Research On Influence Of External Factors On High Performance Magneto-optical Glass Verdet Constant And Its Mechanism

Rare earth doped magneto-optical glass is a very popular optoelectronic material,it has application prospects in many fields due to its excellent magneto-optical performance.Magneto-optical materials can be divided into two types.The first one type is called magneto-optical crystal which has the advantage of high Verdet constant,but crystal materials are difficult to grow and have a single component.In contrast,the components of magneto-optical glass are controllable,and the preparation process of glass is much simpler.Magneto-optical glass has obvious advantages over crystals.And through the modification of its preparation process and external disturbance factors,the Verdet constant of magneto-optical glass can also reach a higher value.Therefore,it has become a highly anticipated new material.The magneto-optical glass can be classified into two types according to the difference in the direction in which the plane of polarization of the incident light is deflected.The type which can cause a right-handed rotation of the plane of polarization is called a diamagnetic magneto-optical glass.Otherwise,it is called a paramagnetic magneto-optical glass.Most of the research on paramagnetic magneto-optical glass nowadays stays in improving the magneto-optical properties by increasing the rare earth content.Therefore,we choose the composition and external disturbance factors as the entry point,the influence of the composition of the rare earth magneto-optical glass and the external disturbance factors on its magneto-optical properties were studied and the influence mechanism was analyzed.Inthispaper,theglasswhichhasthecomponentof20Tb₂O₃-25Ga₂O₃-xB₂O₃?35-x?SiO₂-20GeO₂?x=20,24,26,28,30,35?and the glass which has the component of xTb₂O₃-?34-x?Ga₂O₃-24B₂O₃-22SiO₂-20GeO₂?x=14,18,20,22,25?were prepared.Subsequently,the physical properties,microstructure and magneto-optical properties of the magneto-optical glass with two components were tested and proved.The conclusions are as follows:?1?As the Tb₂O₃ content continues to increase,the density of magneto-optical glass gradually increases.The reason is that the relative mass of Tb is relatively large,which is increasing the number of atoms per unit volume of the glass system.When the B₂O₃ content increases gradually,the density and flexural strength of the glass increase first and then decrease,and the maximum value appears when the B₂O₃ content is 24 mol%.This is due to the boron anomaly which is caused by the increase of B₂O₃ content in the glass system.When the content of B₂O₃ is less than 24 mol%,the free oxygen is sufficient,and the[BO₄]group which is dense is dominant in the glass grid structure.When the content of B₂O₃ is more than 24 mol%,the free oxygen is insufficient,and[BO₄]group depolymerizes to[BO₃]group gradually,resulting in a decrease in mechanical properties.?2?With the increase of B₂O₃ content,the thermal stability of GBSG glass gradually increased??value increased from 0.97 to 1.18?.This is because the increase in the B₂O₃ content is beneficial to lower the coefficient of thermal expansion of the glass.This causes the volume change of the glass to decrease as the temperature changes.Glass becomes less prone to cracking.This ultimately leads to an increase in the thermal stability of the glass.?3?The light transmission of the magneto-optical glass sample is inversely proportional to the content of the rare earth oxide Tb₂O₃.This is because the rare earth Tb ions have a strong accumulation in the glass system,which caused the glass to have a tendency to devitrify.This affects its light transmittance.?4?In the study of the influence of external factors on the Verdet constant of magneto-optical glass,we found that the absolute value of the Verdet constant of magneto-optical glass gradually decreases with the increase of the wavelength of incident light.This is because the refractive index of the magneto-optical glass medium gradually decreases as the wavelength gets closer to the infrared region.In addition,as the wavelength is further away from the effective transition wavelength range of Tb³⁺ions,which is also the cause of the decrease in the absolute value of the Verdet constant.The calculation values of the effective transition wavelength for magneto-optical glass are distributed in the range of290-310 nm.As verified by the fluorescence spectroscopy test results,the valid transition wavelength range corresponds to the 4f⁸-4f⁷5d energy level transition of the Tb³⁺ion.This transition is the source of the strong magneto-optical effect of Tb³⁺ions.By calculating the wavelength dependence of magneto-optical glass,it is found that the amplitude of the Verdet constant as a function of wavelength1?V??dV?d??is only related to the incident light wavelength and the Tb³⁺content.And this value is proportional to the Tb³⁺content when the wavelength is fixed.?5?The theoretical Curie-Weiss temperatures of the magneto-optical glass with different rare earth contents were obtained by studying the temperature characteristics of Verdet constant of magneto-optical glass.Its Curie-Weiss temperature is only related to the rare earth content and is inversely proportional to the rare earth content.By calculating the temperature dependence of magneto-optical glass,it is found that the value of 1?V??dV?dT?,which measures the magnitude of Verdet constant with temperature,is only related to temperature and Curie-Weiss temperature.Taking 25 mol%Tb₂O₃ doped magneto-optical glass as an example,we accurately calculate the value of1?V??dV?dT?.Its value is-2.615×10^-3 1/K.