Classifications

• • 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
  • G02B6/2938—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 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• • 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
  • G02B6/29304—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 diffraction, e.g. grating
  • G02B6/29305—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 diffraction, e.g. grating as bulk element, i.e. free space arrangement external to a light guide
  • G02B6/29307—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 diffraction, e.g. grating as bulk element, i.e. free space arrangement external to a light guide components assembled in or forming a solid transparent unitary block, e.g. for facilitating component alignment

Definitions

• the present invention relates to an optical processing apparatus that performs division or multiplexing of communication light in optical communication performed using wavelength division multiplexed light.
• the light processing device for performing light division or light multiplexing in WDM (wavelength division multiplexing) optical communication includes, for example, dielectric multilayer dichroic mirror, fiber Bragg grating (FBG), grating spectroscope
• FBG fiber Bragg grating
• AWG array waveguide grating
• those using dielectric multilayer film dichroic mirrors and fiber-one Bragg grating have about 4 channels
• those using AWG have about several tens of channels.
• the optical processing system of the dulling spectrometer type can realize several channels to several tens of channels, but it is considered to be more suitable for WDM optical communication than the AWG type optical processing system which requires less channels. There have been several attempts in the past.
• An optical processing apparatus that performs optical demultiplexing or optical wave for WDM optical communication is required to be smaller and have lower loss than anything else.
• a graded refractive index rod lens 101 is used as a so-called Littrow lens, and this is combined with an optical fiber array 102 and a grating 103.
• a light processing device configured as a structure has been devised.
• restrictions on rod lens manufacturing and optical design are large and difficult to achieve in the optimization design, so sufficient performance for multi-channel application is exhibited. Ru It is considered difficult.
• FIG. 24 shows a graded refractive index rod lens 101 as a so-called Littrow lens, and this is combined with an optical fiber array 102 and a grating 103.
• Ru It is considered difficult.
• a two-lens configuration is made by using a first lens 11 1 and a second lens 1 1 2 made of a uniform medium, and the first lens 1 1 1 is an optical fiber.
• a Littrow-type light processing apparatus has also been devised in which an array 113 and a second lens 112 are provided with a diffraction grating 114.
• This type of light processing device has the advantage of greater design freedom than the rod lens method described above, but to achieve the required performance with less loss, it does not require the dimensions required in the optical communication field. It can be said that it is not very realistic because it becomes quite large.
• the main factors that determine the throughput in the grating spectroscope-type optical processing system are the diffraction efficiency of the grating, the anamorphic effect produced by the grating, and the magnitude of geometrical optical aberration generated in the component optical system.
• the diffraction efficiency it is only necessary to use a diffraction efficiency as high as possible, so in order to realize a small-sized, low-loss light processing apparatus, reduction of anamorphic effect generated by the grating and geometry generated in the component optical system It is necessary to reduce the optical aberration. Disclosure of the invention
• the present invention is an optical demultiplexing device that achieves small size and low loss performance by reducing the anamorphic effect generated by the grating and reducing the geometrical optical aberration generated in the constituent optical system.
• a light processing apparatus comprising: an inner space; a case having a light inlet and a light outlet connected to the inner space; and a light incident port connected to the case.
• a flat reflection diffraction surface in which diffraction grooves are arranged at equal intervals is provided in the interior space of the case, and is provided in the inner space of the case to split the light into a plurality of light beams having different wavelengths.
• a second concave reflective surface to be incident on the optical transmission path is provided, and the light entrance and the light exit are provided on both sides of the grating in
• the wavelength division multiplexed light which has entered into the inner space of the case via the incident light transmission path is reflected by the first concave reflection surface to become parallel light, and enters the grating.
• the light incident on the grating is split into a plurality of lights of different wavelengths, each reflected by the second concave reflection surface, and then emitted to the corresponding outgoing light transmission path.
• the grating has a flat reflection diffraction surface in which a plurality of linear diffraction grooves are arranged at equal intervals, and the incident wavelength division multiplexed light is split into a plurality of light beams having different wavelengths.
• the incident light flux to the grating and the reflected diffraction light flux from the grating are The angle with respect to the direction in which light after reflection diffraction disperses can be made extremely small, and the anamorphic effect of light before and after reflection diffraction can be significantly reduced.
• the difference in NA between the incident wavelength division multiplexed light and each light separated for each wavelength after reflection diffraction in grating becomes extremely small (ie, NA is stored at high level), small size, low loss performance is obtained. Further, by providing such performance, when the present demultiplexer is applied to WDM optical communication, the dielectric multilayer film dichroic mirror system and the fiber Bragg grating system have about four waves in the prior art. It is possible to handle more wavelength channels at the same time in a smaller size, while waves and multiplexing are common.
• the inner space is preferably filled with a transparent solid medium, and the end face of the light transmission path for incidence and the end face of the light transmission path for emission are preferably joined to the solid medium.
• the first concave reflecting surface and the second concave reflecting surface are attached to a transparent solid medium having a predetermined shape in advance, and these are integrated (monolithic).
• the present optical processing apparatus can be manufactured according to the procedure of covering a solid medium with a case and attaching an optical transmission path for incidence and an optical transmission path for emission to this, so the manufacturing process becomes very simple.
• the reflection diffraction surface faces air to the inner space of the case, and the light reflected by the first concave mirror is provided with an opening provided in the case and It is preferable that the light which passes through the air and is incident on the reflective diffraction surface, and the light reflected and diffracted in the reflective diffraction surface travels through the air and the opening to reach the second concave mirror.
• air has a smaller temperature change of refractive index than a medium such as glass, so that the wavelength fluctuation of light is also small.
• a vacuum is better. If the wavelength fluctuation of light is large, the diffraction diffraction angle also largely fluctuates, which is not preferable because it causes drift of the imaging position.
• the focal point of the second concave reflective surface is located on or near the reflection diffraction surface of the grating.
