Research And Design Of Semiconductor Lasers

Laser is a laser device capable of launching.The invention of laser science and technology in the 20th century,a major achievement.In 1916,Einstein proposed the concept of stimulated emission which is an important theoretical basis,the so-called stimulated emission is:in the high-energy state of matter particles,when high-energy state by an energy equal to the energy and the second to state the difference between the photon effect,the particle will switch to the second energy state,while the release of a second photon,and a photon be emitted.Such radiation output of the light received amplification,and is coherent,that is,such as multiple photon emission direction,frequency,phase,polarization identical.The rise of science and technology of laser light of the understanding and use of human beings has reached a new level. The traditional classification of laser media based on its work, including: gas laser, solid-state lasers, semiconductor lasers, liquid lasers and free electron laser.Semiconductor laser with other lasers can not match the features, such as: the common use of He-Ne laser excitation, excited by high voltage (about 1500V) and the semiconductor laser 2-3V in low-voltage excitation, compared to the excitation mode semiconductor laser more secure, and high excitation efficiency than conventional lasers the number of times. In some measuring instruments, used semiconductor laser lighting, can meet the color is good, coherent, good, high beam collimation requirements. In the long-distance communications, laser radar, digital signal storage and recovery, laser ranging, robotics, holographic applications, medical diagnosis and so on are widely used.However, in practice, requirement lasers with low electrical noise, and other characteristics of high stability, as drive current fluctuations, not only lead to laser the laser intensity noise, which causes the output wavelength Guang Pu linewidth broadening. In addition to a stable current, the laser diode also requires accurate temperature control. Laser light in the laser stimulated emission process, stimulated source for temperature sensitive, temperature will affect the emission spectra and output power. Typically 1 degree Celsius temperature change, the wavelength change 0.2 ~ 0.3nm.This paper presents a more complete functional semiconductor laser system, to achieve current source drive and protection, optical power feedback control, temperature control, and error alarm and other functions, the system controlled by microcomputer. Current source driver enables APC (automatic static power control) and ACC (automatic steady current control) mode, constant temperature control system, through the precise regulation by TEC (Thermo Electric Coolers) the current size and direction, and with the feedback and thermal resistance PID algorithm, the working environment to realize the laser temperature control.