Real-World Image Variation by Aligning Diffusion Inversion Chain

Recent diffusion model advancements have enabled high-fidelity images to be generated using text prompts. However, a domain gap exists between generated images and real-world images, which poses a challenge in generating high-quality variations of real-world images. Our investigation uncovers that this domain gap originates from a latents' distribution gap in different diffusion processes. To address this issue, we propose a novel inference pipeline called Real-world Image Variation by ALignment (RIVAL) that utilizes diffusion models to generate image variations from a single image exemplar. Our pipeline enhances the generation quality of image variations by aligning the image generation process to the source image's inversion chain. Specifically, we demonstrate that step-wise latent distribution alignment is essential for generating high-quality variations. To attain this, we design a cross-image self-attention injection for feature interaction and a step-wise distribution normalization to align the latent features. Incorporating these alignment processes into a diffusion model allows RIVAL to generate high-quality image variations without further parameter optimization. Our experimental results demonstrate that our proposed approach outperforms existing methods with respect to semantic-condition similarity and perceptual quality. Furthermore, this generalized inference pipeline can be easily applied to other diffusion-based generation tasks, such as image-conditioned text-to-image generation and example-based image inpainting.Comment: 19 pages; Project page: https://rival-diff.github.io/ Code(release later): https://github.com/julianjuaner/RIVAL

Efficient continuous-wave laser operation at 1064 nm in Nd:YVO4 cladding waveguides produced by femtosecond laser inscription

Cladding waveguides have been produced in Nd:YVO4 crystals by using femtosecond laser inscription. Such structures are fabricated with circular cross sections and diameters of ~100-120 μm, supporting multimode guidance in the two orthogonal polarizations. At room temperature continuous wave laser oscillations at wavelength of ~1064 nm have been realized through the optical pump at 808 nm with slope efficiency as high as 65% and a maximum output power of 335 mW

Ref-NPR: Reference-Based Non-Photorealistic Radiance Fields for Controllable Scene Stylization

Current 3D scene stylization methods transfer textures and colors as styles using arbitrary style references, lacking meaningful semantic correspondences. We introduce Reference-Based Non-Photorealistic Radiance Fields (Ref-NPR) to address this limitation. This controllable method stylizes a 3D scene using radiance fields with a single stylized 2D view as a reference. We propose a ray registration process based on the stylized reference view to obtain pseudo-ray supervision in novel views. Then we exploit semantic correspondences in content images to fill occluded regions with perceptually similar styles, resulting in non-photorealistic and continuous novel view sequences. Our experimental results demonstrate that Ref-NPR outperforms existing scene and video stylization methods regarding visual quality and semantic correspondence. The code and data are publicly available on the project page at https://ref-npr.github.io.Comment: Accepted by CVPR2023. 17 pages, 20 figures. Project page: https://ref-npr.github.io, Code: https://github.com/dvlab-research/Ref-NP

Three-Dimensional Waveguide Splitters Inscribed in Nd:YAG by Femtosecond Laser Writing: Realization and Laser Emission

n this paper, we report on a three-dimensional beam splitter monolithically integrated in an Nd:YAG laser crystal wafer by applying the direct femtosecond laser writing technique with the photonic-lattice-like cladding approach, capable of 1 to 2 and 1 to 4 beam splitting. Using the pump at 808 nm, 1064-nm splitting lasers with slope efficiencies of 34% and 22% for 1 to 2 and 1 to 4 configurations were realized. This study paves a way to fabricate direct-pump compact laser devices in a single chip for light guiding and beam dividing in Nd:YAG crystals for various photonic applications.This work was supported by National Natural Science Foundation of China (No. 11274203) and Ministerio de Economía y Competitividad under Project FIS2013–44174-P, Spain

