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20 Nov 2003
Researchers report what they believe to be the first mode-locked ceramic laser.
A team of scientists from Japan, Bulgaria and Russia claim to have demonstrated the first mode-locked ceramic laser. Based on a ytterbium-doped yttrium oxide (Yb3+:Y2O3) crystal, the laser allegedly emits sub-picosecond pulses at 1076.5 nm. (Optics Express 11 2913)
The key to this breakthrough is the team’s nanocrystalline fabrication method, an approach which produces a range of polycrystalline ceramics doped with rare-earth ions. “Our ceramic technique is also scalable,” Ken-ichi Ueda from the Institute of Laser Science at Tokyo’s University of Electro-Communication told Optics.org. “We can develop laser-scale polycrystalline laser materials with low cost in the future.”
An 8% doped, 1.5-mm thick Yb3+:Y2O3 crystal forms the heart of the laser. The crystal sits in a z-fold cavity design and is pumped by a broad-stripe laser diode temperature-tuned to emit at 950 nm.
To mode-lock the laser, Ueda’s team introduce a saturable absorber mirror (SESAM) and a pair of prisms into the set-up, which switches the laser’s output from CW to pulsed. For a pump power of 3.3 W, the modelocked laser emitted 615 fs pulses, with an average power of 420 mW at a repetition rate of 98 MHz.
Ueda’s team is now trying to increase the laser’s output power. “A few-Watts is the target with the extension of the current setup and a few-10s of Watts will be pursued with a thin-disk geometry,” he said. “Sub-200 fs pulse generation will also be investigated by optimizing the cavity dispersion and nonlinearity. We would also like to investigate lasers based on other sesquioxide and disordered ceramics.”
Author
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.
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