High-power laser bar from Osram simplifies fibre-coupled systems
Osram Opto Semiconductors has introduced the SPL BF98-40-5 laser bar, which it says combines a unique combination of power and beam quality that considerably reduces the complexity of coupling light into fibres.
The laser has a wavelength of 976nm and achieves a brilliance of 3 watts per millimeter and solid angle (W/mm*mrad) at an optical output of 44W. The SPL BF98-40-5 laser bar is 5mm wide and consists of five emitters, each 100Âµm wide and each with cavity length of 4mm.
Brilliant laser sources generate a narrow beam of light with extremely small beam divergence and high power density. The lateral divergence of the beam emitted by the SPL BF98-40-5 is between 6 degrees at 30W and approx. 9.5 degrees at 60W. This divergence was calculated for the portion of the laser beam containing 95 percent of the optical output power.
The beam quality of a laser is a crucial factor for coupling laser light into optical fibres. The lower the brilliance, the less light is coupled into the fibre. This in turn makes the systems more inefficient and more expensive. Conversely, a brilliant light source greatly simplifies the design of the optical system. "Our new laser bar can significantly reduce the system costs for fibre-coupled diode lasers", said Christian Lauer, Laser Bar Developer at Osram Opto Semiconductors.
The new laser bar is said to offer excellent electro-optical efficiency of e.g. 65 percent at 44 W. This reduces the level of cooling needed for the laser diode and improves the efficiency of the entire system. The temperature rise at the chip is therefore not as great so the laser exhibits very good aging stability. Tests show a drop in output of less than one percent after 4000 hours of operation at an optical output of 65W and a cooling water temperature of 25degC.
Osram Opto Semiconductors defined the fundamental principles for developing the high-power high-brilliance laser bar within the HEMILAS project sponsored by the Germany Ministry for Education and Research (BMBF).