Research On Narrowing Linewidth Of Diode Laser For Rare Gas Laser Pumping

Semiconductor pumped rare gas laser(DPRGL)is a kind of gas laser combined with electro-optical secondary pumping.Metastable noble gas atom is used as the working medium and electro-optical two-stage pumping structure is used in it.The model of DPRGLs was established in this thesis.Condition for absorption spectrum broadening of argon atoms at the absorption wavelength of 811.53 nm is about 40-60 pm.A design scheme for narrowing the linewidth of a single-tube semiconductor laser using a blazed grating was proposed.The main research contents include the following:(1)The three-level structure of DPRGLs was analyzed,the system structure was designed,and the verification experiment of laser generated of DPRGLs was carried out,and the conditions for pumping the Ar laser were analyzed.The Ar* absorption linewidth is about 16 pm at one atmosphere,and the pump source linewidth can also maintain a high matching efficiency at 40-60 pm;(2)Based on the method of narrowing the linewidth of the semiconductor laser,the relationship between the output linewidth and power of the Littrow blazed grating external cavity system and the laser front-end surface transmittance,grating diffraction efficiency,and outer cavity length were analyzed comprehensively compared with the external cavity feedback component.The multi-beam interference analysis method was used to establish the spectral gain function model of ECDL,and the tuning range corresponding to the different rotation axis points of the grating was calculated.(3)The relationship between the position,tilt angle and lateral offset of the Littrow structure affecting the backward coupling efficiency was analyzed comprehensively.The results show that when the distance between the lens and the output end of the laser is 5mm,the theoretical coupling efficiency can approach 100%.The distance from the lens to the grating at this position has almost no effect on the backward coupling efficiency.The axial positional shift of the lens has a greater impact on the linewidth stability than the angular offset.When the tilt angle of the lens and the y-axis is within 0.0185 rad,the coupling efficiency can be maintained above 99.2%;(4)In the LDA linewidth compression system,the micro-column lens array used to narrow the spectral width was simulated,and the output linewidth(spectral width)of the external cavity was calculated,and the effect of the cylindrical lens on the linewidth narrowing was simulated in Zemax.