• the first concave reflecting surface and the second concave reflecting surface are respectively different portions on the same paraboloid of revolution, and the focal point of the paraboloid of revolution is
• the first concave reflective surface and the second concave reflective surface are arranged such that the first concave reflective surface and the second concave reflective surface are positioned on or near the reflection diffraction surface of the sagittal.
• the first concave reflecting surface and the second concave reflecting surface described above are respectively on the same rotational paraboloid. The same effect as in the case of different parts can be obtained.
• the first concave reflecting surface and the second concave reflecting surface are respectively different portions on the same toric surface,
• the intersection obtained when the toric surface is cut by the equatorial plane, where the plane through which the light passes through is the equatorial plane and the plane perpendicular to the toric surface is a great circle among the planes perpendicular to the generation axis
• the first concave reflecting surface and the second concave reflecting surface are: 1 selected one of the exit surfaces of the toric surface including the two concave reflecting surfaces is the incident light It is parallel to the optical axis of the chief ray of the principal ray of light entering the interior space of the case via the transmission path, and 2) the focal point in the selected in-plane direction is at or near the reflection diffraction surface Located above, and 3) the above-mentioned selected passage plane, through the optical transmission line for incidence When the toric plane is cut by the equatorial plane,
• the first concave reflecting surface and the second concave reflecting surface are selected from among: 1 equatorial plane of the toric surface including these biconcave reflecting surfaces Through the optical transmission line for Parallel to the optical axis of the chief ray of light incident on the interior space of the source, and the focal point in the direction selected in the equatorial plane is located at or near the reflection diffraction surface, 3)
• the above selected equatorial plane includes a principal ray of light incident on the inner space of the case through the incident light transmission path, and a plane extending in a direction parallel to the diffraction grooves of the dummy and the 0 ° to 0 ° It is preferable to be provided at a position that intersects in the range of 45 °.
• the chief ray of light that has entered the inside space of the case through the incident light transmission path and is finally reflected by the second concave reflection surface is the chief ray of the entered light.
• the first concave reflecting surface and the second concave reflecting surface are different portions on the same paraboloid of revolution, respectively. Similar effects can be obtained.
• the larger of the two radii of curvature for the toric surface including the first concave reflecting surface and the second concave reflecting surface is R t, the smaller of the two radiuses of curvature.
• the fiber coupling ratio can be maintained high on the light receiving side, and the loss can be further reduced.
• a light processing apparatus comprising: an inner space; and a case having a light entrance and a light exit respectively connected to the inner space; and a case provided in the inner space of the case A first concave reflecting surface for reflecting wavelength division multiplexed light incident from the light entrance into the interior space into parallel light; and fixed to the case, the first concave reflecting surface being parallel light
• the plurality of light beams having different wavelengths in a planar reflection diffraction surface formed by arranging a plurality of linear diffraction grooves at regular intervals in the wavelength division multiplexed light
• a second concave reflection surface provided in the inner space of the case and causing the light separated by the grating to be incident on the light emission port;
• the entrance and the light exit are provided on both sides of the grating in the extending direction of the diffraction groove in the sag.
• wavelength-division multiple light having n different wavelength components is made incident from a light incident port and n number of emission lights separated for each wavelength are emitted from a light emission port.
• a light branching device comprising: an inner space; and a case configured to have the light entrance and the light exit respectively connected to the inner space; and provided in the inner space of the case, A first concave reflecting surface that reflects the wavelength division multiplexed light incident from the entrance into the interior space into parallel light; and fixed to the case, the first concave reflecting surface converts the light into parallel light.
• a grating for dispersing the wavelength division multiplexed light into a plurality of light beams of different wavelengths on a flat reflection diffraction surface in which a plurality of linear diffraction grooves are arranged at equal intervals; and in the inner space of the case Provided for the sagging And a second concave reflecting surface for allowing the plurality of light beams separated by the incident light to be incident on the light exit, the light entrance and the light exit being in the extending direction of the diffraction groove in the grating, It is provided with a dart hanging.
• an optical processing apparatus comprising: a single light transmission port connected to a single optical fiber guiding wavelength division multiplexed light; and a plurality of diffraction grooves arranged at equal intervals.
• a grating that has a diffractive groove surface and separates wavelength division multiplexed light into a plurality of light of different wavelengths or combines a plurality of light of different wavelengths into a wavelength division multiplexed light, and a plurality of light of different wavelengths
• a first light guiding member for guiding to the diffraction groove surface of the grating or for guiding wavelength division multiplexed light coming from the grating to the single light transmission port; a plurality of lights separated by the grating The And a second light guiding member for guiding a plurality of light from the plurality of light transmission rows to the diffraction groove surface of the grating.
• the light processing apparatus further includes a case having an inner space, and the single light transmission port and the plurality of light transmission port arrays are formed to be open to the outside of the case.
• First and second diffraction grating surfaces of the grating are formed to face the internal space, and the first and second light guide members face the diffraction groove surfaces, respectively; It is preferable to consist of two concave mirrors.
• FIG. 1 is a perspective view of a light processing apparatus according to an embodiment of the present invention.
• 2A, 2B, 2C, and 2D are a front view, a right side view, a plan view, and a left side view showing the light processing device, respectively.
• FIG. 3A is a partially enlarged side view of a case showing a junction between an optical fiber for incidence and a solid medium.
• FIG. 3B is a partially enlarged side view of the case showing the junction between each output optical fiber and the solid medium.
• FIGS. 4A, 4B, 4C, and 4D schematically show the components in the case of the light processing device 1 and the progress of light is shown in FIGS. 4A, 4B, and 4C.
• the left column is the right side view of the inside of the case, and the right column is the plan of the inside of the case.
• FIG. 5A and 5B are diagrams for explaining the generation of anamorphosis that occurs when light is reflected and diffracted in the grating
• FIG. 5A shows the beam width of the beam incident on the grating and the diffraction effect at the grating.
• FIG. 5B is an example of the case where there is no large difference between the above two beam widths.
