M. Maeda

Fabrication of a distributed-feedback dye laser with a grating structure in its plastic waveguide

Two approaches of fabricating grating structures for waveguided plastic dye lasers are described and compared for lasing performance. Rhodamine6G-doped poly(methyl methacrylate) (PMMA) film on a PMMA substrate was used for the waveguide, and a distributed-feedback (DFB) laser operation with a single-propagation mode was demonstrated. The performances of both types of permanent grating structured DFB dye laser were better than those of a DFB dye laser on a plain waveguide with a dynamic grating formed by the interference of two pump beams. Wide tuning range is expected by use of a multistripe DFB laser with different grating pitches.

Tuning of a Ti^3^+:sapphire laser by an electro-optic beam deflection method

A wavelength-switching method for tuning a self-injection-seeded Ti3+:sapphire laser that uses an electro-optic beam deflection technique is reported. A LiNbO3 prism was employed in a tuning arm of the dual-cavity Ti3+:sapphire laser, and wavelength tuning of approximately 94 pm was attained by altering the deflection angle with the application of an electric field of 10 kV/cm to the prism. The spectral characteristics of the output laser were mainly determined by the diffraction grating in the dual-cavity laser, and the electro-optic prism just behaved as a light-beam deflector for the wavelength tuning purpose. This configuration can allow a simple tuning approach where fast and stable electronic wavelength switching is required in a narrow tuning range, on an order between a few tens of picometers to nanometers, without involving any mechanical movement.

Feasibility of nonlinear Raman lidar based on stimulated Raman gain spectroscopy without a tunable laser

A novel technique of lidar for atmospheric gas detection by use of stimulated Raman gain spectroscopy without any tunable laser is proposed. Detection sensitivity and detectable range are estimated on the basis of the lidar equation for CO2, CH4, and H2 in the atmosphere. The feasibility study clearly shows that the technique has a potential for application to lidar and that, in addition, the construction of the system is simpler than those of traditional differential absorption lidars.

Nonlinear Raman spectroscopies with Raman shifter for sensitive gas detection

In recent years, measurements of the trace greenhouse gases such as CO/sub 2/, and CH/sub 4/ has become important due to environment problems. In chemical plants and gas pipe lines, continuous monitoring of the leak of inflammable gases is also very important from the safety point of view. We proposed a new scheme for nonlinear Raman spectroscopy, in which a fixed-frequency laser is combined with a Raman shifter. In the scheme, no IR tunable laser is required like absorption spectroscopy and photo-acoustic spectroscopy (PAS). We applied this scheme to different kinds of nonlinear Raman spectroscopy; photo-acoustic Raman spectroscopy (PARS), coherent anti-Stokes Raman spectroscopy (CARS) and stimulated Raman gain spectroscopy (SRGS).

Analysis of trace element in solids by using laser ablation atomic fluorescence spectroscopy

Summary form only given. We have proposed a very sensitive detection technique of trace element in samples such as polymers, metals and semiconductors. It is called laser ablation atomic fluorescence (LAAF) spectroscopy, which combines laser ablation process to atomize the sample surface and laser-induced fluorescence (LIF) spectroscopy to make a quantitative analysis of the atoms in the ablated plume. LIF provides selective excitation of the trace element to avoid interference due to the resonant excitation with the probe laser. In this study, we demonstrated the availability of LAAF spectroscopy for the nano-meter scale analysis of the sample surface.

Atogram Detection on Solid Surface Analysis Using Laser Ablation Atomic Spectroscopy

Nano-scale solid surface analysis method using laser ablation technique was developed and atogram detection was demonstrated with sodium in PMMA sample. And two dimensional distribution of the ablated atoms was observed by imaging spectroscopy.

Tuning of a spectrally narrowed Ti/sup 3+/:sapphire laser by electro-optic modulation

A wavelength modulation method for tuning a self-injection-seeded Ti/sup 3+/:sapphire laser is reported that uses an electro-optic beam deflection technique. This approach can allow a fast and stable electronic wavelength switching without involving any mechanical movement.

Electric field measurements by combining nonlinear frequency conversion technique with electro-optic effect

A novel electric field measurement method by combining a nonlinear frequency conversion technique, such as second-harmonic generation, with electro-optic effect is proposed and its feasibility for electric field measurements due to dc and impulse voltages is investigated.

Nanometer-scale surface element analysis using laser ablation atomic fluorescence spectroscopy

Using ultraviolet laser ablation, very thin layer removal of a polymer or a glass was found to be possible by using a single laser shot. Elemental analysis with nanometer-scale resolution was demonstrated for polymethyl methacrylate samples in combination with laser-induced fluorescence spectroscopy. Nanometer-scale removal was also possible for silicon and metals by femtosecond laser ablation.

Proposal of nonlinear Raman lidar based on stimulated Raman gain spectroscopy without tunable laser

A novel technique of lidar for atmospheric gas detection by using stimulated Raman gain spectroscopy without any tunable laser is proposed. Detection sensitivity and detectable range are estimated based on the lidar equation for CO/sub 2/, CH/sub 4/ and H/sub 2/ in the atmosphere.