Sub-100 Hz intrinsic linewidth 852 nm silicon nitride external cavity laser.

We demonstrate an external cavity laser with intrinsic linewidth below 100 Hz around an operating wavelength of 852 nm, selected for its relevance to laser cooling and manipulation of cesium atoms. This system achieves a maximum CW output power of 24 mW, a wavelength tunability over 10 nm, and a side-mode suppression ratio exceeding 50 dB. This performance level is facilitated by careful design of a low-loss integrated silicon nitride photonic circuit serving as the external cavity combined with commercially available semiconductor gain chips.

Sub-Hz fundamental, sub-kHz integral linewidth self-injection locked 780 nm hybrid integrated laser.

Today's precision experiments for timekeeping, inertial sensing, and fundamental science place strict requirements on the spectral distribution of laser frequency noise. Rubidium-based experiments utilize table-top 780 nm laser systems for high-performance clocks, gravity sensors, and quantum gates. Wafer-scale integration of these lasers is critical for enabling systems-on-chip.

Anneal-free ultra-low loss silicon nitride integrated photonics.

Heterogeneous and monolithic integration of the versatile low-loss silicon nitride platform with low-temperature materials such as silicon electronics and photonics, III-V compound semiconductors, lithium niobate, organics, and glasses has been inhibited by the need for high-temperature annealing as well as the need for different process flows for thin and thick waveguides. New techniques are needed to maintain the state-of-the-art losses, nonlinear properties, and CMOS-compatible processes while enabling this next generation of 3D silicon nitride integration. We report a significant advance in silicon nitride integrated photonics, demonstrating the lowest losses to date for an anneal-free process at a maximum temperature 250 °C, with the same deuterated silane based fabrication flow, for nitride and oxide, for an order of magnitude range in nitride thickness without requiring stress mitigation or polishing.

Integrated optical frequency division for microwave and mmWave generation.

The generation of ultra-low-noise microwave and mmWave in miniaturized, chip-based platforms can transform communication, radar and sensing systems. Optical frequency division that leverages optical references and optical frequency combs has emerged as a powerful technique to generate microwaves with superior spectral purity than any other approaches. Here we demonstrate a miniaturized optical frequency division system that can potentially transfer the approach to a complementary metal-oxide-semiconductor-compatible integrated photonic platform.

Integrated photonic molecule Brillouin laser with a high-power sub-100-mHz fundamental linewidth.

Photonic integrated lasers with an ultra-low fundamental linewidth and a high output power are important for precision atomic and quantum applications, high-capacity communications, and fiber sensing, yet wafer-scale solutions have remained elusive. Here we report an integrated stimulated Brillouin laser (SBL), based on a photonic molecule coupled resonator design, that achieves a sub-100-mHz fundamental linewidth with greater than 10-mW output power in the C band, fabricated on a 200-mm silicon nitride (SiN) CMOS-foundry compatible wafer-scale platform. The photonic molecule design is used to suppress the second-order Stokes (S2) emission, allowing the primary lasing mode to increase with the pump power without phase noise feedback from higher Stokes orders.

Photonic integrated beam delivery for a rubidium 3D magneto-optical trap.

Cold atoms are important for precision atomic applications including timekeeping and sensing. The 3D magneto-optical trap (3D-MOT), used to produce cold atoms, will benefit from photonic integration to improve reliability and reduce size, weight, and cost. These traps require the delivery of multiple, large area, collimated laser beams to an atomic vacuum cell.

Integrated programmable strongly coupled three-ring resonator photonic molecule with ultralow-power piezoelectric control.

Photonic molecules can realize complex optical energy modes that simulate states of matter and have application to quantum, linear, and nonlinear optical systems. To achieve their full potential, it is critical to scale the photonic molecule energy state complexity and provide flexible, controllable, stable, high-resolution energy state engineering with low power tuning mechanisms. In this work, we demonstrate a controllable, silicon nitride integrated photonic molecule, with three high-quality factor ring resonators strongly coupled to each other and individually actuated using ultralow-power thin-film lead zirconate titanate (PZT) tuning.