• FIG. 6 is a view from above of the grating showing how the respective light fluxes reflected and diffracted at the reflection diffraction surface of the grating and dispersed for each wavelength become parallel to each other.
• FIG. 7 is a simplified side view of the inside of the case showing the optical path of light when the collimator and the imaging mirror are different parts on the same rotation parabola.
• FIG. 8A and 8B show two types of toric surfaces, and FIG. 8A shows the toric of the first evening in which one crossing circle is obtained when the toric surface itself is cut by the equatorial plane.
• Figure 8B shows a second type of 1 ⁇ 1 ric surface where two intersecting circles are obtained when the toric surface itself is cut by the equatorial plane
• FIG. 9 is a view for explaining the arrangement of the collimator and the imaging mirror in the case of adopting the first type of toric surface.
• FIG. 10 is a view for explaining the arrangement of the collimator mirror and imaging mirror when the second type of toric surface is adopted.
• FIG. 11 is a diagram for explaining the power of the concave toric reflecting surface.
• FIG. 12 is a perspective view of a light processing apparatus according to a modification.
• FIG. 13A, 13B, 13C, and 13D are views showing a light processing apparatus according to a modification
• FIG. 13A is a front view
• FIG. 13B is a right side view
• FIG. 13C is a plan view
• FIG. 13D is a left side view.
• FIG. 14A, 14B and 14C are views showing the light processing apparatus according to the first embodiment of the present invention, FIG. 14A is a front view, FIG. 14B is a right side view and FIG. 14C is a plan view. is there.
• FIG. 15 is a chart showing the refractive index characteristics with respect to the wavelength of the solid medium used in the first embodiment.
• FIG. 16 is a chart showing coordinates of image points obtained in the first embodiment.
• FIG. 17A and 17B show one of the imaging performances at the image points obtained in the first embodiment.
• FIG. 17A is a diagram showing an example
• FIG. 17A is a three-dimensional display of the intensity distribution at an image point of light of wavelength 1571 mm
• FIG. 17A is a three-dimensional display of the intensity distribution at an image point of light of wavelength 1571 mm
• FIG. 18A, 18B, 18C, and 18D are views showing a light processing apparatus according to a second embodiment of the present invention
• FIG. 18A is a front view
• FIG. 18B is a right side view
• FIG. 18 C is a plan view
• FIG. 18D is a left side view.
• FIG. 19 is a chart showing the coordinates of the image point obtained in the second embodiment.
• Fig. 2 OA and Fig. 20B are diagrams showing an example of the imaging performance at the image point obtained in the second embodiment, and Fig. 2 OA is a three-dimensional display of the intensity distribution at the image point of light of wavelength 1571 mm. Fig. 20 B shows the contour of this.
• FIG. 21A, 21B, and 21C are views showing a light processing apparatus according to a third embodiment of the present invention
• FIG. 21A is a front view
• FIG. 21B is a right side view
• FIG. 21C is a plan view. It is.
• FIG. 22 is a chart showing the coordinates of the image point obtained in the third embodiment.
• Figs. 23A and 23B are diagrams showing an example of the imaging performance at the image point obtained in the third embodiment, and Fig. 23A is a three-dimensional display of the intensity distribution at the image point of light of wavelength 1571 mm. Figure 23 B shows the contour of this.
• FIG. 24 is a diagram showing a first example of a conventional light processing apparatus.
• FIG. 25 is a diagram showing a second example of the conventional light processing apparatus. Embodiment of the Invention
• the light processing device according to the present invention is used as an optical demultiplexer or an optical multiplexer, but only the operation as an optical demultiplexer will be described here.
• the present optical processing apparatus is used as an optical multiplexer, only the optical path of light is completely reversed. Therefore, in the following, only the case where the present optical processing apparatus is used as an optical demultiplexer will be described.
• FIG. 1 shows a perspective view of a light processing apparatus 1 according to an embodiment of the present invention
• FIG. 2 is a front view of the light processing apparatus 1
• FIG. 2B is a right side view
• FIG. 2C is a plan view
• FIG. 2D is a left side view (however, the upper and lower sides are opposite to the right side view).
• the present light processing device 1 includes a case 10 configured to have an internal space 11, a light entrance 12 connected to the internal space 11, and a light exit 13, and an internal space of the case 10.
• a collimator 20 consisting of a concave reflecting surface provided in 1 1 and a flat reflecting diffraction surface 3 2 fixed to case 10 and having a plurality of linear diffraction grooves 31 arranged at equal intervals.
• An incident mirror connected to the light entrance 12 of the case 10, and an imaging mirror 40 comprising a concave reflecting surface provided in the internal space 11 of the case 10 It has one input optical fiber 50 as an optical transmission path and a plurality of output optical fibers 60 as an output optical transmission path connected to the light outlet 13 of the case 10. Is configured.
• the left and right direction of the paper surface in FIG. 2A is the left and right (width) direction of case 10
• the vertical direction of the paper surface in FIG. 2B is the vertical direction of case 10
• the left and right direction will be described as the front and back direction of Case 10 (the left side of the sheet is the front and the right side is the rear).
• the X axis is in the horizontal direction of case 10
• the Y axis is in the vertical direction of case 10
• the Z axis is in the front and rear direction of case 10.
• the collimator 20 and the imaging mirror 40 are provided side by side at the rear of the case 10
• the diffraction grooves 31 of the grating 30 are provided extending in the direction in which the collimator 20 and the imaging mirror 40 are aligned, that is, vertically.
• the inner space 11 of the case 10 is in a state of being filled with a transparent solid medium (for example, quartz glass) Tm with high light permeability.
• the front center portion of the case 10 is provided with a wall portion 14 positioned vertically to the Z axis, and the front lower portion of the wall portion 14 is perpendicular to the wall portion 14 (that is, the XZ plane)
• Grating mounting portion 15 extending in parallel to Grating 3 0 is mounted on this grating mounting portion 15 in a posture in which the diffraction grooves 31 extend vertically.
