The new device dubbed ML520G54 is packaged into a compact 5.6mm TO can housing and has an operating temperature range of -5°C to +50°C, which is one of the best in the industry. The LD produces 110mW of output power at 50oC, offering the possibility to switch from active cooled to passive cooled operation.
By technological progress during development, both the operating voltage and current of the device have been minimised, enabling the LD to perform at a recorded wall plug efficiency of 28%. High efficiency at the wavelength of 638 nm equates to a high brightness with low power consumption.
In order to collimate a laser beam into a small spot, the laser diode (being the light source) needs a stable lateral single-mode operation. In addition, the emitted wavelength is very important because the human eye’s sensitivity increases rapidly as the wavelength gets shorter in the red colour range. At a given constant output power this basically means that the shorter the emitted wavelength the higher the subjective impression of the light’s brightness. For example 638nm light is perceived to be about 20% brighter than 642nm light, and 642nm is the frequently used wavelength of single-mode laser diodes.
By adopting the Mitsubishi window mirror structure and ridge waveguide structure, the optical power density and the COD (catastrophic optical damage) level of the facet has been significantly improved, resulting in the world’s highest output power of 110mW at 638nm in single-mode operation.