Second harmonic generation from ZnO films and nanostructures

Larciprete, Maria Cristina; Centini, Marco

doi:10.1063/1.4928032

Cited by 57 publications

(43 citation statements)

References 102 publications

(268 reference statements)

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“…The largest tensor element χ zzz we obtain is identical within the experimental error to the values reported for ZnO single crystals and therefore exceeds the χ (2) of traditional nonlinear crystals like BBO and KDP [7]. Second-harmonic generation (SHG) has been detected before in polycrystalline ZnO films grown on a variety of substrates by a multitude of techniques [6,8]. But, no previous realization would integrate easily with complex topology as encountered on a photonic chip and still exhibit maximal χ (2) nonlinearity.…”

supporting

confidence: 59%

“…For the off-diagonal components the dispersion appears larger. This could be attributed to bulk and grain boundary contributions to the total SHG [6]. As the chemical bonds at grain boundaries are different from those in bulk crystal, the resonance wavelength of the grain boundary contributions will also deviate from the bulk material resonance.…”

mentioning

confidence: 99%

“…In this paper, we report on the χ (2) nonlinearities of plasmaenhanced ALD (PE-ALD) ZnO thin films on amorphous glass substrates which are found to be significantly larger than those observed for thermal ALD ZnO [5]. ZnO is a wide band gap material (~3.3 eV) that crystallizes preferably in the hexagonal wurtzite structure, point group 6mm [6]. For ZnO single crystals, χ zzz = -14.31 pm/V and χ zxx = 1.36 pm/V have been found [6].…”

mentioning

confidence: 99%

“…ZnO is a wide band gap material (~3.3 eV) that crystallizes preferably in the hexagonal wurtzite structure, point group 6mm [6]. For ZnO single crystals, χ zzz = -14.31 pm/V and χ zxx = 1.36 pm/V have been found [6]. The largest tensor element χ zzz we obtain is identical within the experimental error to the values reported for ZnO single crystals and therefore exceeds the χ (2) of traditional nonlinear crystals like BBO and KDP [7].…”

mentioning

confidence: 99%

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CMOS-Compatible ALD Zinc Oxide Coating for On-Chip Second-Order Nonlinear Optical Functionalities

Hermans

Daele

Kieninger

et al. 2017

Conference on Lasers and Electro-Optics

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Abstract:We report on the atomic layer deposition of ZnO for interfacing with existing Si 3 N 4 photonics which lacks 2 nd -order nonlinear functionalities. We measure a χ (2) of 15 pm/V in line with a bulk ZnO crystal. ) devices rely on bulk nonlinear crystals or low contrast waveguides. However, the continuing expansion of silicon and silicon nitride photonics requires the intrinsically missing χ (2) nonlinearity to be introduced in a way compatible with CMOS fabrication. Recent studies have pointed out atomic layer deposition (ALD) as a very promising technique to fabricate χ (2) materials suitable for integration with CMOS-compatible photonic integrated circuits. Examples include the reports on ALD ABC-type nanolaminates [3,4] and ZnO nanolaminates [5]. ALD is an attractive technique because it is a low-temperature, conformal deposition process that works on a large variety of substrates and provides thickness precision at the monolayer level. In this paper, we report on the χ (2) nonlinearities of plasmaenhanced ALD (PE-ALD) ZnO thin films on amorphous glass substrates which are found to be significantly larger than those observed for thermal ALD ZnO [5]. ZnO is a wide band gap material (~3.3 eV) that crystallizes preferably in the hexagonal wurtzite structure, point group 6mm [6]. For ZnO single crystals, χ zzz = -14.31 pm/V and χ zxx = 1.36 pm/V have been found [6]. The largest tensor element χ zzz we obtain is identical within the experimental error to the values reported for ZnO single crystals and therefore exceeds the χ (2) of traditional nonlinear crystals like BBO and KDP [7]. Second-harmonic generation (SHG) has been detected before in polycrystalline ZnO films grown on a variety of substrates by a multitude of techniques [6,8]. But, no previous realization would integrate easily with complex topology as encountered on a photonic chip and still exhibit maximal χ (2) nonlinearity. Here, we use ALD that indeed interfaces very well with photonic waveguides [9].The thin films studied here are deposited on glass (BOROFLOAT ® 33, 500 μm thickness) using a homebuilt ALD setup with a base pressure of 10 -6 mbar. Experiments are performed on two different samples: (I) 39.1 nm ZnO on glass, and (II) 36.7 nm ZnO on 6 nm Al 2 O 3 on glass. The thicknesses are determined through x-ray reflectivity measurements. An Al 2 O 3 seed layer is used in sample (II) because it has been shown to promote (002) orientation of the ZnO crystallites (c-axis perpendicular to the substrate) and improve χ (2) [5,10]. The Al 2 O 3 layer is deposited via thermal ALD at a substrate temperature of 120°C (from trimethylaluminium and water, both for 5 s at 5×10 -3 mbar). ZnO deposition is done at a substrate temperature of 300°C by PE-ALD (using 5 s diethyl zinc at 5×10 -3 mbar and 10 s oxygen plasma at 10 -2 mbar). The O 2 plasma is generated at an RF power of 200 W and a frequency of 13.56 MHz.The χ (2) tensor elements of ZnO are determined and verified by SHG experiments using two different setups operating at a fundamental waveleng...

