Road to Silicon Microsphere Fabrication and Mode Coupling
Abstract
As described in this report, silicon microspheres that are ideal for optical use can now be produced through pulsed laser ablation. This is a process in which the surface of a silicon substrate is super-heated by a high-power laser until molten and a second laser pulse hits the molten silicon, ejecting micron-sized spherical particles. Furthermore, silicon is naturally abundant, which further enables the large-scale production of optically compatible microspheres. The experimental free spectral range (FSR) obtained was within 15 percent difference in comparison to the simulation models. The challenge of coupling is the manipulation of the small optical resonator into position. getting the distance between the tapered fiber waveguide and the microsphere correct such that they lie in the critical coupling region to achieve perfect evanescent field coupling was difficult. Over-coupling tends to occur because static electricity causes the tapered fiber to stick to the microsphere when the two objects approach one another. Future studies include functionalizing the microsphere surface for ultrasensitive biochemical sensors through the detection of resonant frequency shifts. Theoretical studies have shown that label-free single molecule detection should be feasible in principle due to the high Q properties of the optical resonator. Disk geometries may be more attractive because of the lower number of modes present and mode engineering is possible through the material modification using a femtosecond laser by generating gratings or photonic crystal patterns on the surface of the disk resonator.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2014
- Accession Number
- ADA607718
Entities
People
- A. D. Ramirez
- B. N. Pascoguin
- J. M. Kvavle
- R. P. Lu
Organizations
- Naval Information Warfare Systems Command