WO2007021041A1 - Variable optical distributors using multi-mode interference - Google Patents
Variable optical distributors using multi-mode interference Download PDFInfo
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- WO2007021041A1 WO2007021041A1 PCT/KR2005/002634 KR2005002634W WO2007021041A1 WO 2007021041 A1 WO2007021041 A1 WO 2007021041A1 KR 2005002634 W KR2005002634 W KR 2005002634W WO 2007021041 A1 WO2007021041 A1 WO 2007021041A1
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- mode waveguide
- optical
- waveguide
- optical signal
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- 230000003287 optical effect Effects 0.000 title claims abstract description 169
- 230000000694 effects Effects 0.000 claims abstract description 18
- 230000005540 biological transmission Effects 0.000 claims abstract description 13
- 230000000737 periodic effect Effects 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 230000003247 decreasing effect Effects 0.000 abstract description 2
- 239000010409 thin film Substances 0.000 abstract description 2
- 241000353097 Molva molva Species 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052691 Erbium Inorganic materials 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Classifications
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- 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
- G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
- G02B6/2808—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using a mixing element which evenly distributes an input signal over a number of outputs
- G02B6/2813—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using a mixing element which evenly distributes an input signal over a number of outputs based on multimode interference effect, i.e. self-imaging
Definitions
- the present invention relates to a variable optical distributors using multi-mode interference.
- a variable optical distributor is one of very important elements of an optical circuit for an optical communication to control an optical signal transmission.
- the variable optical distributor performs an add/drop function to equalize an optical power of channels of a wavelength division multiplexing (WDM) system. Also, when a total power of an erbium doped fiber amplifier (EDFA) is varied, the variable optical distributor flats a gain in order to prevent an output variation according to a wavelength.
- the variable optical distributor is also used to distribute or control an arbitrary optical power to a plurality of transmitting ends.
- the optical distributor As the optical distributor, a fiber optical is widely used. However, the fiber optical distributor is large in size and is complicated in manufacturing process. Therefore, manufacturing yield is low, and a production cost is high. Also, a conventional optical attenuator based on a planar lightwave circuit (PLC) technique (e.g., disclosed in Korean Patent Publication No. 1999-0020073) uses a directional coupler. Thus, the optical attenuator is large in length and wide in width, and is narrow in manufacturing process margin. In addition, since a bent waveguide has to be used at various locations due to the directional coupler, a length of the optical attenuator becomes larger and a loss also becomes larger.
- PLC planar lightwave circuit
- the optical attenuator can be expected to have an improved operation characteristic, production yield, and low cost compared with another conventional optical attenuator (disclosed in Korean Patent No. 0424606 and U.S. Patent No. 6,728,463 B2). Disclosure of Invention
- the present invention is directed to a variable optical distributor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
- An object of the present invention is to provide an optical distributor having a PLC waveguide structure with a multi-mode waveguide, a single-mode waveguide, and a thin film heater for temperature control.
- the optical distributor can distribute an optical power with a desired magnitude by varying a phase of an input optical signal by a multi-mode interference and a thermo-optic effect of the temperature control heater.
- an optical distributor having a strong guiding multi-mode waveguide structure with a predetermined width, a predetermined length, and a predetermined thickness
- the optical distributor including: a first multi-mode waveguide (3) receiving an optical signal at one side thereof, wherein the received optical signal is distributed in one or more self- images at periodic intervals in a proceeding direction, and a predetermined optical power is outputted to the other side of the first multi-mode waveguide (3); one or more transmission lines to which a temperature control heater (6) is attached; and a second multi-mode waveguide (7) receiving the optical signal at one side thereof through the one or more transmission lines, wherein the received optical signal is distributed in one or more self-images at periodic intervals in a proceeding direction, and a predetermined optical power is outputted through the other side of the second multi-mode waveguide (7).
- One or more optical signals are directly inputted to the first multi-mode waveguide
- One or more optical signals are directly outputted from the second multi-mode waveguide (7) or are outputted through a transmission line coupled to the second multi-mode waveguide (7).
- the temperature control heater (6) attached to one or more transmission lines for connecting the first multi-mode waveguide (3) and the second multi-mode waveguide (7) varies phases of the respective optical signals proceeding in the one or more transmission lines to 0-180°by a thermo-optic effect.
- the length (L MMl ), width (W MMl ), and thickness (d) of the first multi-mode waveguide (3) and the input/output position of the optical signal are determined by wavelength ( ⁇ ) of the applied optical signal, refractive index (n) of the waveguide, and general interference. [11] The length (L ), width (W ), and thickness (d) of the first multi-mode
- MMl MMl waveguide (3) and the input/output position of the optical signal are determined by wavelength ( ⁇ ) of the applied optical signal, refractive index (n) of the waveguide, and paired interference.
