Density clamping and longitudinal spatial hole burning in a gain-clamped semiconductor optical amplifier

Abstract

We have directly measured, under operating conditions, the distributions of carrier densities and temperatures in a gain-clamped semiconductor optical amplifier designed for operation at 1.55 μm. As expected, longitudinal spatial hole burning is much smaller than in conventional semiconductor optical amplifiers and the effects of gain clamping are clearly evidenced. The amplifier nevertheless shows a sizeable temperature increase for both the lattice and the carriers at high currents, which are attributed to contributions of Auger recombination, intervalence band absorption, and Joule and recombination heating.

Gain Measurements of THz Quantum Cascade Lasers using THz Time-Domain Spectroscopy

“…just above laser threshold at 623mA), where the gain becomes 'clamped' at the value of the total optical losses. (This is due to the strong negative feedback of the laser intensity on the population inversion that results in gain saturation and stabilizes the carrier density at the threshold value) [17] This behaviour is typical of lasers and semiconductor optical amplifiers (SOA) [21][22][23] and reported previously for a quantum cascade laser [10]. Furthermore, the gain appears to persist even after the laser action has ceased.…”

Semiconductor optical amplifiers: performance and applications in optical packet switching [Invited]

“…The saturation output power of the amplifier is increased, exhibiting a much steeper roll off into saturation as the lasing mode loses power and eventually collapses. Multichannel systems experiments [32] have shown the suitability of such devices for operation in a WDM environment [33]. The performance advantage of gain-clamped devices over a SOA designed to have a similarly low value of gain is complicated, however, since the dynamic behavior does not follow the dc characteristics.…”