ZnO indiffused MgO:PPLN ridge waveguides

Carpenter, Lewis G.; Berry, Sam A.; Bannerman, Rex H. S.; Gray, Alan C.; Gawith, C.B.E.

doi:10.1364/oe.27.024538

Cited by 16 publications

(9 citation statements)

References 20 publications

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“…Our PPLN waveguide manufacturing is based on three simplified steps of zinc indiffusion to create a planar guiding layer, ultra-precision machining to form single-mode ridge waveguides, and preparation of facets by dicing. We deposit a metallic zinc layer to create a uniform indiffusion for the planar guiding layer, ensuring a phasematching response close to the theoretical prediction and improvement over the use of ZnO used in our previous work [23], which describes the steps taken to optimise the indiffusion parameters and ridge widths for single-mode operation. Zinc indiffusion is performed post-poling to preserve the uniformity of the periodically poled domains; it would be possible to perform the zinc indiffusion before poling.…”

Section: Fabricationmentioning

confidence: 94%

Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency

Berry¹,

Carpenter²,

Gray³

et al. 2019

OSA Continuum

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We present a metallic zinc indiffused diced ridge waveguide in magnesium doped periodically poled lithium niobate (MgO:PPLN) capable of generating over 1 W of 780 nm with 70% efficiency. Our 40 mm long waveguide has near circular fundamental mode output with diameter 10.4 µm and insertion loss of -1.17 dB. Using a commercial 2 W EDFA-based system, the SHG output power did not exhibit roll-off at maximum available pump power.

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Section: Fabricationmentioning

confidence: 94%

Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency

Berry¹,

Carpenter²,

Gray³

et al. 2019

OSA Continuum

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“…This results in a planar waveguide which is single-mode in the vertical axis. Thẽ 7 µm-wide ridge waveguide and end facets are formed via ultra-precision dicing, similar to that presented by Carpenter et al [11]. We perform the poling process prior to waveguide fabrication due to findings from Ming et al [6] in which a reduction in poling quality was observed if the fabrication process flow was reversed.…”

Section: Optical Characterisation and Numerical Methodologymentioning

confidence: 99%

“…We assume a maximum ∆n of 0.003, as per Ref. [7], and match the diffusion depth of the model to the evaluated, y-axis mode field diameter; this technique is detailed by Carpenter et al [11]. As the relative nonuniformity is of key interest in this work, the propagation constant associated with each effective index value is offset as a relative propagation constant described by…”

Section: Optical Characterisation and Numerical Methodologymentioning

confidence: 99%

Investigation of PPLN Waveguide Uniformity via Second Harmonic Generation Spectra

Gray

Berry

Carpenter

et al. 2020

IEEE Photon. Technol. Lett.

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Experimental data collection methods and a corresponding numerical model are presented to investigate the quality of waveguide fabrication in nonlinear optics. The method utilises white light interferometry and standard image recognition techniques to calculate a waveguide propagation constant function. This enables comparison of a numerical second harmonic spectrum in quasi-phasematched materials, such as periodically poled lithium niobate, with the waveguide's experimental phasematching spectrum. Using the presented method, a 3 rd order polynomial fit to waveguide ridge width is demonstrated to be in good agreement with experimental phasematching spectra. The presented technique provides a nondestructive route to discriminate between issues in fabrication steps in nonlinear waveguide design. Index Terms-

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“…Our approach to manufacturing PPLN waveguides is reported in our earlier works [14,15] and is based on three successive stages: zinc indiffusion to create a planar guiding layer, ultraprecision machining to form single-mode ridge waveguides, and preparation of the optical facets by dicing. The devices described in this paper were prepared in 1 mm-thick 5% magnesium-doped periodically-poled lithium niobate (MgO:PPLN) wafers (Covesion Ltd) each containing multiple 1.2 mm-wide 18.5 µm period gratings designed to access Type-0 1560-780 nm SHG via the d33 nonlinear coefficient.…”

Section: Fabricationmentioning

confidence: 99%

“…Metallic zinc was sputtered with a thickness of 100 nm on to the +z surface of each MgO:PPLN wafer (Oxford Instruments Plasma Technology, Plasma Lab System 400) and indiffused at 950 ºC in an oxygen atmosphere to promote ZnO formation. To overcome any machining inaccuracy and facilitate high pump and SHG modal overlap at our chosen wavelengths, five ridge widths were cut into each PPLN grating ranging from 11-13 µm in 0.5 µm steps and parallel to the [100] X direction of the crystal [14,15]. Individual chips measuring 4.0 cm-long by 5 mm-wide were singulated from the wafers (Fig.…”

Section: Fabricationmentioning

confidence: 99%

CW demonstration of SHG spectral narrowing in a PPLN waveguide generating 2.5 W at 780 nm

Carpenter¹,

Berry²,

Gray³

et al. 2020

Opt. Express

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Periodically poled lithium niobate (PPLN) waveguides are a proven and popular means for efficient wavelength conversion. However, conventional PPLN waveguides typically have small mode field diameters (MFD) (≲6 µm) or significant insertion and/or propagation losses, limiting their ability to operate at multi-watt power levels. In this work we utilise zinc indiffused PPLN ridge waveguides that have a larger MFD, favourable pump/SHG modal overlap, and low insertion losses. Here for the first time, we have demonstrated continuous wave (CW) spectral narrowing from a PPLN waveguide; both with high efficiency and multi-watt second harmonic generation (SHG). 2.5 W of 780 nm has been produced by SHG of an amplified 1560 nm telecom laser with a device efficiency of 58% in a 4.0 cm-long ridge waveguide. We have modelled conversion efficiency and applied experimentally measured waveguide parameters to show excellent agreement to the SHG spectra. Spectral narrowing of the full width half maximum (FWHM) of 35.7% has been measured as the nonlinear drive is increased. This work demonstrates that single-pass, multi-watt, CW SHG at 780 nm is feasible from our PPLN waveguide in the large conversion regime.

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ZnO indiffused MgO:PPLN ridge waveguides

Cited by 16 publications

References 20 publications

Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency

Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency

Investigation of PPLN Waveguide Uniformity via Second Harmonic Generation Spectra

CW demonstration of SHG spectral narrowing in a PPLN waveguide generating 2.5 W at 780 nm

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