EP1214614A1 - Photonic crystal materials - Google Patents
Photonic crystal materialsInfo
- Publication number
- EP1214614A1 EP1214614A1 EP00960859A EP00960859A EP1214614A1 EP 1214614 A1 EP1214614 A1 EP 1214614A1 EP 00960859 A EP00960859 A EP 00960859A EP 00960859 A EP00960859 A EP 00960859A EP 1214614 A1 EP1214614 A1 EP 1214614A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- photosensitive material
- exposure
- irradiated
- crosslinkable
- photonic crystal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/1225—Basic optical elements, e.g. light-guiding paths comprising photonic band-gap structures or photonic lattices
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/0005—Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
- G03F7/001—Phase modulating patterns, e.g. refractive index patterns
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
Definitions
- This invention relates to photonic crystal materials and a method for their preparation.
- a photonic crystal material that has a 3-D periodic structure with a periodicity that varies on a length scale comparable to the wavelength of electromagnetic radiation.
- the 3-D periodic structure is produced by irradiating photosensitive material with electromagnetic radiation such that interference between radiation propagating in different directions within the sample gives rise to a 3-D periodic variation in intensity within the sample. Thereafter the irradiated material is developed to remove the less or more irradiated regions of the material to produce a structure having 3-D periodicity in the refractive index of the composite material (because irradiation produces a change in the refractive index).
- the less irradiated regions are subsequently removed leaving voids which can, if desired, be filled, for example with material having a refractive index which is different from that of the irradiated photosensitive material.
- the irradiated sample can be used as a template for the production of other materials having periodic variations in refractive index.
- the present invention relates to an improved process for the production of such photonic crystal materials.
- a method forming a photonic crystal material comprising exposing a photosensitive material to an interference pattern of electromagnetic radiation whereby the exposure through the material varies in accordance with the spatially varying intensity created by the interference to produce a three dimensional periodic variation in the refractive index of the photosensitive material based on the exposure, the photosensitive material possessing an average number of crosslinkable groups per molecule of at least 3 or 3.5 with an equivalent weight per crosslinkable group of at most 1000. It has been found that with high functionality the network of crosslinks formed is potentially very dense giving high solubility contrast between strongly and weakly exposed material.
- the photosensitive materials used in this invention are those possessing an average number of crosslinkable groups per molecule of at least 4, preferably at least 6 and especially about 8. They have an equivalent weight per crosslinkable group (XEW) in general at most 500, typically at most 400, preferably at most 300, especially at most 230.
- Suitable photosensitive materials which can be used include epoxy resins ie. epoxy groups act as the crosslinkable groups.
- the glycidyl ether of bisphenol A novolac which is available as EPON-SU-8 from Shell Chemicals.
- the resin can be modified by using a so-called "expanding" monomer such as a spiro-orthocarbonate.
- improved physical properties of the polymer can be obtained by the addition of a binding agent such as a linear polymer.
- any polymer can be used provided that it has sufficiently high functionality and the precursors have a low degree of optical absorption at the laser wavelength within a film typically 10-100 microns thick.
- the photosensitive material is subjected to irradiation in the presence of a photoacid generator. Subsequent to exposure the material is heated to cure the crosslinked material.
- Suitable photoacid generators which can be used, especially with epoxy resins, include onium salts such as triaryl sulfonium salts including triphenyl sulfonium antimony chloride which is available as Cyracure UV1 from Union Carbide.
- This particular generator is well suited to irradiation at 355 nm where it has sufficient absorption (molar extinction coefficient ⁇ 300 mol "1 dm 3 cm “1 ). In general the molar extinction coefficient of the PAG should be from 50 - 2000 mol "1 dm 3 cm “1 at the laser wavelength. If the molecular coefficient is too large, the requirement for the sample to be optically thin means that the concentration of initiators is too small to effect polymerisation. On the other hand if it is too small, the PAG concentration is so high that it adversely affects the properties of the polymer.
- optical thin is meant that at the concentration at which it is used the PAG does not absorb more than 5% of the radiation which is incident upon it.
- quantum efficiency of the PAG should be sufficient for the exposure to cause insolubilisation of the photosensitive material. The effective quantum efficiency will be enhanced if the system involves chemical amplification.
- insolubilisation is meant that there is sufficient proton generation for subsequent acid catalysed polymerisation, as discussed below, to result in a crosslinked material which is insoluble in a solvent which dissolves the unirradiated or weakly irradiated material.
- the subsequent curing or baking of the exposed material is carried out at a temperature below the melting of the precursor in order to suppress proton diffusion and thus maintain a fidelity with the intensity pattern.
- the exposure to light results in the production of a proton from the photochemically induced fragmentation of the PAG molecule.
- Acid catalysed polymerisation of the resin occurs at the post-exposure bake.
- the precise temperature and time will depend on the exposure dose, the concentration of PAG in the resist and the required filling factor. Typically, though, the bake will take place at 40 to 120 °C for, say, 1 to 20 minutes.
