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A quantum well transistor laser with a cavity length of L = 200 μm has been designed and fabricated. Threshold current at 20°C is determined to be ITH = 36 mA at VCE = 1.5 V from measured transistor laser collector current-voltage (IC-VCE) and optical power-voltage (L-VCE) characteristics. The transistor laser is measured to have a modulation bandwidth f-3dB = 8.1 GHz for IB = 75 mA (IB/ITH ~ 2) with a carrier-photon resonance amplitude (~4.2 dB). At the same bias conditions, the transistor laser demonstrates error-free 13.5-Gb/s data transmission at room temperature. [ABSTRACT FROM PUBLISHER]

Highly efficient interface‐dominated electrical injection lasers in the near‐infrared regime based on the type‐II band alignment in (GaIn)As/Ga(AsSb)/(GaIn)As single 'W'‐quantum wells are realised. The structure is designed by applying a fully microscopic theory, grown by metal organic vapour phase epitaxy, and characterised using electroluminescence measurements and broad‐area laser studies. A characteristic blue shift of 93 meV/(kA/cm2) with increasing charge carrier density is observed and compared with theoretical investigations. Low threshold current densities of 0.4 kA/cm2, high differential efficiencies of 66%, optical output powers of 1.4 W per facet, and internal losses of only 1.9 cm−1 are observed at a wavelength of 1164 nm for a cavity length of 930 µm. For a cavity length of 2070 µm, the threshold current density is reduced to 0.1 kA/cm2. No indication for type‐I related transitions for current densities up to 4.6 kA/cm2 is observed. [ABSTRACT FROM AUTHOR]

The dependence of the threshold current density on the number of wells for 1.3-μm-range edge emitting lasers using GaInNAsSb novel material, at which the incorporation of the small amount of Sb make the two-dimensional growth condition wide, is studied. The lowest record ever reported for the threshold current density per well (Jth A/cm2/well@L=900 μm) for 3 QWs lasers was achieved. GaInNAs-based 5 QWs lasers with the very low threshold current density per well of 160 A/cm2 were successfully grown for the first time. Therefore, no significant deterioration of Jth is observed even though the number of wells increased up to 5. Since Jth of 5 QWs doesn't increased rapidly compared to SQW and 3 QWs as decreasing the cavity length, it is considered that lower Jth can be obtained by utilizing 5 QWs in devices such VCSELs which use short cavity length. [ABSTRACT FROM PUBLISHER]

Lasing from the ground subband transition, which has long been attempted in one-dimensional (1-D) structures, has been achieved for the first time with vertically stacked, AlGaAs-GaAs multiple quantum-wire (QWR) lasers, fabricated by flow-rate modulation epitaxy on V-groove substrates. Direct experimental evidence is provided by the consistency of the photon energies of the lasing and photoluminescence peaks, in the temperature range 4.5 K-300 K. It is further ensured by numerical calculation of the electronic subband energy states with the corresponding QWR structure. The lasers with cavity lengths of 350 μm, show fundamental transverse mode, typical threshold current of 5 mA, an internal quantum efficiency of 18.5%, ultrahigh characteristic temperature T0~322 K above room temperature, and remarkably low wavelength-tuning rates of current (<0.012 nm/mA) and temperature (<0.19 nm/°C). Ultrafast lasing behaviors at the ground (n=1) and the second (n=2) transition of the QWR are also investigated in terms of the gain-switching method, using a characteristic of the wavelength shift from the n=1 to the n=2 subband with shortening the cavity length [ABSTRACT FROM PUBLISHER]

We investigate loss mechanisms in 1.55-μm InGaAsP-InP multiquantum-well ridge-waveguide laser diodes at room temperature. The common method of measuring light versus current curves and plotting the inverse slope efficiency versus laser length is employed to extract the internal optical loss αi and the differential internal efficiency η. This method neglects the dependence of both the parameters on the laser cavity length L. We analyze physical mechanisms behind these loss parameters and their length dependence using the commercial laser simulation software PICS3D. Internal optical losses are dominated by carrier density dependent absorption. The differential internal efficiency above threshold is found to be mainly restricted by carrier recombination losses within the quantum wells, i.e., Fermi level pinning is not observed. Both loss mechanisms are enhanced with shorter cavity length due to the higher quantum well carrier density. For the shortest device measured (L=269 μm), we extract αi=20 cm-1 and ηi=66%. With increasing cavity length, the loss parameters approach αi =15 cm-1 and ηi=70%. From the inverse slope efficiency versus cavity length plot, we obtain αi=14 cm-1 and ηi=67% independent of laser length [ABSTRACT FROM PUBLISHER]

The first laterally‐coupled distributed feedback (DFB) laser with first‐order sidewall gratings fabricated by optical interference lithography is experimentally demonstrated. The gratings were first etched into a dielectric mask on the planar top surface of an InP/AlGaInAs laser epiwafer, and then transferred to both sidewalls of a 2 µm deep ridge‐waveguide structure using a novel self‐aligned process. DFB ridge‐waveguide lasers with a cavity length of 650 µm and width of 2.6 µm (with 300 nm gratings on both sidewalls) achieved single longitudinal mode continuous‐wave operation, with a sidemode suppression ratio of 37 dB. The threshold current density is 1.7 kA/cm2 at room temperature, and the slope efficiency is 0.14 mW/mA per facet (uncoated). [ABSTRACT FROM AUTHOR]

