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GaSb on silicon short-wave infrared integrated laser sources

Research Area: Integrated lasers and LEDs , Mid IR silicon photonics , Heterogeneous integration technology for silicon photonics , Silicon photonics for lab-on-chip spectroscopy

Main Researcher: Ruijun Wang

Laser sources emitting in the 2 3 m region has been attracting a lot of attention recently for security and environmental applications, since several important gases, like CO, CH4, N2O, etc. can be detected in this wavelength range. Among the III-V material systems, GaSb-based heterostructures are a perfectly suited semiconductor material for covering this range. In this project, GaSb-based vertical-cavity surface-emitting lasers (VCSELs) and edge emitting lasers are designed and fabricated based on Si-electronics-compatible processes and adhesive wafer bonding technology. The integration of the GaSb die on the SOI is realized by using an ultra-thin Benzocyclobutene (DVS-BCB) layer as an adhesive bonding agent. After bonding, the GaSb substrate is removed and the III-V laser is processed (Figure 1).

Figure 1: GaSb heterogeneous integration process flow.
Figure 1: GaSb heterogeneous integration process flow.

VCSELs are good candidates for sources in the short-wave infrared, since they can provide valuable characteristics such as low power consumption, small beam divergence, wide tunability and cost-effective packaging. Traditional VCSEL consists of two distributed Bragg reflector (DBR) mirrors parallel to the wafer surface with an active region for the laser light generation in between. Since single-layer high contrast grating (HCG) structure can offer very high reflectivity for a certain spectral band by design, it can be used as to replace the traditional very thick DBR. Freestanding HCGs can be actuated resulting in a change of the resonance wavelength of the cavity. So a widely-tunable electrically-pumped GaSb VCSEL can be fabricated based on a CMOS-compatible HCG mirror and adhesive wafer bonding technology.

Figure 2: (a) schematic of the widely tunable GaSb/silicon hybrid VCSEL structure based on a high contrast grating as a bottom mirror; (b) Field profile of the resonant mode of the structure.
Figure 2: (a) schematic of the widely tunable GaSb/silicon hybrid VCSEL structure based on a high contrast grating as a bottom mirror; (b) Field profile of the resonant mode of the structure.

In the telecommunication wavelength range, several III-V on silicon integrated edge-emitting laser structures were developed for silicon photonic circuit light sources. Such structures can however also be realized in the short-wave infrared wavelength rang. Figure 3 shows a GaSb Fabry-Perot laser integrated on a silicon waveguide platform and an SEM cross-section of the fabricated device.

Figure 3: (a) Schematic drawing of the integrated GaSb Fabry-Perot laser, (b) SEM cross-section of the fabricated device.
Figure 3: (a) Schematic drawing of the integrated GaSb Fabry-Perot laser, (b) SEM cross-section of the fabricated device.

Other people involved:

Publications

        International Conferences

      1. Z. Wang, Marianna Pantouvaki, G. Morthier, Clement Merckling, Joris Van Campenhout, D. Van Thourhout, G. Roelkens, Heterogeneous Integration of InP Devices on Silicon, the 28th International Conference on Indium Phosphide and Related Materials (IPRM) (invited), Japan, p.paper ThD1-1 (2016)  Download this Publication (379KB).
      2. R. Wang, D. Sanchez, G. Roelkens, Design of a MEMS tunable mid-infrared VCSEL integrated on the SOI platform , Proceedings of the 2013 Annual Symposium of the IEEE Photonics Society Belenux Chapter, Netherlands, p.159-162 (2013)  Download this Publication (462KB).

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