Abstract

An understanding of the modulation dynamics and phase noise properties of semiconductor lasers will be essential in certain applications of these devices. In this regard two important quantities are the relaxation oscillation frequency ω_R which sets the useful direct modulation bandwidth of the device [1], and the field spectrum linewidth Δω which gives a direct measure of phase noise in single mode operation [2,3], in another paper two of us proposed a new method for control of the above properties [4]. This method, referred to as "detuned loading," was shown in that paper to simultaneously cause enhancement of modulation speed and reduction of phase noise (linewidth). In general, the method involves the introduction of a frequency dependent loss mechanism in the spectral proximity of the lasing frequency and relies upon the unique physics involved in lasing action in a semiconductor (a detuned gain spectrum leading to amplitude-phase coupling in the lasing field [2,3]). In this paper we present the first experimental observations of the detuned loading effect in semiconductor lasers. Specifically, we have observed enhancement of the modulation response with simultaneous reduction of linewidth resulting from application and control of detuned loading.

© 1985 Optical Society of America