Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/144—Beam splitting or combining systems operating by reflection only using partially transparent surfaces without spectral selectivity
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/0087—Phased arrays
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/1086—Beam splitting or combining systems operating by diffraction only
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/145—Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
• • 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
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
  • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
  • G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
  • G02B6/29358—Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator
• • 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
  • G02B6/24—Coupling light guides
  • G02B6/26—Optical coupling means
  • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
  • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
  • G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
  • G02B6/29392—Controlling dispersion
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
  • H04B10/25—Arrangements specific to fibre transmission
  • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
  • H04B10/2513—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion
  • H04B10/25133—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion including a lumped electrical or optical dispersion compensator

Definitions

• the present invention relates to an apparatus producing chromatic dispersion
• the present invention relates to an optical fiber transmission line. More specifically, the present invention relates to an optical fiber transmission line.
• FIG. 1(A) is a diagram illustrating a conventional fiber optic communication
• FIG. 1(A) a system, for transmitting information via light.
• transmitter 30 transmits pulses 32 through an optical fiber 34 to a receiver 36.
• chromatic dispersion also referred to as “wavelength dispersion”
• optical fiber 34 degrades the signal quality of the system. More specifically,
• wavelength for example, a pulse with wavelengths representing a "red" color pulse
• a pulse with a shorter wavelength for example, a pulse with a shorter wavelength
• the dispersion is typically referred to
• a blue color pulse is faster than a pulse with a longer wavelength (such as a red color
• the dispersion is typically referred to as "anomalous" dispersion.
• pulse 32 consists of red and blue color pulses when emitted from
• pulse 32 will be split as it travels through optical fiber 34 so that a
• FIG. 1(A) illustrates a case of "normal" dispersion, where a red color
• FIG. 1(B) is a diagram illustrating
• FIG. 1(C) is a diagram illustrating pulse 42 when
• pulse 42 is broadened in optical fiber 34 and, as illustrated by FIG.
• the fiber optic communication system must compensate for
• FIG. 2 is a diagram illustrating a fiber optic communication system having an
• an opposite dispersion component 44 adds an "opposite"
• FIG. 3 is a diagram illustrating a fiber optic
• compensation fiber 46 provides an opposite dispersion to cancel dispersion caused by
• optical fiber 34 optical fiber 34.
• a dispersion compensation fiber is expensive to manufacture, and must be relatively long to sufficiently compensate for chromatic
• dispersion For example, if optical fiber 34 is 100 km in length, then dispersion
• compensation fiber 46 should be approximately 20 to 30 km in length.
• FIG. 4 is a diagram illustrating a chirped grating for use as an opposite
• Circulator 50 provides the
• Chirped grating 52 reflects the light back towards
• grating 52 can be designed so that longer wavelength components are reflected at a
• Circulator 50 then provides the light reflected from
• chirped grating 52 to an output port 54. Therefore, chirped grating 52 can add
• a chirped grating has a very narrow bandwidth for reflecting
• chirped gratings may be cascaded for wavelength multiplexed signals, but
• a chirped grating with a circulator as in FIG. 4, is more suitable for use when a single channel is transmitted through a fiber
• FIG. 5 is a diagram illustrating a conventional diffraction grating, which can
• grating 56 has a grating surface 58.
• Parallel lights 60 having different wavelengths are
• wavelengths are output from diffraction grating 56 at different angles.
• grating can be used in a spatial grating pair arrangement, as discussed in more detail
• FIG. 6(A) is a diagram illustrating a spatial grating pair arrangement for use as an opposite dispersion component, to compensate for chromatic
• grating 68 into a light 69 for shorter wavelength and a light 70 for longer wavelength.
• a spatial grating pair arrangement as illustrated in FIG. 6(A) has anomalous dispersion.
