It is essential to determine the accumulative ultraviolet(UV)irradiation over a period of time in some cases,such as monitoring UV irradiation to the skin,solar disinfection of water,photoresist exposure,etc.UV colori...It is essential to determine the accumulative ultraviolet(UV)irradiation over a period of time in some cases,such as monitoring UV irradiation to the skin,solar disinfection of water,photoresist exposure,etc.UV colorimetric dosimeters,which use dyes'color change to monitor the amount of UV exposure,have been widely studied.However,the exposure data of these UV colorimetric dosimeters can hardly be converted to digital signals,limiting their applications.In this paper,a UV dosimeter has been proposed and demonstrated based on the persistent photoconductivity(PPC)in zinc oxide microwires(ZnO MWs).The PPC effect usually results in high photoconductivity gain but low response speed,which has been regarded as a disadvantage for photodetectors.However,in this work,the unique characteristics of the PPC effect have been utilized to monitoring the accumulative exposure.We demonstrate that the photocurrent in the ZnO MWs depends on the accumulative UV exposure due to the PPC effect,thus the photocurrent can be utilized to determine the UV accumulation.The dosimeter is immune to visible light and exhibits a photoconductive gain of 2654,and the relative error of the dosimeter is about 10%.This UV dosimeter with electrical output is reusable and convenient to integrate with other electronic devices and may also open a new application area for the PPC effect.展开更多
The 1.4–1.8μm eye-safe lasers have been widely used in the fields of laser medicine and laser detection and ranging.The diamond Raman lasers are capable of delivering excellent characteristics,such as good beam qual...The 1.4–1.8μm eye-safe lasers have been widely used in the fields of laser medicine and laser detection and ranging.The diamond Raman lasers are capable of delivering excellent characteristics,such as good beam quality concomitantly with high output power.The intra-cavity diamond Raman lasers have the advantages of compactness and low Raman thresholds compared to the external-cavity Raman lasers.However,to date,the intra-cavity diamond cascaded Raman lasers in the spectral region of the eye-safe laser have an output power of only a few hundred milliwatts.A 1485 nm Nd:YVO_4/diamond intra-cavity cascaded Raman laser is reported in this paper.The mode matching and stability of the cavity were optimally designed by a V-shaped folded cavity,which yielded an average output power of up to 2.2 W at a pulse repetition frequency of 50 kHz with a diode to second-Stokes conversion efficiency of 8.1%.Meanwhile,the pulse width of the second-Stokes laser was drastically reduced from 60 ns of the fundamental laser to 1.1 ns,which resulted in a high peak power of 40 kW.The device also exhibited single longitudinal mode with a narrow spectral width of<0.02 nm.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61804136,U1604263,and U1804155)China Postdoctoral Science Foundation(Grant Nos.2018M630829 and 2019T120630).
文摘It is essential to determine the accumulative ultraviolet(UV)irradiation over a period of time in some cases,such as monitoring UV irradiation to the skin,solar disinfection of water,photoresist exposure,etc.UV colorimetric dosimeters,which use dyes'color change to monitor the amount of UV exposure,have been widely studied.However,the exposure data of these UV colorimetric dosimeters can hardly be converted to digital signals,limiting their applications.In this paper,a UV dosimeter has been proposed and demonstrated based on the persistent photoconductivity(PPC)in zinc oxide microwires(ZnO MWs).The PPC effect usually results in high photoconductivity gain but low response speed,which has been regarded as a disadvantage for photodetectors.However,in this work,the unique characteristics of the PPC effect have been utilized to monitoring the accumulative exposure.We demonstrate that the photocurrent in the ZnO MWs depends on the accumulative UV exposure due to the PPC effect,thus the photocurrent can be utilized to determine the UV accumulation.The dosimeter is immune to visible light and exhibits a photoconductive gain of 2654,and the relative error of the dosimeter is about 10%.This UV dosimeter with electrical output is reusable and convenient to integrate with other electronic devices and may also open a new application area for the PPC effect.
基金financially supported by the Science and Technology Major Project of Henan Province(No.221100230300)the National Natural Science Foundation of China(No.11774301)。
文摘The 1.4–1.8μm eye-safe lasers have been widely used in the fields of laser medicine and laser detection and ranging.The diamond Raman lasers are capable of delivering excellent characteristics,such as good beam quality concomitantly with high output power.The intra-cavity diamond Raman lasers have the advantages of compactness and low Raman thresholds compared to the external-cavity Raman lasers.However,to date,the intra-cavity diamond cascaded Raman lasers in the spectral region of the eye-safe laser have an output power of only a few hundred milliwatts.A 1485 nm Nd:YVO_4/diamond intra-cavity cascaded Raman laser is reported in this paper.The mode matching and stability of the cavity were optimally designed by a V-shaped folded cavity,which yielded an average output power of up to 2.2 W at a pulse repetition frequency of 50 kHz with a diode to second-Stokes conversion efficiency of 8.1%.Meanwhile,the pulse width of the second-Stokes laser was drastically reduced from 60 ns of the fundamental laser to 1.1 ns,which resulted in a high peak power of 40 kW.The device also exhibited single longitudinal mode with a narrow spectral width of<0.02 nm.