Ultra-low loss quantum photonic circuits integrated with single quantum emitters.

The scaling of many photonic quantum information processing systems is ultimately limited by the flux of quantum light throughout an integrated photonic circuit. Source brightness and waveguide loss set basic limits on the on-chip photon flux. While substantial progress has been made, separately, towards ultra-low loss chip-scale photonic circuits and high brightness single-photon sources, integration of these technologies has remained elusive.

Silicon nitride stress-optic microresonator modulator for optical control applications.

Modulation-based control and locking of lasers, filters and other photonic components is a ubiquitous function across many applications that span the visible to infrared (IR), including atomic, molecular and optical (AMO), quantum sciences, fiber communications, metrology, and microwave photonics. Today, modulators used to realize these control functions consist of high-power bulk-optic components for tuning, sideband modulation, and phase and frequency shifting, while providing low optical insertion loss and operation from DC to 10s of MHz. In order to reduce the size, weight and cost of these applications and improve their scalability and reliability, modulation control functions need to be implemented in a low loss, wafer-scale CMOS-compatible photonic integration platform.

Ultralow 0.034 dB/m loss wafer-scale integrated photonics realizing 720 million Q and 380 μW threshold Brillouin lasing.

We demonstrate 0.034 dB/m loss waveguides in a 200-mm wafer-scale, silicon nitride (SiN) CMOS-foundry-compatible integration platform. We fabricate resonators that measure up to a 720 million intrinsic Q resonator at 1615 nm wavelength with a 258 kHz intrinsic linewidth.

Ultra-low loss visible light waveguides for integrated atomic, molecular, and quantum photonics.

Atomic, molecular and optical (AMO) visible light systems are the heart of precision applications including quantum, atomic clocks and precision metrology. As these systems scale in terms of number of lasers, wavelengths, and optical components, their reliability, space occupied, and power consumption will push the limits of using traditional laboratory-scale lasers and optics. Visible light photonic integration is critical to advancing AMO based sciences and applications, yet key performance aspects remain to be addressed, most notably waveguide losses and laser phase noise and stability.

Visible light photonic integrated Brillouin laser.

Narrow linewidth visible light lasers are critical for atomic, molecular and optical (AMO) physics including atomic clocks, quantum computing, atomic and molecular spectroscopy, and sensing. Stimulated Brillouin scattering (SBS) is a promising approach to realize highly coherent on-chip visible light laser emission. Here we report demonstration of a visible light photonic integrated Brillouin laser, with emission at 674 nm, a 14.

422 Million intrinsic quality factor planar integrated all-waveguide resonator with sub-MHz linewidth.

High quality-factor (Q) optical resonators are a key component for ultra-narrow linewidth lasers, frequency stabilization, precision spectroscopy and quantum applications. Integration in a photonic waveguide platform is key to reducing cost, size, power and sensitivity to environmental disturbances. However, to date, the Q of all-waveguide resonators has been relegated to below 260 Million.

High index contrast photonic platforms for on-chip Raman spectroscopy.

Nanophotonic waveguide enhanced Raman spectroscopy (NWERS) is a sensing technique that uses a highly confined waveguide mode to excite and collect the Raman scattered signal from molecules in close vicinity of the waveguide. The most important parameters defining the figure of merit of an NWERS sensor include its ability to collect the Raman signal from an analyte, i.e.

Integrated optical driver for interferometric optical gyroscopes.

We present the first chip-scale "integrated optical driver" (IOD) that can interrogate with a sensing coil to realize an interferometric optical gyroscope. The chip comprises a light source, three photodiodes, two phase modulators and two 3-dB couplers within an area of 4.5 mm.

