 650nm of 1-amino-2-methylanthraquinone (known as Disperse Orange 11 or DO11) in the common laser dye solvents dimethylformamide and dimethylsulfoxide. Amplified spontaneous emission (ASE) was studied under second-harmonic Nd:YAG laser excitation in a transverse pumping configuration. ASE conversion efficiency is found to be comparable to other laser dyes. Photodegradation of dye solution in a micro-cuvette was investigated. While DO11 in poly(methyl methacrylate) polymer shows reversible photodegradation, in liquid solution, degradation is permanent.

Two-photon Absorption Cross-section Measurements in Common Laser Dyes at 1·06 μm

Using a comparative fluorescence method, two-photon absorption cross-sections at 1·06 w m for seven common laser dyes were measured with a moderate power, Q-switched Nd: YAG laser and an intracavity second harmonic generator. The dyes were Rhodamines (560, 590, 610 and 640), DODCI, DCM and Oxazine 725. Using a new method for a direct determination of the Rayleigh length of the focused incident laser beam, all the parameters needed for the experimental determination of the two-photon absorption cross-section are discussed and independently determined by measurements.

Absorption cross sections of the first excited singlet state of laser dyes at 3371 Å

A new method for obtaining cross sections for absorption from excited states with nanosecond lifetimes using pulsed lasers is introduced. Absorption cross sections of some common laser dyes at 3371 Å are presented.

Quenching of laser dye fluorescence by absorption from an excited singlet state

Quenching of fluorescence of common laser dyes is observed and measured as a function of the intensity of an excitation pulse at 3371 Å and the concentration of the dye. The observed effects can be explained by a model where there are sequential absorptions of pump radiation from the ground state and first excited singlet state followed by a radiationless decay, and where molecules can be cycled many times during each excitation pulse.