High speed optical phased array using high contrast grating all-pass filters

Yang, Wankou; Sun, Tao; Rao, Yi; Megens, Mischa; Chan, Theodore; Yoo, Byung Woo; Horsley, David A.; Wu, M.C.; Chang-Hasnain, Connie J.

doi:10.1364/oe.22.020038

Cited by 53 publications

(33 citation statements)

References 24 publications

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“…SWG reflectors integrated in Fabry-Perot resonators have also been used to realize vertical-cavity surface-emitting lasers (VCSELs) 19 by replacing the conventional DBRs, and also to show novel MEMS devices. 9,20 This asymmetric Fabry-Perot resonator is equivalent to a conventional Gires-Tournois interferometer, with a bottom mirror exhibiting nearly unity reflectivity and a less reflective top mirror, that is widely used for pulse compression bacause of its highly dispersive phase response. Owing to the high electric field energy density in the silicon SWG layer when used in a Fabry-Perot resonator 21 ( Figure 1d), the resonance frequency can be efficiently tuned with respect to the wavelength of the incident light by modulating the refractive index of the silicon bars.…”

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confidence: 99%

High-Speed, Phase-Dominant Spatial Light Modulation with Silicon-Based Active Resonant Antennas

Horie

Arbabi

et al. 2017

ACS Photonics

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Spatiotemporal control of optical wavefronts is of great importance in numerous free-space optical applications including imaging in 3D and through scattering media, remote sensing, and generation of various beam profiles for microscopy. Progress in these applications is currently limited due to lack of compact and high-speed spatial light modulators. Here we report an active antenna comprising a free-space coupled asymmetric Fabry–Perot resonator that produces a phase-dominant thermo-optic modulation of reflected light at frequencies approaching tens of kilohertz. As a proof of concept for spatial light modulation, we demonstrate a 6 × 6 array of such active antennas with beam deflection capability. The robust design of our silicon-based active antenna will enable large-scale integration of high-speed, phase-dominant spatial light modulators.

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confidence: 99%

High-Speed, Phase-Dominant Spatial Light Modulation with Silicon-Based Active Resonant Antennas

Horie

Arbabi

et al. 2017

ACS Photonics

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“…With this technique, each unit cell of the device is composed of a single asymmetric Fabry-Perot resonator. This approach has been well-explored previously, in which such structures have been patterned to form beam-steering arrays and phase-only modulation of spatial light distributions10525354. While this methodology may enable implementation of arbitrary phase profiles up to the limit of the Nyquist-Shannon sampling theorem, it would not provide subwavelength resolution due to the required lateral spatial extent of the cavity.…”

Section: Resultsmentioning

confidence: 99%

“…Asymmetric Fabry-Perot-inspired modulators and phased-arrays have been explored previously105253, but have consisted of an array of grating elements per pixel or stacked high contrast gratings54. Both of these approaches fail to provide subwavelength spatial resolution, which is necessary for micron-scale focal lengths and high phase curvatures.…”

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confidence: 99%

Tunable metasurfaces via subwavelength phase shifters with uniform amplitude

Colburn

Zhan

Majumdar

2017

Sci Rep

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Metasurfaces with tunable spatial phase functions could benefit numerous applications. Currently, most approaches to tuning rely on mechanical stretching which cannot control phase locally, or by modulating the refractive index to exploit rapid phase changes with the drawback of also modulating amplitude. Here, we propose a method to realize phase modulation at subwavelength length scales while maintaining unity amplitude. Our device is inspired by an asymmetric Fabry-Perot resonator, with pixels comprising a scattering nanopost on top of a distributed Bragg reflector, capable of providing a nearly 2π nonlinear phase shift with less than 2% refractive index modulation. Using the designed pixels, we simulate a tunable metasurface composed of an array of moderately coupled nanopost resonators, realizing axicons, vortex beam generators, and aspherical lenses with both variable focal length and in-plane scanning capability, achieving nearly diffraction-limited performance. The experimental feasibility of the proposed method is also discussed.

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“…In this solution, HCG is utilized as ultra-lightweight mirror. With MEMS technology, small HCG displacement (~50 nm) leads to large phase change (~1.7 π) 11 . Therefore, effective beam steering is achieved.…”

Section: Hcg-apf Opamentioning

confidence: 99%

Progress and prospects of silicon-based design for optical phased array

Peng

Chang-Hasnain

2016

SPIE Proceedings

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The high-speed, high-efficient, compact phase modulator array is indispensable in the Optical-phased array (OPA) which has been considered as a promising technology for realizing flexible and efficient beam steering. In our research, two methods are presented to utilize high-contrast grating (HCG) as high-efficient phase modulator. One is that HCG possesses high-Q resonances that origins from the cancellation of leaky waves. As a result, sharp resonance peaks appear on the reflection spectrum thus HCGs can be utilized as efficient phase shifters. Another is that low-Q mode HCG is utilized as ultra-lightweight mirror. With MEMS technology, small HCG displacement (~50 nm) leads to large phase change (~1.7 π). Effective beam steering is achieved in Connie Chang-Hasnian's group. On the other hand, we theoretically and experimentally investigate the system design for silicon-based optical phased array, including the star coupler, phased array, emission elements and far-field patterns. Further, the non-uniform optical phased array is presented.

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High speed optical phased array using high contrast grating all-pass filters

Cited by 53 publications

References 24 publications

High-Speed, Phase-Dominant Spatial Light Modulation with Silicon-Based Active Resonant Antennas

High-Speed, Phase-Dominant Spatial Light Modulation with Silicon-Based Active Resonant Antennas

Tunable metasurfaces via subwavelength phase shifters with uniform amplitude

Progress and prospects of silicon-based design for optical phased array

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