Second harmonic generation of diamond-blade diced KTiOPO_4 ridge waveguides

On-chip waveguide amplifiers offer higher gain in small device sizes and better integration with photonic devices than the commonly available fiber amplifiers. However, on-chip amplifiers have yet to make its way into the mainstream due to the limited availability of materials with ideal light guiding and amplification properties. A low-loss nanostructured on-chip channel polymeric waveguide amplifier was designed, characterized, fabricated and its gain experimentally measured at telecommunication wavelength. The active polymeric waveguide core comprises of NaYF4:Yb,Er,Ce core-shell nanocrystals dispersed within a SU8 polymer, where the nanoparticle interfacial characteristics were tailored using hydrolyzed polyhedral oligomeric silsesquioxane-graft-poly(methyl methacrylate) to improve particle dispersion. Both the enhanced IR emission intensity from our nanocrystals using a tri-dopant scheme and the reduced scattering losses from our excellent particle dispersion at a high solid loading of 6.0 vol% contributed to the outstanding optical performance of our polymeric waveguide. We achieved one of the highest reported gain of 6.6 dB/cm using a relatively low coupled pump power of 80 mW. These polymeric waveguide amplifiers offer greater promise for integrated optical circuits due to their processability and integration advantages which will play a key role in the emerging areas of flexible communication and optoelectronic devices.

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“…2a) 23, 24 . This proposed fabrication method is cost-effective, simple, and does not require lithography and chemical etching.…”

Section: Design and Results Of Low-loss Nanostructured Pwamentioning

confidence: 99%

Low Loss Nanostructured Polymers for Chip-scale Waveguide Amplifiers

Chen

Zhao

Sun

et al. 2017

Sci Rep

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“…Note that the tiny additional loss of HS is another crucial factor that leads to the decrease of 532-nm output power and normalized conversion efficiency when compared with the SSL waveguide. Nonetheless, it is still superior to some reported nonlinear waveguides [35,39]. For example, with similar optical-lattice-like cladding microstructures in CW regime, the SH laser power of HS (0.80 mW from 263.68-mW launched power) is enhanced with respect to the reported waveguide (0.68 mW from 613.3-mW incident power) [35].…”

Section: Resultsmentioning

confidence: 72%

Implementation of nearly single-mode second harmonic generation by using a femtosecond laser written waveguiding structure in KTiOPO4 nonlinear crystal

Nie

Romero

et al. 2018

Optical Materials

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We propose a hybrid photonic structure to realize guided-wave second harmonic generation (SHG) from nearinfrared (NIR at 1064 nm) to visible (green light at 532 nm) wavelength with nearly single-mode output. The periodically arrayed tracks have been produced in KTiOPO 4 nonlinear crystal by femtosecond laser writing, which enable efficient light field confinement with cladding-like refractive index distributions. Particularly, the track-cladding surrounded central region is free of any tracks, which serves as waveguiding cores. With designed core diameters, the structures could enable single-mode propagation at selected wavelength regime on purpose. In this work, the hybrid structure contains a larger-input core section and a connected smaller-output core section, which in principle supports nearly single mode for either fundamental pump beam or second harmonic beam in the input and output channel, respectively. Based on this hybrid structure we implement nearly singlemode SHG at 532 nm, and comparable normalized conversion efficiency (1.1%/W/cm) in the continuous-wave (CW) regime is obtained with respect to that (1.2%/W/cm) of multimode SHG from a single large-core channel structure. This work paves the way to realize mode profile controlling for selected wavelength by using laserwritten arrayed tracks.

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“…SHG is dependent on the optical properties of the material, facilitating KTiOPO 4 been widely used in wavelength conversions (Chen et al, 2016). When the axis of symmetry coincides with the laboratory axis-X, the induced SHG polarization can be expressed as…”

Section: Simulationmentioning

confidence: 99%

Calculations of second harmonic generation with radially polarized excitations by elliptical mirror focusing

Wang

Liu

et al. 2018

Journal of Microscopy

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Summary Second harmonic generation (SHG) polarization intensity distribution illuminated with radially polarized beams by lens focusing appears two peaks, when the nonlinear optical coefficients dominate that is relevant to the transverse electric field components. Such two peaks pattern may result in ghosting and the decrement of imaging resolution. In this paper, an elliptical mirror based system is proposed in the case of radially polarized beams illumination for SHG. The calculated predictions and numerical simulations demonstrate that for radially polarized beams, the proportion of transverse field components at the focal plane under the condition of elliptical mirror focusing is 2.6 times smaller than that with lens focusing when its numerical aperture (NA) is 1. Furthermore, the full width at half maximum (FWHM) of the total field intensity profile is approximately 81% of that in a lens focusing system. Due to the enhancement of longitudinal components of incident field, the distribution of SHG polarization presents a single‐peak pattern, in which two peaks can be observed with lens focusing. The SHG polarizations in collagen fiber, KTiOPO4, and LiNbO3 have been numerical simulated and discussed in detail to verify the validity of the proposed method. Lay Description A novel focusing mode for second harmonic generation (SHG) microscopy is described in this paper. In the case of radially polarized excitations, the SHG polarization distributions of some specimens appear two peaks pattern with traditional lens focusing. Such two peaks pattern may result in ghosting and the decrement of imaging resolution. By introducing elliptical mirror, the modulation of electric field at the focal plane can be realized. Thus, the distribution of SHG polarization is converted into a single‐peak pattern which eliminates the ghosting and improves the spatial resolution on SHG images. This proposed method can be used for SHG in various materials and the full width at half maximum (FWHM) of SHG polarization will compress in different degrees. Besides, there is a significant improvement on signal‐to‐noise ratio in SHG imaging when an annular aperture illumination is applied. The focusing mode with elliptical mirror can also be utilized in other nonlinear optics areas such as polarized third harmonic generation (THG) measurements and two‐photon fluorescence (TPF) microscopy.

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Second harmonic generation of diamond-blade diced KTiOPO_4 ridge waveguides

Cited by 25 publications

References 23 publications

Low Loss Nanostructured Polymers for Chip-scale Waveguide Amplifiers

Low Loss Nanostructured Polymers for Chip-scale Waveguide Amplifiers

Implementation of nearly single-mode second harmonic generation by using a femtosecond laser written waveguiding structure in KTiOPO4 nonlinear crystal

Calculations of second harmonic generation with radially polarized excitations by elliptical mirror focusing

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