Electrically tuneable lateral leakage loss in liquid crystal clad shallow-etched silicon waveguides

Ako, Thomas; Hope, Anthony P.; Nguyen, Thach G.; Mitchell, Arnan; Bogaerts, Wim; Neyts, Kristiaan; Beeckman, Jeroen

doi:10.1364/oe.23.002846

Cited by 12 publications

(8 citation statements)

References 17 publications

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“…In [19], the existence of strong TE radiation as well as suppression of this radiation at the 'magic' widths were also demonstrated by directly observed the radiating TE field on both sides of the ridge. Further investigations have demonstrated that the lateral leakage loss can be electrically tuned when using liquid crystal (LC) as the cladding materials [20], [21].…”

Section: Experimental Observation Of Lateral Leakage In Soi Ridge mentioning

confidence: 99%

Lateral Leakage in Silicon Photonics: Theory, Applications, and Future Directions

Nguyen

Boes

Mitchell

2020

IEEE J. Select. Topics Quantum Electron.

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This paper presents an overview of lateral leakage in silicon photonics due to polarization coupling between the guided mode of a ridge waveguide and unguided slab mode in the etched cladding. We explain the physical origins and provide insight into how this effect can be suppressed or harnessed. We show how lateral leakage can manifest as new resonant behaviour and explore this effect in the context of bound states in the continuum. We review a number of applications for devices based on lateral leakage and present outlook for a new generation of polarization manipulators, antennas and filters. Index Terms-Silicon photonics, optical waveguide, optical resonator, bound states in the continuum.

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Section: Experimental Observation Of Lateral Leakage In Soi Ridge mentioning

confidence: 99%

Lateral Leakage in Silicon Photonics: Theory, Applications, and Future Directions

Nguyen

Boes

Mitchell

2020

IEEE J. Select. Topics Quantum Electron.

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“…The quasi‐TE mode of such a ridge propagates with low loss and is commonly used in silicon photonics for optical transport . Our team discovered that the quasi‐TM mode can radiate strongly and equally to the TE slab mode on either side (as illustrated in Figure b), an effect called lateral leakage . The generated TE slab mode propagates at a particular angle to the waveguide axis given by

θ = \cos^{- 1} (\frac{n_{t m}}{n_{t e}})

where

n_{t m}

and

n_{t e}

are the effective index of the quasi‐TM guided mode and TE slab mode in the claddings, respectively.…”

Section: Lateral Leakage Of Tm Mode In a Ridge: Leakage Of The Bound mentioning

confidence: 99%

“…It can be seen from Figure e that the angular bandwidth of the reflection depends strongly on the ridge width. When the ridge width approaches the “magic” width at which the lateral leakage loss of the guided quasi‐TM mode is zero, the angular bandwidth of the reflection also approaches zero. This phenomenon indicates the presence of bound states in the continuum when the ridge at the “magic” width is excited with a TE beam at an angle resulting in phase matching between the exited TE beam and quasi‐TM guided mode in the ridge.…”

Section: Te Slab Beam Incident On a Ridge: Excitation Of The Bound Stmentioning

confidence: 99%

“…[14,15] Our team discovered that the TM mode can radiate strongly and equally to the TE slab mode on either side (as illustrated in Figure 1(b)), an effect called lateral leakage. [16][17][18][19][20] The generated TE slab mode propagates at a particular angle to the waveguide axis given by…”

Section: Lateral Leakage Of Tm Mode In a Ridge: Leakage Of The Bound ...mentioning

confidence: 99%

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Ridge Resonance in Silicon Photonics Harnessing Bound States in the Continuum

Nguyen

Ren

Schoenhardt

et al. 2019

Laser & Photonics Reviews

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The theoretical analysis and experimental demonstration of a waveguide resonator are presented based on bound states in the continuum in an integrated photonic chip platform. The continuum has the form of a collimated beam of light which is confined vertically in a transverse electric (TE) mode of a silicon slab. The bound state is a discrete transverse‐magnetic (TM)‐like mode of a ridge on the silicon slab. The coupling between the slab and ridge modes results in a single sharp resonance at the wavelength where they phase match. This phenomenon is experimentally demonstrated on a silicon photonic chip using foundry‐compatible parameters and it is interfaced on‐chip to standard single‐mode silicon nanowire waveguides. The fabricated chip exhibits a single sharp resonance near 1550 nm with a line width of a few nanometers, an extinction ratio of 25 dB, and a thermal stability of 19.5 pm °C−1. It is believed that the demonstration of a resonance operating near a bound state in the continuum realized using guided wave components will form the basis of a new approach to on‐chip wavelength filtering and sensing applications.

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“…This increases the field outside the core, i.e., the evanescent field, allowing for easy modification of overall guiding properties. Tuning the evanescent field is possible by changing the effective refractive index of the cladding, by means of an active electrooptical material such as liquid crystal (LC) [1]. On the other hand, the fabrication process determines the dimensions and shape of the waveguide.…”

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confidence: 99%