High-power continuous-wave operation of quantum-cascade lasers up to 60/spl deg/C

High-temperature high-power continuous-wave (CW) operation of high-reflectivity-coated 12-/spl mu/m-wide quantum-cascade lasers emitting at /spl lambda/ = 6 /spl mu/m with a thick electroplated Au top contact layer is reported for different cavity lengths. For a 3-mm-long laser, the CW optical output powers of 381 mW at 293 K and 22 mW at maximum operating temperature of 333 K (60/spl deg/C) are achieved with threshold current densities of 1.93 and 3.09 kA/cm/sup 2/, respectively. At 298 K, the same cavity gives a maximum wall plug efficiency of 3.17% at 1.07 A. An even higher CW optical output power of 424 mW at 293 K is obtained for a 4-mm-long laser and the device also operates up to 332 K with an output power of 14 mW. Thermal resistance is also analyzed at threshold as a function of cavity length.     

Low-threshold high-T/sub 0/ 1.3-/spl mu/m InAs quantum-dot lasers due to p-type modulation doping of the active region

P-type doping is used to demonstrate high-To, low-threshold 1-3 /spl mu/m InAs quantum-dot lasers. A 5-/spl mu/m-wide oxide confined stripe laser with a 700-/spl mu/m-long cavity exhibits a pulsed T/sub 0/ = 213 K (196 K CW) from 0/spl deg/C to 80/spl deg/C. At room temperature, the devices have a CW threshold current of /spl sim/4.4 mA with an output power over 15 mW. The threshold at 100/spl deg/C is 8.4 mA with an output power over 8 mW.     

Ridge-width dependence on high-temperature continuous-wave quantum-cascade laser operation

We report continuous-wave (CW) operation of quantum-cascade lasers (/spl lambda/=6 /spl mu/m) up to a temperature of 313 K (40/spl deg/C). The maximum CW optical output powers range from 212 mW at 288 K to 22 mW at 313 K and are achieved with threshold current densities of 2.21 and 3.11 kA/cm/sup 2/, respectively, for a high-reflectivity-coated 12-/spl mu/m-wide and 2-mm-long laser. At room temperature (298 K), the power output is 145 mW at 0.87 A, corresponding to a power conversion efficiency of 1.68%. The maximum CW operating temperature of double-channel ridge waveguide lasers mounted epilayer-up on copper heatsinks is analyzed in terms of the ridge width, which is varied between 12 and 40 /spl mu/m. A clear trend of improved performance is observed as the ridge narrows.     

Low-threshold continuous-wave 1.5-/spl mu/m GaInNAsSb lasers grown on GaAs

We present the first continuous-wave (CW) edge-emitting lasers at 1.5 /spl mu/m grown on GaAs by molecular beam epitaxy (MBE). These single quantum well (QW) devices show dramatic improvement in all areas of device performance as compared to previous reports. CW output powers as high as 140 mW (both facets) were obtained from 20 /spl mu/m /spl times/ 2450 /spl mu/m ridge-waveguide lasers possessing a threshold current density of 1.06 kA/cm/sup 2/, external quantum efficiency of 31%, and characteristic temperature T/sub 0/ of 139 K from 10/spl deg/C-60/spl deg/C. The lasing wavelength shifted 0.58 nm/K, resulting in CW laser action at 1.52 /spl mu/m at 70/spl deg/C. This is the first report of CW GaAs-based laser operation beyond 1.5 /spl mu/m. Evidence of Auger recombination and intervalence band absorption was found over the range of operation and prevented CW operation above 70/spl deg/C. Maximum CW output power was limited by insufficient thermal heatsinking; however, devices with a highly reflective (HR) coating applied to one facet produced 707 mW of pulsed output power limited by the laser driver. Similar CW output powers are expected with more sophisticated packaging and further optimization of the gain region. It is expected that such lasers will find application in next-generation optical networks as pump lasers for Raman amplifiers or doped fiber amplifiers, and could displace InP-based lasers for applications from 1.2 to 1.6 /spl mu/m.     

Room-temperature continuous-wave laser operation of electrically-pumped 1.55 /spl mu/m VECSEL

A report is presented on room-temperature (RT) continuous-wave (CW) laser emission at 1.55 /spl mu/m of an all InP-based electrically-pumped vertical external-cavity surface-emitting laser (EP-VECSEL). Threshold currents of 1.4 kA/cm/sup 2/ and output powers of up to 0.3 mW were measured under CW operation at RT. A maximum output power of 2.7 mW has been obtained in quasi-CW operation at a heatsink temperature of 10.5/spl deg/C. This first result demonstrates that EP-VECSELs are a potential candidate for the realisation of compact vertical-cavity emitting sources.     

