Demonstration of post-growth wavelength control of VCSELs using high-contrast gratings

Erik Haglund; Johan Gustavsson; Jörgen Bengtsson; Åsa Haglund; Anders Larsson; David Fattal; W. V. Sorin; Michael Tan

Demonstration of post-growth wavelength control of VCSELs using high-contrast gratings
Preprint, 2015

We demonstrate post-growth wavelength setting of vertical-cavity surface-emitting lasers (VCSELs) using high-contrast gratings (HCGs). By fabricating HCGs with different duty-cycle and period, the HCG reflection phase can be varied, in effect giving different optical cavity lengths for HCGVCSELs with different grating parameters. This enables fabrication of monolithic multi-wavelength HCG-VCSEL arrays for wavelength-division multiplexing (WDM). The GaAs HCG is suspended in air by selective removal of an InGaP sacrificial layer. Electrically injected 980-nm HCGVCSELs with sub-mA threshold currents indicate high reflectivity from the GaAs HCGs. Lasing over a wavelength span of 15 nm was achieved, enabling a 4-channel WDM array with 5 nm channel spacing. Device design, fabrication and experimental proof-of-concept are presented.

Wavelength division multiplexing

CWDM

VCSELs

Optical waveguides

Surface emitting lasers

High reflectivity

Semiconducting gallium

Gallium arsenide

Optical interconnects

High-contrast gratings

Sacrificial layer

Threshold currents

High contrast grating

Transceivers

Electrically injected

Diffraction gratings

Wavelength control