Electrical control of terahertz frequency conversion from time-varying surfaces

Lee, Kanghee; Park, Jagang; Son, Juhee; Kang, Bong Joo; Kim, Dong-Won; Lee, Seong Cheol; Min, Bumki; Rotermund, Fabıan

doi:10.1364/oe.27.012762

Cited by 12 publications

(8 citation statements)

References 39 publications

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“…A significant change in transmission is observed, with positive (up to +80% near the resonance central wavelength) and negative variation (down to −25%) in consequence of blue-shift and reduced Q-factor of the resonance in the transmittance spectrum (Figure b) due to the refractive index changes under the induced free carriers. In transient spectroscopy experiments, we focus on negative time delays close to zero delay, where the effects associated with the time-variant nature of the system can be observed. − The photoinduced modulation of the metasurface’s resonance enables frequency conversion of the fundamental beam, as seen in Figure a,b, between −300 and 0 fs time delays. At such negative time delays, as a result of a long lifetime of the mode, characteristic fringes ,, can be observed.…”

Section: Resultsmentioning

confidence: 99%

“…In the extreme case where resonances of metasurfaces are tuned rapidly, a novel class of effects pertaining to the time-variant nature of metasurfaces emerges. Under this framework, harmonic waves cease to be solutions of Maxwell’s equations, and effects such as frequency conversion, − photon acceleration, nonreciprocal light reflection, beam steering, or focusing − that are impossible in stationary systems rise, similar to original works in rapidly generated plasmas. , The frequency conversion that has recently been shown for metasurfaces also has origins similar to that of the coherent artifact in ultrafast time-resolved infrared (IR) spectroscopy of vibrational transitions in chemical systems , and for semiconductors, , which manifest at negative pump–probe time delays when the probe pulse precedes the pump pulse. Even though many systems have revealed linear frequency conversion due to abrupt time modulation, ultrafast studies of the nonlinear response, − which are prominent in resonant metasurfaces, are yet to unveil the control of light frequency for nonlinearly generated waves.…”

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confidence: 99%

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Externally Driven Nonlinear Time-Variant Metasurfaces

et al. 2022

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Resonant photonic nanostructures exhibiting enhanced nonlinear response and efficient frequency conversion are an emergent platform in nonlinear optics. High-index semiconductor metasurfaces with rapidly tuned high-quality-factor (high-Q) resonances enable a novel class of timevariant metasurfaces, which expands the toolbox of color management at the nanoscale. Here, we report on the dynamic control of the nonlinear optical response in time-variant semiconductor metasurfaces supporting high-Q resonances in the near-infrared spectral range. Germanium metasurfaces reveal frequency conversion of the fundamental beam and blue-shift of 10 nm (3.05ω) and 40% broadening in the third-harmonic spectrum due to a subpicosecond-scale time-variant refractive index. A time-dependent coupled-mode theory, in qualitative agreement with the experimental data, validated the time-variant nature of the system. Our findings expand the scope of time-variant metasurfaces and may serve as base for the next generation of nanoscale pulse shapers, optical switches, and light sources.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Externally Driven Nonlinear Time-Variant Metasurfaces

et al. 2022

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“…A 400 nm optical pump pulse was used generated by SHG in a BBO crystal, with a fluence of ≈0.5 µJ cm −2 , except for characterization of the pump fluence dependence. Because the 400 nm pump pulse changed the surface conductivity of GaAs slowly compared with the case with an 800 nm pump pulse, [50] unintended frequency conversion arising from a rapidly time-varying surface [51,52] was suppressed, whereas nonlinear harmonic components were maintained (see Note S8 and Figure S5 in the Supporting Information). The time delay was adjusted between the pump beam and the incident THz wave to maximize the EFISHG efficiency.…”

Section: Methodsmentioning

confidence: 99%

Electrically Controllable Terahertz Second‐Harmonic Generation in GaAs

Lee

Park

Kang

et al. 2020

Advanced Optical Materials

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Terahertz radiation and its nonlinear optical manipulation may possess potential for a variety of applications in next‐generation electronics and optics. Pioneering studies have shown that the nonlinearity of carrier drift in semiconductors and graphene can be utilized for nonlinear optical processes at terahertz frequencies. However, because of the symmetric response of carriers to the terahertz field direction, most experiments have confirmed only the presence of odd‐order nonlinear processes. In this study, electric‐field‐induced terahertz second‐harmonic generation (SHG) in photoexcited gallium arsenide is demonstrated, where an applied bias field breaks the directional symmetry of the drift transport of electrons. The amplitudes of odd‐ and even‐harmonic waves are found to be highly controllable using the bias field. The measured conversion efficiency of SHG reaches beyond 10−5, substantially higher than the value previously reported. This terahertz harmonic generation platform with electrical controllability may be useful for future nonlinear applications at terahertz frequencies.

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“…In the extreme case where resonances of metasurfaces are tuned rapidly, a novel class of effects pertaining to the time-variant nature of metasurfaces emerges. Under this framework, harmonic waves cease to be solutions of Maxwell's equations, and effects such as frequency conversion, [36][37][38] photon acceleration, 35 nonreciprocal light reflection, beam steering or focusing [39][40][41] that are impossible in stationary systems rise, similar to original works in rapidly generated plasmas. 42,43 The frequency conversion that has recently been demonstrated for metasurfaces also has origins similar to that of the coherent artifact in ultrafast time-resolved infrared (IR) spectroscopy of vibrational transitions in chemical systems 44,45 and for semiconductors, 46,47 which manifest at negative time delays, when the probe pulse precedes the pump pulse.…”

Section: Introductionmentioning

confidence: 98%

Externally driven nonlinear time-variant metasurfaces

Zubyuk¹,

Shafirin²,

Shcherbakov³

et al. 2020

Preprint

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Resonant photonic nanostructures exhibiting enhanced nonlinear responses and efficient frequency conversion are an emergent platform in nonlinear optics. High-index semiconductor metasurfaces with rapidly tuned high-Q resonances enable a novel class of time-variant metasurfaces, which expands the toolbox of color management at the nanoscale. Here, we report on the dynamic control of the nonlinear optical response in time-variant semiconductor metasurfaces supporting high-quality factor resonances in the near-infrared spectral range. Pump-probe measurements of germanium metasurfaces at negative pump-probe time delays reveals frequency conversion in the fundamental beam and a blue-shift of 10 nm (3.05ω) and 40% broadening in the third harmonic signal due to the photoinduced time-variant refractive index. A time-dependent coupled-mode theory, in excellent agreement with the experimental data, validated the time-variant nature of the system. Our findings expand the scope of time-variant metasurfaces and may serve as base for the next generation of nanoscale pulse shapers, optical switches and light sources.

show abstract

Electrical control of terahertz frequency conversion from time-varying surfaces

Cited by 12 publications

References 39 publications

Externally Driven Nonlinear Time-Variant Metasurfaces

Externally Driven Nonlinear Time-Variant Metasurfaces

Electrically Controllable Terahertz Second‐Harmonic Generation in GaAs

Externally driven nonlinear time-variant metasurfaces

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