Photonic Nanojet Sub-Diffraction Nano-Fabrication With <italic>in situ</italic> Super-Resolution Imaging

Abstract

In this paper, we report a system that uses a microsphere to induce a photonic nanojet to directly write on a sample surface with sub-diffraction limit resolution, while simultaneously observing the writing processing in situ. Because of diffraction limit, sub-wavelength laser processing resolution has been difficult to achieve. Recently, we have shown that a microsphere-induced photonics nanojet could be used to create an optical light spot size beyond the diffraction limits, i.e., the diameter of the light spot could be reduced to −200 nm or smaller. This capability could allow a laser (with significant reduction in input power) to pattern nano-scale structures on various substrate materials through the use of microspheres. Many researchers have attempted to use this photonic nanojet (PNJ) based technique to process sub-diffraction limit patterns on all types of materials. However, applying this method to process features at precise locations is very difficult, because the technique requires that a sample being "cut" by the PNJ be observed by a common optical microscope, which cannot resolve features smaller than the optical diffraction limit. This disadvantage limits the applicability of this novel method to nanoscale processing; for example, in trimming resistors in an integrated circuit chip, many circuit components on the chip are much smaller than 200 nm, and not being able to see features beyond the diffraction limit will inadvertently destroy many components while PNJ is used to trim resistive elements. We will show in this paper that processing resolution better than 200 nm is achievable using our laser-based photonic nanojet method, whereas a simultaneous imaging resolution of less than λ/2 could be obtained. Therefore,

Nanopatterning with Photonic Nanojets: Review and Perspectives in Biomedical Research

“…The most common approach consists of physically moving the microparticle in the XY plane. Several methods have been developed to achieve such physical displacement, including mechanical [ 62 , 66 , 67 , 68 ], optical [ 20 , 69 , 70 ], and chemical forces [ 71 ]. Among the mechanical ones, mounting a microsphere into the cantilever of an atomic force microscope, or AFM, offers unsurpassed positioning control [ 68 ].…”

All-dielectric concentration of electromagnetic fields at the nanoscale: the role of photonic nanojets

“…This makes it possible to pattern deep subwavelength structures in a form similar to direct laser writing but with much smaller features that are comparable to that of plasmon-assisted lithography. 204,205 In fact, when a microsphere is in close contact with a sample surface, a local eld enhancement in the area between the bottom of the microsphere and the sample surface is established, making it easy to ablate the materials around the contact area. 170 Because of the spherical shape, early studies on microsphere-based laser direct writing were implemented "randomly," i.e., microspheres were randomly distributed on the wafer surface before being illuminated by a laser.…”

“…This explains why microsphere-based nanopatterning is operated in contact mode in most instances. 214 It is apparent that the random distribution of microspheres prohibits the controllable fabrication of desired structures. Diverse methods, including self-assembly, [215][216][217] off-axis irradiation, 218 tweezing (either optical or mechanical), 219 and microlens arrays, 220 have been developed, to manipulate individual microspheres or microsphere arrays for fabricating customized patterns.…”

Novel Bilayer Micropyramid Structure Photonic Nanojet for Enhancing a Focused Optical Field

“…The most outstanding characteristics of the PNJ are the subwavelength focusing [ 6 , 7 ], the long focus range [ 8 , 9 ], and being easily integrated with other technologies [ 10 , 11 ], which can bring a wide range of opportunities for the practical application of the PNJ in nanolithography [ 12 , 13 ], nanoscopy [ 14 , 15 ], all-dielectric switching [ 16 , 17 ], optical trapping and manipulation [ 18 , 19 , 20 ], etc.…”