- ⁇ wavelength of the applied optical signal
- n refractive index
- paired interference paired interference.
- MM2 MM2 waveguide (7) and the input/output position of the optical signal are determined by wavelength ( ⁇ ) of the applied optical signal, refractive index (n) of the waveguide, and general interference.
- ⁇ wavelength of the applied optical signal
- n refractive index
- d thickness
- the optical power distribution can be outputted through a plurality of output terminals.
- a length of the optical distributor according to the present invention becomes short.
- phase variation range due to a thermo-optic effect of a temperature control heater can be decreased.
- Production yield can be improved by extending a manufacturing process margin.
- FIG. 1 is a view illustrating an optical distributor/coupler according to a first embodiment of the present invention
- FIG. 2 is a view illustrating an optical distributor/coupler according to a second embodiment of the present invention
- FIG. 3 is a view illustrating an optical distributor/coupler according to a third embodiment of the present invention
- FIG. 4 is a view illustrating an optical distributor/coupler according a fourth embodiment of the present invention
- FIG. 5 is a view illustrating an optical distributor/coupler according to a fifth embodiment of the present invention.
- ⁇ and ⁇ denote a propagation constant of a standard mode and a propagation constant of a first mode, respectively, ⁇ denotes a wavelength, n denotes
- a first single-mode waveguide 1 and a second single-mode waveguide 2 are directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto.
- the optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached.
- One side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single-mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7.
- the optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7.
- 2, 4, 5, 8 and 9 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W ), thickness (d) and
- the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 and the second single-mode waveguide 2 directly coupled to a width-direction edge of the first multi- mode waveguide 3.
- the optical signal gets to have a phase difference of 270°by a general interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to the width- direction edge of the first multi-mode waveguide 3.
- the temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect.
- the optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index.
- the optical signal having the varied phase is directly coupled to the width-direction edge of the second multi-mode waveguide 7, and the respective input optical signals have a phase difference of 270°by a general interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9 directly coupled to the width-direction edge of the second multi-mode waveguide 7.
- the optical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270° varied by the multi- mode interference are offset or added up.
- a first single- mode waveguide 1 and a second single-mode waveguide 2 are directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto.
- the optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached.
- One side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single-mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7.
- the optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7.
- 2, 4, 5, 8 and 9 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W ), thickness (d) and
- MMl leng & th (L MMl ) of the first multi-mode waveg & uide 3 are determined by J the wavelengbth
- MM2 thickness (d) and length (L MM2 ) of the second multi-mode waveguide 7 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (4) in the case of the paired interference.
- the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 and the second single-mode waveguide 2 directly coupled to a width-direction edge of the first multi- mode waveguide 3.
- the optical signal gets to have a phase difference of 270°by a general interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to the width- direction edge of the first multi-mode waveguide 3.
- the temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect.
- the optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index.
- the optical signal having the varied phase is directly coupled to W /3 and 2W /3 of the width direction of the second multi-mode
- MM2 MM2 waveguide 7 and the respective input optical signals have a phase difference of 270°by a paired interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9 directly coupled to W /3 and 2W MM2 /3 of the width direction of the second multi-mode waveg °uide 7.
- the o r ptical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270°varied by the multi-mode interference are offset or added up. [40] As shown in FIG.
- a first single-mode waveguide 1 is directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto.
- the optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached.
- One side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single- mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7.
- the optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7.
- a predetermined optical power distribution is outputted to the fifth single-mode waveguide 8 and the sixth single- mode waveguide 9.
- SM mode waveguides 1, 4, 5, 8 and 9 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W ),
- MMl thickness (d) and length (L ) of the first multi-mode waveguide 3 are determined by
- the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 directly coupled to W MMl /2 of the width direction of the first multi-mode waveguide 3.
- the o xp-tical sig ⁇ nal gets to have a phase difference of O°by the symmetric interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to W MMl /4 and 3W MMl /4 of the width direction of the first multi-mode waveguide 3.
- the temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect.
- the optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index.
- the optical signal having the varied phase is directly coupled to a width-direction edge of the second multi-mode waveguide 7, and the respective input optical signals have a phase difference of 270°by the general interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9 directly coupled to the width-direction edge of the second multi-mode waveguide 7.
- the optical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270°varied by the multi-mode interference are offset or added up.
- a first single- mode waveguide 1 is directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto.
- the optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached.
- One side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single-mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7.
- the optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7.