- the melting point of the SU-8 resin is 80 to 90°C, the temperature should be kept below this in order that a much "cleaner" lattice is produced. In effect, therefore, exposure produces a latent image which is realised on subsequent baking. In view of this latency it is possible to employ multiple exposures, well separated in time. This can be used, for example, to superimpose two different periodicities or to write specific defect or waveguide structures into the material, before or after the principal exposure.
- a film of the photoresist material it is first dissolved in a suitable solvent.
- the solution is typically spun onto a fused silica disk.
- the film can be prepared by, for example, spreading, moulding or pouring.
- a suitable solvent is ⁇ -butyrolactone, typically at 50 to 60% weight resist concentration, which can be obtained with gentle heating ( ⁇ 30 to 40 °C) and manual stirring, with the resulting viscous solution filtered to exclude particles larger than, say I ⁇ m.
- the 50% weight resist can be used to give rise to a film from 2 to 30 microns thick while the 60% material will give a thickness of 10 to 60 microns.
- the solution also contains the PAG, typically at a concentration of 0.5 to 3%, generally from 1.0 to 2.0%, by weight. The amount of PAG added determines the sensitivity; with this particular combination about
- the photosensitive material can be stored in the dark away from the heat sources until required.
- Approximately 2 ml of the solution can be pipetted onto a disk, typically of fused silica, of about 2 cm diameter so that it is flooded, to prepare a film of about 30 m.
- the film is then spun at, typically 1000 rpm (5s ramp up, 40s hold, 5s ramp down).
- the material is then heated to evaporate the solvent, typically at 50°C for 5 minutes and followed by 15 minutes at 90-100°C.
- the interval between film preparation and exposure should be kept as short as possible and generally less than 30 minutes.
- the films were exposed in a single pulse (6 ns) of the laser.
- the total dose can be varied from 80-200mJcm "2 depending on the required polymer/air ratio in the photonic crystal.
- the filling factor is also related to the time and temperature of the post exposure bake).
- the glass substrate was index matched to a thick glass block using mineral oil in order to reduce back reflections.
- the beam geometries described above are those required to define the appropriate interference pattern in air.
- refraction occurs as the beam enters the film of resist but it is possible to compensate for the refraction by changing the angle of the beams. This can be done, for example, by adding a shaped transparent optical element or elements with refractive index greater than unity into the beam paths, and may include the use of high index liquid between rigid optical elements.
- the pulse duration is not critical. With an injection seeded laser the coherence length is equal to the pulse length, but this requirement can be relaxed if the optical path-lengths are made accurately equal. A cheaper but less effective option for increasing the coherence length is etalon-narrowing. In practice it is only necessary to achieve a coherence length of ⁇ lcm. An ordinary un-narrowed Q-Switched Nd-YAG laser can approach this requirement. More importantly though injection-seeding makes the pulse energies, following third harmonic generation, far more reproducible, so that the control of the dose in a single pulse exposure becomes straightforward. Typically electromagnetic radiation is directed at the sample from at least four beams so as to intersect and interfere within it.
- the film is baked to cure the resin. This can be achieved by placing the glass substrate on a level hotplate at 40-120 °C for 1-20 minutes.
- the film is then developed to dissolve away the uncrosslinked resin.
- For the epoxy resin SU-8 this can be achieved by using propyl glycol methyl ether acetate (PGMEA).
- PGMEA propyl glycol methyl ether acetate
- the substrate with the attached film is placed in a container with the solvent in an ultrasonic bath until the film becomes detached.
- the power is damped or attenuated to ⁇ 7W to avoid mechanical damage to the film as it releases from the substrate.
- this is achieved at a temperature of 40 to 50°C for, say, 40 minutes for a 30 micron film. After this the film is washed with fresh PGMEA and then rinsed before drying.
- an alcohol such as isopropyl alcohol can be used.
- photonic crystal films with thicknesses from 10 to 80 ⁇ m (e.g. 10 to 30 ⁇ m), corresponding to 14 to 84 (e.g. 14 to 42) close-packed layers.
- the photosensitive material can be subjected to multiple exposures, each exposure producing respective interference patterns.
