Takeshi Takagi, Hiroshi Matsuura, Akira Fujisaki and Tomoya Kato
The authors have developed a 488-nm blue laser by combining a 976-nm semiconductor laser Furukawa Electric has long fostered in the optical communications field with a wavelength conversion device based on periodically poled lithium niobate (PPLN). Because of its simple device configuration whereby the semiconductor laser for optical communications - where long-term reliability up to 20 years is required - is directly coupled with the wavelength conversion device, the laser has a long service life, compact size, low cost, and low power consumption. Moreover, by optimizing the spectrum of fundamental lightwave and by providing a feedback circuit in which a fraction of the output light is monitored for control use, the laser has achieved both high output stability and low noise that were unattainable for conventional argon lasers and diode pumped solid state (DPSS) lasers. The obtained performance, i.e. output power ≥ 20 mW, output power stability <2 %, peak-to-peak noise < 1 %, and rms noise < 0.25 %, was confirmed to meet the characteristics required for light sources for biomedical analyzers. In the future strong demand is expected as a light source for bioinstrumentation.