Patent Publication Number: US-2004047039-A1

Title: Wide angle optical device and method for making same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims priority of U.S. Patent Application Serial No. 60/389,224 filed on Jun. 17, 2002, entitled “Optical Device and Method of Making Same,” the entire disclosure of which is incorporated herein, as if set forth in its entirety. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates generally to optical components being suitable for forming or including polarizing mirrors, mirrors, beam splitters, combiners, and/or array optics.  
       BACKGROUND OF THE INVENTION  
       [0003] Broadband mirrors have important applications in photonics and optoelectronics. Conventionally there are two methods of producing mirrors: (1) using a surface of a metal layer, and (2) using multilayer dielectric films. Metal layers generally provide robust performance with respect to angle of incidence properties, wavelength dependence, and polarization characteristics. However, a major limitation stems from nonuniform reflectivity of metal materials across different wavelength bands. Further, wavelength selectivity may be difficult to achieve using metal layers. On the other hand, multilayer dielectric interference mirrors may provide high reflectivity and wavelength-selectivity. However, multilayer dielectric interference mirrors generally lack good performance qualities with respect to angle of incidence, and typically require alternating layers of materials having relatively high and low refractive indices, respectfully.  
       SUMMARY OF THE INVENTION  
       [0004] A device for reflecting a select polarization of at least one transmission of a given wavelength impinging upon the device, the device including: a substrate; and, at least two layers of nanostructures forming a resonant pattern on the substrate adapted to define a plurality of high contrast refractive index interfaces being suitable for reflecting the select polarization of the at least one transmission. 
     
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
     [0005] Understanding of the present invention may be facilitated by consideration of the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, in which like numerals refer to like parts and:  
     [0006]FIG. 1A illustrates a cross-sectional view of a resonant mirror according to an aspect of the present invention;  
     [0007]FIG. 1B illustrates a cross-sectional view of a resonant mirror exhibiting polarization independent properties according to an aspect of the present invention;  
     [0008]FIG. 2A illustrates a top view of the resonant mirror shown in FIG. 1A, according to an aspect of the present invention;  
     [0009]FIG. 2B illustrates a top view of a resonant mirror according to an aspect of the present invention.  
     [0010]FIG. 3 illustrates a cross-sectional view of a resonant mirror according to an aspect of the present invention;  
     [0011]FIG. 4 illustrates a cross-sectional view of a resonant mirror according to an aspect of the present invention;  
     [0012]FIG. 5 illustrates a relationship between the effective index, the birefringence and the filling ratio for different polarization states for the resonant mirror embodied in FIG. 1A;  
     [0013]FIG. 6 illustrates a relationship between transmission/reflection and wavelength for different polarization states for the resonant mirror embodied in FIG. 1A;  
     [0014]FIG. 7 illustrates the relationship of polarization-dependent extinction ratios for the resonant mirror embodied in FIG. 1A;  
     [0015]FIG. 8 illustrates a relationship between transmission/reflection and wavelength for different polarization states for the resonant mirror embodied in FIG. 3;  
     [0016]FIG. 9 illustrates a plot of the reflection of TE as a function of wavelength and incident angle for two one-dimensional layers of a device according to an aspect of the present invention such as is shown in FIG. 4;  
     [0017]FIG. 10 illustrates a plot of the transmission of TM as a function of wavelength and incident angle for two one-dimensional layers of a device according to an aspect of the present invention such as is shown in FIG. 4;  
     [0018]FIG. 11 illustrates a plot of the reflection of TE as a function of wavelength and incident angle for three one-dimensional layers of a device according to an aspect of the present invention such as is shown in FIG. 4;  
     [0019]FIG. 12 illustrates a plot of the reflection of TE as a function of wavelength and incident angle for four one-dimensional layers of a device according to an aspect of the present invention such as is shown in FIG. 4;  
     [0020]FIG. 13 illustrates the relationship between layer thickness, wavelength and reflection of TE for the structure of FIG. 4;  
     [0021]FIG. 14 illustrates the relationship between period of the structure, wavelength and reflection of TE for the structure of FIG. 4;  
     [0022]FIG. 15A illustrates a cross-sectional view of a device incorporating the device of FIG. 1A or  3 ;  
     [0023]FIG. 15B illustrates a top view of the device shown in the cross-sectional view of FIG. 8A, according to an aspect of the present invention;  
     [0024]FIG. 16 illustrates a cross-sectional view of a wavelength filter according to an aspect of the present invention incorporating the resonant grating shown in FIG. 4;  
     [0025]FIG. 17 illustrates a simulated performance of the wavelength filter illustrated in FIG. 16 according to an aspect of the present invention;  
     [0026]FIG. 18 illustrates a simulated performance of the wavelength filter illustrates in FIG. 16 according to an aspect of the present invention;  
     [0027]FIG. 19A illustrates a device suitable for incorporating with the device from FIG. 1A or  3 ;  
     [0028]FIG. 19B illustrates a device incorporating the device from FIG. 19A and the device from FIG. 1A or  3 ;  
     [0029]FIG. 19C illustrates a bottom view of the device shown in FIG. 19B;  
     [0030]FIG. 20 illustrates a device incorporating the device of FIG. 19;  
     [0031]FIG. 21 illustrates a device suitable for use with the device of FIG. 20;  
     [0032]FIG. 22A illustrates a perspective view of a device incorporating the device of FIGS. 20 and 21;  
     [0033]FIG. 22B illustrates a cross sectional view of a device incorporating the device of FIGS. 20 and 21; and,  
     [0034]FIG. 23 illustrates a guiding device according to an aspect of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0035] It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity, many other elements found in typical photonic components and methods of manufacturing the same. Those of ordinary skill in the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein.  
