title: Simple analytical model for low-frequency frequency-modulation noise of monolithic tunable lasers.
abstract: We employ simple analytical models to construct the entire frequency-modulation (FM)-noise spectrum of tunable semiconductor lasers. Many contributions to the laser FM noise can be clearly identified from the FM-noise spectrum, such as standard Weiner FM noise incorporating laser relaxation oscillation, excess FM noise due to thermal fluctuations, and carrier-induced refractive index fluctuations from stochastic carrier generation in the passive tuning sections. The contribution of the latter effect is identified by noting a correlation between part of the FM-noise spectrum with the FM-modulation response of the passive sections. We pay particular attention to the case of widely tunable lasers with three independent tuning sections, mainly the sampled-grating distributed Bragg reflector laser, and compare with that of a distributed feedback laser. The theoretical model is confirmed with experimental measurements, with the calculations of the important phase-error variance demonstrating excellent agreement.
authors.forename: Tam N
authors.initials: TN
authors.lastname: Huynh
authors.forename: Seán P
authors.initials: SP
authors.lastname: Ó Dúill
authors.forename: Lim
authors.initials: L
authors.lastname: Nguyen
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Rusch
authors.forename: Liam P
authors.initials: LP
authors.lastname: Barry