Programmable eye-opener lattice filter for multi-channel dispersion compensation using an integrated compact low-loss silicon nitride platform.

A tunable eye-opening lattice filter for dispersion compensation is demonstrated on an ultra low-loss waveguide platform based on a compact high-aspect ratio SiN core. A programmable 10th order lattice filter is demonstrated by cascading a total of 21 Mach-Zehnder interferometers with programmable delay lines of lengths designed at the baseband data rate. The filter has a footprint of 2.

Frequency modulated lasers for interferometric optical gyroscopes.

We study the use of frequency modulated lasers in interferometric optical gyroscopes and show that by exploiting various frequency modulation signals, the laser coherence can be controlled. We show that both angle random walk and bias stability of an interferometric optical gyroscope based on laser sources can be improved with this technique.

Monolithically integrated dual-channel coherent receiver with widely tunable local oscillator for 100 Gbps dual-polarization quadrature phase shift keying applications.

We report implementation of a monolithically integrated 100 Gbps dual-polarization quadrature phase shift keying (DP-QPSK) wavelength tunable coherent receiver on a 1  mm×3  mm die that consists of a tunable C-Band local oscillator with a 40 nm range, eight 30 GHz photodetectors, and two parallel 90° optical hybrids. A BER of 10(-3) with an OSNR of 7.5 dB operating at 50 Gbps NRZ-QPSK data per channel is reported.

Erbium-doped waveguide DBR and DFB laser arrays integrated within an ultra-low-loss Si3N4 platform.

Record low optical threshold power and high slope efficiency are reported for arrays of distributed Bragg reflector lasers integrated within an ultra-low-loss Si(3)N(4) planar waveguide platform. Additionally, arrays of distributed feedback laser designs are presented that show improvements in pump-to-signal conversion efficiency of over two orders of magnitude beyond that found in previously published devices. Lithographically defined sidewall gratings provide the required lasing feedback for both cavity configurations.

Recovery and resilience after a nuclear power plant disaster: a medical decision model for managing an effective, timely, and balanced response.

Resilience after a nuclear power plant or other radiation emergency requires response and recovery activities that are appropriately safe, timely, effective, and well organized. Timely informed decisions must be made, and the logic behind them communicated during the evolution of the incident before the final outcome is known. Based on our experiences in Tokyo responding to the Fukushima Daiichi nuclear power plant crisis, we propose a real-time, medical decision model by which to make key health-related decisions that are central drivers to the overall incident management.

Role of dicentric analysis in an overarching biodosimetry strategy for use following a nuclear detonation in an urban environment.

In the moments immediately following a nuclear detonation, casualties with a variety of injuries including trauma, burns, radiation exposure, and combined injuries would require immediate assistance. Accurate and timely radiation dose assessments, based on patient history and laboratory testing, are absolutely critical to support adequately the triage and treatment of those affected. This capability is also essential for ensuring the proper allocation of scarce resources and will support longitudinal evaluation of radiation-exposed individuals and populations.

A sustainable training strategy for improving health care following a catastrophic radiological or nuclear incident.

The detonation of a nuclear device in a US city would be catastrophic. Enormous loss of life and injuries would characterize an incident with profound human, political, social, and economic implications. Nevertheless, most responders have not received sufficient training about ionizing radiation, principles of radiation safety, or managing, diagnosing, and treating radiation-related injuries and illnesses.

Arrayed narrow linewidth erbium-doped waveguide-distributed feedback lasers on an ultra-low-loss silicon-nitride platform.

We demonstrate an array of erbium-doped waveguide-distributed feedback lasers on an ultra-low-loss Si(3)N(4) platform. Sidewall gratings providing the lasing feedback are defined in the silicon-nitride layer using 248 nm stepper lithography, while the gain is provided by a reactive co-sputtered erbium-doped aluminum-oxide layer. We observe lasing output over a 12 nm wavelength range (1531-1543 nm) from the array of five separate lasers.