Electrohydrodynamic Jet Printing of 1D Photonic Crystals: Part II—Optical Design and Reflectance Characteristics

Additive manufacturing systems that can arbitrarily deposit multiple materials into precise, 3D spaces spanning the micro‐ to nanoscale are enabling novel structures with useful thermal, electrical, and optical properties. In this companion paper set, electrohydrodynamic jet (e‐jet) printing is investigated for its ability in depositing multimaterial, multilayer films with microscale spatial resolution and nanoscale thickness control, with a demonstration of this capability in creating 1D photonic crystals (1DPCs) with response near the visible regime. Transfer matrix simulations are used to evaluate different material classes for use in a printed 1DPC, and commercially available photopolymers with varying refractive indices (n = 1.35 to 1.70) are selected based on their relative high index contrast and fast curing times. E‐jet printing is then used to experimentally demonstrate pixelated 1DPCs with individual layer thicknesses between 80 and 200 nm, square pixels smaller than 40 µm across, with surface roughness less than 20 nm. The reflectance characteristics of the printed 1DPCs are measured using spatially selective microspectroscopy and correlated to the transfer matrix simulations. These results are an important step toward enabling cost‐effective, custom‐fabrication of advanced imaging devices or photonic crystal sensing platforms.Electrohydrodynamic jet printing is used to create patterned arrays of multimaterial photopolymer 1D photonic crystals. Patterns are demonstrated with in‐plane dimensions below 40 µm, layer thicknesses less than 100 nm, and surface root mean square roughness below 20 nm. This novel fabrication method can enable rapid, reconfigurable manufacturing of custom photonic sensing arrays.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163389/2/admt202000431-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163389/1/admt202000431.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163389/3/admt202000431_am.pd

DBR and DFB lasers in neodymium-and ytterbium-doped photothermorefractive glasses

The first demonstration, to the best of our knowledge, of distributed Bragg reflector (DBR) and monolithic distributed feedback (DFB) lasers in photothermorefractive glass doped with rare-earth ions is reported. The lasers were produced by incorporation of the volume Bragg gratings into the laser gain elements. The need for environment-insensitive, compact, robust, narrow line laser sources has stimulated the development of hybrid devices, such as distributed Bragg reflector (DBR) lasers, in which a laser resonator is produced by Bragg mirrors incorporated in a gain element, or distributed feedback (DFB) lasers, in which a resonator is produced by a Bragg grating that occupies the whole gain element. The concept of DFB was first successfully applied to optically pumped dye lasers The PTR glass has composition (M%) The two last elements are responsible for initiation of the photostructural transformations in the glass and enable VBG recording. As it was demonstrated in our earlier studies Nd-and Yb-doped PTR glasses with 2 wt. % of Yb and Nd ions have been prepared. The measurements of emission spectra were carried out in these glasses using an Ocean Optics spectrometer when glass samples were excited with a diode laser emitting at 808 nm (in the case of Nd ions) and 915 nm (for Yb ones

Accurate determination of the optical performances of antireflective coatings by low coherence reflectometry

International audienc

Mechanisms and kinetics of short pulse laser-induced destruction of silver-containing nanoparticles in multicomponent silicate photo-thermo-refractive glass

International audiencePhoto-thermo-refractive (PTR) glass is a photosensitive multi-component silicate glass that is commercially used for the recording of volume holographic elements and finds many applications in advanced laser systems. Refractive index decrement in this glass is observed after UV exposure followed by thermal development. This procedure also causes the appearance of Ag-containing particles that can then be optically bleached by using the second harmonic of a Nd:YAG laser. Despite the broad usage of this method, its mechanisms are still unclear. In this paper, a systematic study of the short pulse laser-induced destruction of Ag-containing particles’ kinetics versus incident energy per pulse and dosage is presented. We show that no bleaching of Ag-containing particles occurs for an energy density in laser pulses below 0.1  J/cm2 while above 1  J/cm2, the efficiency of bleaching saturates. Efficiency of bleaching depends on the type of particles to be bleached (Ag, AgBr…). Using a simple model of short pulse laser interaction with nanoparticles embedded in glass, the temperature of the Ag-containing particles reached during the laser interaction is shown to be large enough to produce complete dissipation of these particles which is expected to be the main mechanism of short pulse laser-induced destruction of Ag-containing particles

Localized measurement of the optical thickness of transparent window – Application to the study of the photosensitivity of organic polymers

The development of an optical setup that permits us to carry out high-resolution mappings of the absolute optical thickness of plane-parallel transparent windows is described. This measurement is based on the recording and processing of the spectral transmission of the wafer between 1520 and 1570 nm and has a relative precision better than 10-6. Hence it is used for the characterization of the photosensitivity of two organic photopolymers (cationic ring opening polymer and poly(methylmethacrylate)). The refractive index change dynamics for both materials and the spontaneous evolution of the optical thickness are demonstrated. © 2006 Optical Society of America

Extension de la méthode de Pisarenko et ses dérivées au cas des signaux vectoriels et applications à la localisation de sources

Une extension de la méthode de Pisarenko et de ses dérivées au cas des signaux vectoriels est proposée. On montre comment adapter cette méthode aux signaux aléatoires. Différents modèles de bruit vectoriel sont envisagés et les solutions adéquates sont décrites. Cette méthodologie est appliquée en traitement spatial : on défmit une nouvelle méthode de localisation de sources décorrélées - qui ne nécessite que deux capteurs pour détecter un nombre quelconque de sources -, et une variante permet de traiter le cas des sources corrélées

Tunable Ultra-Narrow Band-Pass Filters Based On Volume Bragg Grating

90% efficient large aperture tunable optical filters having very narrow spectral width and realized by the incoherent association of a volume Bragg grating and a Fabry-Perot etalon are described and demonstrated. © 2006 Optical Society of America

Absorption and scattering in photo-thermo-refractive glass induced by UV exposure and thermal development

International audiencePhoto-thermo-refractive (PTR) glass is a multicomponent photosensitive silicate glass that, after successive UV-exposure and thermal treatment, exhibits a refractive index change that results from the precipitation of nano-crystalline NaF. This glass is successfully used for the fabrication of holographic optical elements (volume Bragg gratings) that dramatically enhance properties of numerous laser systems and spectrometers. In this paper, induced absorption and scattering that determine efficiency of such elements were studied. It is found that the main contribution to induced absorption is produced by several types of silver containing particles having absorption bands with maxima in the blue-green region with exponential tails extending to the near IR spectral region. Evolution of all absorption bands was studied for different conditions of UV exposure and thermal development. Complex mechanisms of interconversion of silver containing particles is demonstrated as well as the fact that some of these particles can be associated with catalyzers of the nucleation process. It is also found that induced scattering obeys the classic Rayleigh law with an intensity depending on the conditions of UV exposure and thermal development. For short development times, scattering increases with dosage because of increased volume fraction of crystalline phase. For long development times, scattering decreases with dosage because of decreased size of individual crystals