1. VCSEL Principles
A vertical-cavity surface-emitting laser (VCSEL) is a semiconductor-based laser diode that emits a highly
efficient optical beam vertically from its top surface. VCSELs differ from other common semiconductor optical
sources such as Edge Emitting Lasers (EEL) that emit light from the side. Thus it has quite different performance
compared to edge-emitting laser diode bars.
Due to the DBR cavity design and low optical power density in the emitting aperture, VCSEL has no COD limit
and also its the heat stress during the pulsing will be minimized compared to edge emitting laser bars. This
performance makes VCSEL a more reliable device for pulsed operation with 10~20 times longer life time compared
to laser bars. The low wavelength-temperature shift makes it a perfect pumping source for solid-state
lasers.
2. VCSEL vs Laser Bar Performance
| Performance | VCSEL | Laser Bar |
| EO Efficiency (PCE) | 45~50% | 50%~55% |
| Optical Limit | Thermal Rollover, No COD | COD, Heat Stress |
| Wavelength Shift | 0.068nm/K | 0.3nm/K |
| Pulsing Life Time (@250us) | 20~50G Shots | 2G Shots |
| Max Operation Temperature | >85°C | ~45°C |
| Output Surface Anti-Reflection | >99% | No |
| Cost per Watt | ★★ | ★★★★★ |
| Cost per Shots | ★ | ★★★★★ |