Background: The benefits of microresonator lasers include easy and low-cost fabrication methods and high-quality factor of microresonators, which results in low threshold current of the fabricated laser. However, the lack of tunable fabrication methods with precise size and spacing is a great challenge.
Aim: Based on a microsphere fabrication method that relies on injection and surface tension effects, simultaneous demonstration of an array of cavities with precise spacing and sizes is possible where the size of cavities is widely tunable.
Approach: Using a maskless lithography setup, pillars with base and tip diameters of 250 and 60μm are fabricated, which are used for demonstration of microspheres with tunable size, depending on the applied pump pressure. Microcavities composed of Rhodamine B dissolved in glycerol are injected into the polydimethylsiloxane carrier through a nozzle with a diameter of 70 μm.
Results: An ∼4-μJ / mm2 lasing threshold has been obtained for a laser with a microsphere diameter of ∼350 μm. A redshift originated from the increment of dye concentration has also been observed.
Conclusions: Fabrication of precise microspheres for a microresonator laser is feasible using the introduced method, which can be further generalized using different active materials.
Background: Optical stimulation of the brain is based on optrodes with integrated optical splitters to excite multiple neurons simultaneously. This requires efficient light delivery systems.
Aim: In order to satisfy optical requirements, to reduce the fabrication costs, and to obtain less invasive implantation into the brain, we assess a polymer-based microdevice both in theory and experiments.
Approach: In addition to design and evaluation of the device using Multiphysics software, to achieve a feasible implementation, we base our fabrication process on off-the-shelf ultraviolet adhesives as the functional material with fascinating optical and mechanical characteristics all together, easy photolithographic-only curing, and no more steps required for common soft lithographic-based materials.
Results: Wideband transmission of optical signals over the visible/near-infrared together with uniform splitting of the input power from different light sources has been observed and recorded using an optical setup with acceptable agreement with the simulation outcomes.
Conclusions: Our research proposes a flexible and biocompatible optical splitter to be used as a light delivery system for a wide variety of optical stimulation methods in neuroscience studies with fewer or no changes in the design, dimensions, and even exploited materials. So it is a multipurpose device.
The micromixer is a very common component in the state-of-the-art lab-on-chip devices and occupies large chip areas to fulfill the rather challenging process of mixing in microscales. Two various design micromixers are introduced, which show a step over efficiency in the microlevel mixing. Finite-element method (FEM) tools were utilized to assess the mixing efficiency of the presented micromixers versus common T- and zigzag-shaped mixers. Using the availability of three-dimensional printing features, the chaotic advection is maximized as a mainstream factor affecting microscale behavior of the mixer. Both FEM and experimental results prove a 95% improvement in the performance of micromixers for low Reynolds numbers at 1 versus 8 cm for conventional devices.
Electrothermal actuation provides the long displacement required by an increasing number ofMEMS applications. However, its high power consumption is a limiting factor, especially for applications in which multiple actuators are required. An iris type variable optical attenuator (VOA),5 which was recently introduced by our group, is an example of such an application. In this paper we introduce an improved single sided electrothermal design, which
reduces the power consumption by a factor of 70%, while at the same time removing an undesired mechanical resonance. The optical performance is also improved by the introduction of a novel aperture shape which provides higher extinction, independent of the process technology.