• the reflection diffraction surface 32 is opposed to the wall portion 14 with the air (ie, to the inner space 11 of the case 10).
• the grating 30 is not placed so that the reflection diffraction plane 32 is parallel to the wall portion 14, but as shown in FIG. 2C, the normal GV of the reflection diffraction plane 32 is It is installed so as to be inclined by a certain angle ⁇ with respect to the Z axis (shown by axis ZX in FIG. 2C).
• the wall 14 is provided with an opening 16 having substantially the same size as the projection image of the reflection diffraction surface 32 formed when the reflection diffraction surface 32 of the grating 30 is projected onto the wall 14. It is done.
• the light entrance 12 and the light exit 13 sandwich the grating 30 in the direction in which the diffraction grooves 31 of the grating 30 extend (here, the vertical direction), and the distance from the grating 30 is approximately It is provided to be equidistant.
• the light entrance 12 is above the grating 30 and is opposite to the collimator 20 along the Z-axis direction, and the light exit 13 is below the grating 30 and imaging It is provided at the opposite position along the direction of the Z axis along with the mirror 40.
• One incident optical fiber 50 is attached to the light entrance 12, and the light exit 13 is in the internal space 11 of the case 10 via the incident optical fiber 50 (solid medium
• the number of wavelengths included in the wavelength division multiplexed light to be incident on the quality Tm) in other words, the number of output optical fibers 60 for the number of wavelengths to be split by this wavelength division multiplexer 1 is the case 10 Are aligned and mounted in the width direction (X-axis direction) of the
• the end face of the incident optical fiber 50 is joined to the surface of the solid medium Tm in the internal space 11 in a state of being inserted from the light incident port 12 of the case 10
• each emission optical fiber 60 is joined to the surface of the solid medium Tm in the internal space 11 in a state of being inserted from the light emission port 13 of the case 10
• the emitting part of the solid medium Tm is also inclined as in the receiving part.
• the input optical fiber 50 and the output optical fiber 60 are fixed by an adhesive BD made of a material with a small reflection loss, which is attached to the light entrance 12 or the light exit 13 of the case 10, respectively.
• the bonding surface between the incident optical fiber 50 and the solid medium Tm and the bonding surface between the output optical fiber 60 and the solid medium Tm are filled with a gel agent for refractive index matching. It is also good.
• the gel for refractive index matching is filled in this way, the optical fiber 60 for emission is inserted in the light emission port 13 without being completely fixed to the light emission port 13 of the case 10. It is preferable to be movable by a very small amount in the direction of the central axis CX 2 of the output optical fiber 60. By doing this, it is possible to accurately perform focusing when each light split for each wavelength is incident on the corresponding output optical fiber 60.
• FIG. 1 the optical path of light when light is incident from the incident optical fiber 50 is shown in FIG. 1, FIG. 2A, FIG. 2B, FIG. 2C, FIG. 2D, FIG. 4A, FIG. This will be described using FIGS. 4C and 4D.
• FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D schematically show the components in the case 10 of the present light processing apparatus 1, and the progress of light is shown in FIG. 4A, FIG. 4B, FIG.
• the left figure shows the right side view of the inside of the case 10, and the right figure shows the plan view of the inside of the case 10 (however, in order to make it easy to show the light path of the light, Some are omitted as appropriate).
• This light L 1 is a conical light flux having the light entrance 12 at the top, but it is reflected by the collimator 20 and becomes parallel light, and it travels forward and downward in the solid medium Tm and The light passes through the aperture 16 and further passes through the air layer to reach the reflection diffraction surface 3 2 of the trailing 30 (refer to FIG. 4 B, and this light is L 2.
• the light reaching the reflective diffraction surface 32 of the grating 30 is reflected and diffracted there and splits (splits) into a plurality of light of different wavelengths, passes through the air layer and the opening 16 and is the internal space of the case 10 1 1 and travel backward downward in the solid medium Tm to be incident on the imaging mirror 40.
• This light See Fig. 4 C. Let this light be L 3. Fig. 1, Fig. 2 A, Fig. 2 B, Fig. 2 C, and in FIG. 2D, shown by the optical axis of the chief ray).
• the spectral direction is a direction substantially perpendicular to the direction of the diffraction grooves 3 1.
• the light L 2 incident on the grating 30 is parallel light, but the reflection diffraction surface 32 of the grating 30 is of a type having a flat and linear diffraction groove 31, so The reflected diffracted light L 3 also remains substantially parallel.
• the reflected diffracted light L 3 is one of a plurality of light of different wavelengths generated by being dispersed from the incident light L 1, and a plurality of light of different wavelengths are generated separately from each other. There is.
• the light of each wavelength reflected and dispersed at the grating 30 is parallel light as described above, but is reflected at the imaging mirror 40 to become a conical light flux, and travels forward in the solid medium Tm, Stepwise alignment of the end face of the input optical fiber 50 is formed on the end face of each of the corresponding output light pins 60 (see FIG. 4D, this light is referred to as L 4).
• 2A, 2B, 2C, and 2D (indicated by the optical axis of the chief ray).
• as many optical fibers 60 for emission as the number of light of different wavelengths separated and separated by the grating 30 are provided. There is.
• the wavelength division multiplexed light incident from the incident optical fiber 50 is emitted from the output optical fiber 60 in a state of being demultiplexed for each wavelength.
• the reflection diffraction surface 32 of the grating 30 is a surface diffraction type that diffracts light on the diffraction surface exposed to the air. Regardless of whether the surface is such a surface diffraction type or a back surface reflection type described later, in general, in the case of a grating having a reflection diffraction surface, when light is reflected and diffracted, as shown in FIGS. 5A and 5B. Anamorphosis as shown occurs. That is, as shown in FIG. 5A, the beam width of the beam W1 incident on the grating G and the beam width of the beam W2 after the reflection diffraction action in the grating G are significantly different.
• the cross-sectional shape (the cross-sectional shape perpendicular to the optical axis) of light entering grating G is circular, it will be deformed into an elliptical shape at the image plane as shown in FIG. 5A.
