Small turn-on delay time in 1.3 μm InAsP/InP strained doublequantum-well lasers with very-low threshold current

It is demonstrated for the first time that compressively strained InAsP/InP double quantum-well (DQW) lasers emitting at 1.3 μm performed a very small turn-on delay time by a significant reduction in threshold current. Lasers with 200 μm cavity length and high reflection coating achieved both very low threshold current of 1.8 mA and a small turn-on delay time (200 ps) even under a bias-less 30 mA pulse current. An additional power penalty was simulated, and it was shown that these small-delay and low-threshold performances are suitable for high-speed optical parallel data transmitters in computer networks     

1.3-μm InAsP modulation-doped MQW lasers

The effect of both n-type and p-type modulation doping on multiple-quantum-well (MQW) laser performances was studied using gas-source molecular beam epitaxy (MBE) with the object of the further improvement of long-wavelength strained MQW lasers. The obtained threshold current density was as low as 250 A/cm² for 1200-μm-long devices in n-type modulation-doped MQW (MD-MQW) lasers. A very low CW threshold current of 0.9 mA was obtained in 1.3-μm InAsP n-type MD-MQW lasers at room temperature, which is the lowest ever reported for long-wavelength lasers using n-type modulation doping, and the lowest value for lasers grown by all kinds of MBE in the long-wavelength region. Both a reduction of the threshold current and the carrier lifetime in n-type MD MQW lasers caused the reduction of the turn-on delay time by about 30%. The 1.3-μm InAsP strained MQW lasers using n-type modulation doping with very low power consumption and small turn-on delay time are very attractive for laser array applications in high-density parallel optical interconnection systems. On the other hand, the differential gain was confirmed to increase by a factor of 1.34 for p-type MD MQW lasers (N_A=5×10¹⁸ cm ^-3) as compared with undoped MQW lasers, and the turn-on delay time was reduced by about 20% as compared with undoped MQW lasers. These results indicate that p-type modulation doping is suitable for high-speed lasers     

Room temperature CW operation ofGa0.3In0.7As/GaInAsP/InP strained MQW lasers withwire active region

A room temperature CW operation of Ga_0.3In_0.7As/GaInAsP/InP GRINSCH compressive strained MQW lasers with 30~60 nm wide wire active region was achieved. This device was fabricated by two-step LP-OMVPE growths on p-type InP substrate and wet chemical etching. Threshold current as low as 53 mA ( L=910 μm, J_th=2.9 kA/cm²) was obtained at RT-CW condition. The spontaneous emission peak and the lasing wavelength of strained MQW wire lasers exhibited approximately 20-meV blue shift from those of MQW film lasers cut out from the same wafer     

Single wavelength grating filter laser array withGa0.3In0.7As/GaInAsP/InP strained MQW structure

Stable in-phase lateral- and single-longitudinal-mode operation up to four times the threshold (P_o~100 mW) was achieved in a five-element 1.5-μm-wavelength Ga_0.3In_0.7As/GaInAsP/InP compressive strained MQW grating filter laser array. The threshold current and external differential quantum efficiency under pulsed condition were 330 mA (emitter width of 18 μm, active region length of 480 μm) and 17%, respectively     

Doping-type dependence of turn-on delay time in 1.3-/spl mu/m InGaAsP-InP modulation-doped strained quantum-well lasers

The dependence of turn-on delay time on doping type in 1.3-/spl mu/m InGaAsP-InP modulation-doped (MD) strained quantum-well (QW) lasers is theoretically investigated, based on the detailed band structure model including the band mixing effects. It is found that the turn-on delay time in n-type MD lasers is reduced to 1/4 that of undoped lasers due to both a lower threshold current and a reduced carrier lifetime. The reduction of the delay time is smaller in p-type MD lasers, however, because of the increased threshold current. These results show that the n-type MD-QW lasers are superior for high-speed modulation under zero-bias conditions.     

