We report the laser output of transparent Nd:YAG(Nd:Y3Al5O12) ceramics fabricated from Nd:YAG precursors through the microwave-assisted homogenous precipitation(MAHP) method.Pure phase and uniform Nd:YAG nano-powders ...We report the laser output of transparent Nd:YAG(Nd:Y3Al5O12) ceramics fabricated from Nd:YAG precursors through the microwave-assisted homogenous precipitation(MAHP) method.Pure phase and uniform Nd:YAG nano-powders with average sizes less than 100 nm were obtained by heating treatment of the Nd:YAG precursor particles aged for 6 d in vessel with humidity of 30%-50% at 25°C.Transparent Nd:YAG ceramic pellets were obtained by vacuum sintering at 1730°C for 10 h.Laser output(305 mW) with a slope efficiency of 5.1% was realized through an end-pumped configuration.Our results indicate that the MAHP method could potentially be used for the fabrication of laser ceramic products.展开更多
By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular wavefo...By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular waveform and pulsed output wave superimposed on a rectangular waveform on the penetration depth of weld. Research results indicate that the average power, duty cycle, frequency and peak power of rectangular wave affect the weld penetration depth to different extent. Results of experiments and analysis also indicate that the pulse delay time, pulse width and the power ratio of pulse to rectangular waveform seriously influence the penetration when the pulsed wave is superimposed on a rectangular waveform.展开更多
Theoretical analysis model has been established for CO 2 laser to describe the process of dynamic emission in the electrooptically Q switched laser .The electron excitation and the energy transfer of vibration level a...Theoretical analysis model has been established for CO 2 laser to describe the process of dynamic emission in the electrooptically Q switched laser .The electron excitation and the energy transfer of vibration level and the rotational relaxation of rotational levels are described. The comparison between this model and a set of coupled rat equations model are discussed.展开更多
A copper vapor laser with active medium length of 60 cm and bore of 16 mm has been operated and optimized using different buffer gases to investigate the effect of the gas flow rates on the output power. It is found t...A copper vapor laser with active medium length of 60 cm and bore of 16 mm has been operated and optimized using different buffer gases to investigate the effect of the gas flow rates on the output power. It is found that there is a special optimum gas flow rate associated with the type of buffer gas.展开更多
This paper reports that an output window for optically pumped terahertz (THz) laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate (approximating to 5 mm thick...This paper reports that an output window for optically pumped terahertz (THz) laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate (approximating to 5 mm thick).Unlike the conventional process of depositing a gold film approximating to 100 nm on negative photoresist using electron-beam evaporation,a nickel film approximating to 1.5 μm thick is directly deposited on the clean surface of dielectric substrate using magnetron sputtering and then a positive photoresist is spun onto the nickel metal surface at 6000 r for 60 s.A transmittance spectrum of the output window in a certain frequency range (say,from zero to 1 THz) has been obtained by using THz time domain spectroscopy.Moreover a transmittance spectrum simulated numerically has also been estimated with respect to the output window using the transmission-line model (TLM) containing attenuation component from dielectric substrate.The simulation results show that the TLM can explain well the experimental curve in a certain frequency range from zero to 1 THz.Thus it is demonstrated that the improved optical component can be efficiently used as both output coupler and output window for optically pumped THz lasers.展开更多
A high power GaSb-based laser diode with lasing wavelength at 2 μm was fabricated and optimized. With the optimized epitaxial laser structure, the internal loss and the threshold current density decreased and the int...A high power GaSb-based laser diode with lasing wavelength at 2 μm was fabricated and optimized. With the optimized epitaxial laser structure, the internal loss and the threshold current density decreased and the internal quantum efficiency increased. For uncoated broad-area lasers, the threshold current density was as low as 144 A/cm2 (72 A/cm2 per quantum well), and the slope efficiency was 0.2 W/A. The internal loss was 11 cm-1 and the internal quantum efficiency was 27.1%. The maximum output power of 357 mW under continuous-wave operation at room temperature was achieved. The electrical and optical properties of the laser diode were improved.展开更多
The stability of the drive current is very important for a laser driver,while it is difficult to maintain the current stable at a high value for the laser driver.On the other hand,the range of the drive current is exp...The stability of the drive current is very important for a laser driver,while it is difficult to maintain the current stable at a high value for the laser driver.On the other hand,the range of the drive current is expected to be as wide as possible to be applied to different kinds of lasers.In this paper,a high current laser driver for the superluminescent light emitting diode(SLED) is presented,which is used in the optic fiber gyro embedded by a 0.35 m bipolar complementary metal-oxide-semiconductor transistor(BiCMOS) process.The laser driver provides automatic power control and certain value of current determined by the external resister.The system is based on the optic-electric feedback theory and uses the closed-loop control technique to maintain the drive current stable.The system is capable of producing stable current ranges from 4 mA to 200 mA when the value of external resister changes.展开更多
Using the ray trace method, three-section semiconductor lasers are studied. An analytic expression of output power for the three-section semiconductor lasers is derived for the first time. From this expression, thresh...Using the ray trace method, three-section semiconductor lasers are studied. An analytic expression of output power for the three-section semiconductor lasers is derived for the first time. From this expression, threshold condition is also obtained.展开更多
基金financially supported by the National Natural Science Foundation of China (No.50702031,60974117,50990303,and 50872070)the Excellent Young Investigators Award Foundation of Shandong Province (No.BS2009CL021)the Major State Basic Research Development Program of China (Nos.2009CB93050 and G2004CB619002)
文摘We report the laser output of transparent Nd:YAG(Nd:Y3Al5O12) ceramics fabricated from Nd:YAG precursors through the microwave-assisted homogenous precipitation(MAHP) method.Pure phase and uniform Nd:YAG nano-powders with average sizes less than 100 nm were obtained by heating treatment of the Nd:YAG precursor particles aged for 6 d in vessel with humidity of 30%-50% at 25°C.Transparent Nd:YAG ceramic pellets were obtained by vacuum sintering at 1730°C for 10 h.Laser output(305 mW) with a slope efficiency of 5.1% was realized through an end-pumped configuration.Our results indicate that the MAHP method could potentially be used for the fabrication of laser ceramic products.
