The growing demand for bandwidth makes photonic systems a leading candidate for future telecommunication and radar technologies. Integrated photonic systems offer ultra-wideband performance within a small footprint, which can naturally interface with fiber-optic networks for signal transmission. However, it remains challenging to realize narrowband (∼MHz) filters needed for high-performance communications systems using integrated photonics. In this paper, we demonstrate all-silicon microwave-photonic notch filters with 50× higher spectral resolution than previously realized in silicon photonics. This enhanced performance is achieved by utilizing optomechanical interactions to access long-lived phonons, greatly extending available coherence times in silicon. We use a multi-port Brillouin-based optomechanical system to demonstrate ultra-narrowband (2.7 MHz) notch filters with high rejection (57 dB) and frequency tunability over a wide spectral band (6 GHz) within a microwave-photonic link. We accomplish this with an all-silicon waveguide system, using CMOS-compatible fabrication techniques.
The canonical beam splitter - a fundamental building block of quantum optical systems - is a reciprocal element. It operates on forward- and backward-propagating modes in the same way, regardless of direction. The concept of nonreciprocal quantum photonic operations, by contrast, could be used to transform quantum states in a momentum- and direction-selective fashion. Here we demonstrate the basis for such a nonreciprocal transformation in the frequency domain through intermodal Bragg scattering four-wave mixing (BSFWM). Since the total number of idler and signal photons is conserved, the process can preserve coherence of quantum optical states, functioning as a nonreciprocal frequency beam splitter. We explore the origin of this nonreciprocity and find that the phase-matching requirements of intermodal BSFWM produce an enormous asymmetry (76×) in the conversion bandwidths for forward and backward configurations, yielding ∼25 dB of nonreciprocal contrast over several hundred GHz. We also outline how the demonstrated efficiencies (∼10-4) may be scaled to near-unity values with readily accessible powers and pumping configurations for applications in integrated quantum photonics.
We demonstrate an optical waveguide device, capable of supporting the high, invacuum, optical power necessary for trapping a single atom or a cold atom ensemble with evanescent fields. Our photonic integrated platform, with suspended membrane waveguides, successfully manages optical powers of 6 mW (500 μm span) to nearly 30 mW (125 μm span) over an un-tethered waveguide span. This platform is compatible with laser cooling and magnetooptical traps (MOTs) in the vicinity of the suspended waveguide, called the membrane MOT and the needle MOT, a key ingredient for efficient trap loading. We evaluate two novel designs that explore critical thermal management features that enable this large power handling. This work represents a significant step toward an integrated platform for coupling neutral atom quantum systems to photonic and electronic integrated circuits on silicon.
We present narrowband RF-photonic filters in an integrated silicon platform. Using Brillouin interactions, the filters yield narrowband (∼MHZ) filter bandwidths with high signal rejection, and demonstrate tunability over a wide (∼GHz) frequency range.
Passive silicon photonic waveguides are exposed to gamma radiation to understand how the performance of silicon photonic integrated circuits is affected in harsh environments such as space or high energy physics experiments. The propagation loss and group index of the mode guided by these waveguides is characterized by implementing a phase sensitive swept-wavelength interferometric method. We find that the propagation loss associated with each waveguide geometry explored in this study slightly increases at absorbed doses of up to 100 krad (Si). The measured change in group index associated with the same waveguide geometries is negligibly changed after exposure. Additionally, we show that the post-exposure degradation of these waveguides can be improved through heat treatment.
As self-sustained oscillators, lasers possess the unusual ability to spontaneously synchronize. These nonlinear dynamics are the basis for a simple yet powerful stabilization technique known as injection locking, in which a laser's frequency and phase can be controlled by an injected signal. Because of its inherent simplicity and favorable noise characteristics, injection locking has become a workhorse for coherent amplification and high-fidelity signal synthesis in applications ranging from precision atomic spectroscopy to distributed sensing. Within integrated photonics, however, these injection-locking dynamics remain relatively untapped - despite significant potential for technological and scientific impact. Here, we demonstrate injection locking in a silicon photonic Brillouin laser. Injection locking of this monolithic device is remarkably robust, allowing us to tune the laser emission by a significant fraction of the Brillouin gain bandwidth. Harnessing these dynamics, we demonstrate amplification of small signals by more than 23 dB. Moreover, we demonstrate that the injection-locking dynamics of this system are inherently nonreciprocal, yielding unidirectional control and backscatter immunity in an all-silicon system. This device physics opens the door to strategies for phase-noise reduction, low-noise amplification, and backscatter immunity in silicon photonics.
Silicon photonics is a platform that enables densely integrated photonic components and systems and integration with electronic circuits. Depletion mode modulators designed on this platform suffer from a fundamental frequency response limit due to the mobility of carriers in silicon. Lithium niobate-based modulators have demonstrated high performance, but the material is difficult to process and cannot be easily integrated with other photonic components and electronics. In this manuscript, we simultaneously take advantage of the benefits of silicon photonics and the Pockels effect in lithium niobate by heterogeneously integrating silicon photonic-integrated circuits with thin-film lithium niobate samples. We demonstrate the most CMOS-compatible thin-film lithium niobate modulator to date, which has electro-optic 3 dB bandwidths of 30.6 GHz and half-wave voltages of 6.7 V×cm. These modulators are fabricated entirely in CMOS facilities, with the exception of the bonding of a thin-film lithium niobate sample post fabrication, and require no etching of lithium niobate.
Atomic clocks are precision timekeeping devices that form the basis for modern communication and navigation. While many atomic clocks are room-sized systems requiring bulky free space optics and detectors, the Trapped-lon Clock using Technology-On-Chip (TICTOC) project integrates these components into Sandia's existing surface trap technology via waveguides for beam delivery and avalanche photodiodes for light detection. Taking advantage of a multi-ensemble clock interrogation approach, we expect to achieve record time stability (< 1 ns error per year) in a compact (< /1 2 L) clock. Here, we present progress on the development of the integrated devices and recent trapped ion demonstrations.
We present a 30 GHz heterogeneously integrated silicon photonic/lithium niobate Mach-Zehnder modulator simultaneously utilizing the strong Pockels effect in LiNbO3 while also taking advantage of the ability for photonic/electronic integration and mass production associated with silicon photonics. Aside from the final step of bonding the LiNbO3, this modulator can be entirely fabricated using CMOS facilities.
AVFOP 2019 - Avionics and Vehicle Fiber-Optics and Photonics Conference
Yang, Benjamin B.; Lovelace, Brandon; Wier, Brian R.; Campbell, Jacob; Bolding, Mark; Chan, Cheong W.; Vinson, J.G.; Muthuchamy, Tarun; Bhattacharjea, Rajib; Harris, T.R.; Davis, Kyle; Stark, Andrew; Ward, Christopher; Bottenfield, Christian; Ralph, Stephen E.; Gehl, M.; Kodigala, Ashok; Starbuck, Andrew; Dallo, Christina; Pomerene, Andrew; Trotter, Doug; Lentine, Anthony L.
A compact radio frequency (RF) photonic receiver consisting of several photonic integrated circuits (PIC) that performs channelization and simultaneously downconverts the signal is described. A technique is also presented to adjust the phase shifters of the arrayed waveguide grating channelizer without direct phase measurements.