Source: http://www.google.com/patents/US6791758?dq=4200770
Timestamp: 2015-02-28 15:12:33
Document Index: 53203013

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60']

Patent US6791758 - Optical etalons and methods of making and using them - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn improved etalon has a bulk optic defining the optic cavity between selectively transparent thin film mirror coatings. The bulk optic comprises an optically transparent body, such as a portion of a substrate wafer, along with a wedge correcting coating on at least one of the two surfaces of the optically...http://www.google.com/patents/US6791758?utm_source=gb-gplus-sharePatent US6791758 - Optical etalons and methods of making and using themAdvanced Patent SearchPublication numberUS6791758 B1Publication typeGrantApplication numberUS 10/096,001Publication dateSep 14, 2004Filing dateMar 12, 2002Priority dateMar 15, 2001Fee statusPaidPublication number096001, 10096001, US 6791758 B1, US 6791758B1, US-B1-6791758, US6791758 B1, US6791758B1InventorsMichael A. ScobeyOriginal AssigneeCierra Photonics Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (8), Referenced by (9), Classifications (7), Legal Events (8) External Links: USPTO, USPTO Assignment, EspacenetOptical etalons and methods of making and using them
This application claims the benefit of U.S. Provisional Application No. 60/276,019 filed on Mar. 15, 2001 and titled �Optical Etalons and Methods of Making and Using Them.�
This application is related to commonly assigned U.S. Provisional Application No. 60/275,939 filed on Mar. 15, 2001 and titled �Apparatus and Method for Vacuum Coating Deposition,� U.S. Provisional Application No. 60/276,022 filed on Mar. 15, 2001 and titled �Optical System With 1�N Interleaver and Methods of Making and Using Same,� U.S. Provisional Application No. 60/275,918 filed on Mar. 15, 2001 and titled �Optical System. With Cascaded Interleavers and Methods of Making and Using Same,� U.S. Provisional Application No. 60/276,018 filed on Mar. 15, 2001 and titled �Optically Coupled Etalons and Methods of Making and Using Same,� U.S. Provisional Application No. 60/275,920 filed on Mar. 15, 2001 and titled �Iso-Optical Thermal Compensator and Methods of Making and Using Same,� U.S. Provisional Application No. 60/275,998 filed on Mar. 15, 2001 and titled �Methods of Making Optical Etalons,� U.S. Provisional Application No. 60/276,017 filed on Mar. 15, 2001 and titled �Optical System With Interleaver and Methods of Making and Using Same,� U.S. Provisional Application No. 60/275,997 filed on Mar. 15, 2001 and titled �Optical Filter Elements and Methods of Making and Using Same,� U.S. Provisional Application No. 60/276,020 filed on Mar. 15, 2001 and titled �Wafer Scale Production of Optical Elements,� U.S. Provisional Application No. 60/276,023 filed on Mar. 15, 2001 and titled �Air Space Variable Optical Etalons and Methods of Making and Using Same,� U.S. Provisional Application No. 60/275,945 filed on Mar. 15, 2001 and titled �Air Space Optical Etalons and Methods of Making and Using Same,� and U.S. Provisional Application No. 60/276,316 filed on Mar. 16, 2001 and titled �Optical Monitoring of Thin Film Deposition Thickness,� the entire disclosure of each of which is hereby incorporated herein by reference for all purposes.
In accordance with a first aspect, an etalon comprises a planar bulk optic having first and second parallel, selectively transparent surfaces. The bulk optic comprises an optically transparent body and a wedge correcting coating (referred to here generally as a �wedge coating�) on at least one of the two surfaces of the optically transparent body. The wedge coating, further described below, establishes high precision parallelism of the selectively transparent surfaces of the etalon. The bulk optic is a solid, optically transparent (at the wavelength or wavelengths of interest) body whose thickness, i.e., the dimension between the selectively transparent, parallel surfaces, including the wedge coating, defines the cavity spacing. In particular, the bulk optic, including the wedge coating, will typically have an optical thickness equal to an integral number of half-waves for the wavelength(s) of interest. In preferred embodiments the selectively transparent surfaces are thin film coatings comprising, for example, a film stack of alternating high and low refractive index oxides or a metal thin film in accordance with known thin film technologies.
The thickness of the wedge coating varies progressively across the etalon. That is, the thickness of the wedge coating, viewed in cross-section in at least one plane orthogonal to the parallel, selectively transparent surfaces of the etalon, has a thickness that increases (or decreases in the opposite direction) continuously, typically approximately linearly, to compensate for non-parallelism, or �wedge�, in the underlying body of the bulk optic. As described further below, the bulk optic can be diced from a wafer on which a wedge coating and the two thin film coatings have been deposited by magnetron sputtering, ion beam sputtering or other known deposition techniques. Preferably, surface polishing is performed to first polish the wafer, for example, a silica wafer suitable for optical filter production, to parallelism within 1 to 2 arc seconds and wavefront error of less than {fraction (1/50)} (2.0%) of a wave at the wavelength of interest. For an etalon intended for use as or in an optical element in an optical telecommunication system, the wavefront error will preferably be less than {fraction (1/50)} of a wave at 1550 nm. Low wavefront error can be understood in this context to mean that the thickness of the bulk optic, i.e., the distance between the two opposite surfaces of the bulk optic, is substantially linearly variable and, hence, controllable or correctable by the wedge coating in accordance with the present disclosure. Preferably, for etalons suitable for use in optical communication elements, the wedge coating brings parallelism of the opposite surfaces of the bulk optic body from the 1 to 2 arc seconds of wedge mentioned above to less than 0.1 arc seconds, most preferably less than 0.01 arc seconds.
