The combination of materials with targeted optical properties and of complex, 3D architectures, which can be nowadays obtained by additive manufacturing, opens unprecedented opportunities for developing new integrated systems in photonics and optoelectronics The recent progress in additive technologies for processing optical materials is here presented, with emphasis on accessible geometries, achievable spatial resolution, and requirements for printable optical materials Relevant examples of photonic and optoelectronic devices fabricated by 3D printing are shown, which include light-emitting diodes, lasers, waveguides, optical sensors, photonic crystals and metamaterials, and micro-optical components The potential of additive manufacturing applied to photonics and optoelectronics is enormous, and the field is still in its infancy Future directions for research include the development of fully printable optical and architected materials, of effective and versatile platforms for multimaterial processing, and of high-throughput 3D printing technologies that can concomitantly reach high resolution and large working volumes

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adom.201800419

Additive Manufacturing: Applications and Directions in Photonics and Optoelectronics.

The purpose of the work was to emphasize the main differences and similarities in the degradation mechanisms in the case of polymeric coatings compared with the bulk ones. Combined with the current background, this work reviews the properties of commonly utilized degradable polymers in drug delivery, the factors affecting degradation mechanism, testing methods while offering a retrospective on the evolution of the controlled release of biodegradable polymeric coatings. A literature survey on stability and degradation of different polymeric coatings, which were thoroughly evaluated by different techniques, e.g., polymer mass loss measurements, surface, structural and chemical analysis, was completed. Moreover, we analyzed some shortcomings of the degradation behavior of biopolymers in form of coatings and briefly proposed some solving directions to the main existing problems (e.g., improving measuring techniques resolution, elucidation of complete mathematical analysis of the different degradation mechanisms). Deep studies are still necessary on the dynamic changes which occur to biodegradable polymeric coatings which can help to envisage the future performance of synthesized films designed to be used as medical devices with application in drug delivery.

Degradation Behavior of Polymers Used as Coating Materials for Drug Delivery-A Basic Review.

The phenomenon of synchronization occurs universally across the natural sciences and provides critical insight into the behavior of coupled nonlinear dynamical systems. It also offers a powerful approach to robust frequency or temporal locking in diverse applications including communications, superconductors, and photonics. Here we report the experimental synchronization of two coupled soliton modelocked chip-based frequency combs separated over distances of 20 m. We show that such a system obeys the universal Kuramoto model for synchronization and that the cavity solitons from the microresonators can be coherently combined which overcomes the fundamental power limit of microresonator-based combs. This study could significantly expand applications of microresonator combs, and with its capability for massive integration, offers a chip-based photonic platform for exploring complex nonlinear systems.

Synchronization of coupled optical microresonators.

The ink-jet technique was developed to print the wedge polymer microdisk lasers. The characterization of these lasers was implemented using a free-space optics measurement setup. It was found that disks of larger edge inclination angles have a larger free spectral range (FSR) and a lower resonance wavelength difference between the fundamental transverse electric (TE) and transverse magnetic (TM) whispering-gallery modes (WGMs). This behavior was also confirmed with simulations based on the modified Oxborrow’s model with perfectly matched layers (PMLs), which was adopted to accurately calculate the eigenfrequencies, electric field distributions, and quality parameters of modes in the axisymmetric microdisk resonators. Combined with the nearly equivalent quality factor (Q-factor) and finesse factor (F-factor) variations, the correlations between the TE and left adjacent TM modes were theoretically demonstrated. When the edge inclination angle is varied, the distinguishable mode distribution facilitates the precise estimation of a resonance wavelength shift. Therefore, the flexible and efficient nature of wedge polymer microdisk lasers extends their potential applications in precision sensing technology.

/pdf/effects-of-edge-inclination-angles-on-whispering-gallery-19wtpwwvwz.pdf

Effects of edge inclination angles on whispering-gallery modes in printable wedge microdisk lasers.

Materials with biomolecule-compatible functional groups are desirable for the fabrication of microdisk lasers used in bio-sensing applications. In this study, a microdisk laser was fabricated using a low-viscosity hyper branched polymer FC-V-50 using ink-jet printing, and was surface-modified at room temperature within a relatively short time compared to conventional methods. The carboxyl functional group of the FC-V-50 polymer was used for surface modification and biotinylation. The adsorption characteristics of the microdisk laser were evaluated using bovine serum albumin, avidin, and streptavidin. This study reports the first demonstration of label-free biosensing using the FC-V-50 polymer-based microdisk laser.

