VCSEL
As VCSELs are a surface-emitting laser chip like LEDs, SMD (Surface Mount Devices) is its natural packaging form, and the packaging has many dominant advantages, such as good heat dissipation, easy mounting with electronic components, small size, etc.; yet in SMD packaging may cause deviation in alignment with optical components, most likely when matching with optical lens systems, so in laser industry there has a pressing demand for TO packaging of VCSELs.The beauty of VCSEL is that compare to traditional lasers, it makes packaging become extremely simple, more robust and durable, very compact, and lower manufacturing costs. Combining many of the desired features of an LED and the advantages of a laser diode, VCSEL offer many advantages in sensing applications over infrared LEDs. These devices require substantially lower drive currents to obtain the same amount of output power as LEDs. This feature allows VCSELs to be used in low power consumption applications such as battery-operated equipment. Compared with the traditional EEL (Edge Emitting Laser), VCSEL has better wavelength stability, the wavelength temperature coefficient is 0.07nm/deg or less while that of EEL is 0.25-0.3nm/deg. VCSEL has two characteristics of smaller divergence and circular spot, which is beneficial for collimation or focusing and simplifies the coupling link, it also helps to reduce costs and improve reliability. EEL suffer from catastrophic optical damage (COD) at the facets, a common problem causes reducing reliability in laser diodes. VCSELs do not show this damage as the end facets are designed differently. Moreover, VCSEL has the advantages of high reliability, wide operating temperature range, and can better meet industrial requirements of lasers.