• FIG. 6(B) is a diagram illustrating an additional spatial grating pair arrangement
• lenses 72 and 74 are positioned between first and second
• wavelengths (such as lights 70) travel shorter distance than shorter wavelengths (such as
• FIGS. 6(A) and 6(B) A spatial grating pair arrangement as illustrated in FIGS. 6(A) and 6(B) is
• diffraction grating is usually extremely small, and is typically approximately 0.05
• first and second gratings 68 and 71 would have to be
• VIPA virtual imaged phased array
• VIPA generator VIPA generator
• the apparatus also includes a mirror or reflecting surface which
• the VIPA generator receives
• the reflecting surface reflects the output light back to
• the reflecting surface has different curvatures at different
• the VIPA generator which includes a VIPA generator, a reflecting surface, and a lens.
• the VIPA generator includes a VIPA generator, a reflecting surface, and a lens.
• the reflecting surface has a cone shape, or a modified cone shape.
• the lens focuses the
• the modified cone shape can be designed so that the
• apparatus provides a uniform chromatic dispersion to light in the same channel of a
• the angular dispersive component comprising an angular dispersive component and a reflecting surface.
• dispersive component has a passage area to receive light into, and to output light from,
• the angular dispersive component receives, through
• reflecting surface reflects the output light back to the angular dispersive component to
• the reflecting surface has different curvatures at different
• the angular dispersive component has a passage area to receive light into, and to output light from, the angular dispersive component.
• reflecting surface reflects the output light back to the angular dispersive component to
• the reflecting surface has different curvatures at different
• reflecting surface has a reflectivity which causes a portion of light incident thereon to
• the first and second reflecting surfaces are positioned so that the input light
• the plurality of transmitted lights interfere with each other
• the mirror surface reflects output the light back to the second reflecting surface to pass through the second reflecting surface and undergo multiple
• the mirror surface has
• the VIPA generator receives a line focused wavelength division multiplexed
• WDM wavelength division multiplexing
• the first and second output lights travel from the VIPA generator in first
• the lens focuses the first and second output lights traveling from the
• the first and second mirrors each having a cone shape or a modified cone shape for producing a uniform chromatic dispersion.
• phase mask For example, a phase mask
• VIPA virtual imaged phased array
• VIPA generator VIPA generator
• the apparatus also includes a mirror or reflecting surface which
• the VIPA generator receives
• the reflecting surface reflects the output light back to
• the reflecting surface has different curvatures at different
• VIPA generator or a plane which includes the traveling directions of collimated output
• the VIPA generator which includes a VIPA generator , a reflecting surface , and a lens .
• the VIPA generator includes a VIPA generator , a reflecting surface , and a lens .
• the wavelength ofthe input light, the output light thereby being spatially distinguishable
• the reflecting surface has a cone shape, or a modified cone shape.
• the lens focuses the
• reflecting surface reflects the output light, the reflected light being directed by the lens
• the modified cone shape can be designed so that the
• apparatus provides a uniform chromatic dispersion to light in the same channel of a
• the angular dispersive component comprising an angular dispersive component and a reflecting surface.
• dispersive component has a passage area to receive light into, and to output light from,
• the angular dispersive component receives , through the passage area, an input light having a respective wavelength within a continuous
• reflecting surface reflects the output light back to the angular dispersive component to
• the reflecting surface has different curvatures at different positions along a direction which is perpendicular to a plane which includes the travel
• the angular dispersive component has a passage area to receive light into, and to
• the angular dispersive component output light from, the angular dispersive component.
• reflecting surface reflects the output light back to the angular dispersive component to
• the reflecting surface has different curvatures at different
• the apparatus comprising first and second reflecting surfaces, and a mirror.
• the second reflecting surface has a reflectivity which causes a portion of light incident thereon to
• An input light at a respective wavelength is focused into a line.
