KOBE-Masayosh Watanabe and colleagues at the Electromagnetic Spectroscopy Laboratory of the Communications Research Laboratory (CRL) have developed the world's shortest-wavelength all-solid-state continuous-wave (CW) laser, emitting at 202 nm. Gas lasers already exist in this region, but an all-solid-state system will enable devices to become more compact and energy efficient.
In the new design, the 532-nm output from a commercial Nd:YVO4 laser is converted to 266 nm. This light is then mixed with the output of an amplified 850-nm laser diode in a barium borate (BBO) wavelength converter to produce the 202-nm output beam (see figure).
The wavelength converter uses a low-loss optical resonance cavity made with four mirrors. The light is trapped within the optical system so that the wavelength conversion is more efficient. The temperature is carefully controlled to avoid any thermal effects. An optical output power of 360 µW was observed. The output wavelength can be controlled over a 1-2-nm range by adjusting the wavelength of the laser diode.
This laser can be used in measurement and manufacturing equipment, optical information processing, and communications; however, the CRL group hopes to use it for superhigh-precision ion spectroscopy. A single ion can be forced to essentially freeze in place by laser-cooling, creating an ion trap. Extremely fine spectroscopic measurements can be made of such an ion. The researchers hope to analyze zinc ions, which could lead to the development of superhigh-precision atomic clocks.
Courtesy O plus E magazine, Tokyo