     [0036] Referring now to FIG. 1A, there is shown a cross-sectional view of a resonant mirror  100  according to an aspect of the present invention. Resonant mirror  100  may include a substrate  130 , a pattern of nanostructures  110 , a cladding layer  140  and anti-reflection coatings  150 ,  155 .  
     [0037] As shown in FIG. 1A, pattern of subwavelength elements such as nanoelements or nanostructures  110  may be formed on a surface of substrate  130 . Nanostructures  110  may have dimensions in the range 0.1 nm to 1000 nm. An interface  180  may be created between substrate  130  and pattern of nanostructures  110 . Cladding layer  140  may be added distal to interface  180  on pattern of nanostructures  110 . Anti-reflection coating  150  may be formed on a surface of the cladding layer  140  distal from interface  180 , thereby creating interface  170  there between. A surface of anti-reflection coating  150  distal to interface  170  may form an interface  160 . Anti-reflection coating  155  may be applied to a surface of substrate  130  distal to interface  180 , thereby creating interface  190  therebetween. The surface of anti-reflection coating  155  distal to interface  190  may form an interface  195 .  
     [0038] Resonant mirror  100  may be made from materials suitable for use in optics and known by those possessing ordinary skill in the pertinent arts. In forming resonant mirror  100  high contrast refractive index interfaces providing high reflectivity by regions within nanostructures  110 . Suitable materials may include materials commonly used in the art of grating or optic manufacturing such as glass (like BK7, Quartz and Zerodur, for example), semiconductors, and polymers, including for example GaAs/AlGaAs, GaAs/AlAs, Si/SiO 2  and SiN x /SiO 2  pairs, for example. According to an aspect of the present invention, an underlying one-dimensional (1-D) pattern of nanostructures  110 , preferably formed of materials of high contrast reflective index may be formed on substrate  130 . According to an aspect of the present invention, two-dimensional (2-D) pattern of nanostructures  110 , preferably formed of materials of high contract refractive index may be formed on substrate  130 .  
     [0039] Referring now also to FIG. 1B, there is shown a resonant mirror according to an aspect of the present invention. Resonant mirror  100  as discussed hereinabove may include a lower cladding layer  125  included as a portion of substrate  130 . However, lower cladding layer  125  may be a separate layer from substrate  130 . If a separate lower cladding layer  125  is utilized, pattern of nanostructures  110  may be replicated into lower cladding layer  125 . Inclusion of separate lower cladding layer  125  may lessen the constraint that the materials of substrate  130  may be suited for replication, possibly a strict constraint depending on the technique used for replicating. Lower cladding layer  125  may take these properties and therefore substrate  130  may be any suitable material and may not be constrained by properties required for replication. Lower cladding layer  125  and the substrate  130  may be included within the discussion as substrate  130  while it is known that these may be separate layers.  
     [0040] Pattern of nanostructures  110  may include multiple sub-wavelength elements each of width F G  and height D G . Pattern of nanostructures  110  may have a period of nanostructures, X G . The filling ratio of pattern of nanostructures  110 , denoted F G /X G , is the ratio of the width of the higher index area within the period to the overall period. Filling ratio, F G /X G , may determine the operation wavelength, as would be evident to one possessing an ordinary skill in the pertinent arts.  
     [0041] According to an aspect of the present invention, resonant mirror  100  may reflect or pass transmissions in a certain frequency range depending on the polarization state of the waves as they impinge upon pattern of nanostructures  110 .  