- SM mode waveguides 1, 4, 5, 8 and 9 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W MMl ), thickness (d) and length (L MMl ) of the first multi-mode waveguide 3 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (5) in the case of the symmetric interference.
- the width (W MM2 ), thickness (d) and leng °th (L MM2 ) of the second multi-mode waveg °uide 7 are determined by the wavelength ( ⁇ ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (4) in the case of the paired i nterference.
- the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 directly coupled to W MMl /2 of the width direction of the first multi-mode waveguide 3.
- the o xp-tical sig ⁇ nal gets to have a phase difference of O°by the symmetric interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to W /4 and 3W /4 of the width direction of the first
- the temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect.
- the optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index.
- the optical signal having the varied phase is directly coupled to W /3 and 2W /3 of the width direction of the second multi-mode waveguide 7, and the respective input optical signals have a phase difference of 270°by the paired interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single- mode waveguide 9 directly coupled to W /3 and 2W /3 of the width direction of
- the optical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270°varied by the multi-mode interference are offset or added up.
- the optical distributor of the first embodiment is added in series and in parallel to the output terminal of the optical distributor of the first embodiment, so that the optical power can be distributed to a plurality of output terminals.
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Abstract
Provided is an optical distributor using a multi-mode interference and having a strong guiding PLC waveguide structure with a predetermined width and a predetermined length. A multi-mode waveguide and a temperature control heater are attached to a transmission line, and a phase of an input optical signal is varied by a multi-mode interference and a thermo-optic effect of the thin film heater. Thus, the optical signal is distributed at an optical power with a desired magnitude. A manufacturing process margin can be widened and a length of a coupler for obtaining a certain optical power distribution becomes short. Also, a phase variation range due to the temperature control heater can be decreased, thereby reducing power consumption.
Description
Description
VARIABLE OPTICAL DISTRIBUTORS USING MULTI-MODE
INTERFERENCE
Technical Field
[1] The present invention relates to a variable optical distributors using multi-mode interference. Background Art
[2] A variable optical distributor is one of very important elements of an optical circuit for an optical communication to control an optical signal transmission. The variable optical distributor performs an add/drop function to equalize an optical power of channels of a wavelength division multiplexing (WDM) system. Also, when a total power of an erbium doped fiber amplifier (EDFA) is varied, the variable optical distributor flats a gain in order to prevent an output variation according to a wavelength. The variable optical distributor is also used to distribute or control an arbitrary optical power to a plurality of transmitting ends.
[3] As the optical distributor, a fiber optical is widely used. However, the fiber optical distributor is large in size and is complicated in manufacturing process. Therefore, manufacturing yield is low, and a production cost is high. Also, a conventional optical attenuator based on a planar lightwave circuit (PLC) technique (e.g., disclosed in Korean Patent Publication No. 1999-0020073) uses a directional coupler. Thus, the optical attenuator is large in length and wide in width, and is narrow in manufacturing process margin. In addition, since a bent waveguide has to be used at various locations due to the directional coupler, a length of the optical attenuator becomes larger and a loss also becomes larger. Further, the optical attenuator can be expected to have an improved operation characteristic, production yield, and low cost compared with another conventional optical attenuator (disclosed in Korean Patent No. 0424606 and U.S. Patent No. 6,728,463 B2). Disclosure of Invention
Technical Problem
[4] Accordingly, the present invention is directed to a variable optical distributor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
[5] An object of the present invention is to provide an optical distributor having a PLC waveguide structure with a multi-mode waveguide, a single-mode waveguide, and a thin film heater for temperature control. The optical distributor can distribute an optical power with a desired magnitude by varying a phase of an input optical signal by a
multi-mode interference and a thermo-optic effect of the temperature control heater. Technical Solution
[6] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided an optical distributor having a strong guiding multi-mode waveguide structure with a predetermined width, a predetermined length, and a predetermined thickness, the optical distributor including: a first multi-mode waveguide (3) receiving an optical signal at one side thereof, wherein the received optical signal is distributed in one or more self- images at periodic intervals in a proceeding direction, and a predetermined optical power is outputted to the other side of the first multi-mode waveguide (3); one or more transmission lines to which a temperature control heater (6) is attached; and a second multi-mode waveguide (7) receiving the optical signal at one side thereof through the one or more transmission lines, wherein the received optical signal is distributed in one or more self-images at periodic intervals in a proceeding direction, and a predetermined optical power is outputted through the other side of the second multi-mode waveguide (7).
[7] One or more optical signals are directly inputted to the first multi-mode waveguide
(3) or are inputted through a transmission line coupled to the first multi-mode waveguide 3.