Femtosecond laser micromachined ridge waveguide lasers in Nd:YAG ceramics

We report on the fabrication of ridge waveguides in Nd:YAG ceramic by using femtosecond laser micromachining of the surface of a He ion implanted planar waveguide. Under optical pump of 808 nm light, continuous wave waveguide lasers have been realized at 1.06 μm at room temperature in the Nd:YAG ceramic ridge waveguide system, reaching a maximum output power of 46 mW. The lasing threshold of ∼64.9 mW and the slope efficiency of 42.5% are obtained for the ridge waveguide system, which shows superior lasing performance to the Nd:YAG ceramic planar waveguide.The work is supported by the National Natural Science Foundation of China (No. 10925524), the Spanish Ministerio de Ciencia e Innovación (MICINN) through Consolider Program SAUUL CSD2007-00013, Project FIS2009-09522 and Junta de Castilla y León (Project SA086A12-2). S.Z. acknowledges the funding by the Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF-VHNG-713). Support from the Centro de L seres Pulsados (CLPU) is also acknowledged

Ultrafast laser inscribed cladding waveguides in Nd:YAG crystal for mid-infrared wavelength

We report on tubular cladding optical waveguides fabricated in neodymium doped yttrium aluminum garnet (Nd:YAG) crystal by ultrafast laser inscription. The structure can support guidance at the wavelength of 4 μm for the TE and TM polarizations. The refractive index contrasts of the cladding waveguides for the two transverse polarizations were estimated to be ΔnTE≈−7.5×10−3 and ΔnTM≈−6.5×10−3. The propagation losses of the cladding waveguides at the wavelength of 4 μm were determined to be as low as ~0.7 dB/cm for the TE polarization and ~1.0 dB/cm for the TM polarization.The work is supported by the National Natural Science Foundation of China (Nos. 11274203 and 11111130200), the Spanish Ministerio de Ciencia e Innovación (CSD2007-00013 and FIS2009-09522) and the Junta de Castilla y León (Project SA086A12-2)

Femtosecond laser micromachining of Nd:GdCOB ridge waveguides for second harmonic generation

We report on the fabrication of Nd:GdCOB ridge waveguides by using femtosecond laser micromachining of planar waveguides that were produced by carbon ion irradiation. The guiding properties of the Nd:GdCOB ridge waveguides are investigated. The second harmonic generation (SHG) at 532 nm green laser from ridges in a series of transverse widths is realized. The results show that the optical conversion efficiencies of SHG in the fabricated ridge waveguides are considerably enhanced with respect to the planar waveguide, and the maximum value reaches 11.4% under a pulsed 1064 nm laser pump.The work is supported by the National Natural Science Foundation of China (No. 10925524), the Spanish Ministerio de Ciencia e Innovación (MICINN) through Consolider Program SAUUL CSD2007-00013 and Project FIS2009-09522. S.Z. acknowledges the funding by the Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF-VH-NG-713). Support from the Centro de Láseres Pulsados (CLPU) is also acknowledged

Enhanced Second Harmonic Generation in Femtosecond Laser Inscribed Double-Cladding Waveguide of Nd:GdCOB Crystal

We report on the fabrication of double-cladding waveguides in Nd:GdCOB crystals by using femtosecond laser inscription with scanning speed of 0.5 mm/s. This prototype consists of two concentric tubular structures with nearly circular cross sections with different diameters. The fabricated cladding waveguides possess relatively low propagation losses of less than 0.65 dB/cm. The micro photoluminescence and second harmonic confocal images of the fabricated waveguides, which were performed by using a confocal microscope, have revealed that neither the fluorescence nor the nonlinear properties of the constituent crystals have been deteriorated during femtosecond lasermicromachining procedure. Under the pulsed laser pumping at fundamental wavelength of 1064 nm, the guided wave second harmonic generation (SHG) at 532 nm has been realized from the single and double cladding waveguides. Compared to the single-claddings (2.3 or 4.7%, depending on the diverse cladding diameters), the double cladding architecture has been found to be with enhanced SHG conversion efficiency (∼5.1%).The work was supported by the National Natural Science Foundation of China under Grants 11274203 and 11111130200, the Spanish Ministerio de Ciencia e Innovación (MICINN) through Consolider Program SAUUL CSD2007-00013 and Project FIS2009-09522, and the Centro de Láseres Pulsados (CLPU)