     [0042] Pattern of nanostructures  110  may be formed into or onto substrate  130  using any suitable process for replicating, such as a lithographic process. For example, nanoimprint lithography consistent with that disclosed in U.S. Pat. No. 5,772,905, entitled NANOIMPRINT LITHOGRAPHY, the entire disclosure of which is hereby incorporated by reference as if being set forth in its entirety herein, may be used. This patent teaches a lithographic method for creating ultra-fine patterns of nanostructures  110 , such as sub 25 nm, in a thin film coated on a surface. For purposes of completeness, a mold having at least one protruding feature may be pressed into the thin film applied to substrate  130 . The at least one protruding feature in the mold creates at least one corresponding recess in the thin film. After replicating, the mold may be removed from the film, and the thin film processed such that the thin film in the at least one recess may be removed, thereby exposing an underlying pattern or set of devices. Thus, the patterns in the mold are replicated in the thin film, and then the patterns replicated into the thin film are transferred into the substrate  130  using a method known to those possessing an ordinary skill in the pertinent arts, such as reactive ion etching (RIE) or plasma etching, for example. Of course, any suitable method for forming a structure into or onto an operable surface, such as the substrate, may be utilized though, such as photolithography, holographic lithography, e-beam lithography, for example. Substrate  130  may take the form of silicon dioxide with a thin film of silicon forming the pattern of nanostructures  110 .  
     [0043] As will be recognized by those possessing ordinary skill in the pertinent arts, various patterns may be replicated onto substrate  130 . These patterns may serve various optical or photonic functions. Such patterns may take the form of holes, strips, trenches or pillars, for example, all of which may have a common period or not, and may be of various or common heights and widths. The strips may be of the form of rectangular grooves, for example, or alternatively triangular or semicircular grooves. Similarly pillars, basically the inverse of holes, may be patterned. The pillars may be patterned with a common period in both axes or alternatively by varying the period in one or both axes. The pillars may be shaped in the form of, for example, elevated steps, rounded semi-circles, or triangles. The pillars may also be shaped with one conic in one axis and another conic in the other. In an aspect of the present invention an underlying one-dimensional (1-D) pattern of nanostructures  110 , preferably formed of materials of high contrast reflective index may be formed on substrate  130 . This 1-D pattern may be of the form of trenches, for example. According to an aspect of the present invention, two-dimensional (2-D) pattern of nanostructures  110 , preferably formed of materials of high contract refractive index may be formed on substrate  130 . This 2-D pattern may be of the form of pillars, for example.  
     [0044] As is known in the pertinent arts, transmissions impinging on a high contrast refractive index boundary either reflects, or transmits, or a combination thereof, depending on properties of the transmission including frequency range or wavelength and polarization. Angle relationships for both reflection and refraction may be derived from Fermat&#39;s principle. Of course, reflection may be defined as the return of radiation by a surface, without a change in wavelength and may be commonly defined by the “law of reflection”. Refraction of the transmission may be predominately governed by Snell&#39;s Law, which relates the refractive indices on both sides of the interface to the directions of propagation in terms of the angles to the normal of the surface. Refraction may be the bending of oblique incident rays as they pass from a medium having one refractive index into a medium with a different refractive index. Of course, the refractive index is the speed of light in vacuum divided by the speed of light in the medium. Because the refractive index is a function of wavelength, the angle of the refracted transmission and the quantity of transmission reflected and refracted are a function of the wavelength. In general, the interaction of transmissions and mediums as a function of the wavelength of the transmission is well known by those possessing skill in the pertinent arts.  
     [0045] As is known in the pertinent arts, high reflectivity may be achieved by utilizing multiple layers of alternating high contrast refractive indices. If a transmission impinges onto a structure consisting of multiple layers of such refractive indices, multiple reflections take place within the structure. As a general rule, the more properly designed layers, the higher the reflectivity as each new layer adds to the interacting reflected transmission. However, as set forth, multilayer films may generally not be robust to variations in angle of incidence of the transmission, though.  
     [0046] Substrate  130  may have a refractive index n 1  approximately equal to the refractive index n 2  of cladding layer  140 . Refractive indices n 1  and n 2  may be on the order of approximately 1.5. This may serve to reduce undesirable refraction or reflection at interface  180  as transmissions pass therethrough. Of course, the greater the difference between these two refractive indices (n 1 , n 2 ) the greater the reflection and refraction that may occur at interface  180  as defined by laws commonly known in the art, for example Snell&#39;s Law governing refraction and the Law of Reflection. Filling material  145  has a refractive index n F  approximately equal to refractive indices n 1  and n 2  thereby creating n F ≈n 1 ≈n 2 . Filling material  145  may be positioned between the pattern of nanostructures  110  and may be deposited in this region between the high index gratings using methods known by those possessing an ordinary skill in the pertinent arts, such as physical vapor deposition (thermal evaporation, e-beam deposition, sputtering), chemical vapor deposition (CVD, LPCVD, PECVD, APCVD), reactive sputtering, and flame hydrolysis deposition (FHD).  
