High-Performance Silicon Photonic Single-Sideband Modulators for Cold Atom Interferometry

The most complicated and challenging system within a light-pulse atom interferometer (LPAI) is the laser system, which controls the frequencies and intensities of multiple laser beams over time to configure quantum gravity and inertial sensors. The main function of an LPAI laser system is to perform cold-atom generation and state-selective detection and to generate coherent two-photon process for the light-pulse sequence. Substantial miniaturization and ruggedization of the laser system can be achieved by bringing together most key functions of the laser and optical system onto a photonic integrated circuit (PIC). Here we demonstrate a high-performance silicon photonic carrier-suppressed single-sideband (CS-SSB) modulator PIC with dual-parallel Mach-Zehnder modulators (DP-MZMs) operating near 1560 nm, which can dynamically shift the frequency of the light for the desired function within the LPAI. Independent RF control of channels in SSB modulator enables the extensive study of imbalances in both the optical and RF phases and amplitudes to simultaneously reach 30 dB carrier suppression and unprecedented 47.8 dB sideband suppression with peak conversion efficiency of -6.846 dB (20.7 %). Using a silicon photonic SSB modulator with time-multiplexed frequency shifting in an LPAI laser system, we demonstrate cold-atom generation, state-selective detection, and the realization of atom interferometer fringes to estimate gravitational acceleration, $g \approx 9.77 \pm 0.01 \,\rm{m/s^2}$, in a Rubidium ($^{87}$Rb) atom system.Comment: 18 pages, 9 figure

A Compact Cold-Atom Interferometer with a High Data-Rate Grating Magneto-Optical Trap and a Photonic-Integrated-Circuit-Compatible Laser System

The extreme miniaturization of a cold-atom interferometer accelerometer requires the development of novel technologies and architectures for the interferometer subsystems. Here we describe several component technologies and a laser system architecture to enable a path to such miniaturization. We developed a custom, compact titanium vacuum package containing a microfabricated grating chip for a tetrahedral grating magneto-optical trap (GMOT) using a single cooling beam. In addition, we designed a multi-channel photonic-integrated-circuit-compatible laser system implemented with a single seed laser and single sideband modulators in a time-multiplexed manner, reducing the number of optical channels connected to the sensor head. In a compact sensor head containing the vacuum package, sub-Doppler cooling in the GMOT produces 15 uK temperatures, and the GMOT can operate at a 20 Hz data rate. We validated the atomic coherence with Ramsey interferometry using microwave spectroscopy, then demonstrated a light-pulse atom interferometer in a gravimeter configuration for a 10 Hz measurement data rate and T = 0 - 4.5 ms interrogation time, resulting in $\Delta$ g / g = 2.0e-6. This work represents a significant step towards deployable cold-atom inertial sensors under large amplitude motional dynamics.Comment: 21 pages, 10 figure

Singularities of non-Hermitian Photonic Systems and their Applications

The following dissertation focuses on a new class of devices based on singularities of non-Hermitian photonic systems for applications pertaining to sensing and lasing. These are systems with electromagnetic resonances that exhibit peculiar behavior. One in which multiple resonances of shared symmetry coalesce to form so called Exceptional Point (EP) singularities. Systems at EPs are known to be highly sensitive to environmental perturbations making them conducive for sensing applications. The first half of this dissertation is centered on investigating resonance dynamics of plasmonic nanostructures, comprised of metallic nano-particles, as they have the ability to confine light to an extremely small space (i.e. sub-wavelength) which in turn helps detect particles of equivalent size. Herein, a framework for designing EPs in coupled metallic nano-particle arrays is presented. The latter half is centered on another type of peculiarity in which a resonance lifetime in a cavity diverges to infinity (i.e. infinite quality factor). These are resonance states that defy conventional wisdom by remaining localized, or bound, to a cavity while residing in a continuum of radiating or leaky states. These singularities are appropriately termed Bound States in the Continuum (BICs). This dissertation presents the first experimental demonstration of a BIC laser. It is constructed on a III-V semiconductor material platform (InGaAsP) which emits in the telecommunication band (~1.55 μm) and operates at room temperature. This laser is intrinsically low threshold (i.e., power efficient) and can be compact in size. It offers some unique and useful properties in terms of its tunability in emission wavelength and emission angle. It has the ability to naturally generate vector beams and the potential for high-power emission. A brief discussion on challenges to real-world applications is provided for these technologies

Singularities of non-Hermitian Photonic Systems and their Applications

The following dissertation focuses on a new class of devices based on singularities of non-Hermitian photonic systems for applications pertaining to sensing and lasing. These are systems with electromagnetic resonances that exhibit peculiar behavior. One in which multiple resonances of shared symmetry coalesce to form so called Exceptional Point (EP) singularities. Systems at EPs are known to be highly sensitive to environmental perturbations making them conducive for sensing applications. The first half of this dissertation is centered on investigating resonance dynamics of plasmonic nanostructures, comprised of metallic nano-particles, as they have the ability to confine light to an extremely small space (i.e. sub-wavelength) which in turn helps detect particles of equivalent size. Herein, a framework for designing EPs in coupled metallic nano-particle arrays is presented. The latter half is centered on another type of peculiarity in which a resonance lifetime in a cavity diverges to infinity (i.e. infinite quality factor). These are resonance states that defy conventional wisdom by remaining localized, or bound, to a cavity while residing in a continuum of radiating or leaky states. These singularities are appropriately termed Bound States in the Continuum (BICs). This dissertation presents the first experimental demonstration of a BIC laser. It is constructed on a III-V semiconductor material platform (InGaAsP) which emits in the telecommunication band (~1.55 μm) and operates at room temperature. This laser is intrinsically low threshold (i.e., power efficient) and can be compact in size. It offers some unique and useful properties in terms of its tunability in emission wavelength and emission angle. It has the ability to naturally generate vector beams and the potential for high-power emission. A brief discussion on challenges to real-world applications is provided for these technologies