Wideband and high-power compressively strained GaInAsP/InPmultiple-quantum-well ridge waveguide lasers emitting at 1.3 μm

Compressively strained 1.3-μm GaInAsP/InP multiple-quantum-well (MQW) ridge waveguide lasers were fabricated. Through optimizing the total well thickness, large bandwidth over 11 GHz was achieved, together with high quantum efficiency of about 0.48 W/A and high power output of 60 mW before rollover. The laser also showed less temperature sensitivity up to an elevated temperature of 85°C     

Auger recombination rates in compressively strainedInxGa1-xAs/InGaAsP/InP(0.53⩽x⩽0.73) multiquantum well lasers

The authors have experimentally determined Auger recombination rates in compressively strained In_xGa_1-xAs/InGaAsP/InP MQW lasers for the first time. The Auger recombination rates were derived from the measured turn-on delay times during large-signal modulation of single-mode lasers. The Auger coefficient increases from 5±1×10^-30 to 13±1×10^-30 cm⁶ s^-1 as the indium composition in the quantum well active region, x, increases from 0.53 to 0.73     

1.58-μm lattice-matched and strained digital alloy AlGaInAs-InPmultiple-quantum-well lasers

A versatile, digital-alloy molecular beam epitaxy (MBE) technique is employed to grow lattice-matched and strained AlGaInAs multiple-quantum well (MQW) 1.58-μm laser diodes on InP. A threshold current density as low as 510 A/cm² has been demonstrated for broad area lasers with 1% strained AlGaInAs MQWs, which is the best MBE result in this material system. A single facet pulsed power as high as 0.56 W is obtained. It is also found that the efficiency and internal loss of digital alloy AlGaInAs QW devices are comparable to lasers grown by conventional MBE     

GaInAsP/InP DH laser on semi-insulating InP substrate with terrace structure

GaInAsP/InP DH lasers for the 1.3 ?m region were fabricated through a single LPE process on semi-insulating InP substrates with a terrace structure. The threshold current of the mounted lasers was typically 65 mA under CW operation at room temperature. Light output of 450 mW per facet was achieved at a pulsed injection current of 4.2 A.     

GaInAsP/InP surface-emitting lasers with current confining structure

In order to reduce the threshold current of GaInAsP/InP surface-emitting (SE) lasers, we search for an effective current confining structure and examined several types; round-low-mesa, round-high-mesa/polyimide-buried, buried-heterostructure (BH), and planar-buried-heterostructure (PBH). The minimum threshold current was reduced down to 18 mA at 77 K and the threshold current density was estimated to be reduced to 3 kA/cm². The operating temperature has been raised to -10°C (263 K). The longitudinal-mode hopping was first observed for GaInAsP/InP SE lasers. The effective refractive index for GaInAsP/InP SE lasers was 4-5, that was almost the same as conventional edge-emitting lasers.     

全固源分子束外延InAsP/InGaAsP多量子阱1.55μm激光器

利用新型全固源分子束外延技术 ,对 1 .5 5 μm波段的 In As P/ In Ga As P应变多量子阱结构的生长进行了研究。实验表明 ,较低的生长温度或较大的 / 束流比有利于提高应变多量子阱材料的结构质量 ,而生长温度对材料的光学特性有较大的影响。在此基础上生长了分别限制多量子阱激光器结构 ,制作的氧化物条形宽接触激光器实现了室温脉冲工作 ,激射波长为 1 5 63 nm,阈值电流密度为 1 .4k A/ cm2 。这是国际上首次基于全固源分子束外延的 1 .5 5 μm波段 In As P/ In Ga As P多量子阱激光器的报道     

High quality compressively strained InP-based GaInAs(P)/GaInAsP multi-quantum well laser structures grown by metalorganic vapor phase epitaxy

The growth and characterization of strained GaInAs and GaInAsP multiquantum well (MQW) laser structures has been investigated. The use of triple axis x-ray diffraction (XRD), in addition to the conventional high resolution double crystal XRD, yields further information about the structural integrity of these complex structures. Buried heterostructure lasers with eight GaInAsP wells (+1.0% strain, 80Å thick) exhibit a record low threshold current of 3.1 mA. By using a constant As/P ratio in the wells and barriers of an MQW laser structure, we have shown that the structure can be annealed at 700°C for 1 h with only a minimal shift (-4 nm) in the photoluminescence emission wavelength. Conventional lattice-matched GaInAs/GaInAsP MQW structures exhibit a shift of-46 nm under the same conditions.     

