Engineering topics

Harrington, Mark W.

Publications and source records attributed to Harrington, Mark W..

4 records

DOE OSTI2023

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 (Si 3 N 4 ) 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. The nested waveguide resonators have a 184 million intrinsic and 92 million loaded Q, over an order of magnitude improvement over prior photonic molecules, enabling precision resonance splitting of 198 MHz at the S2 frequency. We demonstrate S2-suppressed single-mode SBL with a minimum fundamental linewidth of 71±18 mHz, corresponding to a 23±6-mHz 2 /Hz white-frequency-noise floor, over an order of magnitude lower than prior integrated SBLs, with an ∼11-mW output power and 2.3-mW threshold power. The frequency noise reaches the resonator-intrinsic thermo-refractive noise from 2-kHz to 1-MHz offset. The laser phase noise reaches −155 dBc/Hz at 10-MHz offset. The performance of this chip-scale SBL shows promise not only to improve the reliability and reduce size and cost but also to enable new precision experiments that require the high-speed manipulation, control, and interrogation of atoms and qubits. Realization in the silicon nitride ultra-low loss platform is adaptable to a wide range of wavelengths from the visible to infrared and enables integration with other components for systems-on-chip solutions for a wide range of precision scientific and engineering applications including quantum sensing, gravitometers, atom interferometers, precision metrology, optical atomic clocks, and ultra-low noise microwave generation.

Liu, Kaikai (ORCID:0000000213609646)↗

DOE OSTI2022

Photonic circuits for laser stabilization with integrated ultra-high Q and Brillouin laser resonators

The integration of stabilized lasers, sources that generate spectrally pure light, will provide compact, low-cost solutions for applications including quantum information sciences, precision navigation and timing, metrology, and high-capacity fiber communications. We report a significant advancement in this field, demonstrating stabilization of an integrated waveguide Brillouin laser to an integrated waveguide reference cavity, where both resonators are fabricated using the same CMOS-compatible integration platform. We demonstrate reduction of the free running Brillouin laser linewidth to a 292 Hz integral linewidth and carrier stabilization to a 4.9 × 10 –13 fractional frequency at 8 ms reaching the cavity-intrinsic thermorefractive noise limit for frequencies down to 80 Hz. We achieve this level of performance using a pair of 56.4 x 10 6 quality factor Si 3 N 4 waveguide ring-resonators that reduce the high-frequency noise by the nonlinear Brillouin process and the low-frequency noise by Pound–Drever–Hall locking to the ultra-low loss resonator. These results represent an important step toward integrated stabilized lasers with reduced sensitivity to environmental disturbances for atomic, molecular, and optical physics (AMO), quantum information processing and sensing, and other precision scientific, sensing, and communications applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2022

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. The silicon nitride integration platform has been successful at realizing extremely low waveguide losses across the visible to infrared and components including high performance lasers, filters, resonators, stabilization cavities, and optical frequency combs. Yet, progress towards implementing low loss, low power modulators in the silicon nitride platform, while maintaining wafer-scale process compatibility has been limited. Here we report a significant advance in integration of a piezo-electric (PZT, lead zirconate titanate) actuated micro-ring modulation in a fully-planar, wafer-scale silicon nitride platform, that maintains low optical loss (0.03 dB/cm in a 625 µm resonator) at 1550 nm, with an order of magnitude increase in bandwidth (DC - 15 MHz 3-dB and DC - 25 MHz 6-dB) and order of magnitude lower power consumption of 20 nW improvement over prior PZT modulators. The modulator provides a >14 dB extinction ratio (ER) and 7.1 million quality-factor (Q) over the entire 4 GHz tuning range, a tuning efficiency of 162 MHz/V, and delivers the linearity required for control applications with 65.1 dB·Hz 2/3 and 73.8 dB·Hz 2/3 third-order intermodulation distortion (IMD3) spurious free dynamic range (SFDR) at 1 MHz and 10 MHz respectively. We demonstrate two control applications, laser stabilization in a Pound-Drever Hall (PDH) lock loop, reducing laser frequency noise by 40 dB, and as a laser carrier tracking filter. This PZT modulator design can be extended to the visible in the ultra-low loss silicon nitride platform with minor waveguide design changes. This integration of PZT modulation in the ultra-low loss silicon nitride waveguide platform enables modulator control functions in a wide range of visible to IR applications such as atomic and molecular transition locking for cooling, trapping and probing, controllable optical frequency combs, low-power external cavity tunable lasers, quantum computers, sensors and communications, atomic clocks, and tunable ultra-low linewidth lasers and ultra-low phase noise microwave synthesizers.

Wang, Jiawei (ORCID:0000000257965220)↗

DOE OSTI2021

Integrated reference cavity with dual-mode optical thermometry for frequency correction

Photonic integrated resonators have advantages over traditional benchtop cavities in terms of size, weight, and cost with the potential to enable applications that require spectrally pure light. However, integrated resonators suffer from temperature-dependent frequency variations and are sensitive to external environmental perturbations, which hinders their usage in precision frequency applications. One solution is to use interrogation of the cavity temperature through dual-mode optical thermometry (DMOT) by measuring the shift of the resonance frequency difference between two polarization or optical frequency modes. Yet this approach has only been demonstrated in bulk-optic whispering gallery mode and fiber resonators. In this paper, we implement dual-mode optical thermometry in an ultra-high Q integrated silicon nitride resonator. A dual-mode resonance frequency difference temperature sensitivity of 188 ± <#comment/> 15 M H z / K is measured. We demonstrate feedforward DMOT frequency correction that, under an applied external temperature ramp, is able to reduce the optical frequency change to 0.31 kHz/s as compared to an uncorrected 10.03 kHz/s, a factor of 30 × <#comment/> reduction. These results show promise for on-chip frequency correction solutions for quantum, metrology, atomic, and coherent optical communications applications.

Zhao, Qiancheng (ORCID:0000000206968667)↗