Carrier confinement and its effect on the internal quantum efficiency and modulation response of quantum well lasers

Recently it was shown that carrier transport can have a significant effect on the modulation response and relative intensity noise of quantum well lasers. We showed that carrier transport across wide undoped separate confinement heterostructure (SCH) regions leads to a severe low frequency rolloff in the modulation response, in addition to a reduction in the effective differential gain. Analytic expressions for the modulation response, resonance frequency and damping were also derived which showed that the differential gain, go, is reduced to go//spl chi/. The transport factor, /spl chi/, is given by (1+/spl tau//sub r///spl tau//sub e/ where /spl tau//sub r/, is the carrier transport time across the SCH and /spl tau//sub e/, is the themioaic emission time out of the quantum well. The rolloff frequency is given by /spl tilde/ 1/2/spl pi/spl tau//sub r/.