Hamamatsu Photonics has developed a four-channel pulsed laser diode that uses a ceramic package with excellent heat dissipation to ensure the reliability required for automotive applications and still emits stable light even in high-temperature environments up to 105°C.
Using this new pulsed laser diode as the light source for in-vehicle lidar modules allows more accurate measurement of objects at far away distances and over wide areas. Hamamatsu Photonics will start shipping sample products of this new pulsed laser diode from next year to automotive manufacturers planning full-scale mass production of self-driving cars that are expected to be available in the near future.
Overview of new pulsed laser diode
For automotive applications such as collision avoidance, Hamamatsu Photonics already manufactures and sells pulsed laser diodes (PLD) mounted in metal can packages that deliver stable operation even in high temperature environments up to 105°C. Among in-vehicle lidar applications, there is recently a growing demand for long-range lidar that measures objects more accurately at far distances and over wide areas. This will also increase demand for PLD with higher output power and faster response time. However, enhancing the performance of metal can package PLD to meet such needs is very difficult from the viewpoint of cost and size.
The new PLD from Hamamatsu Photonics employs a hollow ceramic package that exhibits high reliability equivalent to the can package type and emits stable laser light even at high temperatures. The new PLD also incorporates four PLD chips in the ceramic package and so provides a high output power four times greater than currently available can package types. These four PLD chips are directly mounted (surface mounted) in the package to minimize and optimize electrode wiring patterns and so shorten the laser light pulse width by 20% and enhance the response time as well. The PLD chips are also mounted at a high density that reduces the cubic size of the package to a mere one-fifth the size of the can package type. This makes this new PLD easier to mount into in-vehicle lidar modules and so helps meet the demand for self-driving cars that are expected to go into full-scale mass-production in the near future.
Since lidar systems use a light emitter (PLD etc.) and light sensor (photodiode etc.) together as one set, the performance characteristics of the light emitter and sensor must be optimized to match each other.
Features of new PLD
- Stable operation at high temperatures up to 105°C: Using a hollow ceramic package with excellent heat dissipation guarantees stable operation even in high temperature environments up to 105°C and satisfies the tough reliability requirements needed for automotive applications.
- High laser power generated by multichannel output: The four PLD chips mounted in the package deliver high output power that is about four times that of a single-channel PLD, allowing laser irradiation onto objects at far off distances and over wide areas.
- Short pulse and high repetition rate operation due to optimized electrode wiring patterns: The optimized electrode wiring patterns formed within the package shorten the laser pulse width by 20% compared to the can package type, achieving pulse operation at a high repetition rate. This increases the amount of information obtained per unit time and so allows more accurate measurement of the distance and shape of objects even from a moving car.
- Miniaturized by high-density mounting of PLD chips: The ceramic package allows flexible high-density surface mounting of four PLD chips. This has miniaturized the ceramic package to sizes as small as 5.5 mm × 3.8 mm × 1.7 mm (W×D×H) which is only about one-fifth the volume of the can package type.
- Peak oscillation wavelength: 905 nm
- Number of light-emitting channels: four channels (can be driven separately)
- Peak optical output power (per channel): 100 W
- Operating temperature range: -40°C to +105°C
- Dimensions (W×D×H): 5.5 mm × 3.8 mm × 1.7 mm
- Four-channel pulsed laser diode.