More Like this

1. Photonic crystal resonators for inverse-designed multi-dimensional optical interconnects

   https://doi.org/10.1364/OL.461272  

   Shirpurkar, C. ; Zang, J. ; Yang, K. Y. ; Carlson, D. ; Yu, S. P. ; Lucas, E. ; Pericherla, S. V. ; Yang, J. ; Guidry, M. ; Lukin, D. ; et al ( June 2022 , Optics Letters)

   We experimentally demonstrate a 400 Gbit/s optical communication link utilizing wavelength-division multiplexing and mode-division multiplexing for a total of 40 channels. This link utilizes a novel, to the best of our knowledge, 400 GHz frequency comb source based on a chip-scale photonic crystal resonator. Silicon-on-insulator photonic inverse-designed 4 × 4 mode-division multiplexer structures enable a fourfold increase in data capacity. We show less than −10 dBm of optical receiver power for error-free data transmission in 34 out of a total of 40 channels using a PRBS31 pattern.

    

   more » « less
2. Growing Quantum Communication Capacity with Spatial Modes of Optical Fiber

   M. Vasilyev ( November 2021 , IEEE MetroCon conference, Fort Worth, TX, November 3, 2021)

   Quantum communication links and networks are needed for secure information exchange and for interconnecting future quantum computers. However, their capacity decreases exponentially with distance due to the effect of fiber attenuation that cannot be undone by amplification (although quantum repeaters are an active area of research, they are almost as hard to build as quantum computers). Hence, the only way to increase the quantum communication capacity is by employing more degrees of freedom (optical modes) over which this information can be encoded and transmitted. While frequency (WDM), temporal, and polarization modes have already been exploited for this purpose, the use of many spatial modes has only recently become possible owing to the development of low-loss few-mode fibers (FMFs). This talk will present the work of Prof. M. Vasilyev’s research group on the development of two key enablers of quantum communication over spatial modes of FMFs: 1) generator of spatially-entangled photon pairs and 2) receiver sub-system that can perform projective measurements that alternate between two sets of mutually unbiased bases in a given spatial mode space (this sub-system can also perform dynamically reconfigurable de-multiplexing of spatial modes of the FMF). Both of the above devices / sub-systems are based on the spatial-mode-selective quantum frequency conversion process, implemented in a medium with either second-order nonlinearity (multimode lithium niobate waveguide) or third-order nonlinearity (custom-made FMF). The talk will introduce the principles of their operation, as well as the recent experimental results obtained in both media. 

   more » « less
3. Compact atto-joule-per-bit bus-coupled photonic crystal nanobeam switches

   https://doi.org/10.1117/12.2649250  

   Shen, Jianhao ; Donnelly, Daniel ; Chakravarty, Swapnajit ( March 2023 , Proceedings of SPIE)

   García-Blanco, Sonia M. ; Cheben, Pavel (Ed.)

   The benefits of photonics over electronics in the application of optical transceivers and both classical and quantum computing have been demonstrated over the past decades, especially in the ability to achieve high bandwidth, high interconnectivity, and low latency. Due to the high maturity of silicon photonics foundries, research on photonics devices such as silicon micro ring resonators (MRRs), Mach-Zehnder modulators (MZM), and photonic crystal (PC) resonators has attracted plenty of attention. Among these photonic devices, silicon MRRs using carrier depletion effects in p-n junctions represent optical switches manufacturable in the most compact magnitude at high volume with demonstrated switching energies ~5.2fJ/bit. In matrix multiplication demonstrated with integrated photonics, one approach is to couple one bus straight waveguide to several MRRs with different resonant wavelengths to transport signals in different channels, corresponding to a matrix row or column. However, such architectures are potentially limited to ~30 MRRs in series, by the limited free-spectral range (FSR) of an individual MRR. We show that PC switches with sub-micron optical mode confinements can have a FSR >300nm, which can potentially enable energy efficient computing with larger matrices of ~200 resonators by multiplexing. In this paper, we present designs for an oxide-clad bus-coupled PC switch with 1dB insertion loss, 5dB extinction, and ~260aJ/bit switching energy by careful control of the cavity geometry as well as p-n junction doping. We also demonstrate that air-clad bus-coupled PC switches can operate with 1dB insertion loss, 3dB extinction, and ~80aJ/bit switching energy. 

   more » « less
4. All-acoustic signal modulation and logic operation via defect induced cavity effects in phononic crystal coupled-resonator acoustic waveguides

   https://doi.org/10.1088/1367-2630/ab4f4f  

   Reyes, Delfino ; Walker, Ezekiel ; Zubov, Yurii ; Heo, Hyeonu ; Krokhin, Arkadii ; Neogi, Arup ( November 2019 , New Journal of Physics)

   A coupled resonant acoustic waveguide (CRAW) in a phononic crystal (PnC) was engineered to manipulate the propagation of ultrasonic waves within a conventional phononic bandgap for wavelength division multiplexing. The PnC device included two, forked, distinct CRAW waveguide channels that exhibited strong frequency and mode selectivity. Each branch was composed of cavities of differing volumes, with each giving rise to deep and shallow ‘impurity’ states. These states were utilized to select frequency windows where transmission along the channels was suppressed distinctly for each channel. Though completely a linear system, the mode sensitivity of each CRAW waveguide channel produced apparent nonlinear power dependence along each branch. Nonlinearity in the system arises from the combination of the mode sensitivity of each CRAW channel and small variations in the shape of the incident wavefront as a function of input power. The all-acoustic effect was then leveraged to realize an ultrasonic, spatial signal modulator, and logic element operating at 398 and 450 kHz using input power.

    

   more » « less
5. Spectrally-Selective Holography for Space-Division Modal- Demultiplexing and Dispersion Compensation in Multimode Fiber

   Wagner, K.H. ; Brand, M. ( June 2019 , PhotonIcs and Electromagnetics Research Symposium)

   Spatial-spectral holographic signal processing in cryogenically-cooled spectral-hole burning crystals allows modal-dispersion compensation of multiple orthogonally launched beams to enable wide- band mode-group multiplexing and demultiplexing in spatially-multiplexed multimode fiber networks. 

   more » « less