Direct modulation at 40 Gb/s of a 1.3-mum InGaAlAs distributed feedback ridge waveguide laser is experimentally demonstrated. By combination of the high differential gain of an InGaAlAs multiquantum well active layer, a short cavity length of 100 mum, and a low-resistance notch-free grating, it achieves high bandwidth of 29 GHz and high-extinction ratio of 5 dB at 40-Gb/s modulation. Moreover, the laser operates at a record maximum ambient temperature of 60degC under 40-Gb/s directly modulation. It also achieves 40-Gb/s modulated transmission over 2 km with a low power penalty of 0.25 dB at 25degC . [ABSTRACT FROM PUBLISHER]

Stripe-width and cavity length dependencies of high-temperature performances of 1.3-μm InGaAsP-InP well-designed buried-heterostructure strained multiquantum-well (MQW) lasers were investigated. The threshold currents as low as 4.5/10.5 mA and slope efficiencies as high as 0.48/0.42 mW/mA at 25°C/85°C were obtained in the MQW lasers with 1.5-μm width, 250-μm length, and 0.3/0.85 facet reflectivity. With temperature increasing from 25°C to 85°C, the MQW lasers exhibited lower output power degradation, the minimum value was 1.78 dB at an operation current of 45 mA. The MQW lasers were suitable for application in optical access networks. [ABSTRACT FROM PUBLISHER]

A technique based on the integration of the product of amplified spontaneous emission spectrum and a phase function over one mode interval is proposed for measuring the gain spectrum for Fabry-Perot semiconductor lasers, and a gain correction factor related to the response function of the optical spectrum analyzer (OSA) is obtained for improving the accuracy of the measured spectrum. Gain spectra with a difference less than 1.3 cm-1 from 1500 to 1600 nm are obtained for a 250-μm-long semiconductor laser at an OSA resolution of 0.06, 0.1, 0.2, and 0.5 nm. The corresponding gain correction factor is about 9 cm-1 at a resolution of 0.5 nm. The gain spectrum measured at a resolution of 0.5 nm has the same accuracy as that obtained by the Hakki-Paoli method at a resolution of 0.06 nm for a laser with a mode interval of 1.3 nm. [ABSTRACT FROM PUBLISHER]

Narrow-stripe 1.55-μm wavelength distributed reflector lasers consisting of both distributed Bragg reflectors and vertical grating of the first Bragg order were fabricated. A low threshold current Ith of 2.8 mA, a differential quantum efficiency ηd of 28% from the front facet, and a submode suppression ratio of 44 dB were obtained for structures with a stripe width of 1.3 μm and a cavity length of 150 μm. [ABSTRACT FROM PUBLISHER]

High-performance 1.3-μm-emitting quantum-dot lasers were fabricated by self-organized growth of InAs dots embedded in GaInAs quantum wells. The influence of the number of quantum-dot layers on the device performance was investigated. Best device results were achieved with six-dot layers. From the length dependence; a maximum ground state gain of 17 cm-1 for six dot layers could be determined. Ridge waveguide lasers with a cavity length of 400 μm and high-reflection coatings show threshold currents of 6 mA and output powers of more than 5 mV. Unmounted devices can be operated in continuous wave mode up to 85°C. A maximum operating temperature of 160°C was achieved in pulsed operation for an uncoated 2.5-mm-long ridge waveguide laser [ABSTRACT FROM PUBLISHER]

Continuous-wave (CW) lasing operation with a very low threshold current density (Jth=32.5 A/cm2) has been achieved at room temperature by a ridge waveguide quantum-dot (QD) laser containing a single InAs QD layer embedded within a strained InGaAs quantum well (dot-in-well, or DWELL structure). Lasing proceeds via the QD ground state with an emission wavelength of 1.25 μm when the cavity length is longer than 4.2 mm. For a 5-mm long QD laser, CW lasing has been achieved at temperatures as high as 40°C, with a characteristic temperature T0 of 41 K near room temperature. Lasers with a 20 μm stripe width have a differential slope efficiency of 32% and peak output power of >10 mW per facet (uncoated) [ABSTRACT FROM PUBLISHER]

We demonstrate here 1.2-μm laser emission from a GaAsP-InGaAs strain compensated single-quantum-well (SQW) diode. This development enables the fabrication of vertical-cavity surface-emitting lasers for optical interconnection through Si wafers. Strain compensation and low temperature growth were used to extend the wavelength of emission to the longest yet achieved on a GaAs substrate in this materials system. The minimum threshold density achieved was 273.4 A/cm2 at a cavity length of 610 μm. We have also demonstrated an 1.144-μm lasing wavelength in a 820-μm-long cavity on a GaAs substrate with a strained InGaAs-GaAs SQW laser for comparison using a low-temperature metal-organic chemical vapor deposition growth technique. The threshold current density for a 590-μm-long cavity under CW operation was 149.7 A/cm2 [ABSTRACT FROM PUBLISHER]

Two and four quantum-well (QW) GaInAsSb-AlGaAsSb lasers emitting at 2 μm are reported. In comparison to previously published data, it is found that higher Al content in the QW barrier improves the internal efficiency, saturated modal gain, and characteristic temperature of the lasers. These results are attributed to an increased valence band offset that provides superior hole confinement in the GaInAsSb QW. A differential efficiency of 74% is observed at 25°C under pulsed conditions for a 900-μm cavity length, 2-QW device, and a record characteristic temperature of 140 K is measured for a 4-QW laser [ABSTRACT FROM PUBLISHER]