Heterogeneous HI-V/Si3N4 integration for quantum photonic circuits

Photonic integration is as an enabling technology for photonic quantum science, providing great experimental scalability, stability, and functionality. Although the increasing complexity of quantum photonic circuits has allowed proof-of-principle demonstrations of quantum computation, simulation, and metrology, further development is severely limited by the on-chip photon flux that can be made available from external quantum light sources. Overcoming such limitations would allow a significant scaling of quantum photonic experiments, and enable quantum-level investigation of many physical processes observable on-chip through nanophotonic and nanoplasmonic structures (e.g., Kerr, optomechanical, single-photon nonlinearities). Towards such goals, we have developed a scalable, heterogeneous III-V/Si
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integration platform for quantum photonic circuits based on passive Si
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waveguides which directly incorporate nanophotonic single-photon sources based on self-assembled InAs quantum dots (QDs). InAs quantum dots constitute the most promising solid-state triggered single-photon sources to date, while Si
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waveguides offer low-loss propagation, tailorable dispersion and high Kerr nonlinearities which can be used for linear and nonlinear optical signal processing down to the quantum level. In our platform, the building blocks of which are shown in Fig. 1(a), active GaAs waveguide-based geometries containing InAs QDs are designed to efficiently capture QD-emitted single-photons. Captured photons, confined within the GaAs core, are then transferred with high efficiency into a passive Si
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waveguide network via adiabatic mode transformers. Figure 1(b) shows an example device fabricated with our platform: a GaAs microring resonator containing InAs quantum dots, evanescently coupled to a GaAs bus waveguide, which is in turn coupled to an underlying Si
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N
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waveguide through adiabatic mode-transformers. The photoluminescence spectrum for this device, in Fig. 1(b), shows that a single QD exciton near 1125 nm, coupled to a microring whispering-gallery mode, acts as a source of single-photons that are launched directly into the Si
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waveguide. This geometry also allows us to effectively control the QD spontaneous emission decay lifetime by spectrally detuning the WGM with respect to the QD, as shown in Fig. 1(d).