Numerical model of capacitance in vertical-cavity surface-emitting lasers

• Published in: Journal of physics. D, Applied physics Vol. 49; no. 17; pp. 175104 - 175110
• Main Authors: Wasiak, M, piewak, P, Moser, P, Walczak, J, Sarza a, R P, Czyszanowski, T, Lott, J A
• Format: Journal Article
• Language: English
• Published: IOP Publishing 05.05.2016
• Subjects: capacitance; Constants; high frequency modulation; Impedance; Mathematical analysis; Mathematical models; modeling of semiconductor lasers; Modulation; Three dimensional models; Threshold currents; VCSEL; Vertical cavity surface emission lasers
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/49/17/175104

In this paper we present a model of impedance and modulation time constants for vertical-cavity surface-emitting lasers (VCSELs) operating above threshold current. A 3D numerical model of potential distribution in the device under a constant bias is used to determine resistances and capacitances of an appropriate equivalent circuit. The model has been verified by comparing the theoretical and measured impedance as a function of frequency Z(f). The measured Z(f) is determined from S11 small signal modulation experiments. The comparison has been performed for frequencies up to 40 GHz and a wide range of above threshold currents, for two oxide-confined VCSELs of different aperture diameters. We obtained a very good quantitative agreement for frequencies up to about 15 GHz and qualitative agreement over the entire range of currents and frequencies.