Experimental determination of carrier-induced differential loss in 2-section GaInAsP/InP laser-waveguide

Measurements of threshold current density and external efficiency on broad-area laser-waveguide structure have led to the determination of the optical loss and differential loss d alpha /dN approximately=1.1-2.3 *10/sup -17/ cm/sup 2/ at lambda =1.53 mu m in a lambda /sub g/=1.30 mu m GaInAsP layer. This measurement will be useful for the design of tunable lasers.<>     

Frequency demodulation of a semiconductor laser by FM-AM conversion in an optical fiber

It is theoretically demonstrated that the FM light output of a semiconductor laser can be detected through FM-AM conversion using an optical fiber. The analysis is made in the case of narrow-band FM and for the fundamental mode in a step-index monomode fiber. It is shown that for a 10 GHz modulation frequency, the fiber length necessary to achieve maximum demodulation lies in the range of 10 km.     

Optical repeater using PFM at 1 GHz

We report the first realization of PFM optical communication with a repeater station, using double heterostructure GaAs/GaAlAs semiconductor lasers. The system uses the property of semiconductor lasers for which the optical pulse rate can be locked by an external modulation of the injection current in the vicinity of the resonance frequency of the laser. This modulation scheme has the advantages of a high information rate capability by using the "spiking" resonance of the laser and, more importantly, of a simple repeater station in which another pulsing laser acts as a regenerative pulse amplifier.     

Self-aligned flip-chip packaging of tilted semiconductor opticalamplifier arrays on Si motherboard

An optical self-aligned flip-chip packaging technique for tilted semiconductor optical amplifier arrays is reported. It uses a Si motherboard with V-grooves for self-alignment between the tilted SOA array and angle polished fibre arrays. Fibre-to-fibre gain of 14±1 dB and ripple ±0.1 dB without antireflection coating on the fibres have been achieved     

Analytical model of a semiconductor optical amplifier

The spatial dependence of the material gain is introduced in the model of a semiconductor optical amplifier. Analytical expressions of the profiles of the carrier density, spontaneous emission, and amplified fields are obtained for amplifiers with arbitrary facet reflectivities. The nonuniformity of the carrier density is demonstrated in the case of low facet reflectivities. The model predicts the output saturation power and gain ripple, with good agreement with experimental results in resonant and traveling-wave amplifiers. Very low-gain ripple measured in low facet reflectivities amplifiers is explained by the model. A comparison with the uniform gain model shows that important deviations can occur in the case of low facet reflectivities. It is also shown that with the currently achievable low facet reflectivities, the maximum available gain is limited by spontaneous emission     

Optical coupling of two injection lasers: A new experimental approach to study the gain broadening mechanism

A new type of experiment, the optical coupling of two injection lasers, is presented. This method is used to study the gain broadening mechanism for three different types of laser structures: proton bombarded stripe geometry,V-groove, and channeled substrate planar stripe (CSP) lasers. The gain reduction in the presence of a strong injected light is detected with high sensitivity by a differential measurement. Independent of the laser structure, the homogeneous gain broadening mechanism is by far dominating.     

Spatially resolved emission in stripe geometry GaAlAs DH lasers

Double-peak spatially resolved side emission spectra are observed in GaAlAs DH lasers with proton bombarded stripe contact. Results are explained in terms of internal stress as a result of proton bombardment of the p⁺ region and absorption shift.     

Dielectric guiding due to an inverted gain profile in GaAs/GaAlAs lasers

The waveguiding mechanism in a new GaAs/GaAlAs laser structure has been investigated by near-field and astigmatism measurements. The waist of the beam was observed in front of the mirror facet of the laser, indicating that the inverted gain profile is responsible for dielectric guiding along the junction plane.     

Design and realisation of high-gain 1.5 ?m semiconductor TW optical amplifiers

The influence of the waveguide parameters, leakage current, electrical and thermal resistances on the maximum linear gain and the corresponding tuning wavelength of buried-heterostructure (BH) semiconductor travelling-wave optical amplifiers (TWAs) operating around 1.5 ?m is theoretically analysed. A 26 dB gain TWA has been designed and fabricated from a 400 ?m-long BH laser with a 0.2 ?m-thick active layer by using low-reflectivity SiO (R ? 6 × 10?4) coatings.