Narrow-linewidth strained-layer 1.5 mu m multiquantum well distributed feedback lasers

The performance characteristics of narrow-linewidth strained-layer 1.5 mu m multi-quantum-well distributed feedback (MQW-DFB) lasers are presented. Measured linewidth as low as 3.5 MHz has been observed for one of the 250 mu m long devices at 14.4 mW output. Under 1.7 Gbit/s 1.0, 1.0, . . . pattern signal modulation, the lasers have 20 dB down full width chirp in the range of 5-6 AA for the off state at 0.8 I/sub th/. The chirp widths are about half of those of bulk-active DFB lasers. A 1.7 Gbit/s amplitude-shift-keying transmission experiment using one of the low-chirp lasers has been demonstrated. The transmission over 60 km of standard fibre only result in a 0.8 dB dispersion power penalty and has a receiver sensitivity of -36.2 dBm at BER=10/sup -9/.<>     

Effects of Zn doping on modulation bandwidth of 1.55 mu m InGaAs/InGaAsP multiquantum well DFB lasers

Experimental results are presented that confirm that Zn doping the active region of multiquantum well DFB lasers enhances their modulation bandwidth. This is achieved by reducing both the damping and low frequency rolloff associated with carrier transport. A maximum CW bandwidth of 17 GHz at 20 degrees C is reported.<>     

Very wide spectrum multiquantum well superluminescent diode at 1.5 mu m

An InGaAs-InGaAsP multiquantum well superluminescent diode (SLD) emitting at 1.5 mu m has been studied. Broad spectral widths exceeding 100 nm are achieved under a wide injection current range. The maximum spectral width is 170 nm, which gives a calculated coherence length of 13 mu m, approximately one third that of 1.5 mu m conventionally available bulk SLDs.<>     

High-power AlGaInAs strained multiquantum well lasers operating at 1.52 /spl mu/m

1.75 W CW power in AlGaInAs-InP strained QW lasers is demonstrated. Room temperature threshold current densities are 410 A/cm/sup 2/, and the characteristic temperature is 69 K. The variation in the external differential efficiency with cavity length and temperature reveal the optimum length and show how nonradiative recombination mechanisms limit the performance.     

High temperature operation of lambda =1.5 mu m tensile strained multiple quantum well SIPBH lasers

The high temperature operation of 1.5 mu m wavelength, strained-layer multiple quantum well, semi-insulating planar buried heterostructure lasers is reported. The lasers, which are grown by low-pressure organometallic vapour phase epitaxy and which have four 1.6% tensile strained In/sub 0.3/Ga/sub 0.7/As wells (thickness 8 nm), operate in CW mode up to heatsink temperatures of 140 degrees C. The CW output power at 100 degrees C is 26 mW per facet. These results are a marked improvement when compared to data reported thus far for 1.5 mu m wavelength lasers.<>     

Reduced turn-on delay time in 1.3 μm InGaAsP/lnP n-typemodulation-doped strained multiquantum well lasers

Reductions in carrier lifetime, threshold current, and thus turn-on delay time, due to n-type modulation doping, have been experimentally demonstrated in 1.3 μm InGaAsP strained multiquantum well lasers for the first time     

Demonstration of an InGaAsP/InGaAs multiquantum well active-gratingsurface-emitting amplifier

The design and operating characteristics of an InGaAsP/InGaAs strained-layer multiquantum-well active-grating surface-emitting amplifier operating at a wavelength of 1.6 μm are reported. Single-wavelength operation was obtained with 25-dB suppression of amplified spontaneous emission at 150-mW peak power output with a differential quantum efficiency of 24%. This result verifies earlier theoretical predictions that a power output per unit length of ~1 W/cm is feasible     

Reliable InGaAs quantum well lasers at 1.1 mu m

Strained-layer InGaAs quantum well lasers operating CW at 1.1 mu m have been life tested to over 18000 h, exhibiting a degradation rate of <.8% per kh. These uncoated lasers were life tested at 70 mW (per facet) in constant-power mode at a heatsink temperature of 30 degrees C. The laser structure, grown by metalorganic chemical vapour deposition, incorporates a step-graded quantum well heterostructure with a 30 AA In/sub 0.45/Ga/sub 0.55/As quantum well.<>     

10 Gbit/s, 1.56 mu m multiquantum well InP/InGaAsP Mach-Zehnder optical modulator

10 Gbit/s modulation using a III-V semiconductor Mach-Zehnder interferometer is reported for the first time. The modulator has a -3 dB bandwidth in excess of 15 GHz and is operated in a push-pull drive configuration with only 2 V peak to peak. 10 Gbit/s nonreturn to zero format eye diagrams with an extinction ratio>10 dB are demonstrated.<>     

Spontaneous emission efficiency of compressively strained 1.5 mu m MQW lasers

The spontaneous emission efficiency of 1.5 mu m compressively strained MQW lasers was found to be higher than that of comparable unstrained devices. The activation energy for Auger recombination was higher in the strained devices. Both effects were explained in terms of a reduction in the hole mass by strain.<>     

1.75 μm strained InGaAs multiquantum well laser grown on InAs0.08P0.92 ternary substrate