     [0047] Anti-reflection coatings (ARC)  150 ,  155  may be provided on one or both of interfaces  170 ,  190 . In FIG. 1A, both ARC  150  and ARC  155  are included. ARCs  150 ,  155  generally decrease losses resulting from differences in refractive indices at interfaces  170  and  190 . The use and manufacture of ARCs  150 ,  155  is well understood by those possessing an ordinary skill in the pertinent arts. Briefly, ARCs  150 ,  155  may include a single coating of a refractive index chosen to substantially eliminate reflections at a desired wavelength. ARCs  150 ,  155  may include multi-layer coatings to reduce losses over an expanded spectrum, or a spectrum in which the device or component is designed to be used. For purposes of completeness, anti-reflection coatings generally operate to create a double interface by means of a thin film by providing two reflected waves. If these waves are out of phase, they partially or totally cancel. For example, if coating  150  is a single quarter wavelength thickness having a refractive index less than the element that the coating coats, the two reflections created at each interface  160 ,  170  associated with ARC  150  are 180 degrees out of phase. In such a configuration, reflected waves are substantially the same amplitude and 180 degrees out of phase thereby substantially canceling each other out. As there is substantially zero reflected transmission, the law of conservation of energy holds that the transmitted transmission approaches 100% of the impinging transmission.  
     [0048] Referring now also to FIG. 2A, there is shown a top view of pattern of nanostructures  110  being suitable for use with the resonant mirror  100  of FIG. 1A. Pattern of nanostructures  110  may form an optical grating or grid structure. When a transmission impinges upon pattern of nanostructures  110 , the grid structure transmits radiation with an E vector vibrating perpendicular to the grid (TM shown in FIG. 2A) and reflects radiation with an E vector vibrating parallel to the grid (TE shown in FIG. 2A).  
     [0049] Referring now also to FIG. 2B, there is shown a top view of pattern of nanostructures  110  being suitable for use with a resonant mirror. According to an aspect of the present invention, pattern of nanostructures  110  may form an array of pillars. When transmission impinges upon pattern of nanostructures  110 , the pillar array may reflect and transmit the transmission without the polarization dependent effects that may result from a 1-D configuration, such as that shown in FIG. 1A.  
     [0050] Referring again to FIG. 1A, when transmissions impinge upon resonant mirror  100  at interface  160 , the transmission may be reflected and refracted. The amount of the transmission reflected and refracted depends upon the factors discussed hereinabove, for example the refractive index of material in which the transmission was propagating, such as a core of an optical fiber or air for example, and the refractive index of ARC  150 . If ARC  150  is provided, the quantity of reflected transmission resulting from interface  160  may be relatively small. The transmission portion refracted at interface  160  propagates through ARC  150  and impinges upon cladding layer  140  at interface  170 . Again, this transmission is reflected and refracted at interface  170  with the quantity of each being dependent upon the refractive index of ARC  150  and n 2  (the refractive index of cladding layer  140 ) and other properties discussed herein above, for example. If ARC  150  is provided the reflected portion at interface  170  is likely to be small. Again, the refracted portion of the impinging transmission propagates through cladding layer  140  and impinges upon pattern of nanostructures  110 .  
     [0051] The propagating transmission is reflected and refracted governed by the relationships discussed hereinabove, including between refractive indices n 2 , n 3  and X G , F G , for example. Further, the transmission impinging upon pattern of nanostructures  110  may be governed by the physical property known in the art as diffraction. Of course, diffraction may be generally defined as the effect on transmission as a wavefront of transmission passes through an opening, such as for example an opening of pattern of nanostructures  110 , as secondary wavefronts are generated apparently originating from the opening, interfering with the primary wavefront as well as with each other to form various diffraction patterns.  
     [0052] Additionally, the principle of multiple layer thin films, described hereinabove, is employed. The reflected radiation, vibrating parallel to the grid structure interacts with pattern of nanostructures  110 , similar to the interaction of radiation and multilayer thin films, thereby enhancing reflectivity.  
     [0053] The refracted and diffracted transmission impinges upon substrate  130  of refractive index n 1  at interface  180 . Again, this transmission may be reflected and refracted. The transmission refracted at interface  180  propagates through substrate  130  and impinges upon ARC  155 , if present, at interface  190 . Again, the transmission is reflected and refracted as defined above. Again, if ARC  155  is used the reflected transmission at interface  190  is likely to be small. Again, the refracted transmission propagates through ARC  155  to interface  195 , where the transmission is reflected and refracted. If ARC  155  is used the reflected transmission at interface  195  is likely to be small. Finally, the transmitted portion refracted at interface  195  exits the resonant mirror into another medium, such as an optical fiber core or air, for example.  
