Quasinormal-Mode Perturbation Theory for Dissipative and Dispersive Optomechanics.

Despite the several novel features arising from the dissipative optomechanical coupling, such effect remains vastly unexplored due to the lack of a simple formalism that captures non-Hermiticity in the engineering of optomechanical systems. In this Letter, we show that quasinormal-mode-based perturbation theory is capable of correctly predicting both dispersive and dissipative optomechanical couplings. We validate our model through simulations and also by comparison with experimental results reported in the literature.

Fourier transform spectrometer on silicon with thermo-optic non-linearity and dispersion correction.

Miniaturized integrated spectrometers will have unprecedented impact on applications ranging from unmanned aerial vehicles to mobile phones, and silicon photonics promises to deliver compact, cost-effective devices. Mirroring its ubiquitous free-space counterpart, a silicon photonics-based Fourier transform spectrometer (Si-FTS) can bring broadband operation and fine resolution to the chip scale. Here we present the modeling and experimental demonstration of a thermally tuned Si-FTS accounting for dispersion, thermo-optic non-linearity, and thermal expansion.

Hybrid multimode resonators based on grating-assisted counter-directional couplers.

Research thrusts in silicon photonics are developing control operations using higher order waveguide modes for next generation high-bandwidth communication systems. In this context, devices allowing optical processing of multiple waveguide modes can reduce architecture complexity and enable flexible on-chip networks. We propose and demonstrate a hybrid resonator dually resonant at the 1st and 2nd order modes of a silicon waveguide.

Modeling quasi-dark states with temporal coupled-mode theory.

Coupled resonators are commonly used to achieve tailored spectral responses and allow novel functionalities in a broad range of applications. The Temporal Coupled-Mode Theory (TCMT) provides a simple and general tool that is widely used to model these devices. Relying on TCMT to model coupled resonators might however be misleading in some circumstances due to the lumped-element nature of the model.

Spectral engineering with coupled microcavities: active control of resonant mode-splitting.

Optical mode-splitting is an efficient tool to shape and fine-tune the spectral response of resonant nanophotonic devices. The active control of mode-splitting, however, is either small or accompanied by undesired resonance-shifts, often much larger than the resonance splitting. We report a control mechanism that enables reconfigurable and widely tunable mode splitting while efficiently mitigating undesired resonance shifts.

Embedded coupled microrings with high-finesse and close-spaced resonances for optical signal processing.

Single microring resonators have been used in applications such as wavelength multicasting and microwave photonics, but the dependence of the free spectral range with ring radius imposes a trade-off between the required GHz optical channel spacing, footprint and power consumption. We demonstrate four-channel all-optical wavelength multicasting using only 1 mW of control power, with converted channel spacing of 40-60 GHz. Our device is based on a compact embedded microring design fabricated on a scalable SOI platform.

Carrier saturation in multiple quantum well metallo-dielectric semiconductor nanolaser: is bulk material a better choice for gain media?

Although multi quantum well (MQW) structure is frequently suggested as the appropriate medium for providing optical gain in nanolasers with low threshold current, we demonstrate that in general bulk gain medium can be a better choice. We show that the high threshold gain required for nanolasers demands high threshold carrier concentrations and therefore a highly degenerate condition in which the barriers between the quantum wells are heavily pumped. As a result, there occurs spontaneous emission from the barrier in very dissipative low Q modes or undesired confined higher Q modes with resonance wavelengths close to the barrier bandgap.

Purcell effect in sub-wavelength semiconductor lasers.

We present a formal treatment of the modification of spontaneous emission rate by a cavity (Purcell effect) in sub-wavelength semiconductor lasers. To explicitly express the assumptions upon which our formalism builds, we summarize the results of non-relativistic quantum electrodynamics (QED) and the emitter-field-reservoir model in the quantum theory of damping. Within this model, the emitter-field interaction is modified to the extent that the field mode is modified by its environment.

a-SiOx active photonic crystal resonator membrane fabricated by focused Ga+ ion beam.

We have fabricated thin erbium-doped amorphous silicon sub-oxide (a-SiOx) photonic crystal membrane using focused gallium ion beam (FIB). The photonic crystal is composed of a hexagonal lattice with a H1 defect supporting two quasi-doubly degenerate second order dipole states. 2-D simulation was used for the design of the structure and full 3-D FDTD (Finite-Difference Time-Domain) numerical simulations were performed for a complete analysis of the structure.