Zachary L. Newman, Vincent Maurice, Tara Drake, Jordan R. Stone, Travis C. Briles, Daryl T. Spencer, Connor Fredrick, Qing Li, Daron Westly, B. R. Ilic, Boqiang Shen, Myoung-Gyun Suh, Ki Youl Yang, Cort Johnson, David M. S. Johnson, Leo Hollberg, Kerry J. Vahala, Kartik Srinivasan, Scott A. Diddams, John Kitching, Scott B. Papp, and Matthew T. Hummon. 2019. “
Architecture for the photonic integration of an optical atomic clock.” Optica, 6, 5, Pp. 680–685.
Publisher's VersionAbstractLaboratory optical atomic clocks achieve remarkable accuracy (now counted to 18 digits or more), opening possibilities for exploring fundamental physics and enabling new measurements. However, their size and the use of bulk components prevent them from being more widely adopted in applications that require precision timing. By leveraging silicon-chip photonics for integration and to reduce component size and complexity, we demonstrate a compact optical-clock architecture. Here a semiconductor laser is stabilized to an optical transition in a microfabricated rubidium vapor cell, and a pair of interlocked Kerr-microresonator frequency combs provide fully coherent optical division of the clock laser to generate an electronic 22&\#x00A0;GHz clock signal with a fractional frequency instability of one part in 1013. These results demonstrate key concepts of how to use silicon-chip devices in future portable and ultraprecise optical clocks.
Qi-Fan Yang, Boqiang Shen, Heming Wang, Minh Tran, Zhewei Zhang, Ki Youl Yang, Lue Wu, Chengying Bao, John Bowers, Amnon Yariv, and Kerry Vahala. 2019. “
Vernier spectrometer using counterpropagating soliton microcombs.” Science, 363, 6430, Pp. 965-968.
Publisher's VersionAbstractWhen measuring length, we learn in school that a vernier scale that uses two rulers, slightly offset, can reduce human estimation error and improve the resolution of a measurement. Yang et al. apply the same vernier principle with optical combs to develop a spectrometer that can determine the wavelength of light with high accuracy and precision. Two phase-locked counterpropagating optical microcombs generated in a miniature microresonator provided the rulers. Matching up of the “teeth” of the combs was then used to measure the wavelength of the optical light sources. Science, this issue p. 965 Counterpropagating optical microcombs can be used as a vernier spectrometer to determine the wavelength of light. Determination of laser frequency with high resolution under continuous and abrupt tuning conditions is important for sensing, spectroscopy, and communications. We show that a single microresonator provides rapid and broadband measurement of optical frequencies with a relative frequency precision comparable to that of conventional dual-frequency comb systems. Dual-locked counterpropagating solitons having slightly different repetition rates were used to implement a vernier spectrometer, which enabled characterization of laser tuning rates as high as 10 terahertz per second, broadly step-tuned lasers, multiline laser spectra, and molecular absorption lines. Besides providing a considerable technical simplification through the dual-locked solitons and enhanced capability for measurement of arbitrarily tuned sources, our results reveal possibilities for chip-scale spectrometers that exceed the performance of tabletop grating and interferometer-based devices.
Uwe Niedermayer, A Adelmann, S Bettoni, M Calvi, M Dehler, E Ferrari, F Frei, D Hauenstein, B Hermann, N Hiller, R Ischebeck, C Lombosi, E Prat, S Reiche, L Rivkin, R Aßmann, U Dorda, I Hartl, W Kuropka, F Lemery, B Marchetti, F Mayet, H Xuan, J. Zhu, DS Black, PN Broaddus, RL Byer, A Ceballos, H Deng, S Fan, J Harris, T Hirano, TW Hughes, Y Jiang, T Langenstein, K Leedle, Y Miao, A Ody, A Pigott, N Sapra, O Solgaard, L Su, S Tan, J Vuckovic, K.Yang, Z Zhao, O Boine-Frankenheim, T Egenolf, E Skär, D Cesar, P Musumeci, B Naranjo, J Rosenzweig, X Shen, B Cowan, RJ England, Z Huang, H Cankaya, M Fakhari, A Fallahi, FX Kärtner, T Feurer, P Hommelhoff, J Illmer, A. Li, A Mittelbach, J McNeur, N Schönenberger, R Shiloh, A Tafel, P Yousefi, M Kozak, M Qi, YJ Lee, Y-C Huang, and E Simakov. 2019. “
Challenges in simulating beam dynamics of dielectric laser acceleration.” Int. J. Mod. Phys. A, 34, 36, Pp. 1942031.
Publisher's VersionAbstractDielectric Laser Acceleration (DLA) achieves the highest gradients among structure-based electron accelerators. The use of dielectrics increases the breakdown field limit, and thus the achievable gradient, by a factor of at least 10 in comparison to metals. Experimental demonstrations of DLA in 2013 led to the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. In ACHIP, our main goal is to build an accelerator on a silicon chip, which can accelerate electrons from below 100 keV to above 1 MeV with a gradient of at least 100 MeV/m. For stable acceleration on the chip, magnet-only focusing techniques are insufficient to compensate the strong acceleration defocusing. Thus, spatial harmonic and Alternating Phase Focusing (APF) laser-based focusing techniques have been developed. We have also developed the simplified symplectic tracking code DLAtrack6D, which makes use of the periodicity and applies only one kick per DLA cell, which is calculated by the Fourier coefficient of the synchronous spatial harmonic. Due to coupling, the Fourier coefficients of neighboring cells are not entirely independent and a field flatness optimization (similarly as in multi-cell cavities) needs to be performed. The simulation of the entire accelerator on a chip by a Particle In Cell (PIC) code is possible, but impractical for optimization purposes. Finally, we have also outlined the treatment of wake field effects in attosecond bunches in the grating within DLAtrack6D, where the wake function is computed by an external solver.
Neil V Sapra, Dries Vercruysse, Logan Su, Ki Youl Yang, Jinhie Skarda, Alexander Y Piggott, and Jelena Vuckovic. 2019. “
Inverse design and demonstration of broadband grating couplers.” IEEE J. Sel. Top. Quantum Electron., 25, 3, Pp. 1–7.
Publisher's Version Constantin Dory, Dries Vercruysse, Ki Youl Yang, Neil V Sapra, Alison E Rugar, Shuo Sun, Daniil M Lukin, Alexander Y Piggott, Jingyuan L Zhang, Marina Radulaski, Konstantinos G Lagoudakis, Logan Su, and Jelena Vučković. 2019. “
Inverse-designed diamond photonics.” Nature Communications, 10, 1, Pp. 3309.
Publisher's VersionAbstractDiamond hosts optically active color centers with great promise in quantum computation, networking, and sensing. Realization of such applications is contingent upon the integration of color centers into photonic circuits. However, current diamond quantum optics experiments are restricted to single devices and few quantum emitters because fabrication constraints limit device functionalities, thus precluding color center integrated photonic circuits. In this work, we utilize inverse design methods to overcome constraints of cutting-edge diamond nanofabrication methods and fabricate compact and robust diamond devices with unique specifications. Our design method leverages advanced optimization techniques to search the full parameter space for fabricable device designs. We experimentally demonstrate inverse-designed photonic free-space interfaces as well as their scalable integration with two vastly different devices: classical photonic crystal cavities and inverse-designed waveguide-splitters. The multi-device integration capability and performance of our inverse-designed diamond platform represents a critical advancement toward integrated diamond quantum optical circuits.