Panasonic Corporation today announced that it has developed a blue-violet semiconductor laser operating at output power of 4.5 W, which is 1.5 times higher than that of the conventional one even at 60ºC, the maximum operating temperature for lasers in general.　 It can also oscillate with the high energy conversion efficiency, which is 1.2 times higher than that of conventional lasers. This has been made possible by Panasonic’s unique double heat flow packaging technology that improves the heat dissipation. This newly-developed laser will help laser application systems, such as vehicle and industrial lighting as well as laser machining equipment, to be made smaller and consume less power.

Cross sectional view of laser light source and applied laser module (All photos courtesy of Panasonic)

In general, the output power of semiconductor lasers decreases as the laser chip temperature rises. In addition, because the temperature is the determining factor for the laser reliability (because the laser function reliability is dependent on the laser chip temperature), the actual light output that can be used in practical applications is limited by the laser chip temperature. Conventional blue-violet lasers dissipate heat from only one side of the laser chip, causing the laser chip temperature to increase and limiting the output to approximately 3 W. Laser systems requiring an output of tens of watts would require a large number of lasers, causing more heat to be generated and requiring larger heatsinks. To solve this challenge, individual lasers require higher efficiency and larger output.

The newly-developed double heat flow packaging technology can suppress the temperature increase of laser chip that accompanies laser beam output. Consequently, the drop in laser light output caused by heat can also be prevented, enabling high-output and high-efficiency operation. As a result, in laser systems using multiple lasers, the number of lasers can be reduced to two-thirds of those using conventional lasers. Moreover, because the heatsinks can be smaller, the system itself can be made smaller and lighter.

Schematic View of Developed Structure.

This new development laser has the following features:

High output:
Maximum light output of 4.5 W (1.5 times higher than existing product^*2)

High power conversion efficiency:
33% (1.2 times higher than existing product^*3)

High reliability:
Reduced strain in blue-violet semiconductor laser chip, achieving stable output

This device has been made possible through the following technologies:

·         Excellent heat dissipation structure realized by forming heat flow paths on both sides of the laser chip, thus increasing heat conduction from the laser-chip to 1.6 times that of the existing product (Thermal resistance: 6.6 K/W for new product, 10.5 K/W for existing product)

·         Low-strain heat dissipation block structure using aluminum nitride, which has the almost same coefficient of thermal expansion as the laser chip

On the new high-output blue-violet semiconductor laser technology, Panasonic holds 23 patents in Japan and 31 patents overseas including pending applications.

Panasonic presented the research results at 2015 International Conference on Solid State Devices and Materials to be held in Sapporo, Japan on September 28.

This work is partially supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan, under the Strategic Innovation Program for Energy Conservation Technologies.

*1 Under a state of continuous wave operation at 60ºC with the practical operation. (as of September 29, 2015; Source: Panasonic).

*2 Compared with a Panasonic developed laser with a conventional structure (at operating temperature of 60ºC).

*3 At operating temperature of 60ºC, light output of 3 W.