skip to main content


Title: Guided-mode resonances in flexible 2D terahertz photonic crystals

In terahertz (THz) photonics, there is an ongoing effort to develop thin, compact devices such as dielectric photonic crystal (PhC) slabs with desirable light–matter interactions. However, previous works in THz PhC slabs have been limited to rigid substrates with thicknesses∼<#comment/>100sof micrometers. Dielectric PhC slabs have been shown to possess in-plane modes that are excited by external radiation to produce sharp guided-mode resonances with minimal absorption for applications in sensors, optics, and lasers. Here we confirm the existence of guided resonances in a membrane-type THz PhC slab with subwavelength (λ<#comment/>0/6−<#comment/>λ<#comment/>0/12) thicknesses of flexible dielectric polyimide films. The transmittance of the guided resonances was measured for different structural parameters of the unit cell. Furthermore, we exploited the flexibility of the samples to modulate the guided modes for a bend angle ofθ<#comment/>≥<#comment/>5∘<#comment/>, confirmed experimentally by the suppression of these modes. The mechanical flexibility of the device allows for an additional degree of freedom in system design for high-speed communications, soft wearable photonics, and implantable medical devices.

 
more » « less
Award ID(s):
1708315
NSF-PAR ID:
10160565
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Optica
Volume:
7
Issue:
5
ISSN:
2334-2536
Page Range / eLocation ID:
Article No. 537
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. We experimentally demonstrate simultaneous turbulence mitigation and channel demultiplexing in a 200 Gbit/s orbital-angular-momentum (OAM) multiplexed link by adaptive wavefront shaping and diffusing (WSD) the light beams. Different realizations of two emulated turbulence strengths (the Fried parameterr0=0.4,1.0mm) are mitigated. The experimental results show the following. (1) Crosstalk between OAMl=+1andl=−<#comment/>1modes can be reduced by><#comment/>10.0and><#comment/>5.8dB, respectively, under the weaker turbulence (r0=1.0mm); crosstalk is further improved by><#comment/>17.7and><#comment/>19.4dB, respectively, under most realizations in the stronger turbulence (r0=0.4mm). (2) The optical signal-to-noise ratio penalties for the bit error rate performance are measured to be∼<#comment/>0.7and∼<#comment/>1.6dBunder weaker turbulence, while measured to be∼<#comment/>3.2and∼<#comment/>1.8dBunder stronger turbulence for OAMl=+1andl=−<#comment/>1mode, respectively.

     
    more » « less
  2. Electro-optic quantum coherent interfaces map the amplitude and phase of a quantum signal directly to the phase or intensity of a probe beam. At terahertz frequencies, a fundamental challenge is not only to sense such weak signals (due to a weak coupling with a probe in the near-infrared) but also to resolve them in the time domain. Cavity confinement of both light fields can increase the interaction and achieve strong coupling. Using this approach, current realizations are limited to low microwave frequencies. Alternatively, in bulk crystals, electro-optic sampling was shown to reach quantum-level sensitivity of terahertz waves. Yet, the coupling strength was extremely weak. Here, we propose an on-chip architecture that concomitantly provides subcycle temporal resolution and an extreme sensitivity to sense terahertz intracavity fields below 20 V/m. We use guided femtosecond pulses in the near-infrared and a confinement of the terahertz wave to a volume ofVTHz∼<#comment/>10−<#comment/>9(λ<#comment/>THz/2)3in combination with ultraperformant organic molecules (r33=170pm/V) and accomplish a record-high single-photon electro-optic coupling rate ofgeo=2π<#comment/>×<#comment/>0.043GHz, 10,000 times higher than in recent reports of sensing vacuum field fluctuations in bulk media. Via homodyne detection implemented directly on chip, the interaction results into an intensity modulation of the femtosecond pulses. The single-photon cooperativity isC0=1.6×<#comment/>10−<#comment/>8, and the multiphoton cooperativity isC=0.002at room temperature. We show><#comment/>70dBdynamic range in intensity at 500 ms integration under irradiation with a weak coherent terahertz field. Similar devices could be employed in future measurements of quantum states in the terahertz at the standard quantum limit, or for entanglement of subsystems on subcycle temporal scales, such as terahertz and near-infrared quantum bits.

     
    more » « less
  3. We present a compact heterodyne laser interferometer developed for high-sensitivity displacement sensing applications. This interferometer consists of customized prisms and wave plates assembled as a quasi-monolithic unit to realize a miniaturized system. The interferometer design adopts a common-mode rejection scheme to provide a high rejection ratio to common environmental noise. Experimental tests in vacuum show a displacement sensitivity level of11pm/Hzat100mHzand as low as0.6pm/Hzabove1pm. The prototype unit is20mm×<#comment/>20mm×<#comment/>10mmin size and weighs4.5g, allowing subsequent integration in compact systems.

     
    more » « less
  4. We experimentally demonstrate the utilization of adaptive optics (AO) to mitigate intra-group power coupling among linearly polarized (LP) modes in a graded-index few-mode fiber (GI FMF). Generally, in this fiber, the coupling between degenerate modes inside a modal group tends to be stronger than between modes belonging to different groups. In our approach, the coupling inside theLP11group can be represented by a combination of orbital-angular-momentum (OAM) modes, such that reducing power coupling in OAM set tends to indicate the capability to reduce the coupling inside theLP11group. We employ two output OAM modesl=+1andl=−<#comment/>1as resultant linear combinations of degenerateLP11aandLP11bmodes inside theLP11group of a∼<#comment/>0.6-kmGI FMF. The power coupling is mitigated by shaping the amplitude and phase of the distorted OAM modes. Each OAM mode carries an independent 20-, 40-, or 100-Gbit/s quadrature-phase-shift-keying data stream. We measure the transmission matrix (TM) in the OAM basis withinLP11group, which is a subset of the full LP TM of the FMF-based system. An inverse TM is subsequently implemented before the receiver by a spatial light modulator to mitigate the intra-modal-group power coupling. With AO mitigation, the experimental results forl=+1andl=−<#comment/>1modes show, respectively, that (i) intra-modal-group crosstalk is reduced by><#comment/>5.8dBand><#comment/>5.6dBand (ii) near-error-free bit-error-rate performance is achieved with a penalty of∼<#comment/>0.6dBand∼<#comment/>3.8dB, respectively.

     
    more » « less
  5. The mid-IR spectroscopic properties ofEr3+doped low-phononCsCdCl3andCsPbCl3crystals grown by the Bridgman technique have been investigated. Using optical excitations at∼<#comment/>800nmand∼<#comment/>660nm, both crystals exhibited IR emissions at∼<#comment/>1.55,∼<#comment/>2.75,∼<#comment/>3.5, and∼<#comment/>4.5µ<#comment/>mat room temperature. The mid-IR emission at 4.5 µm, originating from the4I9/2→<#comment/>4I11/2transition, showed a long emission lifetime of∼<#comment/>11.6msforEr3+dopedCsCdCl3, whereasEr3+dopedCsPbCl3exhibited a shorter lifetime of∼<#comment/>1.8ms. The measured emission lifetimes of the4I9/2state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the4I9/2→<#comment/>4I11/2transition inEr3+dopedCsCdCl3andCsPbCl3were determined to be∼<#comment/>0.14×<#comment/>10−<#comment/>20cm2and∼<#comment/>0.41×<#comment/>10−<#comment/>20cm2, respectively. The results of Judd–Ofelt analysis are presented and discussed.

     
    more » « less