• the first and second reflecting surfaces are positioned so that the input light
• the plurality of transmitted lights interfere with each other
• the mirror surface reflects output the light back to the second
• the mirror surface has
• the VIPA generator receives a line focused wavelength division multiplexed
• the first and second output lights travel from the VIPA generator in first
• the lens focuses the first and second output lights traveling from the
• the first and second mirrors each having a cone shape or a modified cone shape for producing a uniform chromatic dispersion.
• phase mask For example, a phase mask
• variable curvature mirror positioned to reflect light produced by a
• VIPA virtually imaged phased array
• VIPA virtually imaged phased array
• variable curvature mirror positioned to reflect
• VIPA virtually imaged phased array
• variable curvature mirror positioned to reflect the output light back to the VIPA
• apparatus which includes (a) a radiation window; (b) first and second reflecting
• the second reflecting surface having a reflectivity which causes a portion of
• variable curvature mirror reflecting the output light back to the second reflecting surface to pass through the second reflecting surface and undergo
• the holder being rotatable around the rotation axis to bring a
• VIPA virtually imaged phased array
• VIPA virtually imaged phased array
• the holder being rotatable around the rotation axis to bring a different, respective
• VIPA virtually imaged phased array
• reflecting surfaces are positioned so that the input light radiates from the line to be
• collimated output light which travels from the second reflecting surface along a
• holder having a rotation axis and holding the plurality of mirrors equidistantly from the rotation axis, the holder being rotatable around the rotation axis to bring a different,
• VIPA virtually imaged phased array
• VIPA virtually imaged phased array
• VIPA virtually imaged phased array
• reflecting surfaces are positioned so that the input light radiates from the line to be
• collimated output light which travels from the second reflecting surface along a
• VIPA virtually imaged phased array
• VIPA virtually imaged phased array
• VIPA virtually imaged phased array
• apparatus which includes (a) a radiation window; (b) first and second reflecting
• the second reflecting surface having a reflectivity which causes a portion of
• the first and second reflecting surfaces are positioned so that the input light radiates from the line to be reflected a plurality of times between the first and second reflecting
• an off-axis parabolic mirror rotatable about a rotation axis to reflect the output light traveling from the second reflecting surface to a respective fixed mirror of the plurality of fixed mirrors, and to reflect the light reflected by the respective fixed mirror back to the second reflecting surface to pass through the second
• FIG. 1(A) (prior art) is a diagram illustrating a conventional fiber optic
• FIG. 1(B) is a diagram illustrating a pulse before transmission through a fiber
• FIG. 1(C) is a diagram illustrating a pulse after being transmitted through a fiber in a conventional fiber optic communication system.
• FIG. 2 (prior art) is a diagram illustrating a fiber optic communication system
• FIG. 3 (prior art) is a diagram illustrating a fiber optic communication system
• FIG. 4 (prior art) is a diagram illustrating a chirped grating for use as an
• FIG. 5 is a diagram illustrating a conventional diffraction grating.
• FIG. 6(A) is a diagram illustrating a spatial grating pair arrangement
• FIG. 6(B) (prior art) is a diagram illustrating a spatial grating pair arrangement
• FIG. 7 is a diagram illustrating a VIPA.
• FIG. 8 is a detailed diagram illustrating the VIPA of FIG. 7.
• FIG. 9 is a diagram illustrating a cross-section along lines IX—IX of the VIPA
• FIG. 10 is a diagram illustrating interference between reflections produced by
• FIG. 11 is a diagram illustrating a cross-section along lines IX-IX of the VIPA
• FIG. 7 for determining the tilt angle of input light.
• FIGS. 12(A), 12(B), 12(C) and 12(D) are diagrams illustrating a method for
• FIG. 13 is a diagram illustrating an apparatus which uses a VIPA as an angular
• FIG. 14 is a more detailed diagram illustrating the operation of the apparatus
• FIG. 15 is a diagram illustrating various orders of interference of a VIPA.
• FIG. 16 is a graph illustrating the chromatic dispersion for several channels of
• FIG. 17 is a diagram illustrating different channels of a wavelength division
• multiplexed light being focused at different points on a mirror by a VIPA.
