Tunable quantum emitters on large-scale foundry silicon photonics.

Controlling large-scale many-body quantum systems at the level of single photons and single atomic systems is a central goal in quantum information science and technology. Intensive research and development has propelled foundry-based silicon-on-insulator photonic integrated circuits to a leading platform for large-scale optical control with individual mode programmability. However, integrating atomic quantum systems with single-emitter tunability remains an open challenge.

A self-referenced interferometer for in situ cryogenic wafer curvature measurements.

A self-referenced interferometer to measure time-varying curvature in mechanically unstable environments is needed in many applications. One application that demands this measurement technique with fast data acquisition, 2D sensitivity, and insensitivity to vibration is the measurement of thermal strain in thin films in operational environments. The diverging beam interferometer described here demonstrates an angular sensitivity to the local curvature using interferograms captured by a CMOS camera.

Bright Telecom-Wavelength Single Photons Based on a Tapered Nanobeam.

Telecom-wavelength single photons are essential components for long-distance quantum networks. However, bright and pure single photon sources at telecom wavelengths remain challenging to achieve. Here, we demonstrate a bright telecom-wavelength single photon source based on a tapered nanobeam containing InAs/InP quantum dots.

Super-Radiant Emission from Quantum Dots in a Nanophotonic Waveguide.

Future scalable photonic quantum information processing relies on the ability of integrating multiple interacting quantum emitters into a single chip. Quantum dots provide ideal on-chip quantum light sources. However, achieving quantum interaction between multiple quantum dots on-a-chip is a challenging task due to the randomness in their frequency and position, requiring local tuning technique and long-range quantum interaction.

Perfect Strain Relaxation in Metamorphic Epitaxial Aluminum on Silicon through Primary and Secondary Interface Misfit Dislocation Arrays.

Understanding the atomically precise arrangement of atoms at epitaxial interfaces is important for emerging technologies such as quantum materials that have function and performance dictated by bonds and defects that are energetically active on the micro-electronvolt scale. A combination of atomistic modeling and dislocation theory analysis describes both primary and secondary dislocation networks at the metamorphic Al/Si (111) interface, which is experimentally validated by atomic resolution scanning transmission electron microscopy. The electron microscopy images show primary misfit dislocations for the majority of the strain relief and evidence of a secondary structure allowing for complete relaxation of the Al-Si misfit strain.

Hybrid Integration of Solid-State Quantum Emitters on a Silicon Photonic Chip.

Scalable quantum photonic systems require efficient single photon sources coupled to integrated photonic devices. Solid-state quantum emitters can generate single photons with high efficiency, while silicon photonic circuits can manipulate them in an integrated device structure. Combining these two material platforms could, therefore, significantly increase the complexity of integrated quantum photonic devices.

Two-Photon Interference from the Far-Field Emission of Chip-Integrated Cavity-Coupled Emitters.

Interactions between solid-state quantum emitters and cavities are important for a broad range of applications in quantum communication, linear optical quantum computing, nonlinear photonics, and photonic quantum simulation. These applications often require combining many devices on a single chip with identical emission wavelengths in order to generate two-photon interference, the primary mechanism for achieving effective photon-photon interactions. Such integration remains extremely challenging due to inhomogeneous broadening and fabrication errors that randomize the resonant frequencies of both the emitters and cavities.

Enhanced continuous-wave four-wave mixing efficiency in nonlinear AlGaAs waveguides.

Enhancements of the continuous-wave four-wave mixing conversion efficiency and bandwidth are accomplished through the application of plasma-assisted photoresist reflow to reduce the sidewall roughness of sub-square-micron-modal area waveguides. Nonlinear AlGaAs optical waveguides with a propagation loss of 0.56 dB/cm demonstrate continuous-wave four-wave mixing conversion efficiency of -7.

Efficient continuous-wave four-wave mixing in bandgap-engineered AlGaAs waveguides.

We present a side-by-side comparison of the nonlinear behavior of four passive AlGaAs ridge waveguides where the bandgap energy of the core layers ranges from 1.60 to 1.79 eV.

Low propagation loss AlGaAs waveguides fabricated with plasma-assisted photoresist reflow.

We report low-loss deep-etch AlGaAs optical waveguides fabricated with nitrogen plasma-assisted photoresist reflow. The simultaneous application of a nitrogen plasma and heat is used to reduce the line edge roughness of patterned photoresist and limit the lateral spread of the photoresist patterns of submicron-scale waveguides. Comparison of the edge roughness of the etched sidewalls between the as-developed and smoothed photoresist etch samples show a reduction of the RMS roughness from 3.

Mid-infrared difference-frequency generation in suspended GaAs waveguides.

We experimentally demonstrate mid-infrared difference-frequency generation in suspended 181 nm thick GaAs waveguides. Generation of the idler at wavelengths between 2800 and 3150 nm is enabled by form-birefringent phase-matching in ultrahigh index-contrast waveguides. Nonlinear mixing has a measured efficiency of 0.

Measurement of small birefringence and loss in a nonlinear single-mode waveguide.

We design and fabricate a birefringent semiconductor waveguide for application to nonlinear photonics, demonstrating that it is possible to engineer a small birefringence into such a device using multiple core layers. We also demonstrate a simple technique to accurately determine small waveguide birefringence using a differential measurement, present useful methods for coupling light into and out of the device, and make estimates of coupling and linear device losses.

Phase-sensitive amplification using gain saturation in a nonlinear Sagnac interferometer.

Phase-sensitive amplification of picosecond optical pulses was demonstrated using an SOA as the nonlinear medium inside a Sagnac interferometer. Ratios of maximum to minimum gain of more than 3:1 were experimentally measured. Numerical simulations using a semiconductor amplifier model are consistent with experiments.

Implementation of discrete unitary transformations by multimode waveguide holograms.

Integration of holograms into multimode waveguides allows the implementation of arbitrary unitary mode transformations and unitary matrix-vector multiplication. Theoretical analysis is used to justify a design approach to implement specific functions in these devices. Based on this approach, a compact mode-order converter, a Hadamard transformer, and a spatial pattern generator-correlator are proposed and analyzed.

Narrowband generation of ultrafast acoustic and thermal transients in thin films for enhanced detectability.

A technique for the narrowband generation of ultrafast acoustic and thermal transients in thin films is demonstrated; this technique allows for enhanced detectability of these transients. The approach pursued uses a reduced-bandwidth, optical pulse train for excitation that is constructed from a series of time-delayed pulses derived from a single-laser pulse. The underlying physical limitations of this approach are considered in order to assess conditions under which successful bandwidth reduction can be realized.