This appendix provides a more detailed account of the classic rate-equation analyses of appropriately uniform lasers and shows the first-order effects of carrier transport into the active quantum-well region, and the effects of spontaneous emission and gain saturation on damping of the photon electron resonance. The appendix ends with large-signal rate equations showing the influence of four key parameters which shape the main features of the large-signal response.

A4.1 Rate Equations: Steady-State and Small-Signal

This appendix evaluates the small-signal responses of a laser diode to modulation of the drive current more comprehensively than in Chapter 4. The photonic equation (eqn. 4.1) is now written as

(A4.1)

The effective photon lifetime ?' _p has been used as in Chapter 4. The intervalence-band-absorption term bNS is added here for completeness and the spontaneous emission is recognised as being formed from bipolar recombination so that, when the holes and electrons are of equal density, the radiative spontaneous emission is proportional to N ². The gain is linearised about the transparency density N _tr but gain saturation with optical density is included. The spontaneous-emission coupling ? _sp is now assumed to have absorbed the confinement factor. The electronic eqn. 4.2 is also written more fully as

(A4.2)

where the effective recombination rate N/ ? _r in eqn. 4.2 has been expanded to become

(A4.3)

The first (linear) term is often identified with nonradiative recombinations and the final (cubic) term identified with Auger (nonradiative) recombinations. The current density...