• FIG. 18 is a diagram illustrating a side view of an apparatus which uses a VIPA
• FIG. 19 is a diagram illustrating a side view of an apparatus which uses a VIPA
• FIGS. 20(A) and 20(B) are diagrams illustrating side views of an apparatus
• FIG. 21 is a graph illustrating the output angle of a luminous flux from a VIPA
• FIG. 22 is a graph illustrating the angular dispersion of a VIPA versus the
• FIG. 23 is a graph illustrating the effect of different mirror types in an
• FIG. 24 is a diagram illustrating chromatic dispersion versus wavelength in an
• FIG. 25 is a graph illustrating the effect of a mirror in an apparatus which uses
• FIG. 26 is a graph illustrating constant chromatic dispersion of an apparatus
• FIG. 27 is a graph illustrating characteristics of different mirror designs for an apparatus using a VIPA.
• FIGS. 28(A), 28(B), 28(C), 28(D), 28(E) and 28(F) are diagrams illustrating
• FIG. 29 is a diagram illustrating a cylindrical mirror.
• FIG. 30(A) is a graph illustrating chromatic dispersion versus wavelength for
• FIG. 30(B) is a graph illustrating chromatic dispersion versus wavelength for
• FIG. 31(A) is a graph illustrating chromatic dispersion versus wavelength for
• FIG. 31(B) is a graph illustrating chromatic dispersion versus wavelength for
• FIG. 32 is a diagram illustrating a top view of an apparatus using a VIPA to
• variable chromatic dispersion to light according to a further embodiment of
• FIGS. 33(A) and 33(B) are diagrams illustrating how a mirror can be formed from a section of a cone, according to an embodiment of the
• FIG. 34(A) is a graph illustrating the amount of chromatic dispersion versus
• FIG. 34(B) is a diagram illustrating radii of curvature of FIG. 34(A), according
• FIG. 34(C) is a diagram illustrating modified radii of curvature, according to
• FIG. 35 is a graph illustrating the chromatic dispersion versus wavelength for
• FIG. 36 is a diagram illustrating various angles in an apparatus which uses a
• VIPA according to an embodiment of the present invention.
• FIG. 37 is an additional diagram illustrating angles in an apparatus which uses
• FIG. 38 is a diagram illustrating how chromatic dispersion is generated in an
• FIGS. 39(A), 39(B) and 39(C) are graphs illustrating mirror curves, according
• FIG. 40 is a diagram illustrating a cone for forming a mirror, according to an
• FIG. 41 is a diagram illustrating a step shaped mirror surface, according to an
• FIG. 42 is a diagram illustrating a side view of an apparatus using a VIPA to
• FIG. 43(A) is a graph illustrating the amount of chromatic dispersion for all
• FIG. 43(B) is a graph illustrating the amount of chromatic dispersion for all
• FIG. 44 is a diagram illustrating the use of a holographic grating between a
• VIPA and a lens, according to an embodiment of the present invention.
• FIG. 45 is a diagram illustrating the use of a reflection type grating between
• a VIPA and a lens according to an embodiment of the present invention.
• FIGS. 46 and 47 are diagrams illustrating the use of quarter wave plate
• FIG. 48(A) is a diagram illustrating a side or top view of an apparatus which
• FIG. 48(B) is a graph illustrating chromatic dispersion versus wavelength for
• FIG. 49 is a diagram illustrating a side or top view of an apparatus which uses
• FIG. 50 is a graph illustrating insertion loss in an apparatus which uses a VIPA
• FIG. 51 is a diagram illustrating different diffraction efficiency at different
• FIG. 52 is a diagram illustrating the light intensity of light traveling out of a
• FIG. 53 is a diagram illustrating a side view of an optical phase mask on an
• FIG. 54 is a diagram illustrating a cross-sectional view along lines 54-54 in
• FIG. 53 according to an embodiment of the present invention.
