We study self-assembled InP quantum dot (QD) laser structures grown at two temperatures (690 ° C and 730 ° C) each with three different quantities of deposited quantum dot material (2, 2.5, and 3 ...mono-layers). The absorption spectra of these structures show features associated with the QD distributions and the magnitude of the absorption increases for samples where more material is deposited and for lower growth temperature. The 690 ° C growth temperature structures exhibit nonradiative recombination and internal optical mode loss that increase with the quantity of material deposited; we suggest that the laser performance is limited by the presence of defects. The higher growth temperature samples have lower threshold current density and are limited by gain saturation. For these samples and for 2-mm long lasers with uncoated facets, the threshold current density is as low as 150 A cm -2 , emitting in the wavelength range around 730 nm.
Electron and hole multiplication characteristics have been measured on a series of Al 0.52 In 0.48 P p + -i-n + and n + -i-p + homojunction diodes with nominal avalanche region thicknesses ranging ...from 0.22 to 1.03 μm. From these, the electron and hole impact ionization coefficients are deduced over an electric-field range from 530 to 990 kV/cm. The results suggest that the electron ionization coefficient is larger than the hole ionization coefficient, particularly at lower electric fields. Extremely low dark currents were obtained, and there was no evidence of any tunneling dark current even at electric fields of approximately 1.0 MV/cm. From these ionization coefficients, we deduce that the breakdown voltage in Al 0.52 In 0.48 P is almost 2.5× greater than that of GaAs and 4.5× lower than that of GaN.
Electron and hole multiplication characteristics have been measured on a series of Formula Omitted and Formula Omitted homojunction diodes with nominal avalanche region thicknesses ranging from 0.22 ...to 1.03 Formula Omitted. From these, the electron and hole impact ionization coefficients are deduced over an electric-field range from 530 to 990 kV/cm. The results suggest that the electron ionization coefficient is larger than the hole ionization coefficient, particularly at lower electric fields. Extremely low dark currents were obtained, and there was no evidence of any tunneling dark current even at electric fields of approximately 1.0 MV/cm. From these ionization coefficients, we deduce that the breakdown voltage in Formula Omitted is almost 2.5Formula Omitted greater than that of GaAs and 4.5Formula Omitted lower than that of GaN.
Electron and hole multiplication characteristics have been measured on a series of hbox Al 0.52 hbox In 0.48 hbox P Unknown character hbox p + hbox - i - n + and hbox n + hbox - i - p + homojunction ...diodes with nominal avalanche region thicknesses ranging from 0.22 to 1.03 mu hbox m . From these, the electron and hole impact ionization coefficients are deduced over an electric-field range from 530 to 990 kV/cm. The results suggest that the electron ionization coefficient is larger than the hole ionization coefficient, particularly at lower electric fields. Extremely low dark currents were obtained, and there was no evidence of any tunneling dark current even at electric fields of approximately 1.0 MV/cm. From these ionization coefficients, we deduce that the breakdown voltage in hbox Al 0.52 hbox In 0.48 hbox P is almost 2.5 greater than that of GaAs and 4.5 lower than that of GaN.
We demonstrate λ ~ 9 μm GaAs/Al 0.45 Ga 0.55 As quantum cascade lasers (QCLs) operating up to 320 K. Metal- organic vapor phase epitaxy has been used throughout for the growth of the devices. ...Detailed comparison has been carried out for the QCLs with various waveguides and grown on (100) GaAs substrates with different miscut angles towards (111)A. Introduction of InGaP cladding layers into the optical waveguide significantly improves the QCL performance due to a better optical confinement and lower waveguide losses compared with the GaAs-based waveguide. A 20- μm-wide 4-mm-long device with high reflectivity coating on the laser back facet demonstrates room-temperature pulsed output power of 220 mW and a lowered threshold current density of 6.5 kA/cm 2 .
We review the recent development of high-perfor- mance short-wavelength (λ ∼ 3.05-3.8 μm) strain-compensated InGaAs/AlAs(Sb)/InP quantum cascade lasers (QCLs). The lasers are demonstrated in which ...wavelengths as low as 3.05 μm are obtained at temperatures up to 295 K. We also verify that strain-compensated InFormula OmittedGaFormula OmittedAs/AlAs(Sb) QCLs with AlAs barriers in the active region operate with much better performance compared with the lasers having identical design but with AlAsSb barriers throughout the whole core region. λ ∼ 3.3-3.7 μm laser emission is observed at temperatures up to at least 400 K and up to 20 W of output optical power at 285 K for the QCLs with various core region designs. Room temperature distributed feedback InGaAs/AlAs(Sb) QCLs with buried third-order gratings have been also developed, displaying single-mode operation in the wavelength range of 3.358-3.380 μm for temperatures between 270 and 360 K.
We report bidirectional link characterization and the first IEEE 802.11a wireless local area network (WLAN) data transmission using an electromagnetic bandgap (EBG) photonic antenna with an ...integrated InGaAs/AlInGaAs multiple quantum-well (MQW) asymmetric Fabry-Perot modulator/detector (AFPM). The dual-function AFPM performs as an optical intensity modulator on the uplink and as a conventional photodetector on the downlink in a single device. This new InGaAs/AlInGaAs AFPM device has also shown an improved modulation slope -dR/dV of 17%/V, where dR is the differential optical reflectance and dV is the differential terminal voltage, compared to the previously reported 6%/V achieved with an InGaAsP/InGaAsP MQW AFPM. Half-duplex IEEE 802.11a connection was successfully established between a laptop computer and the photonic antenna which in turn was connected via an optical fiber to a wireless access point. A maximum data throughput of 7 Mbps was achieved at 8-m separation between the laptop and the photonic antenna.
We report the development of high-peak-power Formula Omitted strain-compensated Formula Omitted quantum cascade lasers (QCLs). The QCLs operate up to at least 400 K with high wall-plug efficiency ...(Formula Omitted9% at 300 K) in the pulsed regime. The lasers are based on a vertical transition bound-to-continuum design. Devices of 30-Formula Omitted width and 4-mm length, with high reflectivity coating on the rear facet, deliver more than 20-W peak optical power at 285 K with a threshold current density of 3.1 Formula Omitted. Over 2 W of peak power is obtained at 400 K.
We report the development of high-peak-power λ ~ 3.6 μm strain-compensated In 0.7 Ga 0.3 As-AlAs(Sb) quantum cascade lasers (QCLs). The QCLs operate up to at least 400 K with high wall-plug ...efficiency (~9% at 300 K) in the pulsed regime. The lasers are based on a vertical transition bound-to-continuum design. Devices of 30-μm width and 4-mm length, with high reflectivity coating on the rear facet, deliver more than 20-W peak optical power at 285 K with a threshold current density of 3.1 kA/cm 2 . Over 2 W of peak power is obtained at 400 K.
