Double-channel Planar Buried Heterostructure Lasers Research Articles

Low threshold and high uniformity for novel 1.3-/spl mu/m-strained InGaAsP MQW DC-PBH LDs fabricated by the all-selective MOVPE technique

1.3-μm-strained InGaAsP multiquantum-well (MQW) double-channel planar buried heterostructure laser diodes (DC-PBH-LDs) were fabricated by all-selective metalorganic vapor phase epitaxy (MOVPE). In the fabrication process, the strained MQW active layer and current-blocking structures were directly formed by selective MOVPE without a semiconductor etching process. A low-threshold current (I/sub th/=2.6 mA@25/spl deg/C for 200-μm-long 70%-90% facets) and excellent high-temperature operation (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> =84 K, 25/spl deg/C-60/spl deg/C and T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> =70 K, 25/spl deg/C-85/spl deg/C) were achieved. Furthermore, extremely uniform threshold current and slope efficiency were observed, The median time to failure for these LDs was estimated to be more than 100000 h under the 85/spl deg/C-5 mW aging condition.

Electro-optical effects of externally applied 〈100〉 uniaxial stress on InGaAsP 1.3 and 1.5 μm injection lasers

The changes in the polarization of the emission, spectrum, and light-current (L-I) behavior of a 1.3 and 1.5 μm InGaAsP channeled substrate buried heterostructure laser and double-channel planar buried heterostructure laser under an external uniaxial compressive stress perpendicular to the junction were studied at room temperature. It was found that the TM emission (electric vector perpendicular to the junction) reached threshold even at a stress level of ∼1×108 dyn cm−2. For stress ≤4×108 dyn cm−2, the TM emission, although reaching threshold first, was found to exist only over a limited range of currents. At high currents only TE emission (electric vector parallel to the junction) was observed. The appearance of the TE emission gave rise to nonlinear L-I characteristics. When both TM and TE emissions were seen, the former occurred at a higher energy. The limited stability of TM emission with current at low stresses is explained by invoking spectral hole burning effects which reduce the gain saturation power for TM mode than the TE mode. At high stresses ≥4×108 dyn cm−2, the increased gain for TM-polarized light ensures its stability at all currents. From our results it can be concluded that to avoid TM emission, and the associated spectral changes and nonlinear L-I characteristics, the tensile stress in the plane of the active layer should be less than 108 dyn cm−2.

High-power operation of InP/InGaAsP double-channel planar buried-heterostructure lasers with asymmetric facet coatings

We report the high-power operation of λ=1.3 μm InGaAsP double-channel planar buried-heterostructure lasers with asymmetric mirror coatings. A stack of four dielectric layers is used to raise the reflectivity of one facet to over 80%, and the thickness of a single layer coating on the output facet is chosen to reduce the reflectivity to about 4%. The resulting lasers are characterized by a low threshold current of 25 mA, slope efficiency as high as 50%, and a power output of as much as 150 mW (at 5 °C) at a current of less than 300 mA. The lasers operate in a single transverse mode over the entire current range and as much as 45 mW of power could be coupled into a lensed single-mode fiber. Preliminary high-power aging data show excellent device reliability.

High-power operation of DCPBH lasers emitting at 1.52 μm wavelength

Double-channel planar buried heterostructure (DCPBH) lasers emitting at 1.52 μm wavelength have been made with considerably reduced current leakage. These devices have reached a maximum CW output power of 50 mW per facet at 20°C and have operated CW up to 125°C. Both these figures are the highest values yet achieved for lasers emitting in the 1.52 μm wavelength region.

Highly efficient single-longitudinal-mode operation of antireflection-coated 1.3 μm DFB-DC-PBH LD

Lasing characteristics for a 1.3 μm InGaAsP/InP distributed-feedback double-channel planar buried-heterostructure laser diode (DFB-DC-PBH LD) have been remarkably improved by antireflection (AR) coating applied on the front facet. CW single-longitudinal-mode (SLM) operation power as high as 55 mW, and differential quantum efficiency as high as 36%, have been obtained from the coated front facet. CW SLM operation has been achieved up to 105°C.

0.81 μm band AlGaAs/GaAs double-channel planar buried-heterostructure laser with large optical cavity

0.81 μm-band AlGaAs/GaAs double-channel planar buried-heterostructure laser diodes with large optical cavity have been developed as light sources for use in analogue optical fibre communication systems. Linear light-output/current characteristics and a single-longitudinal-mode spectrum at a modulation frequency f = 100 MHz with modulation index m = 0.9 have been attained.

High-power aging test on 1.3 μm DC-PBH lasers with reflective coated mirror

High-power aging tests on 1.3 μm double-channel planar buried-heterostructure (DC-PBH) lasers with a reflective coated mirror have been performed. Stable operation for over 6000 h has been demonstrated under constant power conditions of 20 and 30 mW from the front facet at 50°C.

Double-channel planar buried-heterostructure laser diode with effective current confinement

An InGaAsP double-channel planar buried-heterostructure laser diode has been developed in which a p-n-p-n current confinement structure effectively reduces the leakage current. High-power operation over 50 mW and high-temperature operation up to 130°C have been attained.