The authors have demonstrated a strained InGaAs multiquantum well laser grown on an InAs_0.08P_0.92 ternary substrate. The epitaxial structure was grown using metal organic vapour phase epitaxy (MOVPE). The InAsP wafers were characterised using room temperature photoluminescence, X-ray diffraction and X-ray topography. Pulsed power levels of 60 mW/facet at h=1.75 μm were measured at T=250 K. A characteristic temperature of T₀=46 K was observed over a temperature range of 78-250 K     

Intervalence band absorption coefficient measurements in bulk layer, strained and unstrained multiquantum well 1.55 mu m semiconductor lasers

Measurements are reported of intervalence band absorption (IVBA) coefficient k/sub 0/ in three types of active layer structure: bulk, unstrained (MQW) and strained multiquantum wells. The IVBA measurements are performed by observing the spontaneous emission from the uncleaved facets of DCPBH Fabry-Perot lasers. k/sub 0/=(3.7+or-0.3)*10/sup -17/ cm/sup 2/ is obtained for bulk, (1.4+or-0.2)*10/sup -16/ cm/sup 2/ for MQW unstrained and (3.5+or-0.3)*10/sup -17/ cm/sup 2/ for strained MQW structures.<>     

Low threshold 1.5 mu m tensile-strained single quantum well lasers

The authors have experimentally found that the threshold current density of 1.5 mu m tensile-strained single quantum well lasers decreases with increased tensile strain. A threshold current density as low as of 197 A/cm/sup 2/ is obtained with an In/sub 0.3/Ga/sub 0.7/As well. With semi-insulating current blocking layers and high reflection facet coatings, a threshold current as low as 2 mA is obtained from 150 mu m long lasers and a maximum CW operation temperature of 135 degrees C is achieved from 1 mm long lasers.<>     

1.27 /spl mu/m metamorphic InGaAs quantum well lasers on GaAs substrates

Pulsed operation at a wavelength of 1.27 /spl mu/m from metamorphic ridge-waveguide (RWG) InGaAs quantum well lasers on GaAs substrates using an alloy graded buffer, grown by molecular beam epitaxy, is demonstrated. Laser performance is anisotropic along the two orthogonal <1/spl plusmn/10> directions with lower threshold currents along the <1-10> direction. Post-growth rapid thermal annealing further reduces threshold currents. For 4 /spl mu/m-wide RWG lasers, minimum threshold current densities are 1-2.5 kA/cm/sup 2/ for cavity lengths 0.6-1.5 mm.     

1.3 μm InGaAs/GaAs strained quantum well lasers with InGaPcladding layer

Using MOVPE, we fabricated strained quantum well 1.3 μm lasers with an InGaP cladding layer on a GaAs substrate. The lasers had a high gain coefficient of 60 cm^-1. Lasers with high reflection facets had a low threshold current density of 500 A/cm², and a high characteristic temperature of 100 K     

Demonstration of passive Q-switching in multiquantum well InGaAs/AlGaInAs diode laser

The first passive Q-switched operation is reported of an InGaAs-AlGaInAs diode laser with a frequency repetition ranging from 1 to 2.5 GHz at the emitting wavelength of 1.58 /spl mu/m. This material is important as a thermally stable alternative to InGaAsP based laser systems operating around 1.5 /spl mu/m.     

Improved-performance, InGaAs/InGaAsP (/spl lambda/=980 nm) asymmetric broad-waveguide diode lasers via waveguide-core doping

Doping the waveguide core (p=2/spl times/10/sup 17/ cm/sup -1/) in asymmetric-waveguide InGaAs/InGaAsP, two-quantum-well diode lasers (/spl lambda/=980 nm) raises the injection efficiency to 90% and decreases the threshold-current density, J/sub th/. For 2 mm long, 100 /spl mu/m wide stripe, uncoated chips J/sub th/ decreases from /spl sim/188 A/cm/sup 2/ to /spl sim/150 A/cm/sup 2/. High characteristic temperatures for J/sub th/ and the slope efficiency are obtained: T/sub 0/=215K and T/sub 1/=600K.     

Inhibited dark-line defect formation in strained InGaAs/AlGaAsquantum well lasers

Dark-line defect formation is compared in GaAs/AlGaAs and strained InGaAs/AlGaAs quantum well lasers. Dark-line defects have high growth velocity along 〈100〉 in GaAs quantum well lasers, causing rapid degradation. In contrast, the 〈100〉 dark-line defect is suppressed in the structures with a strained InGaAs quantum well, so that rapid degradation does not occur     

GaSb-based tapered diode lasers at 1.93 /spl mu/m with 1.5-W nearly diffraction-limited power

High-power high-brightness 1.93-/spl mu/m wavelength (AlGaIn)(AsSb) tapered diode lasers with a narrow vertical waveguide design are reported for the first time. A nearly diffraction-limited continuous-wave output power of 1.5 W together with a remarkable low fast axis divergence of 43/spl deg/ full-width at half-maximum have been demonstrated. The maximum brightness amounts to 32 MW/cm/sup 2/sr.