     [0054] Thus, resonant mirror  100  may serve to select wavelengths and polarization thereby operating as a wavelength selecting polarization selective mirror  100 . The resonant mirror  100  may be configured to perform broadband or narrowband wavelength selection, resulting in a resonant mirror  100  having a polarization-dependent forbidden band over certain wavelength ranges, for example. In particular, if the forbidden band for the transverse electric field (TE) is the allowed band for transverse magnetic field (TM) in the optical frequency range then the structure may be used to perform polarization beam splitting and/or combining. The forbidden band and pass band can be related to the quantities Xg and Fg, for example, through FIG. 5, discussed hereinbelow. For example, for refractive indices of the grating layers approximately equal to the refractive indices of the TM component, the reflections of the incident waves may be substantially zero. For the same structure, the TE component may encounter significant reflection due to the relatively higher indices of the grating layer. Thus one may create a polarization dependent transmission and reflection. Similarly, for mediums of higher indices of refraction, the TE component may become the transmission band and the TM component of the field may be reflected. Grating based polarization mirrors may permit incident angles to be varied from substantially 0 degrees to substantially 90 degrees. Thin film filter may be generally restricted to incident angles in the vicinity of the Brewster angle, which is generally larger than 30 degrees.  
     [0055] Referring now to FIG. 3, resonant mirror  100  may also have a residual layer  320  of refractive index n 3 . Residual layer  320  may be placed between grating  110  and substrate  130  along interface  180 . Residual layer  320  may increase the thickness of the n 3  refractive index region from D G  to D R . Residual layer  320  may provide increased reflectivity and may be suited for use when resonant mirror  100  is used in reflection for example. Residual layer  320  may be used for a narrow-band mirror or filter, for example.  
     [0056] Referring now to FIG. 4, there is shown a resonant grating  400  suitable for accepting beams having a relatively wide angle of incidence according to an aspect of the present invention. Resonant grating  400  may include a substrate  130 , a pattern of nanostructures  110  (or  110 ′- 110 ′″), a cladding layer  140  and anti-reflection coatings  150 ,  155 , as was described hereinabove with respect to FIG. 1A. Resonant grating  400  may also include a lower cladding layer  125 . As may be seen in FIG. 4, resonant grating  400  may include additional layers of pattern  110  (shown as  110 ′,  110 ″,  110 ′″) and lower cladding layer  125  (shown as  125 ′,  125 ″,  125 ′″). The number of additional layers is by way of non-limiting example only and any suitable number of layers may of course be utilized. The additional layers of pattern  110  and lower cladding layer  125  may be oriented in a substantially co-planar relationship, in an alternating pattern, sequentially sandwiched, in a stacked configuration between cladding layer  140  and substrate  130 , for example. As with pattern  110 , each of the additional layers of pattern  110  (shown as  110 ′,  110 ″,  110 ′″) may include multiple nanostructures each of width F G  and height D G . Elements of additional layers of pattern  110  (shown as  110 ′,  110 ″,  110 ′″) may also be chirped or varied. While, for ease of reference, each layer of nanostructures, is referred to as having elements of the same height and width, the elements within one layer may differ from the elements within other layers. As discussed hereinabove, one or more filling materials  145  may be positioned interspersed between the multiple nanostructures of width F G  and height D G  of pattern of nanostructures  110  (either 110′,  110 ″,  110 ′″) and may be deposited in this region between the high index elements using methods known by those possessing an ordinary skill in the pertinent arts. The elements of layer  110 ′ for example, may be substantially position insensitive to the elements of  110 ″ and similarly  110 ′″ as shown. Benefits gained by co-registering elements within patterns in the sandwich may be minimal. That is, one layer of elements  110 , such as layer  110 ′, may not need to be registered with another layer  110 , such as layer  110 ″ to achieve improved performance characteristics of reflectivity as compared to a single aligned layer  110 .  
     [0057] Referring to FIG. 5, there is shown a relationship between the effective index, the birefringence and the filling ratio for different polarization states according to an aspect of the present invention. According to an aspect of the present invention n F ≈n 1 ≈n 2 ≈1.5 and n 3 ≈3.0. As will be recognized by those possessing an ordinary skill in the pertinent arts, the apparent refractive index for each of the polarization states is provided, as a function of the filling ratio.  
     [0058] Referring to FIG. 6, there is shown a relationship between the transmission/reflection and wavelength for different polarization states according to an aspect of the present invention shown in FIG. 1A.  
     [0059] Referring to FIG. 7, there is shown a relationship of the polarization-dependent extinction ratios according to an aspect of the present invention shown in FIG. 1A.  