Continuous-wave operation of quantum cascade laser emitting near 5.6 /spl mu/m

Buried heterostructure quantum cascade lasers emitting at 5.64 /spl mu/m are presented. Continuous-wave (CW) operation has been achieved at -30/spl deg/C for junction down mounted devices with both facets coated. A 750 /spl mu/m-long laser exhibited 3 mW of CW power with a threshold current density of 5.4 kA/cm/sup 2/.     

Type-II interband cascade lasers in the 4.3-4.7-/spl mu/m wavelength region

Operation of type-II interband cascade lasers in the 4.3-4.7-/spl mu/m wavelength region has been demonstrated at temperatures up to 240 K in pulsed mode. These lasers fabricated with 150-/spl mu/m-wide mesa stripes operated in continuous-wave (CW) mode up to a maximum temperature of 110 K, with an output power exceeding 30 mW/f and a threshold current density of about 41 A/cm/sup 2/ at 90 K. The maximum CW operation temperature of 110 K is largely limited by the high specific thermal resistance of the 150-/spl mu/m-wide broad area lasers. A 20-/spl mu/m-wide mesa stripe laser was able to operate in CW mode at higher temperatures up to 125 K as a result of the reduced specific thermal resistance of a smaller device.     

Electrically pumped room temperature CW VCSELs with 2.3 /spl mu/m emission wavelength

Continuous wave (CW) operation at room temperature of electrically pumped InGaAlAs/InP vertical-cavity surface-emitting lasers (VCSELs) at emission wavelengths as high as 2.3 /spl mu/m is demonstrated for the first time. Devices with 15 /spl mu/m active region diameter show a maximum output power of 0.75 mW at 20/spl deg/C and a maximum CW operating temperature of 45/spl deg/C.     

High-power highly reliable 1.02-1.06-/spl mu/m InGaAs strained-quantum-well laser diodes

By growing the InGaAs active layer at temperatures lower than in conventional growth, we extended the lasing wavelength and presented the high reliability in InGaAs strained-quantum-well laser diodes. Equivalent I-L characteristics were obtained for 1.02-, 1.05-, and 1.06-/spl mu/m laser diodes with a cavity length of 1200 /spl mu/m. Maximum output power as high as 800 mW and fundamental transverse mode operation at up to 400 mW were obtained at 1.06 /spl mu/m and an 1800-/spl mu/m cavity. Stable operation was observed for over 14 000 h under auto-power-control of 225 mW at 50/spl deg/C for the 1.02-, 1.05-, and 1.06-/spl mu/m lasers with a 900-/spl mu/m cavity.     

Vertical-cavity surface-emitting lasers in the 8-/spl mu/m midinfrared spectral range with continuous-wave and pulsed emission

Continuous-wave (CW) as well as pulsed-laser emission from a midinfrared (/spl lambda/=7.92 /spl mu/m) IV-VI vertical-cavity surface-emitting laser at 1.8 K is presented. The high-finesse microcavity, containing PbSe as an active medium, was optically pumped with a carbon monoxide laser at a wavelength of 5.28 /spl mu/m (1894 cm/sup -1/) in either CW or Q-switched mode. The maximum achieved CW power was 4.8 mW and pulsed peak powers were up to 23 W. Linewidths are considerably narrower than 0.10 cm/sup -1/, corresponding to 0.6 nm.     

1.3 /spl mu/m InGaAsN vertical cavity surface emitting lasers grown by MOCVD

The first InGaAsN VCSELs grown by MOCVD with CW lasing wavelength longer than 1.3 /spl mu/m are reported. The devices were of conventional p-i-n structure with doped DBR mirrors. CW lasing up to 65/spl deg/C was observed, with a maximum output power at room temperature of 0.8 mW for multimode devices and nearly 0.3 mW for single-mode devices.     

High-power ridge waveguide InGaAsN lasers fabricated with pulsed anodic oxidation

High-power InGaAsN triple-quantum-well strain-compensated lasers grown by metal-organic chemical vapor deposition were fabricated with pulsed anodic oxidation. A maximum light power output of 145 mW was obtained from a 4-/spl mu/m ridge waveguide uncoated laser diode in continuous-wave (CW) mode at room temperature. The devices operated in CW mode up to 130/spl deg/C with a characteristic temperature of 138 K in range of 20/spl deg/C-90/spl deg/C.     