Fully room temperature and label free biosensing based on an ink-jet printed polymer microdisk laser

We developed an ink-jet printing method for fabricating inorganic microdisks at room temperature, which is much lower than the melting point of solid-state inorganic oxide, and have fabricated an organic-inorganic hybrid microdisk laser. Silica was used as the inorganic disk material, and microdisk-shaped aggregates were formed by the ink-jet printing method using a solution in which nanosilica particles were dispersed in propylene glycol monomethylether (PGME) solvent. Then, a microdisk capable of laser oscillation was also prepared by preliminarily adding the laser dye rhodamine 6G to the ink to form a mixed organic material. The structural evaluation of the printed microdisk was first conducted using an optical microscope, a scanning electron microscope (SEM), and an atomic force microscope (AFM). The results of laser oscillation evaluation by optical excitation showed that the printed microdisk sufficiently functions as an optical resonator with a low optical loss. In these evaluations, excellent values such as a surface roughness of 5.83 nm from root mean square (R. M. S.) which is one forth smaller than the particle diameter, and a laser oscillation threshold of 4.76 µJ/mm2 at a wavelength of 601.4 nm were obtained. To the best of our knowledge, this is the first time that an inorganic microdisk has been fabricated at room temperature to realize an organic-inorganic hybrid microdisk laser.

Organic-inorganic hybrid microdisk laser with dye and silica mixed doping prepared by ink-jet printing method.

Biopolymers, which are organic macromolecules produced by living systems, are promising materials in terms of biodegradability and sustainability. However, in the field of optical sensing, most devices or their elements still rely on synthetic inorganic or organic compounds. In this study, we successfully transform pristine silk fibroin (SF), a naturally abundant and eco-friendly material, into discrete, well-defined microspherical particles that function as an active optical resonator for precise moisture sensing over a wide humidity range. The SF self-assembles into microspherical particles upon water-in-oil emulsification. When being photoexcited, the SF microspheres, doped with a fluorescent ionic dye, display whispering gallery mode (WGM) resonant luminescence. Because of their excellent hygroscopic properties, the SF microspheres expand in size as the surrounding humidity is increased, and the WGM resonant peaks exhibit a red shift with a linear relation to the surrounding humidity over a wide humidity range of up to 95 percent relative humidity (%RH) with a sensitivity as high as 187 pm/%RH. Furthermore, the SF microsphere works as a laser resonator upon femto-second pumping. The fully natural microspheres as presented in this work serve as sustainable and environmentally friendly optical resonators and sensors.

https://pubs.rsc.org/en/content/articlepdf/2021/qm/d1qm00451d

Silk fibroin microspheres as optical resonators for wide-range humidity sensing and biodegradable lasers

https://iopscience.iop.org/article/10.7567/1347-4065/ab1e3c/pdf

Lasing characteristics of a pyrromethene597-doped microdisk laser fabricated by the ink-jet printing method

A novel white compound material with spectral band pass filtering was proposed and demonstrated in the UV region for wavelengths smaller than 310 nm. This compound material can be obtained by dispersing CaF2 in polydimethylsiloxane (PDMS). Refractive index matching (RIM) of the compound material resulted in transmittance of up to 80% at RIM wavelength. In no-RIM wavelength region, refractive index difference about 0.005 could result in transmittance of down to 30% due to intense Rayleigh isotropic scattering. A good reproducibility of the transparent wavelength can be obtained with the specific CaF2 particle and PDMS matrix in this study. Meanwhile, simple calculation based on Rayleigh-Gans-Debye approximation [J. Am. Ceram. Soc.86(3), 480 (2003)] in the soft diffusion model can explain the CaF2: PDMS compound film transmittance spectrum in the UV region, and the bandwidth narrowing condition.

Investigation and modeling of UV band-pass-filtering white compound materials for potting or embedding in micro-optical applications

A blended FC-V-50 and TZ-001 polymer-based microdisk laser was fabricated by the ink-jet printing method and used for biosensing applications. The FC-V-50 polymer has a negative charge due to the presence of carboxyl functional groups, and the TZ-001 polymer has a positive charge due to the tertiary amine group at a pH of seven. In biosensing applications, non-specific adsorption due to opposite charges of biomolecules and microdisk surfaces can adversely affect the performance of the biosensor. By mixing FC-V-50 and TZ-001 polymers in different ratios, the microdisk surface charge was controlled, and the non-specific adsorption of bovine serum albumin and lysozyme was studied. In addition, the label-free biosensing of streptavidin was demonstrated using a blended polymer-based microdisk laser. This work reports, to the best of our knowledge, the first demonstration of a blended polymer microdisk laser for controlling the non-specific adsorption of biomolecules.

Yuya Mikami

Papers

Organic-inorganic hybrid microdisk laser with dye and silica mixed doping prepared by ink-jet printing method.

Silk fibroin microspheres as optical resonators for wide-range humidity sensing and biodegradable lasers

Lasing characteristics of a pyrromethene597-doped microdisk laser fabricated by the ink-jet printing method

Investigation and modeling of UV band-pass-filtering white compound materials for potting or embedding in micro-optical applications

Ink-jet printed, blended polymer-based microdisk resonators for controlling non-specific adsorption of biomolecules.