Preparation And Device Research Of Novel Tellurite Acousto-optic Materials

Laser Q-switch is a kind of pulse modulation technology which can compress laser energy to a very narrow width in time domain.The progress of this technology is an important breakthrough in the history of laser development,which promotes the extensive and in-depth study of laser output power and pulse compression technology,thus expanding the application range of laser.Acousto-optic Q-switch devices based on acousto-optic matrix materials have the advantages of low driving voltage,high repetition rate,low insertion loss and low cost.Therefore,high repetition rate,high-power all solid-state lasers and fiber lasers based on acousto-optic Q-switched devices have been widely studied,such as laser cutting,laser engraving,laser communication,laser medical treatment,laser printing in the civil field;in the military field they can be used in laser ranging,laser guidance,laser radar and other fields,and also play a vital role.Acousto-optic matrix material is the basis of acousto-optic modulation devices.With the development of acousto-optic crystals,such as TeO2,PbMoO4,GaP and other excellent acousto-optic materials,the performance of acousto-optic devices has been greatly improved.As the development of laser applications,higher requirements are put forward for acousto-optic devices.Based on traditional acousto-optic materials,device design and fabrication cannot fully meet the needs of devices.The development of new and efficient acousto-optic crystal is the key to the breakthrough of acousto-optic devices.In recent years,our group has been committed to the research of new photoelectric functional crystals.Under the guidance of the second-order Jahn-Teller(SOJT)distortions,our group has grown more than 10 kinds of tungsten molybdate crystals represented by BaTeMo2O9.In 2017 and 2020,we have reported ?-BaTeMo2O9(?-BTM)and ?-BaTeMo2O9(?-BTM)acousto-optic devices,and obtained a number of national and international patents.At low frequency,acousto-optic glass has been widely used.Tellurite glass is a promising acousto-optic matrix material in theory because of its high acousto-optic quality and low ultrasonic absorption.At the same time,the glass preparation process is relatively simple,the growth cost is low,the driving voltage is low,and the device is isotropic.In addition,the combination of glass and acousto-optic crystal working frequency can cover low frequency and high frequency.Based on the above analysis,the main research direction of this paper is the exploration of new tellurite acousto-optic materials and the preparation of acousto-optic devices.This paper is divided into six chapters.The main research contents and results are as follows:I.Brief introduction of acousto-optic effectThis chapter mainly introduces the basic principle of acousto-optic effect,the classification of acousto-optic devices and the application of acousto-optic devices.In addition,the new acousto-optic crystals grown by our group in recent years and the functional composite research based on acousto-optic properties are briefly introduced.?.Fabrication and characterization of acousto-optic devicesThis paper mainly introduces the design process of acousto-optic devices,such as acousto-optic crystal design,piezoelectric transducer design and other film design.The most important is to improve the diffraction efficiency of the device.? Device fabrication and performance characterization of new acousto-optic crystal ?-BTMAt present,the growth technology of ?-BTM crystal has been basically mature,and the process parameters have been solidified;the large size and high-quality crystal can fully meet the requirements of device preparation and optimization.Our previous experimental results show that ?-BTM has excellent acousto-optic properties.In this paper,based on ?-BTM,several acousto-optic Q-switched devices at 633 nm,1064 nm and 1550 nm are designed and fabricated,and the performance parameters are systematically characterized.The diffraction efficiencies of 633 nm,1064 nm and 1550 nm acousto-optic devices are 85%,84%and 70%respectively.In order to meet the demand of fiber laser for acousto-optic devices,we designed fiber acousto-optic Q-switched devices based on ?-BTM.The design wavelength of the device is 1064 nm,the driving frequency is 100 MHz,the rise time and extinction ratio are 32.8 ns and 65 dB respectively,and the insertion loss is 3.66 dB.The device has been successfully applied to ytterbium doped all fiber Q-switched fiber coupled laser.The maximum output power is about 5.3 mW,the minimum pulse width can be modulated to 167 ns,and the maximum peak power is 1.6 W.Aiming at the problem that the insertion loss is larger than that of the existing devices,the insertion loss of the device is reduced to 1.8 dB through the optimization of the preparation process,which reaches the existing technical index of acousto-optic products.At 200MHz,the insertion loss is 4.5 dB,the extinction ratio is 58dB,and the rise time is 10 ns.?.Fabrication of acousto-optic modulator and Raman shift combined with acousto-optic modulator of CTW crystalThe function combination is beneficial to the miniaturization of the laser.In this paper,the stimulated Raman scattering effect of CTW crystal is combined with the acousto-optic effect to realize the acousto-optic Raman composite laser output.At 1064nm,the CTW acousto-optic Q-switch device can realize the first-order Raman laser output(1178 nm)and self-Q-switch at the same time.The maximum average output power is 18 mW.V.Preparation and device fabrication of new tellurite acousto-optic glass(KTeP)A new tellurite glass K2O-TeO2-P2O5(KTeP)was prepared by using TeO2 as intermediate and KH2PO4 as network modifier.When KH2PO4:TeO2=1:2,the glass does not deliquescence.The results show that the optimum annealing temperature is 350 ?.The light transmission band of the glass is 380 nm?3000 nm.In order to study the laser self-Q-switching characteristics of KTeP glass,rare earth ions were doped into the glass.Under 808nm excitation,the emission wavelength of Nd3+ ion doped glass is 1057nm;under 450 nm excitation,the emission wavelength of Dy3+ion doped glass is 482nm,576nm and 665nm.The Yellow emission peak at 576 nm is the strongest.Based on KTeP glass(KH2PO4:TeO2=1:2),the performance of acousto-optic Q-switch device shows that the diffraction efficiency of the device reaches 50.8%at 1550 nm and 70.6%at 1064 nm.