• the beam focusing NA numbererical aperture
• a large coupling loss will occur when the light after reflection diffraction is incident on the optical fiber. It will be.
• the dummy grating is configured to couple light by equal magnification before and after reflection diffraction.
• the light from the optical fiber and the light processing device on the side to which the light is made incident In principle, high coupling efficiency can be obtained when the same side (same material, same diameter) of the optical fiber on the side of emitting light is used.
• the light entrance 12 and the light exit 13 are disposed so as to sandwich the grating 3 0 in the direction in which the diffraction grooves 31 of the grating 30 extend. ing.
• the angle formed by the light flux incident on the grating 30 and the light flux reflected and diffracted in the grating 30 is extremely reduced.
• the deformation of the cross-sectional shape of light before and after reflection diffraction is reduced, and the anamorphic effect generated in grating 30 can be significantly reduced.
• the difference in NA between the incident wavelength division multiplexed light and each light separated for each wavelength after reflection diffraction at the grating 30 becomes extremely small (ie, NA is It is stored at high level), small size, and low loss performance is obtained.
• NA is It is stored at high level
• small size small size
• low loss performance is obtained.
• one of the conventional dielectric multi-layer film dichroic mirror one type and the fiber Bragg grating type usually has four waves. It is possible to simultaneously handle, for example, more wavelength channels such as 16 waves at the same time as a small size, while the degree of demultiplexing and multiplexing is limited.
• the deformation of the image becomes small.
• the mode field image of the end of the optical fiber at the incident side is well reproduced as an image.
• the NA of the optical fiber will be faithfully reproduced.
• the aberration at the image point is corrected well.
• these features have the effect of increasing the coupling efficiency of light energy to the optical fiber more than that of the conventional grating spectroscope system, and when the blaze wavelength range of the grating matches the used wavelength range, There is a possibility that demultiplexing and multiplexing can be realized with low internal loss, which is not possible with any of the above methods.
• the feature of being extremely miniaturized is suitable as an optical component of an optical communication access system where space saving is strongly required.
• the present demultiplexer 1 has an integral structure other than the optical fiber array. As a result, it is also suitable as an optical component for optical communication systems that can realize demultiplexing and multiplexing with excellent mechanical stability.
• the interior space 11 of the case 10 is filled with the solid medium Tm with good light transmittance.
• the transparent medium filled in the internal space 1 1 is a solid, but it may be a liquid (including a gel-like substance) having good light permeability.
• the inner space 11 of case 10 may be a simple cavity. However, in this case, the inside is more preferably in a vacuum state. Further, when the internal space 11 of the case 10 is thus filled with a cavity or liquid, the end face of the light incidence optical fiber 50 and the end face of the light emission optical fiber 60 are the internal space 1 1. It will be in the state of being exposed inside or in the liquid.
• the present light processing apparatus 1 when the internal space 11 is configured to be filled with the transparent solid medium Tm, a collimator 20 and an imaging mirror 4 are used to form the solid medium Tm that has been made into a predetermined shape in advance.
• the solid light medium Tm is covered with a case 10, and the optical fiber 50 for incidence and the optical fiber 60 for emission are attached to the solid medium Tm. Since the processing apparatus 1 can be manufactured, the manufacturing process becomes very simple.
• connection surface between the incident optical fiber 50 and the solid medium Tm, and the connection surface between the output optical fiber 60 and the solid medium Tm all together.
• both connection surfaces be parallel to one another.
• the chief ray of the incident light flux L 1 deviates upward.
• the chief ray of the outgoing light beam L 4 is also shifted downward by the same amount, but here, the inclination in the direction as shown in FIG. 3A and FIG. 3B is provided parallel to the both connection surfaces.
• the mounting position of the incident optical fiber 50 is shifted upward, the light entrance port 12 for light is incident to the incident light due to the above-mentioned inclination.
• the focal point of the imaging mirror 40 be located on (or in the vicinity of) the reflection diffraction surface 32 of the grating 30. If the imaging mirror 40 is arranged in this way, each light flux reflected and diffracted at the reflection diffraction surface 32 of the grating light 30 and separated (split) for each wavelength is a grating. As can be seen from FIG. 6 in which 30 is viewed from above, the principal rays of light of each wavelength become parallel to each other after reflection at the imaging mirror 40 (that is, a telecentric imaging mode is obtained).
• a plurality of emission optical fibers 60 connected to the light emission port 13 of the case 10 are arranged in parallel, and all the angles of the end face cut of each emission optical fiber 60 are the same. If processed in parallel, the imaging rays of light for each wavelength will be incident on the core 61 of the corresponding outgoing optical fiber 60 at approximately equal angles. . Therefore, if the incident angle of the light L 4 for each wavelength reflected by the imaging mirror 40 on the output optical fiber 60 is adjusted to an optimal value, the coupling between the solid medium Tm and the output optical fiber 60 The loss can be reduced to further reduce the overall loss of the optical processing device 1.
• the grating 30 shown in the above embodiment is a surface reflection type grating that performs reflection diffraction on the reflection diffraction surface 32 exposed to the air. If such a surface reflection type grating is used, the temperature change of the refractive index of the medium (not necessarily a solid) occupying the internal space 11 of the case 10 becomes a problem. It becomes effective in the case. That is, in general, a medium made of solid or liquid such as glass has a temperature change of the refractive index that is larger than that of a gas, and when the temperature changes, the refractive index changes. As a result, the diffraction angle may be changed due to the diffraction, which may cause the drift of the image point position.
• image point drift due to temperature change is significantly increased. It can be reduced.
• both the collimator 20 and the imaging mirror 40 are concave reflecting surfaces, but in the present light processing apparatus 1, they are demultiplexed for each wavelength by forming them into a paraboloid shape in particular.
• the coupling loss that occurs when each of the light L 4 is coupled to the corresponding outgoing optical fiber 60 can be reduced to reduce the overall loss of the present demultiplexer multiplexer 1.
