摘要:

Operations in a new high-power laser called the twin-ridge substrate (TRS) laser, which has been previously proposed by the present authors, are discussed in full detail on a theoretical and experimental basis. From the viewpoint of practical applications, the following considerations are discussed: device design, device fabrication, the catastrophic failure limit, degradation, life and the oscillation mode. A stable fundamental transverse-mode operation has been obtained up to a maximum power of 40 mW. The typical threshold currents and differential quantum efficiencies are 50–60 mA and 40–50% (both facets), respectively. The typical beam divergences in the far-field pattern are 8° and 23° in the directions parallel and perpendicular to the junction plane, respectively. The room temperature lifetime is expected to exceed 66000 hours at 20 mW.

DOI:10.1049/ip-j.1985.0003

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Using a highly selective external cavity for a TS laser, the oscillation in a single longitudinal mode of the external cavity, with output power of up to 35 mW, was obtained.

DOI:10.1049/ip-j.1985.0004

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper describes the design and fabrication of distributed feedback lasers operating at around 1.5 μm, which utilise the ridge waveguide design for lateral mode and current confinement. The design considerations presented concentrate on the optimisation of waveguide layer compositions and thicknesses, together with the appropriate selection of diffraction-grating profile, in order to obtain strong grating coupling with the optical wave in the final device. We show that the devices made have operating characteristics comparable with the best DFB laser results so far reported. The high modulation capabilities afforded by the ridge waveguide structure are also demonstrated, and systems results show conclusively the high potential of these devices for future long-haul, high-bandwidth optical communication systems.

DOI:10.1049/ip-j.1985.0005

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Intensity noise and its enhancement by external optical feedback in DFB lasers are investigated for the first time. Without external optical feedback, relative intensity noise of the DFB laser consistently decreases down to the detector noise limit as the injection current increases, because of the absence of mode hopping noise. The external feedback causes mode hopping among the external cavity modes or among the DFB modes. If the required threshold gain difference among the DFB modes is large, mode hopping among the DFB modes is suppressed; however, mode hopping remains among the external cavity modes. Mode hopping among the DFB modes and among the external cavity modes both cause a strong noise similar to hopping between laser modes in a FP laser. A numerical investigation shows that, even in the worst case, DFB lasers having a large coupling coefficient (KL≥2) endure more strongly against the external optical feedback when compared with conventional FP lasers having the same output facet reflectivity.

DOI:10.1049/ip-j.1985.0006

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The damping and strength of relaxation oscillations in BH long-wavelength lasers have been investigated. In addition to previously published papers, the relative contribution of carrier diffusion effects and spontaneous emission is analysed. At moderate pumping rates, the calculated damping factor, using singlemode rate equations and a constant spontaneous carrier lifetime, is found to be in good agreement with experimental results if the finite rise time of the pulse generator is introduced. It is also shown that the overshoot depends mainly on the spontaneous emission factor. However, in general, for the calculated spontaneous emission factor, the predicted overshoot is greater than the measured one. Possible reasons for this disagreement are discussed.

DOI:10.1049/ip-j.1985.0007

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Using the computed solution of multimode rate equations, and including wavelength-chirping effects via the dependence of the refractive index on carrier concentration, it is possible to calculate time-averaged spectra of rapidly-modulated lasers. The averaging time may be used to simulate the effects of measuring equipment with a specific time response. The results show a characteristic fine structure within the dominant longitudinal mode spectrum, and are in qualitative agreement with experimental measurements reported by other authors.

DOI:10.1049/ip-j.1985.0008

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A critical examination of the conventional rate equation connecting the photon density, the spontaneous emission and the gain parameter reveals an internal inconsistency; while the first two quantities are pro-rated over the spectrum of the mode, the last is evaluated at the mode centre. Because interference between incident and reflected waves rapidly reduces the rate of stimulation as the optical frequency departs from resonance, pro-rating the net gain parameter over the spectral line gives a power-dependent first-order correction to its effective value. Examination of treatments of the optical noise amplifier as a lumped-element classical device and as a classical travelling-wave amplifier suggests ways to modify the conventional rate equation. If the usual concept of the spontaneous emission factor is retained in the equation, the net gain parameter is replaced by its square root. Alternative modifications redefine the dependent variable describing the output or the spontaneous emission factor. One result of the correction of the rate equation is a strong reduction in the predicted damping of the noise amplifier.

DOI:10.1049/ip-j.1985.0009

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The basic equations for analysis of semiconductor lasers are presented and discussed in detail. Numerical and analytical methods for solution of these equations, as well as various approximations and simplifications, are described. Various models for the static properties are reviewed, with emphasis on models including the field distribution. Some models for the dynamic properties are also discussed.

DOI:10.1049/ip-j.1985.0010

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A description is given of a computer model for the analysis of semiconductor lasers in which longitudinal variations in such devices are taken into account. The construction of the model ensures that a detailed description of the transverse variations in the device is also maintained, and, furthermore, that a variety of cross-sectional geometries may be examined. Numerical results are presented to illustrate longitudinal variations occurring in the device due to asymmetries in facet reflectivities.

DOI:10.1049/ip-j.1985.0011

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A new analytical model for semiconductor laser amplifiers is presented. It has the virtue of avoiding excessive numerical computation and yet retaining sufficient accuracy for most cases of interest. The essentially new feature is the use of an appropriate mean photon density obtained by averaging the axial field distribution along the cavity length. Calculated results are presented for gain, saturation power and tuning characteristics, and their sensitivity to current density, facet reflectivities, and the spontaneous emission coefficient is explored.

DOI:10.1049/ip-j.1985.0012

出版商:IEE    

年代:1985

数据来源: IET