     [0060] Referring to FIG. 8, there is shown a relationship between the transmission/reflection and wavelength for different polarization states according to an aspect of the present invention shown in FIG. 3 for the embodiment wherein the filling material may take the form of a semiconductor band material. Depicted in FIG. 8 there is shown the band structure as represented by the device in FIG. 3 with n 3 ≈3.5 and the geometrical parameters, period and thickness of the pattern of nanostructures and the index-loading rib in FIG. 3 designed such that the optical waves would be at resonant Bragg condition to the guiding mode.  
     [0061] Referring now to FIGS.  9 - 11 , there may be seen plots of reflection or transmission vs. wavelength and incident angle. As may be seen in FIG. 9, there is shown a plot of the reflection of TE as a function of wavelength and incident angle for two one-dimensional layers. As demonstrated in FIG. 9, incorporating two one-dimensional layers may serve to increase the accepted incident angle to ±5 degrees. As may be seen in FIG. 10, there is shown a plot of the transmission of TM as a function of wavelength and incident angle for two one-dimensional layers. As demonstrated in FIG. 10, incorporating two one-dimensional layers increases the accepted incident angle to ±5 degrees. Similarly, in FIG. 11, there is shown a plot of the reflection of TE as a function of wavelength and incident angle for three one-dimensional layers. As demonstrated in FIG. 11, incorporating three one-dimensional layers increases the accepted incident angle to ±5 degrees. Further, in FIG. 12, there is shown a plot of the reflection of TE as a function of wavelength and incident angle for four one-dimensional layers. As demonstrated in FIG. 12, incorporating four one-dimensional layers increases the accepted incident angle at least to ±5 degrees.  
     [0062] Now referring to FIG. 13, there is illustrated the relationship between layer thickness, wavelength and reflection of TE for the structure of FIG. 4. Specifically, in FIG. 13, the relationship between wavelength, in the range of 1.3 μm to 2.0 μm, layer thickness, in the range from 0 μm to 2 μm, and the associated change in the TE reflection varying from 0 to 1 is demonstrated. As is known to those possessing an ordinary skill in the pertinent arts, zero reflection refers to the instance when total absorption or transmission occurs and a reflection equal to 1 refers to complete reflection.  
     [0063] Now referring to FIG. 14, there is illustrated the relationship between period, X G , of pattern of nanostructures  110 , wavelength and reflection of TE for the structure of FIG. 4. Specifically, in FIG. 14, the relationship between wavelength, in the range of 1.3 μm to 2.0 μm, period, in the range of 0.2 μm to 1.4 μm, and the associated change in the TE reflection varying from 0 to 1 is demonstrated. As is known to those possessing an ordinary skill in the pertinent arts, zero reflection refers to the instance when total absorption or transmission occurs and a reflection equal to 1 refers to complete reflection. As may be seen in FIG. 14, wavelength of incident radiation and period, X G , may be configured to provide the desired reflection of TE, such as for example, if a high reflection of TE is desired at 1200 nm, then a period of 800 nm may be selected.  
     [0064] Referring now to FIGS. 15A and B, there is shown a device  800  incorporating resonant mirror  100 . Device  800  may include a first substantially reflective device  810  and a second substantially reflective device  820  each incorporated at distal ends of cavity  850 . Device  810  and/or  820  may take the form of device  100  of FIG. 1 or  3 , for example. Device  800  may take the form of a type III-V semiconductor compound band vertical-cavity surface emitting laser (VCSEL), for example.  
     [0065] First substantially reflective device  810  may be oriented to reflect a desired polarization as described hereinabove. First substantially reflective device  810  may be additionally or alternatively configured to reflect a desired wavelength band, for example. Cavity  850  may be defined by an oxide/insulator confinement boundary  860 . Second substantially reflective device  820  may be provided upon the distal end of cavity  850 , with pattern of nanostructures  830  substantially aligned to pattern of nanostructures  840  of first substantially reflective device  810 . Second substantially reflective device  820  may be designed to have a reflectivity slightly less than 1.0 with respect to desired polarization and wavelength band, thereby transmitting a portion of the energy resonant in cavity  850  with the desired polarization and desired wavelength band corresponding to first substantially reflective device  810 . Use of first substantially reflective device  810  and second substantially reflective device  820  with cavity  850  and confinement  860  may produce a VCSEL with a preferred polarization direction and wavelength band. ARC  870  may be provided on one interface  880 . As set forth, ARC  870 , if provided, may generally decrease losses resulting from differences in refractive indices at interface  880 .  
