Angled Flip-Chip Integration of VCSELs on Silicon Photonic Integrated Circuits
Journal article, 2022

An investigation of angled flip-chip integration of a singlemode 850 nm vertical-cavity surface-emitting laser (VCSEL) on a silicon nitride photonic integrated circuit (PIC) is presented. Using numerical FDTD simulations, we consider the conditions under which the VCSEL can be integrated at an angle over a grating coupler with high coupling efficiency and low optical feedback. With both coupling efficiency and feedback decreasing with increasing angle, there is a trade-off. With co-directional coupling, first-order diffraction loss sets in at a critical angle, which further reduces the coupling efficiency. No such critical angle exists for contra-directional coupling. We also experimentally demonstrate angled flip-chip integration of GaAs-based 850 nm single transverse and polarization mode VCSELs over grating couplers on a silicon-nitride PIC. At the output grating coupler, light is either collected by an optical fiber or converted to a photocurrent using a flip-chip integrated GaAs-based photodetector. The latter forms an on-PIC optical link. We measured an insertion loss of 21.9, 17.6 and 20.1 dB with a singlemode fiber, multimode fiber and photodetector over the output grating coupler, respectively.

Optical feedback

Optical waveguides


Vertical cavity surface emitting lasers

Diffraction gratings

optical feedback



silicon-nitride photonic integrated circuit

Flip-chip integration

vertical-cavity surfaceemitting laser

coupling efficiency


Alexander Caut

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Mehdi Jahed

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

J. Goyvaerts

Ghent university

Marc Rensing

Tyndall National Institute at National University of Ireland, Cork

Magnus Karlsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Anders Larsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Gunther Roelkens

Ghent university

Roel G. Baets

Ghent university

Peter O'brien

Tyndall National Institute at National University of Ireland, Cork

Journal of Lightwave Technology

0733-8724 (ISSN) 1558-2213 (eISSN)

Vol. 40 15 5190-5200

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Other Electrical Engineering, Electronic Engineering, Information Engineering



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