In accordance with a method aspect of the present disclosure, the wedge coating is deposited onto the optically transparent body of the bulk optic by physical vapor deposition, e.g., magnetron sputtering or ion beam sputtering in a vacuum chamber, with the bulk optic (alone or as part of a larger substrate, such as a typical 6 inch or larger substrate wafer used in the production of optical filters) not spinning during deposition. Preferably the coating is a low defect coating to allow bonding or other optical coupling. Deposition can be otherwise in accordance with known techniques, whose applicability and mariner of implementation will be within the ability of those skilled in the art given the benefit of this disclosure. The substrate is oriented at an angle to the target or otherwise arranged to receive progressively different deposition rates from one edge to the opposite edge. The target is preferably an elongate source to provide a coating with a roughly linear profile. Preferably, the target is tangential to the circumference of the substrate and is about four times as large as the substrate, e.g. for a 6 inch diameter substrate the target can be about 20 inches long. The thinnest point of the substrate is positioned closest to the target or otherwise oriented or favored to have the fastest rate of deposition. Conversely, the thickest point is positioned or oriented to have the lowest deposition rate. Thus, the sputtered material will deposit fastest and, therefore, the most heavily, i.e., the thickest, where the bulk optic was thinnest, with progressively thinner deposition toward the area where the least was wanted. Since the substrate is not spinning and is oriented or arranged as just described, the thickness of the resulting wedge coating will change progressively (hence the term �wedge�), with the change in the thickness of the wedge coating being opposite that of the underlying body. The net effect is that the thickness of the bulk optic is substantially uniform over all or a large portion of its area. Where the bulk optic is prepared in the form of a typical substrate wafer, Fabry-Perot thin films can then be deposited to complete the etalon (subject to any further production or packaging steps etc.) in the same or a different sputter deposition chamber. Deposition of a wedge coating and thin films on another, second surface of the bulk optic may be performed in accordance with the embodiments described here.
Certain preferred embodiments of the etalons disclosed here comprise first and second Fabry-Perot thin film coatings on parallel opposite sides of a cavity formed by a bulk optic comprising a solid, optically transparent body and a wedge coating on a surface of the optically transparent body. The wedge coating underlies the first Fabry-Perot coating and the axial dimension of the bulk optic, i.e., the dimension of the bulk optic (with the wedge coating and any thickness- adjustment layer) in the direction of light passage, defines the cavity spacing of the etalon. As used here, in certain instances as will be clear from context, the term �bulk optic� refers to a component of the etalons disclosed above comprising a solid, optically transparent body, such as a portion of an optically transparent wafer diced into multiple pieces after being coated, together with the wedge coating and/or a thickness-adjustment layer. The solid, optically transparent body is an optically transparent substrate having first and second generally flat surfaces on opposite sides, which is self-supporting in the sense that it does not require an underlying support member to retain its shape and integrity during handling, packaging and transport in manners typical for optical elements intended for use as sensors, fiber optic communication system components or the like. Most preferably the transparent body of the bulk optic is a monolithic body, that is, a one-piece, unitary, self-supporting body of material. The wedge coating overlies a surface of the transparent body of the bulk optic, and there may or may not be a visible or discernable seam or interface between them. In certain preferred embodiments the wedge coating and optional thickness adjustment layer are formed of material that is the same as that of the transparent body. In other preferred embodiments, the wedge coating and/or thickness-adjustment layer are formed of a material comprising substantially the same refractive index as the material comprising the optically transparent body, e.g. the refractive indices differ by less than about �0.01. It may, therefore, be difficult or impossible to see the boundaries between the bulk optic, the wedge-correction layer and the thickness-correction layer. It is, of course, desirable generally that there be no or substantially no optical effect at such boundaries which would adversely impact the performance of the etalon. Thus, the wedge coating and thickness-adjustment coating may be difficult or even impossible to distinguish from the material of the underlying optically transparent body, at least without observing the manner in which the etalon was produced. This typically will not be the case where different materials are used for the optically transparent body, wedge coating and thickness-adjustment coating. In any event, these components of the bulk optic are distinct from each other in the function they perform and in their position in the bulk optic.
In accordance with additional preferred embodiments, optical elements are provided comprising an etalon as disclosed above. Such optical elements may further comprise a bandpass filter optically coupled to the etalon to remove combing. Also, such optical elements may comprise a long wave or short wave pass filter optically coupled to the etalon. Also, such optical elements may comprise a temperature compensator joined to the etalon. Suitable temperature compensators are known to those skilled in the art, including for example the temperature compensators disclosed in U.S. Pat. No. 5,982,488 to Shirasaki and in U.S. Provisional Application No. 60/275,920 titled �Iso-Optical Thermal Compensator and Methods of Making and Using Same,� the entire disclosures of which are incorporated herein by reference.
In accordance with certain preferred embodiments, methods are provided of making an etalon as disclosed above. Such methods comprise the step of polishing at least one surface of an optically transparent substrate to produce an optically transparent body having opposite sides parallel preferably to within 5 arc seconds, more preferably to within 2.0 arc seconds. As discussed above, typical commercial processes do not reliably give adequate thickness and/or parallelism for good yield of etalons intended for use in communication systems, etc. The methods further comprise depositing an optically transparent wedge coating on at least one of the opposite sides of the optically transparent body to produce a bulk optic having opposite sides parallel to within less than about 0.4 arc seconds, more preferably less than about 0.2 arc seconds, most preferably, for higher performance etalons, less than 0.1 arc second. Continual two-spot optical monitoring can be used to control deposition of the wedge coating as disclosed above. Reference here to �continually� monitoring thickness during deposition should be understood to meaning optionally, but not necessarily, monitoring continuously, and optionally monitoring regularly or repeatedly during the deposition.
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