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supporting

confidence: 59%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

CMOS-Compatible ALD Zinc Oxide Coating for On-Chip Second-Order Nonlinear Optical Functionalities

Hermans

Daele

Kieninger

et al. 2017

Conference on Lasers and Electro-Optics

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“…have been revealed. On the other hand, SHG effect of ZnO has also been well explored, including the exciton enhanced SHG [35], SHG that influenced by crystalline structure, dimensions, grains and doping [36], second harmonic polaritons [37] etc. Taking advantage of coherent polariton states and SHG continuum states with comparable strength in ZnO, Fano resonances with high coupling coefficiency can be expected.…”

mentioning

confidence: 99%

Exciton-Polariton Fano Resonance Driven by Second Harmonic Generation

Wang

Liao

et al. 2017

Phys. Rev. Lett.

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Angle-resolved second harmonic generation (SHG) spectra of ZnO microwires show characteristic Fano resonances in the spectral vicinity of exciton-polariton modes. The output SHG spectra after SHG interacting with exciton polariton shows a resonant enhancement peak accompanied by a suppression dip originating from the constructive and destructive interference respectively. It is demonstrated that the Fano line shape, and thus the Fano asymmetry parameter q, can be tuned by the phase-shift of the two channels. The phase-dependent q was calculated and the model describes our experimental results well. In particular, the phase-to-q relation unveil the crucial information about the dynamics of the system, e.g., defining the line shape of output SHG spectra in a superposition of quantum states.Fano resonance, known as a fingerprint of quantum interference effect, has attracted much attention since discovered by Ugo Fano.[1] It originates from the interference between a discrete state and a continuum of quantum states, giving rise to a characteristic asymmetric emission line shape. First introduced to describe the atomic photo-ionization [1, 2], exploration of this important phenomenon and the underlying physics have been extended to the fields of photonic crystals [3,4], plasmonic devices [5][6][7], metamaterials [8,9], fiber-cavity systems [10],Raman scattering [11, 12], nonlinear optics, etc. [13-20]. The Fano line shape is considered as a unique asymmetric spectral response, and its tunability in a discrete-continuum coupled quantum system provides great opportunities for developing optronic devices such as on chip

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Anomalously Strong Second‐Harmonic Generation in GaAs Nanowires via Crystal‐Structure Engineering

Bin

Stehr

Chen

et al. 2021

Adv Funct Materials

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GaAs‐based semiconductors are highly attractive for diverse nonlinear photonic applications, owing to their non‐centrosymmetric crystal structure and huge nonlinear optical coefficients. Nanostructured semiconductors, for example, nanowires (NWs), offer rich possibilities to tailor nonlinear optical properties and further enhance photonic device performance. In this study, it is demonstrated highly efficient second‐harmonic generation in subwavelength wurtzite (WZ) GaAs NWs, reaching 2.5 × 10−5 W−1, which is about seven times higher than their zincblende counterpart. This enhancement is shown to be predominantly caused by an axial built‐in electric field induced by spontaneous polarization in the WZ lattice via electric field‐induced second‐order nonlinear susceptibility and can be controlled optically and potentially electrically. The findings, therefore, provide an effective strategy for enhancing and manipulating the nonlinear optical response in subwavelength NWs by utilizing lattice engineering.

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Second harmonic generation from ZnO films and nanostructures

Cited by 57 publications

References 102 publications

CMOS-Compatible ALD Zinc Oxide Coating for On-Chip Second-Order Nonlinear Optical Functionalities

CMOS-Compatible ALD Zinc Oxide Coating for On-Chip Second-Order Nonlinear Optical Functionalities

Exciton-Polariton Fano Resonance Driven by Second Harmonic Generation

Anomalously Strong Second‐Harmonic Generation in GaAs Nanowires via Crystal‐Structure Engineering

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