We all know that the laser diode driving circuit is relatively complicated. Today, Xiaobian gives you a brief talk about the QSI laser diode circuit. Many people are asking what are the benefits of the constant power output circuit? Let's answer it today.

1. What's going on with the laser diode circuit?

Laser diode (LD) is essentially a semiconductor device that converts electric energy into laser energy. The seemingly simple three feet: positive electrode (LD+), negative electrode (LD-) and monitoring terminal (PD) have very exquisite circuit logic hidden behind them.

In general, the laser diode should be used with the driving circuit. This drive circuit has two main control modes:

Constant current drive: keep the current constant, make the LD work stably and not be burnt out by current impact.

Constant power drive: By monitoring the feedback signal of photodiode (PD), the current output can be adjusted in real time to keep the laser brightness consistent.

Simply put, constant current means "I am only responsible for giving you a fixed current", while constant power means "I adjust it dynamically according to your brightness". It doesn't sound much different, but in actual use, the effect is completely different.

Second, what are the advantages of constant power output?

There is an enterprise that does industrial dust detection. When the laser diode is driven by ordinary constant current, the light intensity is very high at first, but after half an hour of operation, the light output is obviously attenuated and the detection error is getting bigger and bigger. Later, they switched to the constant power control scheme of QSI in South Korea. With the same power, the fluctuation of light intensity was reduced from 10% to less than 1%, and the detection stability of the whole machine was doubled.

It can effectively solve the temperature drift, the laser diode will generate heat when working, and the increase of temperature will lead to the decrease of luminous efficiency. Constant power can automatically compensate the current and keep the output power. At the same time, the service life is prolonged: the current will not suddenly impact the LD chip, which can reduce the internal lattice stress damage.

This is one of the reasons why QSI laser diode can be widely used in medical treatment, detection, optical communication and other industries.

The above is the benefits of QSI laser diode circuit analysis and constant power output circuit. I hope you will have some help after reading it.