- the accompanying Figure shows a scanning electron micrograph (SEM) of a polymeric microstructure produced by exposure to the interference pattern created at the intersection of four beams from a frequency-tripled injection seeded
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Biophysics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optical Integrated Circuits (AREA)
- Epoxy Resins (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9922196.2A GB9922196D0 (en) | 1999-09-20 | 1999-09-20 | Photonic crystal materials |
GB9922196 | 1999-09-20 | ||
PCT/GB2000/003603 WO2001022133A1 (en) | 1999-09-20 | 2000-09-20 | Photonic crystal materials |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1214614A1 true EP1214614A1 (en) | 2002-06-19 |
Family
ID=10861237
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00960859A Withdrawn EP1214614A1 (en) | 1999-09-20 | 2000-09-20 | Photonic crystal materials |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1214614A1 (en) |
JP (1) | JP2003510630A (en) |
AU (1) | AU7302500A (en) |
GB (1) | GB9922196D0 (en) |
WO (1) | WO2001022133A1 (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2003071587A1 (en) | 2002-02-15 | 2003-08-28 | University Of Delaware | Process for making photonic crystal circuits using an electron beam and ultraviolet lithography combination |
DE10332651A1 (en) | 2002-07-22 | 2004-02-26 | Forschungszentrum Karlsruhe Gmbh | Holographic lithography in three-dimensional photo lacquer body, employs multi-faced optical entry element, having planar- or curved surfaces |
DE10310645B3 (en) * | 2003-03-12 | 2004-11-18 | Forschungszentrum Karlsruhe Gmbh | Optical spectrometer for recording optical spectra, especially visible, ultraviolet and/or infrared, feeds fraction of beam transmitted through photonic crystal to absorber or out of spectrometer |
EP1723455B1 (en) | 2003-12-05 | 2009-08-12 | 3M Innovative Properties Company | Process for producing photonic crystals |
US20050124712A1 (en) * | 2003-12-05 | 2005-06-09 | 3M Innovative Properties Company | Process for producing photonic crystals |
US9069256B2 (en) * | 2005-10-03 | 2015-06-30 | Carnegie Mellon University | Method of optical fabrication of three-dimensional polymeric structures with out of plane profile control |
JP4382791B2 (en) | 2006-05-16 | 2009-12-16 | Nec液晶テクノロジー株式会社 | Manufacturing method of light direction control element |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB9717407D0 (en) * | 1997-08-18 | 1997-10-22 | Isis Innovation | Photonic crystal materials and a method of preparation thereof |
-
1999
- 1999-09-20 GB GBGB9922196.2A patent/GB9922196D0/en not_active Ceased
-
2000
- 2000-09-20 EP EP00960859A patent/EP1214614A1/en not_active Withdrawn
- 2000-09-20 AU AU73025/00A patent/AU7302500A/en not_active Abandoned
- 2000-09-20 WO PCT/GB2000/003603 patent/WO2001022133A1/en active Search and Examination
- 2000-09-20 JP JP2001525446A patent/JP2003510630A/en not_active Withdrawn
Non-Patent Citations (2)
Title |
---|
See also references of WO0122133A1 * |
SENSORS AND ACTUATORS, vol. A64, 1998, pages 33 - 39 * |
Also Published As
Publication number | Publication date |
---|---|
WO2001022133A1 (en) | 2001-03-29 |
GB9922196D0 (en) | 1999-11-17 |
AU7302500A (en) | 2001-04-24 |
JP2003510630A (en) | 2003-03-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3809732A (en) | Photo-locking technique for producing integrated optical circuits | |
JP2004503413A (en) | Fine processing of organic optical elements | |
US10343332B2 (en) | Production of 3D free-form waveguide structures | |
EP1005661A1 (en) | Photonic crystal materials and a methdo of preparation thereof | |
US20120164587A1 (en) | Hybrid lithographic method for fabricating complex multidimensional structures | |
WO2001022133A1 (en) | Photonic crystal materials | |
JPH0618739A (en) | Production of waveguide | |
JP3706496B2 (en) | Manufacturing method of optical waveguide | |
Singer et al. | Focused laser spike (FLaSk) annealing of photoactivated chemically amplified resists for rapid hierarchical patterning | |
JP2002350664A (en) | Optical waveguide, optical wiring board, electric and optical mixed circuit board, and manufacturing method optical waveguide | |
JPH06172533A (en) | Polymer for forming optical waveguide and production of polysiloxane-based optical waveguide | |
US20230042586A1 (en) | Interference lithography using reflective base surfaces | |
WO2001021285A1 (en) | Porous filter element and method of fabrication thereof | |
Lyubin | Chalcogenide glassy photoresists: history of development, properties, and applications | |
JP3504683B2 (en) | Method of forming lens region, lens and lens array plate | |
US3961102A (en) | Scanning electron microscope fabrication of optical gratings | |
US20060028634A1 (en) | Multiple exposures of photosensitve material | |
JP2001100001A (en) | Method and device for manufacturing optical element, and optical element | |
US7244369B2 (en) | Method for producing active or passive components on a polymer basis for integrated optical devices | |
JP3181998B2 (en) | Method for producing polymer and method for producing crosslinked product | |
JPS6230492B2 (en) | ||
CN115356895A (en) | System and method for preparing micro-nano structure in one step by utilizing positive and negative adjustable photoresist characteristics | |
Lange et al. | 3D defect engineering in polymer opals | |
CN115356896A (en) | System and method for preparing double-ring structure in one step based on laser direct writing | |
Dedman et al. | Characterisation of photonic crystals fabricated by holographic lithography |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20020408 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
17Q | First examination report despatched |
Effective date: 20020801 |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
RTI1 | Title (correction) |
Free format text: A METHOD OF FORMING A PHOTONIC CRYSTAL |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20051206 |