• FIG. 55 is a diagram illustrating a side view of phase masks on a VIPA to
• FIG. 56 is a diagram illustrating a side view of phase masks on a VIPA to provide a double-humped shape far field distribution with respect to light received
• FIGS. 57 and 58 are diagrams illustrating a side view of phase masks on a
• FIG. 59 is a diagram illustrating excessive loss added to a loss curve, according
• FIG. 60 is a diagram illustrating the use of an excess loss component to provide
• FIG. 61 is a diagram illustrating a side view of a mirror for use with a VIPA
• FIG. 62 is a diagram illustrating a front view of a mirror, according to an
• FIGS. 63(A), 63(B) and 63(C) are diagrams illustrating a way to modulate effective reflectivity in an apparatus using a VIPA, according to an embodiment ofthe
• FIG. 64 is a diagram illustrating the use of a grating between a VIPA and a
• FIGS. 65, 66 and 67 are diagrams illustrating the use of a VIPA with a movable
• FIGS . 68 and 69 are diagrams illustrating a tunable dispersion compensator that
• FIG. 70 is a diagram illustrating an example of a variably curved mirror for
• FIG. 71 is a diagram illustrating a tunable dispersion compensator that utilizes
• FIG. 72 is a diagram illustrating a tunable dispersion compensator that utilizes
• FIG. 73 is a diagram illustrating a tunable dispersion compensator that utilizes
• FIG. 7 is a diagram illustrating a virtually imaged phased array (VIPA).
• VIPA virtual imaged phased array
• a VIPA 76 is preferably made of a thin plate of glass.
• Line 78 is hereinafter referred to as
• focal line 78 Input light 77 radially propagates from focal line 78 to be received
• VIPA 76 inside VIPA 76.
• VIPA 78 then outputs a luminous flux 82 of collimated light, where
• the output angle of luminous flux 82 varies as the wavelength of input light 77 changes.
• VIPA 76 when input light 77 is at a wavelength ⁇ l, VIPA 76 outputs a luminous
• VIPA 76 outputs a luminous flux 82b at wavelength ⁇ l in a different
• VIPA 76 produces luminous fluxes 82a and 82b which are
• FIG. 8 is a detailed diagram illustrating VIPA 76. Referring now to FIG. 8,
• VIPA 76 includes a plate 120 made of, for example, glass, and having reflecting films
• Reflecting film 122 preferably has a reflectance of approximately
• Reflecting film 124 preferably has a reflectance
• a radiation window 126 is formed on plate 120 and
• Input light 77 is focused into focal line 78 by lens 80 through radiation window 126, to undergo multiple reflection between reflecting films 122 and 124.
• 78 is preferably on the surface of plate 120 to which reflecting film 122 is applied.
• focal line 78 is essentially line focused onto reflecting film 122 through radiation
• focal line 78 can be referred to as the "beam waist" of input
• FIG. 8 focuses the beam waist of input light 77 onto the far surface (that is, the surface having reflecting film 122 thereon) of plate 120. By focusing the beam
• reflecting film 124 for example, the area "b" illustrated in FIG. 11 , discussed in more detail further below. It is desirable to reduce
• an optical axis 132 of input light 77 has a small tilt angle ⁇ .
• reflecting film 124 After being reflecting by reflecting film 124 for the first time, the
• the light is split into many paths with a constant separation d.
• path forms so that the light diverges from virtual images 134 of the beam waist.
• Virtual images 134 are located with constant spacing 2t along a line that is normal to
• virtual images 134 are self-aligned, and there is no need to adjust individual positions.
