From Toyohashi University of Technology:

IMAGE: This photo shows researchers working with the MO Q-switched laser. Left: PhD candidate Ryohei Morimoto. Right: Assistant Professor Taichi Goto. view more


The “Industry 4.0” concept, first introduced by the German government, has recently extended the scope of compact high-power laser applications to, for instance, laser manufacturing, vehicle engine development, or thruster systems for space exploration.

However, integration of a controllable Q-switch into compact solid-state lasers has been challenging because of the mechanisms of EO and AO effects. In addition, previous Q-switches needed a large-sized power supply, which prevented downscaling of the entire system.

Now, researchers at Toyohashi University of Technology, Iowa State University, and the Institute for Molecular Science have developed a magneto-optic (MO) Q-switched laser for the first time, using a 190-micron-thick magnetic garnet film with labyrinth-shaped magnetic domains. They used custom-made coil and circuits to generate the pulsed magnetic field to be applied to the magnetic garnet, and successfully generated optical output with a pulse width of tens of nanoseconds. This is the first demonstration ever of a Q-switched laser driven by magnetic domain motions, and also the first evidence of the possibility of an integrated Q-switched laser. “The device was two orders of magnitude smaller than other reported controllable Q-switches,” commented Associate Professor Taira.

“The most difficult part of realizing MO Q-switching was to combine three different techniques/fields: the preparation of a magnetic material, the fabrication of a high-speed magnetic field switch, and the construction of a laser cavity,” explained PhD candidate Ryohei Morimoto.

According to the first author, Assistant Professor Taichi Goto, “there are no previous reports of MO Q-switches using thin garnets. This is surely the first demonstration, and it also becomes an important first step in …

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