InGaAsP/InP dual wavelength lasers

The first successful dual wavelength lasers emitting at 1.2 ?m and 1.3 ?m wavelengths are described. The lasers operated up to 0°C.     

Dual-wavelength (GaAl)As laser

A monolithic structure integrating two stripe-geometry (GaAl)As lasers emitting at 8500 and 8850 ? is described. The threshold currents for both lasers are in the 50?70 mA range. The spacing between the stripes for the device reported here is 25 ?m; it can be reduced to 10 ?m in order to optimise the direct coupling to a 50 ?m diameter fibre.     

Low threshold ridge waveguide laser at 1.55 ?m

Fundamental-transverse-mode ridge waveguide lasers have been operated at 1.55 ?m with threshold current as low as 42 mA. The threshold of fabrication and performance are similar to that of 1.3 ?m ridge lasers, including the large modulation bandwidth.     

Fabrication and performance characteristics of InGaAsP ridge-guide distributed-feedback multiquantum-well lasers

The fabrication and performance characteristics of InGaAsP ridge-guide distributed-feedback lasers with multiquantum-well active layers are reported. The lasers are 320 ?m long and have four active wells (?300 ? thick). The lasers have threshold current ?100 mA at 30°C, external differential quantum efficiency ?0.1 mW/mA/facet at 30°C and To? 60 K and can be operated in the same DFB mode up to 70°C. The measured frequency chirp is about a factor of 3 smaller than that for conventional double-heterostructure lasers. The smaller chirp should allow larger repeater spacing for high-bit-rate long-distance fibre transmission systems applications.     

High-power aging tests of 1.3 and 1.5 ?m VIPS lasers

1.3 and 1.5 ?m VIPS lasers were tested under high-power aging levels up to 130 mW. The output powers of the lasers were enhanced by AR/HR-coating of facets and optimisation of cavity lengths. Aging power levels were 75% of ?Pmaxand were up to 130mW at 25°C and up to 90 mW at 70°C for 1.3?m VIPS lasers. The median lifetimes were estimated to be 150,000 h at 25°C and 60,000 h at 70°C. For the 1.5?m VIPS lasers, the aging power levels were up to 90 mW at 25°C and up to 50 mW at 70°C. Median lifetimes of about 60,000 h and 45,000 h for 25 and 70°C aging tests, respectively, were achieved.     

InGaAsP/InP double heterostructure lasers grown by atmospheric-pressure MOCVD

Room-temperature operation of InGaAsP-InP double-heterostructure lasers grown by atmospheric pressure metalorganic chemical vapour deposition is reported. Optically pumped laser operation at 1.36 ?m and 1.45 ?m has been achieved and broad-area injection lasers operating at 1.37 ?m with threshold current densities as low as 3.6 kA/cm2 have been demonstrated.     

InGaAsP/InP dual-wavelength BH laser array

A dual-wavelength BH laser array emitting at 1.26 and 1.55 ?m has been fabricated. Spacing between the two BH lasers is 30 ?m, and simultaneous CW operation of the two lasers at room temperature has been achieved. Measured crosstalk was ?50 dB.     

1.55 ?m InGaAsP low-threshold buried-crescent injection laser

Fabrication of 1.55 ?m InGaAsP buried-crescent (BC) injection lasers with a p-n-p-n blocking structure is described. The BC lasers exhibit a threshold current as low as 14 mA at 25°C, very high yield, output power more than 10 mW and high-temperature operation up to 80°C. These BC lasers have continued to operate in stable CW mode at 50°C for more than 1000 h. The lifetime of the 1.55 ?m InGaAsP lasers at 50°C is estimated to exceed about 2.5 × 104 h.     

High-power operation of DCPBH lasers emitting at 1.52 ?m wavelength

Double-channel planar buried heterostructure (DCPBH) lasers emitting at 1.52 ?m 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 ?m wavelength region.     

Low threshold channelled-substrate buried crescent InGaAsP lasers emitting at 1.54 ?m

Double-heterostructure lasers with crescent-shaped InGaAsP active layers have been fabricated with CW emission of 1.54 ?m. Lowest CW thresholds are 45?47 mA for a 200 ?m long cavity at 25°C. The lasing near-field widths are 2.5?3.0 ?m and the spectral widths to 10% of peak are 4?5 nm under both CW conditions and modulation up to 320 Mbit/s.     