• the lights diverging from virtual images 134 interfere with each other and form collimated light 136 which propagates in a direction that changes in accordance with
• the angular dispersion is proportional to the ratio
• FIG. 9 is a diagram illustrating a cross-section along lines IX--IX of VIPA 76
• plate 120 has reflecting surfaces 122
• Reflecting surfaces 122 and 124 are in parallel with each other and
• Reflecting surfaces 122 and 124 are typically
• reflecting films deposited on plate 120 As previously described, reflecting surface 124
• reflecting surface 122 has a reflectance of approximately 95% or higher. Therefore,
• reflecting surface 122 has a transmittance of approximately 5% or less so that
• reflectances of reflecting surfaces 122 and 124 can easily be changed in accordance
• Radiation window 126 Radiation window
• Radiation window 126 receives input light 77 to allow input light 77 to be
• FIG. 9 represents a cross-section along lines IX— IX in FIG. 7, focal line
• focal line 78 is positioned on
• focal line 78 is on reflecting
• a shift in the positioning of focal line 78 may cause small changes in the characteristics of VIPA 76.
• input light 77 enters plate 120 through an area A0 in
• Points PI indicate peripheral points of area Al.
• reflection off of reflecting surface 122 also results in a respective output light being
• Points P2 indicate peripheral points of area A2
• points P3 indicate peripheral points of
• output light Out3 is defined by rays R2
• output light Out4 is
• FIG. 9 only illustrates output lights OutO, Outl, Out2,
• the luminous flux can be described as being a resulting output light formed from the interference of output lights OutO, Outl , Out2,
• FIG. 10 is a diagram illustrating interference between reflections produced by
• reflecting surface 124 has a
• output light Outl can be optically analyzed as if reflecting surfaces 122 and
• output lights Out2, Out3 and Out4 can be optically analyzed as if they were
• focal lines I l5 1 2 , 1 3 and I 4 are emitted from focal lines I l5 1 2 , 1 3 and I 4 , respectively.
• the focal lines I 2 , 1 3 and I 4 are emitted from focal lines I l5 1 2 , 1 3 and I 4 , respectively.
• focal line I j is a distance 2t from focal line I 0 , where t equals the distance between reflecting surfaces 122 and 124.
• each subsequent focal line is a distance 2t from the immediately preceding focal line.
• focal line I 2 is a distance 2t from focal line I lt Moreover, each subsequent
• Out2 is weaker in intensity than output light Outl.
• focal lines I l5 I 2 , I 3 and I 4 are the virtual
• the strengthening conditions of the VIPA are represented by the
• ⁇ indicates the wavelength of the input light
• t indicates the distance between the
• ⁇ can be determined.
• input light 77 is radially dispersed from focal line 78 through
• focal line 78 in many different direction from focal line 78, to be reflected between reflecting
• the strengthening conditions of the VIPA cause light traveling
• FIG. 11 is a diagram illustrating a cross-section along lines IX-IX ofthe VIPA
• FIG. 7 showing characteristics of a VIPA for determining the angle of
• input light 77 is collected by a cylindrical lens (not
• input light 77 covers
• input light 77 travels along optical axis 132 which
• the tilt angle ⁇ l should be set to prevent input light 77 from traveling out of
• the tilt angle ⁇ l should be set so that input light 77
• the tilt angle ⁇ l should be set in accordance with
• a VIPA receives an input light having
• the VIPA causes
• the output light is spatially distinguishable from an output light formed for an input light having any other wavelength within the continuous range of
• FIG. 9 illustrates an input light 77 which experiences
• An input light can be at any wavelength within a continuous range of
• the input light is not limited to being a wavelength which is a
• the traveling direction that is, a
• spatial characteristic of the luminous flux 82 is different when input light 77 is at
• FIGS. 12(A), 12(B), 12(C) and 12(D) are diagram illustrating a method for producing a VIPA.
• a parallel plate 164 is preferably made of glass
• Reflecting films 166 and 168 are formed on both
• One of reflecting films 166 and 168 has a reflectance of nearly 100%, and the other reflecting film has a reflectance of lower than 100%, and preferably higher
• one of reflecting films 166 and 168 is partially
• reflecting film 166 is
• a radiation window can be on either side of parallel plate 164.