基金Sponsored by National Science Fund!( 59881 0 0 2 )
文摘By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular waveform and pulsed output wave superimposed on a rectangular waveform on the penetration depth of weld. Research results indicate that the average power, duty cycle, frequency and peak power of rectangular wave affect the weld penetration depth to different extent. Results of experiments and analysis also indicate that the pulse delay time, pulse width and the power ratio of pulse to rectangular waveform seriously influence the penetration when the pulsed wave is superimposed on a rectangular waveform.
文摘Theoretical analysis model has been established for CO 2 laser to describe the process of dynamic emission in the electrooptically Q switched laser .The electron excitation and the energy transfer of vibration level and the rotational relaxation of rotational levels are described. The comparison between this model and a set of coupled rat equations model are discussed.
文摘A copper vapor laser with active medium length of 60 cm and bore of 16 mm has been operated and optimized using different buffer gases to investigate the effect of the gas flow rates on the output power. It is found that there is a special optimum gas flow rate associated with the type of buffer gas.
基金Project supported by the Creative Foundation of Wuhan National Laboratory for Optoelectronics (Grant No. Z080007)partly by the National Basic Research Program of China (973 Program)(Grant No. 61328)
文摘This paper reports that an output window for optically pumped terahertz (THz) laser has been fabricated by depositing a capacitive nickel-mesh on a thick high-resistivity silicon substrate (approximating to 5 mm thick).Unlike the conventional process of depositing a gold film approximating to 100 nm on negative photoresist using electron-beam evaporation,a nickel film approximating to 1.5 μm thick is directly deposited on the clean surface of dielectric substrate using magnetron sputtering and then a positive photoresist is spun onto the nickel metal surface at 6000 r for 60 s.A transmittance spectrum of the output window in a certain frequency range (say,from zero to 1 THz) has been obtained by using THz time domain spectroscopy.Moreover a transmittance spectrum simulated numerically has also been estimated with respect to the output window using the transmission-line model (TLM) containing attenuation component from dielectric substrate.The simulation results show that the TLM can explain well the experimental curve in a certain frequency range from zero to 1 THz.Thus it is demonstrated that the improved optical component can be efficiently used as both output coupler and output window for optically pumped THz lasers.
基金supported by the Beijing Natural Science Foundation, China (Grant No. 4112058)
文摘A high power GaSb-based laser diode with lasing wavelength at 2 μm was fabricated and optimized. With the optimized epitaxial laser structure, the internal loss and the threshold current density decreased and the internal quantum efficiency increased. For uncoated broad-area lasers, the threshold current density was as low as 144 A/cm2 (72 A/cm2 per quantum well), and the slope efficiency was 0.2 W/A. The internal loss was 11 cm-1 and the internal quantum efficiency was 27.1%. The maximum output power of 357 mW under continuous-wave operation at room temperature was achieved. The electrical and optical properties of the laser diode were improved.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60308001 and 60490280-1, the Knowledge Innovation Project of Chinese Academy of Sciences under Grant No KJXC-SW-W14, the National Natural Science Foundation of China under Grant Nos 50572054 and 50590401, the Natural Science Foundation of Shandong Province under Grant No Y2004F01, and the National Basic Research Program of China under Grant No 2004CB619002.
文摘The stability of the drive current is very important for a laser driver,while it is difficult to maintain the current stable at a high value for the laser driver.On the other hand,the range of the drive current is expected to be as wide as possible to be applied to different kinds of lasers.In this paper,a high current laser driver for the superluminescent light emitting diode(SLED) is presented,which is used in the optic fiber gyro embedded by a 0.35 m bipolar complementary metal-oxide-semiconductor transistor(BiCMOS) process.The laser driver provides automatic power control and certain value of current determined by the external resister.The system is based on the optic-electric feedback theory and uses the closed-loop control technique to maintain the drive current stable.The system is capable of producing stable current ranges from 4 mA to 200 mA when the value of external resister changes.
文摘Using the ray trace method, three-section semiconductor lasers are studied. An analytic expression of output power for the three-section semiconductor lasers is derived for the first time. From this expression, threshold condition is also obtained.