Pulsed operation of long-wavelength (/spl lambda//spl sime/11.3 /spl mu/m) MOVPE-grown quantum cascade lasers up to 350 K

Pulsed laser action above room temperature at /spl lambda//spl sime/11.3 /spl mu/m has been achieved in quantum cascade devices grown by metal organic vapour phase epitaxy (MOVPE). The emission wavelength (/spl lambda//spl sime/11.3 /spl mu/m) is the longest reported for QC lasers grown with this technique. The peak output power at 77 K is approximately 315 mW, decreasing to /spl sime/100 mW at room temperature. The devices display laser operation up to at least 350 K.     

High-performance singlemode InGaNAs/GaAs laser

Performance characteristics of an InGaNAs/GaAs ridge-waveguide in-plane laser diode, which is grown by molecular beam epitaxy, are reported. The laser emits at a wavelength of 1.262 /spl mu/m in a single lateral mode, launching an output up to 240 mW at 20/spl deg/C and 20 mW at 120/spl deg/C. The threshold is 15 mA at 20/spl deg/C, corresponding to a threshold current density of 313 A/cm/sup 2/.     

Resonant-phonon terahertz quantum-cascade laser operating at 2.1 THz (/spl lambda//spl sime/141 /spl mu/m)

The development of quantum-cascade lasers (QCLs) at 2.1 THz (/spl lambda//spl sime/141 /spl mu/m), which is the longest wavelength QCL to date without the assistance of magnetic fields, is reported. This laser uses a structure based on resonant-phonon depopulation, and a metal-metal waveguide to obtain high modal confinement with low waveguide losses. Lasing was observed up to a heatsink temperature of 72 K in pulsed mode and 40 K in continuous-wave (CW) mode, and 1.2 mW of power was obtained in CW mode at 17 K.     

Quantum dot superluminescent diodes emitting at 1.3 /spl mu/m

We report ridge-waveguide superluminescent diodes based on five stacks of self-assembled InAs-GaAs quantum dots. Devices with output powers up to 10 mW emitting around 1.3 /spl mu/m are demonstrated. Spectral analysis shows a broad emission peak (26-nm full-width at half-maximum) from the dot ground state at low injection, and an additional peak from the excited state at higher bias. Temperature characteristics in the range 10/spl deg/C-80/spl deg/C are also reported. The experimental curves are in good agreement with simulations performed using a traveling-wave rate equation model.     

2.0-/spl mu/m single-mode operation of InGaAs-InGaAsP distributed-feedback buried-heterostructure quantum-well lasers

Distributed-feedback (DFB) buried-heterostructure (BH) lasers with quantum-well active region emitting at 2.0 /spl mu/m have been fabricated and characterized. The lasers with four wells showed performance of practical use: threshold current as low as 15 mA for 600-/spl mu/m-long devices and CW single-mode output up to 5 mW at 2.03 /spl mu/m under operation current of 100 mA were observed. The current- and temperature-tuning rates of DFB mode wavelength are 0.004 nm/mA and 0.125 nm/K, respectively.     

All-epitaxial InAlGaAs-InP VCSELs in the 1.3-1.6-/spl mu/m wavelength range for CWDM band applications

All-epitaxial InAlGaAs-InP vertical-cavity surface-emitting lasers grown by metal-organic chemical vapor deposition were successfully demonstrated in the wavelength ranging from 1.3 to 1.6 /spl mu/m. The devices showed the high performances such as single-mode output power of higher than 1.1mW, sidemode suppression ratio of 37 dB, divergence angle of 9/spl deg/, and CW operation of temperature up to 80 /spl deg/C. We achieved the modulation bandwidth exceeding 2.5 Gb/s and power penalty free transmission over 30 km.     

120/spl deg/C 10-gb/s uncooled direct Modulated 1.3-/spl mu/m AlGaInAs MQW DFB laser diodes

A 1.3-/spl mu/m AlGaInAs multiquantum well ridge waveguide distributed feedback laser diode was developed. By forming n-InGaAsP grating in the n-InP cladding layer close to the active region, accumulation of the holes in the grating layer was reduced and over 5 mW of output power was obtained at 120/spl deg/C. Clear eye opening was confirmed with no mask hits for OC-192 under 10-Gb/s direct modulation at the temperature up to 120/spl deg/C.     

Room-temperature continuous-wave operation of GaInNAsSb laser diodes at 1.55 /spl mu/m

The first 1.55 /spl mu/m room-temperature continuous-wave (CW) operation of GaAs-based laser diodes utilising GaInNAsSb/GaNAs double quantum well active regions grown by molecular beam epitaxy is reported. In electrically-pumped CW operation the narrow ridge waveguide devices have a room temperature lasing wavelength of 1550 nm near threshold, increasing to 1553 nm at thermal rollover. The CW threshold current was 132 mA for a 3/spl times/589 /spl mu/m device, with a characteristic temperature of 83 K, measured in pulsed mode between 20 and 70/spl deg/C.