Self-Sustaining Water Microdroplet Resonators Using 3D-Printed Microfluidics.

Microdroplet resonators provide an excellent tool for optical studies of water, but water microdroplets are difficult to maintain outside a carefully controlled environment. We present a method for maintaining a water microdroplet resonator on a 3D-printed hydrophobic surface in an ambient environment. The droplet is maintained through a passive microfluidic system that supplies water to the droplet through a vertical channel at a rate equivalent to its evaporation.

Deep learning-enhanced, open-source eigenmode expansion.

We present an open-source eigenmode expansion (EME) software package entirely implemented in the Python programming language. Eigenmode expansion Python (EMEPy) utilizes artificial neural networks to reproduce electromagnetic eigenmode field profiles to accelerate the EME process by a factor of 3. EMEPy provides an intuitive scripting interface, is easily compatible with a number of other Python packages, and is useful for educators and new designers.

3D printed mounts for microdroplet resonators.

Liquid microdroplet resonators provide an excellent tool for optical studies due to their innate smoothness and high quality factors, but precise control over their geometries can be difficult. In contrast, three dimensional (3D) printed components are highly customizable but suffer from roughness and pixelation. We present 3D printed structures which leverage the versatility of 3D printing with the smoothness of microdroplets.

Post-fabrication tuning of microring resonators using 3D-printed microfluidics.

We demonstrate a method of tuning the resonant frequencies of silicon microring resonators using a 3D-printed microfluidic chip overlaid directly on the photonic circuit with zero energy consumption following the initial tuning. Aqueous solutions with different concentrations of NaCl are used in experimentation. A shift of a full free spectral range is observed at a concentration of 10% NaCl.

Automated Photonic Tuning of Silicon Microring Resonators Using a 3D-printed Microfluidic Mixer.

We demonstrate a novel method to automate tuning of microring resonators using 3D-printed microfluidic control capable of resonance wavelength shifts of 4 nm. We use a custom 3D-printer that can fabricate microfluidic devices with sub-10 μm features and that perform automatic pumping, mixing, and dilution operations.

Self-Sustaining 3D Thin Liquid Films in Ambient Environments.

Thin liquid films (TLF) have fundamental and technological importance ranging from the thermodynamics of cell membranes to the safety of light-water cooled nuclear reactors. The creation of stable water TLFs, however, is very difficult. In this paper, the realization of thin liquid films of water with custom 3D geometries that persist indefinitely in ambient environments is reported.

Designing integrated photonic devices using artificial neural networks.

We develop and experimentally validate a practical artificial neural network (ANN) design framework for devices that can be used as building blocks in integrated photonic circuits. As case studies, we train ANNs to model both strip waveguides and chirped Bragg gratings using a small number of simple input and output parameters relevant to designers of integrated photonic circuits. Once trained, the ANNs decrease the computational cost relative to traditional design methodologies by more than 4 orders of magnitude.

Entangled photon generation using four-wave mixing in azimuthally symmetric microresonators.

A novel quantum mechanical formulation of the bi-photon wavefunction and spectra resulting from four-wave mixing is developed for azimuthally symmetric systems. Numerical calculations are performed verifying the use of the angular group velocity and angular group velocity dispersion in such systems, as opposed their commonly used linear counterparts. The dispersion profile and bi-photon spectra of two illustrative examples are given, emphasizing the physical origin of the effects leading to the conditions for angular momentum and energy conservation.

Optomechanical crystals.

Periodicity in materials yields interesting and useful phenomena. Applied to the propagation of light, periodicity gives rise to photonic crystals, which can be precisely engineered for such applications as guiding and dispersing optical beams, tightly confining and trapping light resonantly, and enhancing nonlinear optical interactions. Photonic crystals can also be formed into planar lightwave circuits for the integration of optical and electrical microsystems.

Characterization of radiation pressure and thermal effects in a nanoscale optomechanical cavity.

Optical forces in guided-wave nanostructures have recently been proposed as an effective means of mechanically actuating and tuning optical components. In this work, we study the properties of a photonic crystal optomechanical cavity consisting of a pair of patterned Si3N4 nanobeams. Internal stresses in the stoichiometric Si3N4 thin-film are used to produce inter-beam slot-gaps ranging from 560-40 nm.

Realization of an all-optical zero to pi cross-phase modulation jump.

We report on the experimental demonstration of an all-optical pi cross-phase modulation jump. By performing a preselection, an optically induced unitary transformation, and then a postselection on the polarization degree of freedom, the phase of the output beam acquires either a zero or pi phase shift (with no other possible values). The postselection results in optical loss in the output beam.

Preservation of energy-time entanglement in a slow light medium.

We demonstrate the preservation of entanglement of an energy-time entangled biphoton through a slow light medium. Using the D(1) and D(2) fine structure resonances of Rubidium, we delay one photon of the 1.5 THz biphoton by approximately 1.

Storage and retrieval of multimode transverse images in hot atomic Rubidium vapor.

We report on the experimental realization of the storage of images in a hot vapor of Rubidium atoms. The images are stored in and retrieved from the long-lived ground state atomic coherences. We show that an image impressed onto a 500 ns pulse can be stored and retrieved up to 30 mus later.

Slow-light fourier transform interferometer.

We describe a new type of Fourier transform (FT) interferometer in which the tunable optical delay between the two arms is realized by using a continuously variable slow-light medium instead of a moving arm as in a conventional setup. The spectral resolution of such a FT interferometer exceeds that of a conventional setup of comparable size by a factor equal to the maximum group index of the slow-light medium. The scheme is experimentally demonstrated by using a rubidium atomic vapor cell as the tunable slow-light medium, and the spectral resolution is enhanced by a factor of approximately 100.

Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow light in cesium vapor.

We demonstrate an all-optical delay line in hot cesium vapor that tunably delays 275 ps input pulses up to 6.8 ns and 740 input ps pulses up to 59 ns (group index of approximately 200) with little pulse distortion. The delay is made tunable with a fast reconfiguration time (hundreds of ns) by optically pumping out of the atomic ground states.

All-optical delay of images using slow light.

Two-dimensional images carried by optical pulses (2 ns) are delayed by up to 10 ns in a 10 cm cesium vapor cell. By interfering the delayed images with a local oscillator, the transverse phase and amplitude profiles of the images are shown to be preserved. It is further shown that delayed images can be well preserved even at very low light levels, where each pulse contains on average less than one photon.