Controlled waveguide coupling for photon emission from colloidal PbS quantum dot using tunable microcavity made of optical polymer and silicon

• Tunable microcavity device on Si substrate is proposed as a single-photon source.
• The device is composed of optical polymer and Si layers with a colloidal QD.
• Cavity size is controlled by electrostatic micromachine behavior.
• The prototype device successfully showed the tunability of cavity size.
• The device is suitable to quantum device integration with Si photonics technology.

A tunable microcavity device composed of optical polymer and Si with a colloidal quantum dot (QD) is proposed as a single-photon source for planar optical circuit. Cavity size is controlled by electrostatic micromachine behavior with the air bridge structure to tune timing of photon injection into optical waveguide from QD. Three-dimensional positioning of a QD in the cavity structure is available using a nanohole on Si processed by scanning probe microscope lithography. We fabricated the prototype microcavity with PbS-QD-mixed polymenthyl methacrylate on a SOI (semiconductor-on-insulator) substrate to show the tunability of cavity size as the shift of emission peak wavelength of QD ensemble.