VCSEL is an abbreviation of Vertical Cavity Surface Emitting Laser, and is one kind of
semiconductor laser. Conventional semiconductor lasers (edge emitting laser) emit light in a
horizontally to the substrate, whereas VCSELs emit laser light vertically to the substrate.
VCSEL is characterized by its small size, high luminous efficiency, low power consumption, and high directivity. Since VCSEL die can be arranged in two dimensions, the output as a
package can be increased, and it also features a high-speed response that enables highspeed pulse lighting (high-speed modulation) in the gigabits.
Advantages of IR VCSEL Light Source: Comparison with LED
The advantages of VCSELs in smart in-cabin IR sensing applications are mainly the following four points compared with IR LEDs;
1Pattern of Irradiation: Light distribution control suitable for camera (Field of View) is available
The IR LEDs have a circular light distribution with a peak in the center, while VCSELs are surface-emitting lasers that can
be arranged in two dimensions, resulting in uniform irradiation. Furthermore, the light distribution can be controlled in a
rectangular shape by installing a diffuser, which improves the performance of occupant monitoring systems (OMS) that
monitor the entire vehicle. The light distribution of the VCSEL in the figure below show examples of two types of
irradiation angles possible with diffusers.
2Response Speed: Achieves image resolution enhancement, wider angle and real-time data processing due to
high-speed pulsed lighting
Since the VCSEL has a small volume, pulse lighting (on/off operation) is possible at a frequency in the gigabits, which is
not available with LEDs. Due to this, when using a VCSEL as a TOF light source for IR detection and distance
measurement, image resolution enhancement, wider angle and real-time data processing can be achieved.
3Emission Spectrum: The narrow spectrum emission reduces the influence of ambient light and the loss due to
the band pass filter is also small
Compared to LEDs, VCSELs have a narrower wavelength spectrum. In the example below, it is in the range of a few nm
with respect to the standard value of 940 nm. Band pass filter can be narrowed, and even if it is narrowed, the output loss
can be kept low. Therefore, the influence of ambient light such as sunlight can be reduced, which enables highly accurate
detection.
4Less impact of temperature changes on emission wavelength
Compared to LEDs, the emission wavelength of VCSEL is more stable against temperature changes, and achieves this even under severe temperature change conditions such as in-cabin use. They also maintain this performance even when more heat is generated at high currents.
Stanley Electric's IR VCSEL's Features
Consolidating Stanley Electric's
Devices used in automotive in-cabin applications are required to have stable quality even in harsh environments. Stanley Electric has developed a highly heat-dissipating / highly reliable VCSEL device using the packaging technology cultivated with high-power LEDs for headlamps, etc., and has achieved the automotive standard AEC-Q102. In addition, we have obtained a light distribution according to each application by using light distribution control technology, which is our strength that has handled light for various purposes such as lamps and lighting.
IR VCSEL Product Lineup
There are two types of products with different light distribution as standard products, and we will further expand the lineup in the future. Regarding eye safety, all products are safety standard class 1 of IEC60825-1 & CFR Part1040.10, and are designed so that there is no problem even if they emit light towards people.
