High speed low current density 850 nm VCSELs
Paper i proceeding, 2010

The design of an oxide confined 850 nm VCSEL has been engineered for high speed operation at low current density. Strained InGaAs/AlGaAs QWs, with a careful choice of In and Al concentrations based on rigorous band structure and gain calculations, were used to increase differential gain and reduce threshold carrier density. Various measures, including multiple oxide layers and a binary compound in the lower distributed Bragg reflector, were implemented for reducing capacitance and thermal impedance. Modulation bandwidths > 20 GHz at 25°C and > 15 GHz at 85°C were obtained. At room temperature, the bandwidth was found to be limited primarily by the still relatively large oxide capacitance, while at 85°C the bandwidth was also limited by the thermal saturation of the resonance frequency. Transmission up to 32 Gb/s (on-off keying) over multimode fiber was successfully demonstrated with the VCSEL biased at a current density of only 11 kA/cm2. In addition, using a more spectrally efficient modulation format (16 QAM sub-carrier multiplexing), transmission at 40 Gb/s over 200 m multimode fiber was demonstrated.


electrical parasitics

high speed

differential gain

vertical cavity surface emitting laser

subcarrier multiplexing


Anders Larsson

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Petter Westbergh

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Johan Gustavsson

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Åsa Haglund

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Proceedings of SPIE - The International Society for Optical Engineering

0277786X (ISSN) 1996756X (eISSN)

Vol. 7615 761505-1-11- 761505
9780819480118 (ISBN)







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