skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Non-Cubic Eightfold Constellation for High-Performance Stokes Vector Modulation
A novel non-cubic constellation for eightfold Stokes vector modulation improves modulation loss, link budget, and intersymbol interference at high speed, while using simpler drive signals. Experiments confirm 5.2 dB improvement at 30 Gb/s.  more » « less
Award ID(s):
1910140
PAR ID:
10466579
Author(s) / Creator(s):
; ;
Publisher / Repository:
Optica Publishing Group
Date Published:
ISBN:
978-1-957171-17-3
Page Range / eLocation ID:
JTu7A.3
Format(s):
Medium: X
Location:
Rochester, New York
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, Applied Physics Letters)
    We report the nonvolatile modulation of microwave conductivity in ferroelectric PbZr0.2Ti0.8O3-gated ultrathin LaNiO3/La0.67Sr0.33MnO3 correlated oxide channel visualized by microwave impedance microscopy. Polarization switching is obtained by applying a tip bias above the coercive voltage of the ferroelectric layer. The microwave conductivity of the correlated channel underneath the up- and down-polarized domains has been quantified by finite-element analysis of the tip-sample admittance. At room temperature, a resistance on/off ratio above 100 between the two polarization states is sustained at frequencies up to 1 GHz, which starts to drop at higher frequencies. The frequence-dependence suggests that the conductance modulation originates from ferroelectric field-effect control of carrier density. The modulation is nonvolatile, remaining stable after 6 months of domain writing. Our work is significant for potential applications of oxide-based ferroelectric field-effect transistors in high-frequency nanoelectronics and spintronics. 
    more » « less
  2. ; ; ; ; (, Optica)
    The Pound–Drever–Hall (PDH) cavity-locking scheme has found prevalent uses in precision optical interferometry and laser frequency stabilization. A form of frequency modulation spectroscopy, PDH enjoys superior signal-to-noise recovery, large acquisition dynamic range, wide servo bandwidth, and robust rejection of spurious effects. However, residual amplitude modulation at the signal frequency, while significantly suppressed, still presents an important concern for further advancing the state-of-the-art performances. Here we present a simplified and improved scheme for PDH using an acousto-optic modulator to generate digital phase reference sidebands instead of the traditionally used electro-optic modulator approach. We demonstrate four key advantages: (1) the carrier and two modulation tones are individually synthesized and easily reconfigured, (2) robust and orthogonal control of the modulated optical field is applied directly to the amplitude and phase quadratures, (3) modulation synthesis, demodulation, and feedback are implemented in a self-contained and easily reproducible electronic unit, and (4) superior active and passive control of residual amplitude modulation is achieved, especially when the carrier power is vanishingly low. These distinct merits stimulate new ideas on how we optimally enact PDH for a wide range of applications. 
    more » « less
  3. ; ; ; (, IEEE Journal of Solid-State Circuits)
    This article presents a novel eight-ary modulation technique with improved signal-to-noise ratio (SNR) compared to conventional pulse amplitude modulation 8 (PAM-8). The proposed SNR-enhanced 8-ary (SNRE-8) scheme modulates pulse width, position, and amplitude to improve the SNR. The proposed SNRE-8 modulation leverages the wireline channel loss to perform the modulation. Digital decoding of mutually exclusive eyes generated by the proposed SNRE-8 modulation further improves the eye margin at the receiver. A 27-Gb/s transceiver is implemented in a 65-nm CMOS process employing the proposed modulation. A PAM-8 transmitter is implemented on the same chip for comparison purposes. Compared to the PAM-8 modulation, the proposed SNRE-8 modulation shows an average SNR improvement of 10.6 dB at the near-end eye at the cost of 6.6% eye width reduction. With the aid of a time-domain feed-forward equalizer (FFE) and a continuous-time linear equalizer (CTLE), the proposed SNRE-8 transceiver achieves a bit error rate (BER) of 10−8 on a 9-dB loss channel with an energy efficiency of 5.39 pJ/bit. 
    more » « less
  4. ; ; ; (, Optics Letters)
    In this Letter, we propose and experimentally demonstrate the first, to our knowledge, integrated liquid-crystal-based (LC-based) variable-tap devices for visible-light amplitude modulation. These devices leverage the birefringence of LC medium to actively tune the coupling coefficient between two waveguides. First, we develop the device structure, theory of operation, and design procedure. Next, we summarize the fabrication and LC packaging procedure for these devices. Finally, we experimentally demonstrate amplitude modulation with 15.4-dB tap-port extinction within ±3.1 V for a 14-µm-long device at a 637-nm operating wavelength. These small-form-factor variable-tap devices provide a compact and low-power solution to integrated visible-light amplitude modulation and will enable future high-density integrated visible-light systems. 
    more » « less
  5. ; ; (, The Astrophysical Journal)
    Abstract A key goal of heliophysics is to understand how cosmic rays propagate in the solar system’s complex, dynamic environment. One observable is solar modulation, i.e., how the flux and spectrum of cosmic rays change as they propagate inward. We construct an improved force-field model, taking advantage of new measurements of magnetic power spectral density by Parker Solar Probe to predict solar modulation within the Earth’s orbit. We find that modulation of cosmic rays between the Earth and Sun is modest, at least at solar minimum and in the ecliptic plane. Our results agree much better with the limited data on cosmic-ray radial gradients within Earth’s orbit than past treatments of the force-field model. Our predictions can be tested with forthcoming direct cosmic-ray measurements in the inner heliosphere by Parker Solar Probe and Solar Orbiter. They are also important for interpreting the gamma-ray emission from the Sun due to scattering of cosmic rays with solar matter and photons. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email