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     

High temperature characteristic T0 and low thresholdcurrent density of 1.3 μm InAsP/InGaP/InP compensated strainmultiquantum well structure lasers

A high device quality material consisting of 10 compensated strained quantum well InAsP/InGaP structures was grown by MOCVD at atmospheric pressure. The estimated threshold current density for an infinite cavity length was 130 A/cm² per well. A high characteristic temperature of 117 K was obtained. To the authors' knowledge, this is the highest value for as-cleaved lasers at 1.3 μm on InP substrates     

Reduced turn-on delay time in 1.3-/spl mu/m InGaAsP-InP n-type modulation-doped strained multiquantum-well lasers with a buried heterostructure

A reduction in both the threshold current and carrier lifetime is demonstrated, for the first time, in an n-type modulation-doped InGaAsP strained multiquantum well laser with a buried heterostructure. Threshold current and carrier lifetime is reduced by 10% and 15%, respectively, as compared with a undoped MQW laser, which results in a 35% decrease in the turn-on delay time. This confirms the suitability of this type of laser for use as a light source for high-density parallel optical interconnection.     

Improved performance of 2-μm GaInAs strained quantum-well laserson InP by increasing carrier confinement

We have fabricated and analyzed strained GaInAs quantum-well diode lasers emitting at wavelengths above 2 μm, grown by metal-organic chemical vapor phase epitaxy on InP substrates. To study the effect of carrier confinement on laser performance, lasers grown with nearly lattice matched ternary GaInAs barriers and quaternary GaInAsP barriers were compared. The use of quaternary barriers improves the device performance in terms of output power, emission wavelength, characteristic temperature, differential quantum efficiency, and power efficiency. Internal losses and internal quantum efficiency remain unchanged. At a heat sink temperature of 330 K index guided diode lasers with GaInAsP-barriers emitting at 2.092 μm showed a continuous-wave (CW) output power of 42 mW/facet     

1.5 ?m region InP/GaInAsP buried heterostructure lasers on semi-insulating substrates

InP/GaInAsP buried heterostructure (BH) lasers for the 1.5 ?m region have been fabricated on semi-insulating InP substrates. The threshold current of the lasers is as low as 38 mA under CW operation at 25°C, which is nearly the same as for BH lasers fabricated on n-type InP substrates.     

The temperature dependence of the threshold current of GaInAsP/InP DH lasers

The temperature dependence of the threshold current of GaInAsP/InP lasers was considered in terms of linear gain, loss, and carder lifetime. The linear gain was calculated taking into account electronic intraband relaxation effects. The carrier lifetime, intraband relaxation time, loss in the active region, and dipole moment, all of which determine the threshold condition, were estimated from the experiments. The main loss mechanism which determines the temperature dependence of the differential quantum efficiency appears to be the absorption due to transitions between the split-off and heavy-hole valence bands. The temperature dependence of the theoretical threshold current Ithcalculated in terms of these parameters was compared with the measured results and reasonable agreement was obtained.     

AlGaInAs/InP strained-layer quantum well lasers at 1.3 µm grown by solid source molecular beam epitaxy

Al_xGa_yIn_1−x−yAs/InP strained-layer multiple-quantum-well lasers emitting at 1.3 μm have been grown by solid source molecular beam epitaxy, and the performance characteristics have been studied. The lasers contain 4, 5, or 6 compressively strained quantum wells in the active region. They exhibit low transparency current densities, high gain coefficients, and high characteristic temperatures compared to conventional GaInAsP/InP quantum well lasers. The results show that desired lasing features can be achieved with relatively simple layer structures if the doping profiles and waveguide structures are properly designed and the material is grown to high structural perfection.     

Preserving InP surface corrugations for 1.3 ?m GaInAsP/InP DFB lasers from thermal deformation during LPE process

First-order InP surface corrugations for 1.3 ?m distributed feedback (DFB) GaInAsP/InP lasers have been effectively preserved from thermal deformation that occurred during the soaking period just before LPE growth by employing a GaAs cover instead of a conventional InP cover. This technique has contributed greatly to GaInAsP/InP DFB laser reproducible fabrication.