[8] One or more optical signals are directly outputted from the second multi-mode waveguide (7) or are outputted through a transmission line coupled to the second multi-mode waveguide (7).
[9] The temperature control heater (6) attached to one or more transmission lines for connecting the first multi-mode waveguide (3) and the second multi-mode waveguide (7) varies phases of the respective optical signals proceeding in the one or more transmission lines to 0-180°by a thermo-optic effect.
[10] The length (L MMl ), width (W MMl ), and thickness (d) of the first multi-mode waveguide (3) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and general interference. [11] The length (L ), width (W ), and thickness (d) of the first multi-mode
MMl MMl waveguide (3) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and paired interference. [12] The length (L ), width (W ), and thickness (d) of the first multi-mode w
MMl MMl aveguide (3) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and
symmetric interference. [13] The length (L ), width(W ), and thickness (d) of the second multi-mode
MM2 MM2 waveguide (7) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and general interference. [14] The length (L ), width (W ), and thickness (d) of the second multi-mode
MM2 MM2 waveguide (7) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and paired interference. [15] By adding a predetermined number of the optical distributors in series and in parallel, the optical power distribution can be outputted through a plurality of output terminals.
Advantageous Effects
[16] A length of the optical distributor according to the present invention becomes short.
In addition, a phase variation range due to a thermo-optic effect of a temperature control heater can be decreased. Production yield can be improved by extending a manufacturing process margin.
Brief Description of the Drawings [17] FIG. 1 is a view illustrating an optical distributor/coupler according to a first embodiment of the present invention; [18] FIG. 2 is a view illustrating an optical distributor/coupler according to a second embodiment of the present invention; [19] FIG. 3 is a view illustrating an optical distributor/coupler according to a third embodiment of the present invention; [20] FIG. 4 is a view illustrating an optical distributor/coupler according a fourth embodiment of the present invention; and [21] FIG. 5 is a view illustrating an optical distributor/coupler according to a fifth embodiment of the present invention.
Best Mode for Carrying Out the Invention [22] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to accompanying drawings. [23] When an optical signal is input to a multi-mode waveguide and proceeds, the optical signal is distributed, and an image of a wave excited in an input optical signal is reproduced in a predetermined length by a constructive interference between modes.
This is an inherent characteristic of light called a self-image formation, and is a phenomenon that one or more images are periodically formed along a proceed direction of the waveguide. A basic principle of this self-image formation is described
in J. Lightwave Technol., vol. 13, p. 615, 1995. The optical wave distribution within the multi-mode waveguide can be expressed as Equation (1): [24] MathFigure 1 m- \
[25] where ψ denotes an excited mode, and v denotes order of mode.
[26] When the input position of the optical signal is located at a general location of the multi-mode waveguide, the length that a desired number of self-images are formed is given by Equation (2): [27] MathFigure 2
[28] where M is an integer representing period, N denotes the number of self-images, and L denotes a beat length and is obtained by Equation (3): [29] MathFigure 3
[30] where β and β denote a propagation constant of a standard mode and a propagation constant of a first mode, respectively, λ denotes a wavelength, n denotes
0 e an effective refractive index, and W denotes a substantial width of the standard mode. e
In case that I/O terminals are located at a W/3 position or a 2W/3 position of the multi- mode waveguide, when a paired interference is used, and a length that a desired number of the self-images are formed is obtained by Equation (4): [31] MathFigure 4
L = L.
[32] When the I/O terminals are located at a W/2 position of the multi-mode waveguide, a symmetric interference is used, a length that a desired number of self-images are formed is obtained by Equation (5):
[33] MathFigure 5
[35] The widths (W SM ) and thickness (d) of the first to sixth single-mode waveguides 1,
2, 4, 5, 8 and 9 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W ), thickness (d) and
MMl length (L ) of the first multi-mode waveguide 3 and the width (W ), thickness (d)
MMl MM2 and length (L ) of the second multi-mode waveguide 7 are determined by the
& MM2 & J wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (3) in the case of the general interference. [36] In the case of the general interference, the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 and the second single-mode waveguide 2 directly coupled to a width-direction edge of the first multi- mode waveguide 3. The optical signal gets to have a phase difference of 270°by a general interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to the width- direction edge of the first multi-mode waveguide 3. The temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect. The optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index. The optical signal having the varied phase is directly
coupled to the width-direction edge of the second multi-mode waveguide 7, and the respective input optical signals have a phase difference of 270°by a general interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9 directly coupled to the width-direction edge of the second multi-mode waveguide 7. The optical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270° varied by the multi- mode interference are offset or added up.
