The temporal characteristics of a distributed feedback dye laser are investigated both theoretically and experimentally. It is shown that the feedback is provided by the gain modulation and that the effect of refractive index modulation is negligible. The solution of the coupled rate equations predicts the generation of picosecond pulses. The mechanism of short pulse formation is self Q -switching which differs fundamentally from mode locking. A novel experimental arrangement for pumping the distributed feedback laser is described which makes it possible to obtain transform-limited pulses even with a partially coherent pumping source such as the N 2 laser. The experimental results show excellent qualitative and satisfactory quantitative agreement with the computer solutions. A very simple and reliable method for generation of tunable, nearly transform-limited single pulses with 36 ps duration (FWHM) is demonstrated experimentally. The feasibility of picosecond and subpicosecond pulse generation in the entire visible and near IR region is discussed.

Tunable picosecond pulse generation by an N 2 laser pumped self Q-switched distributed feedback dye laser

Longitudinally two-photon pumped (TPP) and frequency-upconverted cavity lasing is achieved in a planar leaky waveguide configuration which utilizes a dye-doped polymer film coating on the surface of an optical glass prism. The TPP lasing dye is 4-dimethylamino-N-methylstilbazolium tosylate (DAST) that has been extensively studied as a second order nonlinear optical material. The spectral, temporal, and spatial structures as well as the output-input characteristics of the TPP cavity lasing were measured using a /spl sim/170-/spl mu/m-thick film with a /spl sim/2.4-mm pump depth. The leaky waveguide lasing was featured by a nearly single transverse-mode and five axial-modes structure. In our preliminary study, the net conversion efficiency from the absorbed 1064-nm pump pulse energy to the output /spl sim/607-nm upconverted cavity lasing energy was found to be /spl sim/0.65%. However, this efficiency can be considerably increased by further optimizing the system parameters.

Longitudinally two-photon pumped leaky waveguide dye film laser

Dye film leaky waveguide laser

Distributed feedback laser action in an optical fiber by evanescent field coupling

Super radiant film laser operation of perylimide dyes doped silica-polymethylmethacrylate composite

Laser action was produced in a polymethylmethacrylate film activated with rhodamine 6F and deposited on a quartz substrate. The film was pumped with two converging second-harmonic neodymium laser beams, which formed an interference pattern. The rectangular edge of the quartz substrate acted also as a beam splitter of the pumping radiation. The output frequency of the film laser was tuned by altering the angle which the quartz plate made with the direction of the pumping radiation.

I V Cheremiskin

Papers

Thin-film waveguide laser with a distributed feedback and gain modulation