Optical Feedback Sensitivity Of A Circular-side Hexagonal Micro-cavity Semiconductor Laser

Semiconductor lasers can generate numerous dynamic states under optical feedback with different level,which can find important applications in such fields as communication,measurement,radar.For example,the phenomenon of chaotic oscillation in semiconductor lasers with optical feedback can be used to achieve high-speed physical layer secured communications,high-speed physical random number generation,anti-j amming lidar,high-precision optical time-domain reflection(OTDR)measurements,etc.It is worth noting that the dynamics output of the semiconductor laser with optical feedback has time delay signature——the time-frequency characteristics of the laser output can reflect the position and feedback level of the external reflector.Therefore,OTDR or radar measurement can also be realized by using the time delay signature of laser.At present,the OTDR measurement based on the time delay signature of the distributed feedback(DFB)semiconductor laser has been proposed and applied to the fiber network fault detection.This method avoids the limitation of laser coherence length and has the advantage of long-distance measurement.However,its sensitivity is limited by the optical feedback sensitivity of the DFB laser.As the result,the improvement of the optical feedback sensitivity of laser become very key to achieve high-sensitivity measurement of the time-delay-signature-based OTDR.We noticed that,two-dimensional microcavity semiconductor lasers have a smaller active region and a shorter inner cavity(about one order of magnitude lower)compared with DFB lasers.Theoretically,it is more sensitive to feedback light.This thesis takes the circular-side hexagonal microcavity laser as the object to investigates the optical feedback sensitivity of two-dimensional microcavity laser.The main work carried out is as follows:(1)We theoretically investigate the route to laser chaos in circular-side hexagonal microcavity laser subjected to optical feedback,and analyze the critical feedback level of the laser from stable state to nonlinear dynamic by using the laser rate equation.We discover and reveal the SQPS(switching between stable state and Quasi-period oscillation)phenomenon of the laser under long cavity feedback.The critical feedback level of the circular-side hexagonal microcavity laser is studied,the results show that it is about an order of magnitude lower than that of the traditional DFB laser.(2)Through the methods of autocorrelation function,delay mutual information and permutation entropy,the time delay signature and the influence parameters of optical feedback circular-side hexagonal microcavity laser are studied.The results show that the time delay signature change rate of microcavity laser is about 20 times higher than that of DFB laser.(3)The phenomenon of high-frequency regular pulse package oscillation of the circular-side hexagonal microcavity laser under short cavity feedback is discovered,and its physical mechanism and production conditions are also revealed.