Research On Narrow Linewidth Single-Mode Technique Of Nanoplasmonic Laser

Traditional nanoplasmonic lasers can break through the optical diffraction limit and compress the size to the deep subwavelength level,but they have shortcomings such as multi-longitudinal mode lasing and wide linewidth.The narrow linewidth and singlemode output characteristics of semiconductor lasers are crucial for further development of high-performance lasers.Semiconductor lasers with narrow linewidth and single-mode output have broad application prospects in fields such as optoelectronic sensing,highprecision measurement,microscopy,spectroscopy,and on-chip communication.Linewidth compression and mode selection are essential for improving information transfer speed,communication system throughput,measurement accuracy,and other aspects.However,achieving linewidth compression and mode selection simultaneously in nanolasers is challenging.Therefore,research on linewidth compression and mode selection of nanoplasmonic lasers is of great significance.This thesis focuses on the following aspects of linewidth compression and mode selection technology:(1)The optimal structural parameter model of DFB nanoplasma laser is established.Based on the theory of plasmonic lasers,a structural design model of nanoplasmonic lasers was established.The optical field distribution was simulated to verify the optical enhancement,confinement,and modulation characteristics of nanoplasmonic lasers.To address the problem of wide linewidth and multimode output of nanoplasmonic lasers,a new design structure of DFB nanoplasmonic lasers coupled with Bragg gratings was proposed.By analyzing the optical field distribution of this structure,the role of the grating in selecting the optical wave mode was verified.By studying the mode characteristics,gain threshold,and quality factor of DFB nanoplasmonic lasers,the optimal parameters for SiO2 and Ag films were obtained,with a thickness of 5 nm and 25 nm,respectively.By studying the grating structure,the optimal parameters for the grating were obtained,with a period of 203.67 nm,thickness of 85 nm,duty cycle of 0.5,and residual layer thickness of 53 nm.The optimal structure of the DFB nanoplasmonic laser was obtained,providing a structural basis for studying the spectral output characteristics of the laser.(2)The mode selection and linewidth compression techniques of DFB nanoplasma lasers are verified by simulation.The semiconductor laser was numerically simulated using the time-domain traveling-wave method,and the lasing spectrum of the DFB nanoplasmonic laser was simulated to obtain single longitudinal mode output characteristics.Based on the linewidth theory of semiconductor lasers,linewidth compression technology was studied,and the effects of different parameters on the laser performance were simulated to obtain the best optical characteristics,including the spectrum and linewidth.Finally,a narrow linewidth single-mode laser with a peak output of 514 nm,linewidth of 0.1 pm,threshold current of 16 mA,and output power of 52 mW was achieved.(3)A preliminary study was conducted on the preparation process and performance testing of the DFB nanoplasmonic laser.N-type CdS nanobelt arrays were prepared on a P-type GaN substrate using chemical vapor deposition(CVD)method.The morphology and optical properties of the grown array were characterized,and high-quality CdS nanobelts with a width of about 500 nm and a PL peak at 513 nm were obtained.Finally,the electrode preparation,nanobelt selection and transfer,coating,and grating etching technologies were briefly introduced,providing a basis for experimental verification of narrow linewidth single-mode technology.