• the collimator 20 and the imaging mirror 40 respectively have different portions on the same rotation paraboloid PS, and the rotation paraboloid PS
• the rotation axis PX is parallel to the chief ray of the light L 1 incident on the inner space 11 (in the solid medium Tm) of the case 10 via the incident light fiber 50 and is also rotated.
• the collimator 20 and the imaging mirror 40 are placed so that the focal point PF of the object plane PS is located on (or a position near) the reflective diffraction surface 32 of the grating 30.
• the collimator 20 and the imaging mirror 40 are arranged as described above, the light L 1 incident on the inner space 11 of the case 10 (in the solid medium Tm) through the incident optical fiber 50 is present.
• the chief ray of the light L 2 reflected in the curve 20 reaches the reflection diffraction surface 32 of the grating 30, but the point at which the optical axis of the principal ray of this light L 2 intersects the reflection diffraction surface 32 Is located on the generation rotational axis PX of the paraboloid PS comprising the surface shape of the collimator lens 20 and the imaging mirror 40, and is coincident with the focal point PF of the paraboloid PS (or Almost match).
• the light L 3 reflected and diffracted by the reflection diffraction surface 32 of the grating 30 is the focal point P of the rotation paraboloid PS Since the light is emitted from F, the chief ray of light L 4 reflected by the imaging mirror 40 which is a part of the paraboloid PS is the generation axis of rotation PX of the paraboloid PS and the light L 1 Parallel to the optical axis of the chief ray of the lens (a telecentric imaging mode).
• the rows of the plurality of emitting optical fibers 60 connected to the light emitting port 13 of the case 10 are arranged in parallel, and the end faces of the emitting optical fibers 60 described above If the cut angles are all the same and processed so as to be parallel to each other, (the chief rays of) the imaging rays of light for each wavelength are at approximately the same angle, and the corresponding output optical fibers 60 Since the light is incident on the core 61, if the incident angle of the light L 4 for each wavelength reflected by the imaging mirror 40 on the outgoing optical fiber 60 is adjusted to an optimum value, the solid medium Tm and the outgoing light The coupling loss with the optical fiber 60 can be reduced to further reduce the overall loss of the optical processing apparatus 1.
• the grating 30 is replaced with a simple plane mirror, and its reflection surface is perpendicular to the generation rotation axis PX of the paraboloid surface PS including the surface shapes of the collimator mirror 20 and the imaging mirror 40. If it is installed, it enters the interior space 11 of the case 10 (in the solid medium Tm) through the incident optical fiber 50, passes through the collimator 20, the plane mirror, and the imaging mirror 40, and is used for emission.
• the end face image of the input optical fiber 50 that can be formed at the end face of the optical fiber 60 will be approximately aplanatic imaging, and the geometrical optical aberration will be very small. Even when the grating 30 acts as a grating as in the present optical processing apparatus 1, the tendency remains, so that geometrical optical aberrations are also very small.
• the surface shapes of the collimator lens 20 and the imaging mirror 40 instead of making the surface shapes of the collimator lens 20 and the imaging mirror 40 have a paraboloid surface as described above, the surface shapes of the collimator 20 and the imaging mirror 40 have a toric surface and In this way, the coupling loss generated when coupling each of the light L 4 demultiplexed for each wavelength to the corresponding outgoing optical fiber 60 is reduced, and the present demultiplexer 1 Reduce overall losses Can.
• the toric surface Before starting with the specific description, the toric surface will be described first.
• the plane that passes through the rotation axis AX of the Lick surface is the plane M, the plane perpendicular to the generation axis AX!
• the first type There are two types of circles (the second type of toric surface) where two intersecting circles are obtained when the toric surface itself is cut by the equatorial plane E). .
• Fig. 8A and Fig. 8B the plane that passes through the rotation axis AX of the Lick surface is the plane M, the plane perpendicular to the generation axis AX!
• Fig. 8 A shows an example of the former
• Fig. 8 B shows an example of the latter.
• Both of these types of toric surfaces have two different radiuses of curvature, but the larger radius of curvature is the radius of curvature R t in the tangential (meridional) direction, while the smaller radius of curvature Is the curvature radius R s in the sagittal direction.
• the first type is adopted as the tracking surface including the surface shapes of the collimator 20 and the imaging mirror 40, as shown in FIG.
• One of these collimators 20 and the imaging mirror 40 are selected from among the surfaces M of the toric surface TS, with each 40 being a different part on the same toric surface TS.
• Light enters the inner space 11 of the case 10 (in solid medium Tm) through the incident optical fiber 50 with respect to the optical axis of the chief ray of the light L 1 Parallel to each other, and 2 the focal point RMF in the selected warp plane M l in the inward direction is located on the reflective diffraction plane 32 (or a position near it), and 3 the above selected warp plane M l is ,
• the imaging mirror 140 are different parts on the same one Rick surface TS, respectively, and then these two imaging mirror 20 and the imaging mirror 1 40
• a selected one of the equatorial planes E (referred to as the equatorial plane E 1) is parallel to the optical axis of the chief ray of the light L 1 and 2) the direction in the selected equatorial plane E 1
• the focal point REF is located on (or in the vicinity of) the reflective diffractive surface 32 and 3 the above selected equatorial plane E 1 is parallel to the diffractive groove 31 of the grating 30 including the light L 1. It is placed at a position where it intersects with the plane BS 2 extending in the normal direction in the range of 0 ° to 45 ° (The angle ⁇ 2 shown in Fig. 10 becomes the range of 0 ⁇ 2 ⁇ 45 °).
• the collimator 20 and the imaging mirror 40 are arranged as described above, when the toric surface TS is of the first type, the inner space 1 1 1 of the case 10 through the incident optical fiber 50
• the light L 1 incident on the inside (in the solid medium Tm) is reflected at the collimator 20, and the chief ray of the light L 2 reaches the reflection diffraction surface 32 of the trailing 30, but this light L 2
• the point at which the optical axis of the chief ray intersects the reflection / diffraction surface 32 is the surface of the collimator mirror 20 and the imaging mirror 40.
