The performance of a 3.4-Gb/s system using a low-power 1.318- mu m distributed-feedback (DFB) laser transmitter and a traveling-wave semiconductor laser power amplifier is studied. The -14.5-dBm, input from a directly modulated DFB laser is boosted to +10.3 dBm, of which +4.8 dBm is coupled into the transmission fiber. The penalty, caused by amplifier noise and pattern effects due to gain saturation, is less than 0.5 dB.< >

Reports travelling-wave 1.5 mu m semiconductor laser amplifiers with very low gain ripple. The average facet reflectivity is less than 5*10/sup -5/ over a 170 AA interval. The minimum gain ripple is below the measurement accuracy, 0.2 dB, at 27.5 dB gain. When used as an optical preamplifier in a 4 Gbit/s receiver, a sensitivity of -34.3 dBm is achieved.<>

The authors report an optical transmission experiment at a data rate of 8 Gbit/s over an unrepeatered distance of 76 km. The transmitter was a directly modulated, 1.3 mu m-wavelength, distributed-feedback laser. The receiver employed an avalanche photodiode and a high-impedance GaAs MESFET preamplifier.<>

Single-frequency integrated external cavity distributed Bragg reflector lasers emitting near 1.5 μm have been fabricated. The chirp and cw linewidth measurements of these devices show that lasers with long external cavity exhibit lower chirp and lower cw linewidth compared to lasers with short external cavity. The experimental data are explained by using theoretical calculations.

The fabrication and performance characteristics of a laser structure with monolithically integrated monitoring photodiode are described. The structure utilises semi-insulating Fe doped InP layers for confinement of the current to the active region of the laser and for the separation of the laser and the photodetector sections. The lasers have threshold currents in the range 3-40 mA and emit in a s...

An 8 Gb/s optical transmission experiment was conducted over an unrepeater distance of 76 km. The transmitter used direct modulation of a high-power distributed-feedback laser at a wavelength of 1.3 μm, and the receiver used a high-speed InGaAs avalanche photodiode and a GaAs FET preamplifier. An error rate of 1×10-10 was obtained at a received power level of -21.8 dBm. Because of operation close to the fiber zero dispersion wavelength, no dispersion penalty from laser chirp was observed. The relatively high laser power obtained (+6.7 dBm coupled into the fiber) helped to overcome the fiber loss, allowing a long unrepeatered distance to be achieved. The experiment demonstrates that long-distance 1.3-μm transmission at multigigabit-per-second rates over conventional fiber is a feasible option for future lightwave systems

The fabrication and performance characteristics of integrated thermally and electronically tunable distributed feedback and distributed Bragg reflector type single wavelength laser diodes are described. Continuously tunable sources of this type are useful for coherent transmission systems.

The fabrication and performance characteristics of a thermoelectrically tunable single-wavelength integrated external cavity distributed Bragg reflector laser are described. The tunability arises from a variation of the effective index in the external cavity obtained by varying the temperature. The active cavity section of these devices utilises the double-channel planar buried-heterostructure sch...

The fabrication and performance characteristics of an independently controllable closely spaced dual wavelength laser structure are described. The laser structure utilizes semi-insulating (Fe-doped InP) layers both for confinement of the current to the active regions and for separation of the active regions of the two lasers. Both lasers emit in single frequencies near 1.55 μm by virtue of frequency selective feedback provided by a second order grating. The light coupled into a single mode fiber from both lasers is about 5 dB smaller than that for optimum coupling arrangement of each laser. Dual wavelength laser structures of this type are useful for wavelength multiplexed optical transmission systems.

Fabrication and performance characteristics of both gain-guided and index-guided laser arrays emitting near 1.3μm are reported. The ten emitter laser arrays have threshold currents in the 300-500 mA range and have been operated to output powers of 600 mW near room temperature. The power output characteristics of these lasers are compared to that of a single emitter device where pulsed output powers of 200 mW have been obtained using a good current confining structure. The phase locked laser arrays exhibit rise and fall times of 1 ns under high current injection and can be modulated at 500 Mb/s.

The fabrication and performance characteristics of single-wavelength integrated external cavity distributed Bragg reflector lasers are described. The active cavity section of these devices utilize the double-channel planar-buried heterostructure scheme for current confinement. The 4-mm-long lasers have threshold current ∼70 mA and emit near 1.3 μm. The lasers exhibit lower dc chirp than distributed feedback lasers.

