Studies on first GaN-based blue-violet laser diodes(LDs) in China mainland are reported.High quality GaN materials as well as GaN-based quantum wells laser structures are grown by metal-organic chemical vapor depositi...Studies on first GaN-based blue-violet laser diodes(LDs) in China mainland are reported.High quality GaN materials as well as GaN-based quantum wells laser structures are grown by metal-organic chemical vapor deposition method.The X-ray double-crystal diffraction rocking curve measurements show the full-width half maximum of 180″ and 185″ for (0002) symmetric reflection and (10 12) skew reflection,respectively.A room temperature mobility of 850cm2/(V·s) is obtained for a 3μm thick GaN film.Gain guided and ridge geometry waveguide laser diodes are fabricated with cleaved facet mirrors at room temperature under pulse current injection.The lasing wavelength is 405 9nm.A threshold current density of 5kA/cm2 and an output light power over 100mW are obtained for ridge geometry waveguide laser diodes.展开更多
Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and ...Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and outside the ridge are generated due to the poor thermal conductivity of the sapphire substrate and the large threshold current and voltage. The temperature step is thought to have a strong influence on the characteristics of the laser diodes. Time-resolved measurements of light-current curves,spectra, and the far-field pattern of the InGaN laser diodes under pulsed operation are performed. The results show that the thermal lensing effect improves the confinement of the higher order modes and leads to a lower threshold current and a higher slope efficiency of the device while the high temperature in the active layer results in a drastic decrease in the slope efficiency.展开更多
We propose to generate controllable time delay using slow/fast light in fiber ring resonators with gain manipulation.The dispersion and group delay of active fiber ring resonator can be controlled by manipulating its ...We propose to generate controllable time delay using slow/fast light in fiber ring resonators with gain manipulation.The dispersion and group delay of active fiber ring resonator can be controlled by manipulating its gain level below the lasing threshold.Controllability of the negative group delay in the undercoupled regime and the positive group delay in the overcoupled regime is theoretically demonstrated.Besides,large group delay can be obtained accompanied by signal gain in active ring resonators.In addition,we describe wide bandwidth and large group delay in 4-stage cascaded ring resonators.展开更多
文摘Studies on first GaN-based blue-violet laser diodes(LDs) in China mainland are reported.High quality GaN materials as well as GaN-based quantum wells laser structures are grown by metal-organic chemical vapor deposition method.The X-ray double-crystal diffraction rocking curve measurements show the full-width half maximum of 180″ and 185″ for (0002) symmetric reflection and (10 12) skew reflection,respectively.A room temperature mobility of 850cm2/(V·s) is obtained for a 3μm thick GaN film.Gain guided and ridge geometry waveguide laser diodes are fabricated with cleaved facet mirrors at room temperature under pulse current injection.The lasing wavelength is 405 9nm.A threshold current density of 5kA/cm2 and an output light power over 100mW are obtained for ridge geometry waveguide laser diodes.
文摘Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and outside the ridge are generated due to the poor thermal conductivity of the sapphire substrate and the large threshold current and voltage. The temperature step is thought to have a strong influence on the characteristics of the laser diodes. Time-resolved measurements of light-current curves,spectra, and the far-field pattern of the InGaN laser diodes under pulsed operation are performed. The results show that the thermal lensing effect improves the confinement of the higher order modes and leads to a lower threshold current and a higher slope efficiency of the device while the high temperature in the active layer results in a drastic decrease in the slope efficiency.
基金supported by the National Natural Science Foundation of China (Grant No. 61168002)the Provincial Natural Science Foundation of Jiangxi (Grant No. 20132BAB201048)+1 种基金the Science & Technology Project of Science & Technology of Yichun Committee (Grant No. JXYC2013-KGA01)the Opening Foundation of the State Key Laboratory of Advanced Optical Communication Systems and Networks (Grant No.2011GZKF031105)
文摘We propose to generate controllable time delay using slow/fast light in fiber ring resonators with gain manipulation.The dispersion and group delay of active fiber ring resonator can be controlled by manipulating its gain level below the lasing threshold.Controllability of the negative group delay in the undercoupled regime and the positive group delay in the overcoupled regime is theoretically demonstrated.Besides,large group delay can be obtained accompanied by signal gain in active ring resonators.In addition,we describe wide bandwidth and large group delay in 4-stage cascaded ring resonators.