• the imaging mirror which is a part of the toric surface TS
• the chief ray of the light L 4 reflected at the point L 2 is parallel to the optical axis of the chief ray of the light L 1 (a telecentric imaging mode is obtained).
• the chief ray of the light L 2 reflected at the point reaches the reflection diffraction surface 32 of the grating 30, and the point at which the optical axis of the principal ray of this light L 2 intersects the reflection diffraction surface 32 is
• the imaging mirror 40 comprises the surface shape!
• a single rectilinear surface TS coincides with (or approximately one of) the focal point REF in the selected equatorial plane E 1
• the light L 3 reflected and diffracted by the reflection diffraction surface 32 of the grating 30 becomes light emitted from the focal point REF of the toric surface TS, so the imaging mirror 1 which is a part of the toric surface TS 4
• the chief ray of the light L 4 reflected at 0 is parallel to the optical axis of the chief ray of the light L 1 as in the case where the toric surface TS is of the first type (a telecentric imaging mode).
• a row of a plurality of emission optical fibers 60 connected to the light exit 13 of the case 10 Are arranged in parallel, and if the angles of the end face cut of each of the above-described output optical fibers 60 are all the same and processed so as to be parallel to one another, Since the (principal rays of) light is incident on the core 61 of the corresponding outgoing optical fiber 60 at approximately the same angle, the light L for each wavelength reflected at the imaging mirror 40 By adjusting the incident angle to the output optical fiber 60 of 4 to an optimum value, the coupling loss between the solid medium Tm and the output optical fiber 60 is reduced, and the loss of the present optical processing apparatus 1 as a whole. It is possible to further reduce
• the angle between the optical axis of the chief ray of the light L 1 and the normal of the reflection point on the collimator 20 is 0 If it is 1, the angle between the light axis of the chief ray of the light L 2 and the normal to the reflection point on the collimator 20 is also 0 1, and the light axis of the chief ray of the light L 3 is the imaging mirror 1 Assuming that the reflection point normal on 0 is 0 2, the angle between the optical axis of the chief ray of light L 4 and the reflection point normal on the imaging mirror 40 is 0 2.
• the above 0 1 and S 2 are almost equal. (0 1 ⁇ 6 2), if the angle is set to 0, the angle between the light axis of the chief ray of light L 1 and the light axis of the chief ray of light L 2 is 2 ⁇ .
• the angle between the optical axis of the chief ray and the optical axis of the chief ray of the light L 4 is also 2 ° (see FIGS. 9 and 10).
• the collimator 20 and the imaging mirror 40 are toric surfaces as described above, by satisfying the conditions shown below, light is generated in the collimator 20 and the imaging mirror 40. It is possible to easily suppress geometrical optical aberration caused by reflection. Before entering into the specific description, first, the power of the concave reflecting surface will be described using FIG.
• FIG. 11 shows how a parallel luminous flux is incident and reflected at an angle ⁇ ⁇ ⁇ ⁇ with respect to the normal RpV at the reflection point Rp of the concave toric reflection surface MS.
• the luminous flux L t is a tangential direction (merical) incident component of the concave toric reflecting surface MS of the parallel luminous flux
• s is a sagittal direction incident component of the concave toric reflecting surface MS of the parallel luminous flux.
• this focal length is f
• the distance ⁇ is the distance between the reflection point Rp in FIG. 11 and the focusing point BF of light), and the following equations (1) and (2) should be satisfied.
• the scope of the invention is as follows: It is not limited to what was shown to the above-mentioned embodiment.
• the collimator lens 20 and the imaging mirror 40 are separate members, but they may be integrally formed.
• the surface shape of the collimator 20 and the imaging mirror 40 is a paraboloid or toric surface, fabrication and configuration become very simple.
• the reflection diffraction surface 32 of the grating 30 is opposed to the internal space 11 (solid medium Tm) of the case 10 with air separated, but the reflection diffraction surface It is not necessary that 32 separate air and face the internal space of case 10.
• gratings 30 ' have a plurality of linear diffraction grooves 31' equally spaced. It may have a back surface reflection type in which reflection diffraction surfaces 32 'formed in a row are formed, and the reflection diffraction surfaces 32' are formed in the medium constituting the grating 30 '. .
• the light L 2 reflected in the collimator 20 passes from the solid medium Tm through the material (for example, quartz glass) constituting the grating 30 and reaches the reflection diffraction surface 32 ′, and after reflection diffraction The light again passes through the material constituting the grating 30 and enters the solid medium Tm, and takes an optical path leading to the imaging mirror 40 (at this time, the grating 30 0 is a back reflection type grating).
• 12 is a perspective view of the light processing apparatus 1 'according to such a modification
• FIG. 13A is a front view of the light processing apparatus 1'
• FIG. 13B is a right side view
• FIG. 3C is a plan view
• 13 D is a left side view (however, the upper, lower, left, and right sides of the right side view are reversed). Further, in both the drawings, the same reference numerals are given to the same components as those in the above-described embodiment. Even in the case of the surface reflection type, this can be positioned in the internal space 11 of the case 10 (or in the solid medium Tm that fills the internal space 11). In addition, when the light processing apparatus according to the present invention is used as an optical multiplexer, the light input / output directions are completely reversed.
• the present optical processing apparatus can be used for demultiplexing of wavelength division multiplexed light and multiplexing to wavelength division multiplexed light, but its application is not necessarily limited to demultiplexing of these lights. It is not something to be done.
• Fig. 14 A, Fig. 14 B and Fig. 14 C show an optical processing apparatus according to a first embodiment of the present invention
• Fig. 14 A is a front view of a branching multiplexer. Only the incident light optical fiber 50 and the output optical fiber 60 are shown)
• FIG. 14 B is a right side view
• FIG. 14 C is a plan view.
