Abstract:

A digital high precision constant current driver power is designed for array QC(Quantum Cascade) lasers in the Midinfrared gas detection system. Time division multiplexing is applied in this system to drive several QC lasers which are series and parallel. TMS320F28335 is used as a control center and the constant current driver power has a frequency range of 1~10 kHz, duty cycle from 0.5% to 40%, current amplitude range of 0~4 A by using big power semiconductor devices. In the control scheme, analog PI(Proportion Integral) control algorithm is adopted to improve the precision and stability of the driving current by using double feedback mode of two level analog PI links. Considering of the security of QC lasers, the system is designed with a slow start circuit, over-current and over-voltage protection circuit, ESD(Electro Static Disoharge) protection circuit, etc. The results show that when working in a certain condition that the pulse amplitude is 2.0 A, pulse frequency is 5 kHz, the pulse width is 2 μs the stability of output current pulse is better than 1.7×10^-3 A, the stability of pulse width is better than 2.4×10^-2 μs, the pulse rise is less than 11.9 ns. and the pulse fall time is less than 9.6 ns. At last, driving several QC lasers for testing at the same time, the results show that there is no glitch regarding the driving current and the center wavelength of the tested QC lasers does not shift. Therefore, the fabricated driver provides superior perform
ance that guarantees the application of the QC lasers in infrared gas detection.

Key words: mid-infrared gas detection, quantum cascade laser, constant current driver power