The fabrication and performance characteristics of a InGaAsP laser structure with semi-insulating current confining layers are reported. The semi-insulating layers are Fe-doped InP and are grown using the metalorganic chemical vapor deposition growth technique. The lasers have threshold currents in the range 20–30 mA and external differential quantum efficiency ∼0.2 mW/mA/facet at 30 °C. The bandwidth for small-signal response is ∼2 GHz which suggests that the laser structure is suitable for high bit rate lightwave transmission systems. Initial aging results yield an estimated operating lifetime of 10 years at 20 °C.

The fabrication and performance characteristics of frequency tunable two-section distributed feedback lasers are reported. The lasers are of the double channel planar buried heterostructure type and utilize a second order grating for frequency selective feedback. The laser emits in a single frequency with a cw linewidth of ∼50 MHz. The single frequency output can be tuned by ∼2 Å by varying the current through one of the two sections. Electronically tunable sources of this type are potentially useful for coherent fiber transmission systems.

The fabrication and performance characteristics of 1.3-μm InGaAsP distributed feedback (DFB) double-channel planar buried heterostructure (DCPBH) laser are reported. The lasers utilize a second-order grating with a periodicity of ∼3800 Å for frequency selective feedback. The lasers have threshold currents in the range 25–35 mA at 30 °C. The lasing mode shifts to longer wavelengths with increasing temperature at 1 Å/°C. The dynamic linewidth under 40-mA current modulation is ∼1 Å. The cw linewidth at an output power of 1 mW is ∼90 MHz. A monolithically integrated thermoelectric-controlled laser diode utilizing the DFB-DCPBH laser structure has been fabricated. The emission frequency of the laser can be continuously tuned by ±4 Å using 50-mA controller current.

The fabrication and performance characteristics of integrated electronically and thermally tunable distributed feedback laser diodes are described. The distributed feedback lasers are of the double-channel buried heterostructure type and emit near 1.3 or 1.55 μm.

Phase-locked InGaAsP index-guided multirib waveguide laser arrays emitting at 1.3 μm have been fabricated. These devices have threshold currents in the range 400-500 mA at 30°C and have been operated to pulsed output powers as high as 400 mW. More than 100 mW of output power has been obtained up to an ambient temperature of 60°C. The lasers emit in multilongitudinal modes with a far-field divergen...

The fabrication and performance characteristics of a monolithically integrated thermoelectric controlled laser diode are described. The thermoelectric element is the n-InP substrate. The lasers (λ∼1.51 μm InGaAsP) have threshold currents of ∼20 mA and operate kink free to >10 mW/facet. A variation of active region temperature of ± 2.5 °C has been achieved using 50 mA of thermoelectric controller current. The observed frequency tuning rate associated with this temperature shift is ∼0.5 GHz/mA. The device is useful for applications that require a high degree of frequency stability or small frequency tuning. Some potential lightwave system applications are in single-frequency transmission systems, coherent transmission systems, optical amplifiers, resonant external cavity modulators, and injection locking.

Fabrication and performance characteristics of both gain-guided and index-guided laser arrays emitting near 1.3 µm are reported. The ten emitter laser arrays have threshold currents in the 300-500-mA range and have been operated to output powers of 600 mW near room temperature.

We have fabricated InGaAsP gain-guided laser arrays emitting at 1.3 μm. These devices have threshold currents in the range 300–400 mA at 30 °C and have been operated to pulsed output powers as high as 400 mW. More than 100 mW of output power has been obtained up to an ambient temperature of 60 °C. The lasers emit in multilongitudinal modes with a far-field divergence of 20°×35°. A gain-guided InGaAsP laser array of the type described here can be used in some applications requiring high-power lasers emitting at 1.3 μm.

The fabrication of single longitudinal mode (SLM) distributed feedback (DFB) InGaAsP/InP lasers emitting at 1.55µm using the double channel planar buried heterostructure (DCPBH) laser structure is reported. The distributed feedback configuration has the second order feedback grating etched directly upon the InP substrate before the first growth of the double heterostructure. These DFB-DCPBH lasers have CW threshold currents of 25 mA at 30°C and a threshold current temperature sensitivity (T o ) of 55 K. Single longitudinal mode operation between 15° and 75°C and mode suppression ratios as high as 30 dB have been obtained.