• the collimator 20 and the imaging mirror 40 are formed from a paraboloid of revolution, and the inside space 11 of the case 10 has the refractive index characteristic described later. Filled with solid medium Tm.
• the grating 30 is a back surface reflection type (corresponding to the light processing device 1 'according to the modification of the above embodiment), and the surface facing the reflection diffraction surface 32' is a wall portion 14 of the case 10
• the solid medium Tm was joined via a through hole (not shown) provided in Also, with the reflection point of the light on the grating 30 as the origin, the ⁇ 2 coordinate system is set as shown in Fig. 14 h, Fig. 14 B and Fig. 14 C. Coordinate data of main specifications, incident points, and image points are shown in Table 1 below.
• Refractive index characteristics with respect to wavelength of solid medium shown in the table of FIG.
• Image point acne shown in the table in Figure 16
• FIG. 17 and Fig. 17B An example of imaging performance at an image point is shown in Fig. 17 and Fig. 17B.
• the figure showing this imaging performance is shown by the three-dimensional display (FIG. 17A) and the contour display (FIG. 17B) of the intensity distribution at the image point of the light of wavelength 1571 mm selected from the above 16 division wavelengths. (In decibels).
• the contour display is shown in 3 dB increments up to 30 dB with O dB at the top.
• the light incident surface and the image surface are planes perpendicular to the generation rotation axis of the paraboloid of revolution.
• FIG. 18A, 18B, 18C and 18D show an optical processing apparatus according to a second embodiment of the present invention
• FIG. 18A is a front view of a demultiplexer (but for incident light).
• 18B shows a right side view
• FIG. 18C shows a plan view
• FIG. 18D shows a left side view (however, the upper side is the reverse of the right side view).
• the collimator 20 and the imaging mirror 40 are formed from a paraboloid of revolution, and the inside space 11 of the case 10 has the same refractive index characteristics as those in the first embodiment. Filled with solid medium Tm.
• the grating 30 is a surface reflection type (corresponding to the light processing device 1 according to the above-described embodiment), and the reflection diffraction surface 32 is positioned to face the solid medium Tm with air separated. Also, with the light reflection point on the dusting 30 as the origin, the ⁇ 2 coordinate system is set as shown in Fig. 18B, Fig. 18B, Fig. 18C, and Fig. 18D. Coordinate data of main specification and incident point, image point Is shown in Table 2 below.
• Demultiplexed wavelength 16 waves as in the first embodiment
• the angle ⁇ 17.5 ° that the normal GY of the reflective diffractive surface makes with the Z axis
• FIG. 2 OA and FIG. 20B An example of imaging performance at an image point is shown in FIG. 2 OA and FIG. 20B.
• the figure showing this imaging performance is shown on the 3D display (Fig. 2 OA) and the contrast display (Fig. 20B) of the intensity distribution at the image point of light of wavelength 1 57 1 mm selected from the demultiplexed wavelength of 16 above. It is shown (in decibels).
• Fig. 20B the contour is displayed with O dB at the top,
• FIG. 21A, 21B, and 21C show an optical processing apparatus according to a third embodiment of the present invention
• FIG. 21A is a front view of a demultiplexer (but incident light).
• 2B is a right side view
• FIG. 2 1C is a plan view.
• the collimator 20 and the imaging mirror 40 are formed from the toric surface of the second type described above, and the inside space 11 of the case 10 is the above-described first inside. It filled with solid medium Tm which has the same refractive index characteristic as an Example.
• the grating 30 is a back surface reflection type (the variation of the above embodiment is The surface facing the reflective diffractive surface 32 'is connected to the solid medium Tm via a through hole (not shown) provided in the wall 14 of the case 10). I did.
• the XYZ coordinate system was set as shown in Fig. 21A, Fig. 21B, and Fig. 21C, with the reflection point of the light on the grating 30 as the origin.
• the main data, incident point, coordinate data of image point, etc. are shown in Table 3 below.
• Demultiplexed wavelength 16 waves as in the first embodiment
• FIGS. 23A and 23B An example of imaging performance at an image point is shown in FIGS. 23A and 23B.
• the figure showing this imaging performance is shown by the three-dimensional display (Fig. 23A) and the con- dition display (Fig. 23B)) of the intensity distribution at the image point of the light of wavelength 1571 mm selected from the 16 demultiplexed wavelengths. (In decibels).
• Fig. 23B the contour is shown with O dB at the top, and in steps of 3 dB up to -30 dB.
• the light incident surface and the image surface Is in a plane substantially perpendicular to the Z axis.
• the wavelength after demultiplexing has a Gaussian beam intensity distribution in which the light intensity at the central portion is significantly higher than the light intensity at the peripheral portion. Also, the aberration is well corrected. From these facts, in the light processing device according to the present invention, the NA is stored at a high level from incidence to emission, and the loss is suppressed to a low level, and it is good while handling multiple wavelengths (16 wavelengths in these examples). It can be seen that it has imaging performance.
• the light entrance and the light exit are provided with the grating interposed in the direction in which the diffraction grooves in the grating extend, incident light flux to the grating is And the angle of reflection of light from the grating and the direction of dispersion of the light after reflection and diffraction can be made extremely small, and the anamorphic effect of the light before and after reflection and diffraction is greatly reduced. Can. For this reason, the difference in NA between the incident wavelength division multiplexed light and each light separated for each wavelength after reflection diffraction in the grating is extremely small (ie, the NA is stored at a high level). The small size, low loss performance can be obtained.
• the dielectric multilayer film dichroic mirror system and the fiber-one Bragg grating system have about four waves of the prior art. It is possible to handle more wavelength channels at the same time, though it is compact, while waves and multiplexing are common.

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• 2002
  • 2002-06-25 JP JP2002184435A patent/JP2004029298A/ja active Pending
• 2003
  • 2003-06-02 WO PCT/JP2003/006927 patent/WO2004001485A1/ja not_active Ceased
  • 2003-06-02 AU AU2003241730A patent/AU2003241730A1/en not_active Abandoned

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