• Shaving off a reflecting film can be performed by an etching process, but a
• window can be produced by preliminarily masking a portion of parallel plate 164
• a transparent adhesive 172 is applied onto
• Transparent adhesive 172 should generate the smallest possible
• a transparent protector plate 174 is applied onto
• transparent adhesive 172 is applied to fill the concave portion generated by removing
• transparent protector plate 174 can be provided in parallel with the
• an adhesive (not illustrated) can be
• reflecting film 168 has a reflectance of about 100% , and there
• protector plate do not necessarily have to be transparent.
• an anti-reflection film 176 can be applied on transparent protector
• transparent protector plate 174 and radiation window 170 can be used.
• transparent protector plate 174 and radiation window 170 can be used.
• anti-reflection film 176 be covered with anti-reflection film 176.
• a focal line can be on the surface of a radiation window or on the opposite
• the focal line can
• two reflecting films reflect light therebetween, with the reflectance of one reflecting film being approximately 100% .
• a reflectance of one reflecting film being approximately 100% .
• both reflecting films can have a reflectance of 95 % .
• each reflecting film has light traveling therethrough and causing interference.
• a waveguide device is formed by a parallel plate
• reflecting surfaces do not necessarily have to be parallel.
• a VIPA uses multiple-reflection and maintains a
• the VIPA are stable, thereby reducing optical characteristic changes causes by
• a VIPA provides luminous fluxes which are
• luminous fluxes being distinguishable in space. For example, various luminous fluxes
• FIG. 13 is a diagram illustrating an apparatus which uses a VIPA as an angular
• a VIPA 240 has a first surface 242 with a
• VIPA 240 also includes a radiation
• VIPA 240 is not limited to this specific configuration.
• VIPA 240 can have many different configurations as described herein.
• a light is output from a fiber 246, collimated by a
• VIPA 240 then produces a collimated light 251 which is
• Mirror 254 can be a mirror portion
• Mirror 254 reflects the light back through focusing lens 252 into VIPA 240. The light then undergoes multiple reflections in VIPA 240 and is output from radiation
• FIG. 14 is a more detailed diagram illustrating the operation of the VIPA in
• FIG. 13 Assume a light having various wavelength components is received by VIPA
• VIPA 240 will cause the formation of virtual images
• each virtual image 260 emits light.
• focusing lens 252 focuses the different wavelength
• a longer wavelength 264 focuses at point 272, a center wavelength
• Shorter wavelength 268 returns to a
• Mirror 254 is designed to reflect only light in a specific interference order
• a VIPA will output a collimated light.
• collimated light will travel in a direction in which the path from each virtual image has
• the mth order of interference is defined as an output light corresponding to m.
• FIG. 15 is a diagram illustrating various orders of interference
• a VIPA such as VIPA 240, emits collimated lights 276, 278 and 280.
• Each collimated light 276, 278 and 280 corresponds to a
• collimated light 276 is collimated
• collimated light 278 is collimated
• collimated light 280 is
• n is an integer.
• Collimated light 276 is illustrated as having several wavelength components 276a, 276b
• collimated light 278 is illustrated as having wavelength
• collimated light 280 is illustrated as having
• wavelength components 280a, 280b and 280c are wavelength components 280a, 280b and 280c.
• wavelength components 276a, 280b and 280c are wavelength components 276a, 280b and 280c.
• Wavelength components 276b, 278b and 280a have the same wavelength. Wavelength components 276b, 278b and
• Wavelength components 276a, 278a and 280a have
• FIG. 15 only illustrates collimated light for three different
• mirror 254 can be made to reflect only light from a single interference order back into VIPA 240.
• a wavelength division multiplexed light usually mcludes many channels.
• each channel has a center wavelength.
• wavelengths are usually spaced apart by a constant frequency spacing.
