We all know that butterfly-shaped packaged lasers are rare in daily life, so what are the main advantages of this packaging form? Let's take a look at it from the perspective of Xiaobian.

The biggest advantage of butterfly package is stability. The laser device is most afraid of temperature and current fluctuations. Generally, a thermoelectric cooler (TEC) and a temperature sensor (NTC) are integrated in the butterfly package, which are the "constant temperature air conditioning system" of the laser. For example, in an optical communication system, if the temperature rises, the laser wavelength will shift and data transmission will be prone to errors. With this package, the chip works at a stable temperature and the light output is much more stable.

Another advantage is that the packaging structure is tight. Butterfly shell is all-metal sealed, which can effectively prevent moisture and dust, which is very important for long-term use.

One more thing, I have to mention that optical fiber coupling efficiency is high. Butterfly packages are generally reserved for optical fiber extraction, and many of them are also equipped with collimating lenses and isolators, which have small coupling loss and good output spot quality. For example, when we do optical communication and optical sensing projects, the output light is often required to be stable to the micro-watt level, and butterfly packaging can ensure this accuracy.

Of course, it is not perfect. For example, the cost is high and the machining accuracy is particularly high. The installation and alignment of each component have to be actively adjusted by laser, and packaging once is sometimes more expensive than the chip itself. But because of this, it is particularly popular in high-end scenes. Applications that require high temperature control and stability, such as DFB laser, pump source and narrow linewidth laser, are almost all packaged in butterfly shape.

Generally speaking, as long as the system requires high stability, such as optical communication, precision measurement, medical laser, and even industrial pump light source, butterfly packaging is almost suitable.