Tatsuhiro Sato

Suppression mechanism by Ca additive of photo-darkening effect in Yb-doped silica glass fiber

We found that Ca additive effectively suppresses the photo-darkening (PD) effect in Yb-doped silica fiber even at 6.0 wt% of high Yb2O3 concentration. Ca ion works as a stabilizer to maintain the Yb3+ valence state. We hypothesize that this phenomenon may reflect the local charge balance effect in silica glass. This Yb-Ca co-doped silica fiber can be useful for high-power fiber lasers.

Demonstration of 4-mm short length fiber laser oscillation in Nd-doped silica fiber fabricated by zeolite method

We demonstrated a laser oscillation in the shortest Nd-doped silica fiber, an only 4-mm multimode Nd-doped silica fiber. This fiber-core glass was fabricated by the zeolite method, and the glass contained 1.25 wt% of Nd2O3.

Suppression of photo-darkening by Ca additive in Yb-doped silica fiber

Researches on additive effects have been reported that phosphorous and cerium additives effectively reduce the photo-darkening (PD) effect in Yb-doped silica fiber. Lee et al. presented another solution to suppress PD by preventing Yb-Yb clustering in a fiber material using phosphate glass. In this work, a Yb-doped silica glass (YbZSG) and a Yb-Ca co-doped silica glass (YbCaZSG) for the core materials were fabricated by the zeolite method to get homogeneous dispersion of rare earth ions in silica glass.

Conceptual study on planar-core optical fiber for high power fiber lasers

We present a new concept of planar-core optical fiber and show a fabricated planar-core fiber and a laser oscillation demonstration. The planar-core fiber will work as a medium of high power fiber lasers.

Laser demonstration in short length single-mode Nd-doped silica fiber fabricated by zeolite method

We present a laser oscillation in the shortest Nd-doped silica fiber, an only 4-cm singlemode Nd-doped silica fiber. This fiber-core glass was fabricated by the zeolite method, and the Nd2O3 concentration is 12,500 ppm.

Laser oscillation in 4-cm single-transverse-mode Nd-doped silica fiber fabricated by zeolite method

Short length fiber less than a few centimeters has many attractive applications in information and communication fields, for example, developments of over GHz clocking signals, optical integrated circuit elements.

Laser oscillation of Nd-doped silica glass with a high thermal shock parameter for high-average-power laser

In this paper, high-average-power laser media must be operated under strict heating conditions during excitation, laser medium based on silica glass (Nd-doped silica glass:NdSG) is one of the candidate, because it has many favorable thermo-mechanical characters. The mechanical toughness of a laser medium can be evaluated by the thermal shock parameter R/sub T/. It is considered that NdSG can work as a high-average power laser medium, such as an optical booster amplifier for Nd:YAG. Furthermore, since a high-power Nd:YAG laser with an NdSG booster amplifier can also be adapted for excitation of a Ti:Al/sub 2/O/sub 3/ amplifier or an optical parametric chirped-pulse amplification system, it is expected that the realization of a 10-Hz, PW-class table-top laser system will be possible in the future. As the bandwidth of NdSG is wide enough to oscillate and amplify ultra-short pulses, high-average-power laser systems with ultra-short pulses may be also realized.