Rohm Crafts Tiny 1 kW Infrared Laser Diode for LiDAR
The eight-channel, 125 W laser diode SMD array improves the measurement distance and resolution in LiDAR applications.
Rohm Semiconductor has recently developed a new high-power laser diode that builds upon Rohm’s established portfolio of proprietary diodes.
RLD8BQAB3.
The company previously released a 25 W laser diode in 2019 and a high-power, 120 W diode in 2023. The new RLD8BQAB3 builds upon these successes and brings their offerings to the 1 kW level.
An Ultra-Compact, High-Power Laser Diode
The RLD8BQAB3 (datasheet linked) is an eight-channel laser diode array in a 5.6 mm × 3.3 mm SMD package. Rohm claims that this form factor reduces size by 33% over conventional four-channel diodes from competitors. Each channel features a 300 × 10 μm emission area wired to a common cathode.
Its irradiation method allows it to adapt to different needs. It can perform individual emissions to simultaneous emissions. With a 125 W peak power in each channel, the combined simultaneous emission of all eight channels allows the diode to achieve a total output of 1 kW, an output class Rohm claims is industry-leading for its size.
Rohm’s new laser diode comes in a new SMD form factor while maintaining the uniform profile and other features from Rohm’s conventional diodes.
The RLD8BQAB3 has similar key features found in Rohm’s other laser diodes. It provides a more uniform emission profile across its beam width than standard products. Its wavelength-temperature dependence is at an average of 0.10 nm/°C compared to standard products' 0.26 to 0.28 nm/°C. When operating in the practical temperature ranges of -20°C to 85°C, the RLD8BQAB3 results in a ⊿9.0 nm shift. It has a narrow bandpass filter that reduces sunlight and other ambient light effects. These all contribute to better long-distance detection and higher definition LiDAR.
A New Emitting Surface With Improved Beam Quality
Laser diodes tend to be built with an emitting surface to encapsulate the diode itself from its environment. For the RLD8BQAB3, Rohm introduced a clear glass cap that serves as the device’s emitting surface. Rohm says this is an industry first for surface-mount laser diodes. The glass cap leads to better beam quality than typical resin surfaces.
The RLD8BQAB3 incorporates a clear glass cap instead of a surface resin, which reduces the effects of scratches caused during dicing.
Scratches often appear when dicing components during the semiconductor fabrication process. These scratches mean that the emitting surface is no longer uniform and can cause light scattering, decreasing the quality of the diode beam. The clear glass cap, Rohm claims, is less affected by light scattering caused by scratches.
Better Distance Measurements for Autonomous Systems
LiDAR systems have increased in smaller consumer and industrial applications like drones, robot vacuum cleaners, service robots, and self-driving cars. LiDAR provides much-needed distance measurements and spatial recognition for these applications. The distance and resolution of LiDAR systems are highly dependent on the output levels of their diodes, which are hard to achieve with small sizes. Rohm asserts that its new SMD diode will achieve a 1 kW class and achieve industry-leading output levels.
