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: High Efficiency Antenna Integrated Electro-Optic modulator for Sensing Applications
Abstract—The efficiency of Electro-Optic Modulators (EOM) is directly related to how the rf signal is imposed onto the optical signal. Other factors affecting this efficiency are: the selected architecture and the Electro-Optic materials responsible for modulation through the Electro-Optic Effect. In this paper we demonstrate a millimeter wave antenna integrated EOM that operates at 94 GHz. To improve efficiency, the antenna is integrated directly onto the active region of the electro-optic effect based EOM. Notably, conventional antennas had to be modified to achieve a feed port that is best suited for the selected EOM architecture. For the antenna design optimization, we devised a design procedure that is more suitable for these type of devices. We proposed a design methodology that insures an optimum Field Enhancement (FE) that is responsible for modulation. A novel overall EOM architecture that promotes increased efficiency that makes use of the inherently lossy EO material only where needed in the optical link by making use of an adiabatic transition from a passive Optical waveguide to active portion of the optical link.  more » « less
Award ID(s):
1809728
PAR ID:
10341416
Author(s) / Creator(s):
Date Published:
Journal Name:
2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, Singapore
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. (, 2020 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting)
    null (Ed.)
    On chip antennas with integrated electro-optic modulators (EOMs) are attractive for millimeter wave applications. Such EOMs are placed at the antenna feed and enable the mixing of the incoming millimeter wave (mm-wave) signal with an optical carrier. As such, the mm-wave capture is turned into an optical signal that can be easily processed for imaging using standard infrared cameras. Our proposed on-chip antenna with the EOM modulator operated at 94 GHz or 77 GHz, with the antenna tuned at that frequency. For high modulation efficiency, it is critical that the modulator region is as small as possible with the optical waveguide leading to the EOM, also being well-matched. Notably, the enhanced field at the antenna feed leads to higher modulation efficiency and sensitivity. Therefore, an optimum antenna design must hasve as large as possible field strength at the feed. 
    more » « less
  2. ; ; ; (, Optics Express)
    We propose an on-chip triply resonant electro-optic modulator architecture for RF-to-optical signal conversion and provide a detailed theoretical analysis of the optimal “circuit-level” device geometries and their performance limits. The designs maximize the RF-optical conversion efficiency through simultaneous resonant enhancement of the RF drive signal, a continuous-wave (CW) optical pump, and the generated optical sideband. The optical pump and sideband are resonantly enhanced in respective supermodes of a two-coupled-cavity optical resonator system, while the RF signal can be enhanced in addition by an LC circuit formed by capacitances of the optical resonator active regions and (integrated) matching inductors. We show that such designs can offer 15-50 dB improvement in conversion efficiency over conventional microring modulators. In the proposed configurations, the photon lifetime (resonance linewidth) limits the instantaneous RF bandwidth of the electro-optic response but does not limit its central RF frequency. The latter is set by the coupling strength between the two coupled cavities and is not subject to the photon lifetime constraint inherent to conventional singly resonant microring modulators. This feature enables efficient operation at high RF carrier frequencies without a reduction in efficiency commonly associated with the photon lifetime limit and accounts for 10-30 dB of the total improvement. Two optical configurations of the modulator are proposed: a “basic” configuration with equal Q-factors in both supermodes, most suitable for narrowband RF signals, and a “generalized” configuration with independently tailored supermode Q-factors that supports a wider instantaneous bandwidth. A second significant 5-20 dB gain in modulation efficiency is expected from RF drive signal enhancement by integrated LC resonant matching, leading to the total expected improvement of 15-50 dB. Previously studied triply-resonant modulators, with coupled longitudinal (across the free spectral range (FSR)) modes, have large resonant mode volume for typical RF frequencies, which limits the interaction between the optical and RF fields. In contrast, the proposed modulators support maximally tightly confined resonant modes, with strong coupling between the mode fields, which increases and maintains high device efficiency across a range of RF frequencies. The proposed modulator architecture is compact, efficient, capable of modulation at high RF carrier frequencies and can be applied to any cavity design or modulation mechanism. It is also well suited to moderate Q, including silicon, implementations, and may be enabling for future CMOS RF-electronic-photonic systems on chip. 
    more » « less
  3. ; ; ; ; ; (, Nanophotonics)
    Abstract Commercial production of integrated photonic devices is limited by scalability of desirable material platforms. We explore a relatively new photonic material, AlScN, for its use in electro-optic phase shifting and modulation. Its CMOS-compatibility could facilitate large-scale production of integrated photonic modulators, and it exhibits an enhanced second-order optical nonlinearity compared to intrinsic AlN, indicating the possibility for efficient modulation. Here, we measure the electro-optic effect in Al0.80Sc0.20N-based phase shifters. We utilized the TM0 mode, allowing use of ther33electro-optic coefficient, and demonstratedVπLaround 750 V cm. Since the electro-optic response is smaller than expected, we discuss potential causes for the reduced response and future outlook for AlScN-based photonics. 
    more » « less
  4. ; ; ; ; (, 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
  5. ; ; ; ; ; ; ; (, Optics Letters)
    Electro-optic (EO) transduction of weak radio frequency (RF) and millimeter-wave signals, such as those received by an antenna, onto laser sidebands for processing in the optical domain requires efficient EO modulators. Microrings offer spatial density and efficiency advantages over Mach–Zehnder modulators (MZMs), but conventional single-ring modulators suffer a fundamental trade-off between resonantly enhanced conversion efficiency and the RF carrier frequency that it can accommodate. Dual-cavity “photonic molecule” modulators resolve this trade-off, allowing high efficiency independent of the RF carrier frequency by providing separate resonant supermodes to enhance the laser local oscillator (LO) and the narrowband RF-detuned sideband. However, the RF frequency is fixed at design time by geometry, with efficiency dropping quickly for RF carriers away from the design value. We propose a novel, to the best of our knowledge, triple-cavity configuration with an off-resonant middle ring acting as an effective tunable coupler between two active modulator cavities. This configuration provides wideband tunability of the target RF carrier while maintaining efficient sideband conversion. When the middle ring is passive (highQ), this configuration provides wide RF tunability with no efficiency penalty over the fixed dual-cavity case and could become an important building block for future RF/mm-wave photonic integrated circuits (PICs). 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email