     [0066] Referring now to FIG. 16, there is shown a wavelength filter  1600  incorporating the resonant grating shown in FIG. 4 which may be suited for accepting wide angle of incident beams according to an aspect of the present invention. As may be seen in FIG. 16, wavelength filter  1600  may include a substrate  130 , a pattern of nanostructures  110 , a cladding layer  140 , as was described hereinabove with respect to FIGS. 1A and 4. As discussed with respect to FIG. 4, resonant grating  400  may include additional layers of pattern  110  (shown in FIGS. 4 and 16 as  110 ′,  110 ″), the number of additional layers is by way of non-limiting example only and any suitable number of layers may of course be utilized, and lower cladding layer  125  (shown in FIGS. 4 and 16 as  125 ′,  125 ″). As was discussed hereinabove additional layers of pattern  100  and lower cladding  125  may be oriented in a co-planar relationship, in an alternating pattern substantially sandwiched between cladding layer  140  and substrate  130 . As with pattern  110 , each of the additional layers of pattern  110  (shown as  110 ′,  110 ″) may include multiple nanostructures each of width F G  and height D G . While, for ease of reference, each layer of nanostructures, is referred to as having elements of the same height and width, the elements within one layer may differ from the elements within other layers and may differ from other elements in same layer as well, for example elements of pattern  110  may also be chirped or varied. As discussed hereinabove, a filling material  145  may be positioned between pattern of nanostructures  110  (either  110 ′,  110 ″) and may be deposited in this region between the high index gratings using methods known by those possessing an ordinary skill in the pertinent arts. The elements of layer  110 ′ for example, may be position insensitive to the elements of  110 ″. Benefits gained by co-registering elements within patterns in the sandwich may be minimal.  
     [0067] Similar to the layers  110 ′,  110 ″ discussed hereinabove, a second series of patterns  1210 , similar to series  110  may be located proximate to layers  110 ′,  110 ″ creating a cavity  1250  therebetween. Series of patterns  1210  may take the form, as discussed with respect to pattern  110 , of multiple layers of patterns with cladding layers interspersed therebetween. Additionally, antireflection coatings  1280 ,  1290  may be added to reduce losses and reflections as will be known to those possessing an ordinary skill in the pertinent arts.  
     [0068] Referring now to FIG. 17, there is shown a simulated performance of wavelength filter  1600  of FIG. 16. As may be seen in FIG. 17, the simulated performance of the wavelength filter  1600  is plotted in absolute efficiency as a function of wavelength. As demonstrated by the results of FIG. 17, absolute efficiency may be maximized and may approach unity. Further, these reflectors of FIG. 16, may be designed to select a narrow bandwidth region of the incoming radiation, such as for example 1.4645 μm. Now referring also to FIG. 18, where there is shown a simulated performance of a tunable wavelength filter  1600  of FIG. 16. As may be seen in FIG. 18, the simulated performance of the wavelength filter  1600  tuning is plotted as a function of wavelength. The absolute efficiency of the PCM based filter of FIG. 16 is shown as a function of wavelength. The various curves simulate changes in the refractive index of layer  1250  shown in FIG. 16.  
     [0069] Referring now to FIGS. 19A, 19B, and  19 C, a device  900  incorporating device  100  from FIG. 1 or  3  is shown. Device  900  may include micro-lenses  910  formed in an array  915  aligned to device  100  suitable for use as a polarization beam splitter and combiner (PBS/C). PBS/C  900  may be formed using a microlens  910 , with a pitch size that is substantially uniform or varied to achieve desired results as will be recognized by those possessing an ordinary skill in the pertinent arts. Each micro-lens  910  may be of a form known to those having ordinary skill in the pertinent arts, such as refractive, diffractive, or hybrid, for example and may have a refractive index n m . Briefly, array  915  includes a plurality of micro-lenses  910  arranged in an ordered or desired pattern. Using micro-lens  910  array  915 , each lens  910  may focus incident light on an individual area. In general, the use and design of micro-lens arrays is well known by those possessing skill in the pertinent arts. Resonant mirror  100  may be placed substantially the focal length of micro-lens  910  away from array  915 , thereby having each lens  910  of array  915  focus on a corresponding portion of resonant mirror  100 . Additionally, the device of FIG. 4 may also be used in the configuration of FIG. 19.  
     [0070] Referring now to FIG. 20, there is shown a device  1000  incorporating device  900  of FIG. 19. According to an aspect of the present invention, a second micro-lens  1010  array  1015  having a refractive index nm may be added to device  900 . Second micro-lens  1010  array  1015  may be aligned on a surface of resonant mirror  100  distal to micro-lens array  915  for example. Micro-lens array  1015  may be aligned such that each lens  1010  array  1015  is substantially aligned to a corresponding lens  910  in a telecentric mode. An ARC  1050  may be applied to a surface of array  1015  distal to resonant mirror  100 . Similarly, an ARC  1060  may be applied to a surface of array  915  distal to resonant mirror  100 .  
