Application Of Low Frequency 1/f Noise In The Reliability Of Semiconductor Laser

Recently, the photoelectron technology and the micro-electronics become the more and more useful. Semiconductor lasers(LDs) plays a very important role in society. Semiconductor laser which works as a light source is widely used in many fields as optical-communication, information-memory, medical treatment, military affairs , pumping the solid lasers and optical fiber amplifier ,so the semiconductor is important for the economy and construction of national defence. Compared to other lasers semiconductor lasers has a lot of advantages, it is small, light., convenient, very saving power with a high transition rate. Semiconductor is also easy to integrate with other equipment, because the technics of LDs manufacture is similar to the technics of other semiconductor apparatus and integrate circuit. The frequency of LDs has a wide range and both the power and the frequency can be straight modulated. The semiconductor is more and more widely used with the capability improved. So how the LDs can work steadily in a long range time is important. So the research on rule of reliability, improving the capability, prolong the life of LDs is meaningful. The traditional method of the research on the reliability is electrical aging. This examnation waste a lot of time and energy. At the process of electrical aging, the device will be heated, impacted, so, the lifetime of device will be shorten. At the long electrical aging course, if some fortuitous event happened, such as system crash or breakdown, the device will be spoiled in batch, and the method of electrical aging is stochastic and uncertain. So that how to prepare high reliability device, how to analysis the factor which impact the device reliability and how to screen out the disqualification device rapidly, non-destructive and conveniently is an important problems.In this paper we summarize the fundamental and configuration of LDs, then we discuss the category and characteristic of the voltage noise and point out several way how to measure the voltage noise. Then we expatiate on the factor which affect the reliability, the principle of degeneration, at last we bing forward several way to how to improve the reliability of LDs. after all this preparation we start my experiment on the relativity of the reliability and the voltage noise.:(1)We screen out two laser diodes NO.NL1W40 and NO.NL1W42 and carry out some voltage and optical emperiment (IdV/dI-I,P-I,V-I)on this two LDs, the two V-I curve are similar, this indicates that V-I test is not sensitive to the reliability test, but we can still distinguish the differences in capability and reliability between the LDs, for NL1W42,the threshold current is high, the outer quantum rate is very low, there is a kink in the P-I curve. The junction parameter is high, this indicates the recombination current is dominant. The intercept b after threshold increase indicates there is current leakage in this LD. The result of the test shows the mechanics of the loss of quality, at the same time it shows that the increasement of nonradiation recombination current because of COD is an important reason of the leakage current. The leakage current, nonradiation recombination and COD are relative.(2)We also carry out the low frequency noise(LFN) test to the two LDs, we find that there is a peak(around 1mA) in the Bv-I curve of the 1/f noise, this peak is supposed to be relative to the shunt-wound configuration of the junction, the junction resistance can be describe as dV / dI= {(mkT/qI₁ +R_s )^-1 +R_p^-1}^-1,this formula can explain the peak, on the right side of the peak the Bv decrease as the crrrent increases, B_v∝Iβ_v,β_v is the index of the current. Based on the mechanic of how the current makes the voltage noise,we can conclude that the slower the Bv decrease as the inject current gose up ,the higher the nonradiation recombination current is, the worse the reliability is which means there probably is COD in LD. We can judge the reliability of LDs by this discovery. The 1/f noise Bv gose up again after the peak so we can conclude the the noise gose in the field which the linear resistance is dominant. The position of the Bv can bu used as another indicator of the reliability of the LD. The electrical test and the optical test after the NL1W40 degenerate can support this conclusion.Above all, we can conclude that this is relativity among the noise, leakage current, nonradiation recombination and COD. The conclusion by the experiment can be used as a new method of testing the reliability of the LDs. The reaserch of the LFN under low bias current is significant to the reliability of the p-n junction device.