Silicon integrated 850-nm hybrid vertical-cavity laser for life science applications
Paper in proceedings, 2017
The integration of efficient laser sources on silicon would enable fully integrated silicon photonic circuits with a high degree of functionality and performance complexity for many applications . Different integration concepts have therefore been suggested, where one such technique is the heterogeneous integration of a vertical-cavity laser (VCL), referred to as a hybrid VCL. It is promising as it has potential to offer low drive currents, high modulation bandwidths, and small footprint [2-4]. In-plane emission with waveguide-coupling can be achieved by an intra-cavity waveguide embossed with a weak diffraction grating, as an example . Integration of such short-wavelength laser sources on a silicon-nitride (SiN) waveguide platform on silicon may enable fully integrated silicon photonic circuits for applications not only in short-reach optical interconnects but also in life science and bio-photonics.
As a first step in realizing short-wavelength hybrid VCLs with in-plane emission coupled to a SiN waveguide, we have developed a technique to produce high performance 850-nm hybrid VCLs with out-of-plane emission. It is based on adhesive bonding of epitaxial AlGaAs-material onto a dielectric distributed Bragg reflector (DBR) on silicon [6-8]. We have fabricated devices with surface emission having sub-mA threshold current, >2 mW output power, and 25 Gbit/s modulation speed .
To be able to demonstrate in-plane emission with SiN waveguide coupling from our hybrid 850-nm VCLs, our next step is to add a SiN waveguide structure with embossed grating on top of the dielectric DBR, before adhesively bonding the AlGaAs-material. So far, based on numerical simulations, we have designed a device that is predicted to yield a slope efficiency of ~0.3 W/A at 25 °C for the light coupled to a single-mode waveguide, while maintaining a sub-mA threshold current for the lasing .
This work is supported by the European Union’s Horizon 2020 research and innovation program under grant agreement no. 688519 (PIX4life), the Swedish Foundation for Strategic Research (SSF), and the European FP7-ERC-InSpectra Advanced Grant.
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