Multi-transverse Mode Operation in Vertical-cavity Surface-emitting Lasers: Effects of Wideband Modelling on Spectral Characteristics and Noise

A dynamic model for the vertical-cavity surface-emitting laser aimed to study the precise oscillation frequencies of the transverse modes is presented. The model performs the computation of the longitudinal distribution of the field inside the laser cavity, to take account of distributed boundary conditions at the Bragg reflectors. The latter are approximated by means of autoregressive moving-average (ARMA) digital filters, in order to reduce the computational load without loss of precision in wideband scenarios. With the aid of the developed model, a detailed analysis of the frequency and relative intensity noise spectra is carried out, thus allowing to evaluate the spectral quality of the laser emission. Particularly, the results reveal that each of the transverse modes oscillates with a frequency detuning from the central design wavelength, which is in good agreement with experimental observation.