• t of VIPA 240 between first and second surfaces 242 and 244 should be set so that all
• the thickness t is set so that, for each channel, the round-trip optical
• center wavelength is a multiple of the center wavelength of each channel. This amount
• ⁇ indicates the small tilt
• VIPA 240 can be
• FIG. 16 is a graph illustrating the amount of dispersion of several channels of
• dispersions are not continuous
• VIPA 240 will compensate for dispersion can be set by appropriately setting the size
• channels of a wavelength division multiplexed light will be focused at different points
• each channel may be focused on the same mirror, with each channel being
• FIG. 17 is a diagram illustrating different channels being focused
• VIPA 240 can adequately compensate for dispersion in all
• FIG. 18 is a diagram illustrating a side view of an apparatus
• VIPA 240 causes each different interference order to have a different angular
• interference order is focused on mirror 254 and reflected back into VIPA 240.
• FIG. 19 is a diagram illustrating a side view of an apparatus which uses a VIPA
• mirror 252 and mirror 254 changes the shift of light returning to VIPA 240 from mirror 254,
• FIGS. 20(A) and 20(B) are diagrams illustrating side views of apparatuses which use a VIPA to provide various values of chromatic dispersion to light.
• FIGS. 20(A) and 20(B) are diagrams illustrating side views of apparatuses which use a VIPA to provide various values of chromatic dispersion to light.
• FIGS. 20(A) and 20(B) are similar to FIG. 14, in that FIGS. 20(A) and 20(B) illustrate the
• mirror 254 is a convex mirror. With a convex
• the convex shape can typically only be seen from a side
• mirror 254 is a concave mirror. With a concave mirror,
• the concave shape can typically only be seen from a side view and
• mirror 254 would appear flat in the top view.
• mirror 254 it is possible for mirror 254 to also be a concave or a convex mirror when viewed by
• the top thereby indicating that the mirror is a "one-dimensional" mirror.
• mirror 254 is located at or near the focal point of
• mirror 254 can be convex or concave in the side
• FIGS. 20(A) and 20(B) respectively.
• a convex mirror generates larger dispersion in the negative direction
• a concave mirror generates smaller dispersion in the negative direction or dispersion
• FIG. 21 is a graph illustrating the output angle of a luminous flux from VIPA
• dispersion is referred to as the higher order dispersion.
• FIG. 22 is a graph illustrating the angular dispersion of VIPA 240 versus the
• the curve 284 in FIG. 22 represents the
• FIG. 23 is a graph illustrating the term (l-f-(l/R)) in Equation 3, above, versus
• line 286 represents a graph of the term (l-f-(l/R))
• Line 288 represents a graph of the term (l-f-(l/R)) versus wavelength for a concave mirror
• Line 290 represents a graph of the term (l-f-(l/R)) versus wavelength for convex mirror (radius of curvature equals "-").
• each of the mirrors has a constant radius of curvature.
• FIG. 24 is a diagram illustrating the chromatic dispersion versus wavelength of
• mirror 254 is a convex mirror
• curve 292 is a curve of the
• Curve 296 is a curve of the chromatic dispersion versus wavelength when
• mirror 254 is a concave mirror.
• curves 292, 294 and 296 each represent a product of
• curve 294 represents a product of curve 284 in FIG. 22 and line 286 in FIG. 23.
• curve 296 represents a product of curve 284 in FIG. 22 and line 288 in FIG.
• the chromatic dispersion is not constant whether a convex, flat or concave mirror is used as mirror 254.

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• Spectroscopy & Molecular Physics (AREA)
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• 2000
  • 2000-12-13 EP EP00990211A patent/EP1252544A1/en not_active Withdrawn
  • 2000-12-13 AU AU27270/01A patent/AU2727001A/en not_active Abandoned
  • 2000-12-13 WO PCT/US2000/033679 patent/WO2001050177A1/en active Application Filing
  • 2000-12-13 CN CN 00817151 patent/CN100514118C/zh not_active Expired - Fee Related
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