Monolithic integration of low-threshold-current 1.3 ?m GaInAsP/InP DFB lasers

Two 1.3 ?m GaInAsP/InP DFB lasers with low threshold currents (28 and 29 mA) were successfully integrated. Both DFB lasers operated continuously at temperatures of up to 68°C. The 12 ? separation in wavelength between the two lasers was produced by a 2 ? difference of the grating periods. A thermal interaction between the two lasers was estimated from the shift in their wavelengths.     

Measurements of refractive-index variation with free carrier density and temperature for 1.6 ?m GaInAsP/InP lasers

The refractive-index variation with injected carrier density and temperature was measured for GaInAsP/InP b.h. lasers emitting at 1.6 ?m. Values of dn/dN = ?5.9 × 10?27 m3 and dn/dT = 3 × 10?4/°C resulted. The investigation was based on measurements of the wavelength shift of individual longitudinal modes in the spectra of the lasers.     

High-temperature operation of 1.55 ?m InGaAsP double-channel buried-heterostructure lasers grown by LPE

High-temperature operation of InGaAsP double-channel buried-heterostructure (DCBH) lasers emitting at 1.55 ?m is reported. The 1.55 ?m InGaAsP DCBH lasers have threshold currents as low as 18 mA at 20°C. The threshold current temperature sensitivity between 10°C and 75°C is characterised by a T0 value of 55?66 K. Electro-optical derivative measurements show that the 1.55 ?m InGaAsP DCBH laser does not have substantial above-threshold leakage current for junction temperatures as high as 75°C. Finally, these devices were operated at temperatures as high as 110°C, the highest CW operating temperature obtained to date for a 1.55 ?m InGaAsP laser.     

Dispersion of linewidth-broadening factor in 1.5 ?m laser diodes

Measurements which demonstrate the strong dependence of the linewidth-broadening factor ? on photon energy in 1.5 ?m lasers are reported, ? was found to vary between 3 and 11 over a 40 meV energy range. The consequences for the linewidth and transient wavelength chirping in 1.5 ?m DFB lasers, where the operating wavelength may be different from the peak gain wavelength, are examined.     

Low-threshold oxide stripe GaAs/GaAlAs lasers grown by MOCVD

MOCVD-grown insulator defined stripe GaAs/GaAlAs lasers with stripe widths of 6, 10, 20 and 150 ?m have been characterised. Uniform CW threshold currents as low as 45 mA, differential quantum efficiencies as high as 74%, and kink-free power levels as high as 20 mW/facet have been obtained in 160 ?m long, 6 ?m stripe lasers. The internal differential quantum efficiency measured from our 6 ?m stripe lasers approaches one. Single longitudinal mode operation of these lasers has also been observed.     

Three-channel buried-crescent InGaAsP laser with 1.51 ?m wavelength on semi-insulating InP

Laser diodes with current threshold as low as 16 mA for lasers of 300 ?m length and channel width of 2?3 ?m were obtained with operational wavelength of 1.51 ?m. These lasers are fabricated with one liquid-phase-epitaxy growth step and a lateral zinc diffusion process. Current confinement is achieved by use of the semi-insulating substrate material.     

Single-mode c.w. ridge-waveguide laser emitting at 1.55 ?m

Single-mode c.w. operation at ?=1.55 ?m has been achieved in ridge-wavelength lasers fabricated using InGaAsP quaternary alloys. These lasers are promising candidates for future long-distance optical communications systems.     

1.3 ?m/1.5 ?m bidirectional WDM optical-fibre transmission system experiment at 144 Mbit/s

Results are reported of a 1.3 ?m/1.5 ?m bidirectional WDM transmission system experiment operating at 144 Mbit/s over 58 km of cabled single-mode fibre. Regenerators used Bell Laboratories-developed 1.3 and 1.5 ?m InGaAsP semiconductor lasers, InGaAs PIN diodes, microwave monolithic amplifiers and optical bidirectional couplers.     

1.3 ?m InGaAsP DCPBH multiquantum-well lasers

We report the fabrication and performance characteristics of InGaAsP double-channel planar buried heterostructure (DCPBH) lasers with multiquantum-well active layers emitting at 1.3 ?m. These lasers have threshold currents in the range 40?50 mA at 30°C, external differential quantum efficiencies of ?50% at 30°C and T0 values ?160 to 180 K in the temperature range 10?60°C.     

Low threshold 1.55 ?m InGaAsP lasers double clad with InGaAsP confining layers

Preliminary results for 1.55 ?m InGaAsP double-heterostructure lasers with symmetrical InGaAsP confining layers are presented. The lowest broad-area threshold is 1.36 kA/cm2, which is 30% lower than the best value previously reported for 1.55 ?m lasers. This improvement is believed to be related to the absence of terracing on InGaAsP confining layers.