Sadao Uemura

Sub-40-fs Pulses from a Diode-Pumped Kerr-Lens Mode-Locked Yb-Doped Yttrium Aluminum Garnet Laser

We have generated ultrashort pulses with a duration as short as 35 fs from a diode-pumped Kerr-lens mode-locked Yb-doped yttrium aluminum garnet (Yb:YAG) laser. This is, to our knowledge, the shortest pulse in Yb-doped bulk laser oscillators. Here we increased the Yb:YAG crystal length for gain suppression and applied a prism pair to precisely compensate the intracavity group-delay dispersion. The spectral width, center wavelength, and laser output power were 40 nm, 1060 nm, and 107 mW, respectively.

Kerr-Lens Mode-Locked Diode-Pumped Yb:YAG Laser with the Transverse Mode Passively Stabilized

We report what we believe to be the first demonstration of a Kerr-lens mode-locked diode-pumped Yb:YAG laser. The spectral width is 30 nm, which corresponds to 38 fs of pulse duration assuming Fourier-transform-limited sech-shaped pulses.

Generation of 10 fs Pulses from a Diode-Pumped Kerr-Lens Mode-Locked Cr : LiSAF Laser

We demonstrate 10 fs pulse generation from a diode-pumped Kerr-lens mode-locked Cr:LiSAF laser without chirped mirrors on the basis of an improved estimation of intracavity dispersion compensation. This is, to our knowledge, the shortest pulse ever produced from a mode-locked Cr:LiSAF laser.

Femtosecond Cr:LiSAF laser pumped by a single diode laser

Abstract Using a single diode laser to pump a Kerr-lens mode-locked Cr:LiSAF laser, we demonstrate the generation of Fourier-transform limited 26-fs pulses with spectral bandwidth of 34 nm. A novel cavity design for the mode-locked laser was used to focus tightly the pump beam. We have pointed out that the prism edge near the folding mirrors in the laser cavity plays a role of the hard aperture for Kerr-lens mode-locking.

Center-wavelength-shifted passively mode-locked diode-pumped ytterbium(Yb): yttrium aluminum garnet(YAG) laser

We generate 136-fs pulses from a passively mode-locked diode-pumped ytterbium(Yb):yttrium aluminum garnet(YAG) laser. This is to our knowledge the shortest pulse from a Yb:YAG laser. We shift the laser center wavelength from the commonly used 1030 nm to around 1050 nm to utilize the Yb:YAG spectrum broader.

Development of a diode-pumped Kerr-lens mode-locked Cr:LiSAF laser

Kerr-lens mode-locked Cr:LiSrAlF/sub 6/ lasers are demonstrated with various prism pairs based on a recalculation of the condition for compensating the intracavity dispersion. The minimum pulse duration is 9.9 fs, which is the limit for ordinary nonchirped dielectric mirrors. To develop an efficient diode-pumped Kerr-lens mode-locked Cr:LiSAF laser, diode-pumping geometry is also discussed.

Thermal Characteristics of a Continuous-Wave Cr:LiSAF Laser.

Thermal power density produced in the laser medium of a continuous-wave (cw) Cr:LiSAF laser has been investigated to clarify the laser output characteristics. For the cw Cr:LiSAF laser using axially symmetrical end pumping, the available pump power density has been found to be limited to less than ?100 W/mm3. Based on the thermal characteristics studied, an efficient diode-pumped cw Cr:LiSAF laser has been developed.

Observation of the time evolution of persistent holes in an organic amorphous system using a diode laser

Abstract By rapid current of the wavelength of a diode laser, we have observed the time evolution of the persistent hole in 1,3,3,1′,3′,3′-hexamethyl-2,2′-indotricarbocyanine iodide embedded in poly(vinyl alcohol) in the range from 10 ms to 5000 s after burning. Following a rapid decay until about 0.1 s, the hole depth decreased logarithmically as a function of time. By using this method, we could probe a single hole more than a thousand times with a good signal to noise ratio. The time evolution of the hole-erasing process by the irradiation with a light-emitting diode has also been observed.

Dispersion Compensation for a Femtosecond Cr:LiSAF Laser

The group delay per length for Cr:LiSAF crystal has been measured, and the result indicates that the refractive index of Cr:LiSAF has a large error. The dispersion of a prism pair is calculated without approximations to be estimated in a large wavelength range. The conditions in which the group delay dispersion and third order dispersion of a femtosecond-Cr:LiSAF-laser cavity are simultaneously zero have been discussed.

Fluorescence lifetime measurement of semiconductor doped glass by using an incoherent light gated optical Kerr shutter

Abstract We measured the fluorescence lifetime of a semiconductor doped glass (Toshiba R-63 red color filter) at the liquid nitrogen temperature by using a novel technique of an incoherent light gated optical Kerr shutter. When the peak intensity of nanosecond excitation pulses was increased to more than 1 kW/mm2, a short lifetime (70 ps) component built up at the high energy side of the exciton band emission besides the already reported component of several hundred picosecond lifetime.