     [0071] Referring now to FIGS. 21A and B, a device  1100  suitable for use with device  1000  of FIG. 20 is shown. Device  1100  may include a substrate  1110 , and fibers  1130 . In FIGS. 21A and B, there is shown a substrate  1110 , for example a silicon wafer, lithographically patterned with selective portions  1120  etched through. Portions  1120  etched through may be sized to accept one or two single-mode or multi-mode fibers  1130 , for example. Fibers  1130 , which may be polished to optical flatness and may be AR coated, as known in the pertinent arts, may be fed through etched portions  1120  and fixed in place. Polarization maintaining fibers  1130  may be used for example, and two orthogonal axes of the polarization maintaining fibers  1130  may be aligned into orthogonal positions inside each etched portion  1120 .  
     [0072] Referring now also to FIGS. 22A and B, there is shown a perspective view and a cross sectional view, respectively, of a device  1200  incorporating device  1100  and  1000  of FIGS. 21 and 20, respectively. Device  1200  may include a two dimensional array of fibers  1100  and a resonant mirror  100  is shown. Depicted in FIGS. 22A and B there is a finished multilayer PBS/C array  1200  with fibers  1130  substantially aligned to a corresponding lens  915  of array  910  in a telecentric mode. Lens  1010  array  1015  may be included and substantially aligned to a corresponding lens  915  of array  910  in a telecentric mode on the distal side of resonant mirror  100  from array  915 . Resonant mirror  100  may be located at the focal plane of micro-lens array  910  as discussed hereinabove.  
     [0073] Operationally, for example, PBS/C device  1200  may function as shown in FIG. 22B, wherein input unpolarized transmissions impinge upon resonant mirror  100  via fiber  1210 . Based on the discussion herein above, particularly for FIGS.  1 - 3 , polarization selection may occur at pattern of nanostructures  110  within resonant mirror  100 . The transmission incident on pattern of nanostructures  110  from fiber  1210  may interact with pattern of nanostructures  110  based on the wavelength and polarization state of the transmission. As shown, for example, pattern of nanostructures  110  may transmit the TM polarization component, in fiber  1220  for example, and reflect the TE polarization component, in fiber  1230  in FIG. 22B. The TE polarization component reflected may be the drop portion of PBS/C  1200 . Additionally, as shown in FIG. 22B, an additional fiber  1240  may inject one or more transmissions of polarization TE from the distal end of resonant mirror  100  from fiber  1210 . As resonant mirror  100  reflects TE polarized transmission, substantially all of the transmission injected using fiber  1240  may be reflected and collected in fiber  1220  as fiber  1240  is injecting TE polarized transmission. Thus a polarizing beam splitter and combiner is advantageously achieved.  
     [0074] Referring now to FIG. 23, there is shown a guiding device according to an aspect of the present invention. Guiding device  2300  may include a waveguiding core  2310 , and four distinct regions (A-D), aligned on a substrate  130 . Region C is located substantially adjacent to substrate  130 . Waveguiding core  2310  may be located substantially adjacent to Region C distal to substrate  130 . Region A may be located substantially adjacent to core  2310  distal to Region C. Region B may be located substantially adjacent to core  2310  and substantially between Region A and Region C. Similarly, Region D may be located substantially adjacent to core  2310  distal to Region B and substantially between Region A and Region C.  
     [0075] Each region, A-D, may include an assembly of alternating layers of  110 ″,  125 ′,  110 ″, and  125 ″ as described hereinabove with respect to at least FIG. 16. Region A and Region C may have similar periods or different periods; they also may be formed of the same materials or varied materials. Region B and Region D may have similar periods or different periods; they also may be the same materials or varied materials. Each region, A-D, may include the same numbers of layers or may have different numbers of layers.  
     [0076] According to an aspect of the present invention, guiding device  2300  may have Region A and Region C having relatively similar periods and Region B and Region D having relatively similar periods, and Region A and Region B having relatively different periods. The period for Region B and Region D may be determined with n B,D  being the effective refractive index for Region B and Region D, respectively. λ center  may be the center wavelength of the operational band of core  2310 , and m is an integer, such as, for example, unity. The period for Region B and Region D (Λ B,D ) may be determined by:  
     Λ B,D   D=m*λ   center /(2* n   B,D )  
     [0077] According to an aspect of the present invention, the period of Region B and Region D may be substantially half of the period of Region A and Region C. Guiding device  2300  may be designed to confine traversing electromagnetic waves using principles of Bragg reflection. Further, guiding device  2300  may be employed to remove portions of traversing electromagnetic radiation.  
     [0078] Those of ordinary skill in the art may recognize that many modifications and variations of the present invention may be implemented without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modification and variations of this invention provided they come within the scope of the appended claims and their equivalents.