[37] As shown in FIG. 2, in an optical distributor having a strong guiding waveguide structure according to a second embodiment of the present invention, a first single- mode waveguide 1 and a second single-mode waveguide 2 are directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto. The optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached. One side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single-mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7. The optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7. By the combination of the phases of the optical signals varied due to the phase variation of the input optical signal at the first multi-mode waveguide 3 and the second multi-mode waveguide 7 and the thermo- optic effect at the third single-mode waveguide 4 and the fourth single-mode waveguide 5, a predetermined optical power distribution is outputted to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9.
[38] The widths (W ) and thickness (d) of the first to sixth single-mode waveguides 1,
SM
2, 4, 5, 8 and 9 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W ), thickness (d) and
MMl leng &th (L MMl ) of the first multi-mode waveg &uide 3 are determined by J the wavelengbth
(K) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (3) in the case of the general interference. The width (W ),
MM2 thickness (d) and length (L MM2 ) of the second multi-mode waveguide 7 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (4) in the case of the paired interference. [39] In the case of the general interference, the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 and the second
single-mode waveguide 2 directly coupled to a width-direction edge of the first multi- mode waveguide 3. The optical signal gets to have a phase difference of 270°by a general interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to the width- direction edge of the first multi-mode waveguide 3. The temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect. The optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index. The optical signal having the varied phase is directly coupled to W /3 and 2W /3 of the width direction of the second multi-mode
MM2 MM2 waveguide 7, and the respective input optical signals have a phase difference of 270°by a paired interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9 directly coupled to W /3 and 2W MM2 /3 of the width direction of the second multi-mode waveg °uide 7. The o rptical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270°varied by the multi-mode interference are offset or added up. [40] As shown in FIG. 3, in an optical distributor having a strong guiding waveguide structure according to a third embodiment of the present invention, a first single-mode waveguide 1 is directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto. The optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached. One side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single- mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7. The optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7. By the combination of the phases of the optical signals varied due to the phase variation of the input optical signal at the first multi-mode waveguide 3 and the second multi-mode waveguide 7 and the thermo-optic effect at the third single-mode waveguide 4 and the fourth single-mode waveguide 5, a predetermined optical power distribution is outputted to the fifth single-mode waveguide 8 and the sixth single- mode waveguide 9.
[41] The widths (W ) and thickness (d) of the first, third, fourth, fifth and sixth single-
SM mode waveguides 1, 4, 5, 8 and 9 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W ),
MMl thickness (d) and length (L ) of the first multi-mode waveguide 3 are determined by
MMl the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (5) in the case of the symmetric interference. The width (W MM2 ), thickness (d) and leng σth (vL MM2 )/ of the second multi-mode waveg σuide 7 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (3) in the case of the general interference. [42] In the case of the symmetric interference, the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 directly coupled to W MMl /2 of the width direction of the first multi-mode waveguide 3. The o xp-tical sigσnal gets to have a phase difference of O°by the symmetric interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to W MMl /4 and 3W MMl /4 of the width direction of the first multi-mode waveguide 3. The temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect. The optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index. The optical signal having the varied phase is directly coupled to a width-direction edge of the second multi-mode waveguide 7, and the respective input optical signals have a phase difference of 270°by the general interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-mode waveguide 9 directly coupled to the width-direction edge of the second multi-mode waveguide 7. The optical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270°varied by the multi-mode interference are offset or added up. [43] As shown in FIG. 4, in an optical distributor having a strong guiding waveguide structure according to a fourth embodiment of the present invention, a first single- mode waveguide 1 is directly coupled to one side of a first multi-mode waveguide 3 and an optical signal is inputted thereto. The optical signal is distributed to one side of a third single-mode waveguide 4 to which a temperature control heater 6 directly coupled to the other side of the first multi-mode waveguide 3 is attached and a fourth single-mode waveguide 5 to which the temperature control heater 6 is attached. One
side of the second multi-mode waveguide 7 is directly coupled to the other side of the third single-mode waveguide 4 and the fourth single-mode waveguide 5, so that the distributed optical signal is inputted to the second multi-mode waveguide 7. The optical signal is distributed to one side of a fifth single-mode waveguide 8 and a sixth single-mode waveguide 9 directly coupled to the other side of the second multi-mode waveguide 7. By the combination of the phases of the optical signals varied due to the phase variation of the input optical signal at the first multi-mode waveguide 3 and the second multi-mode waveguide 7 and the thermo-optic effect at the third single-mode waveguide 4 and the fourth single-mode waveguide 5, a predetermined optical power distribution is outputted to the fifth single-mode waveguide 8 and the sixth single- mode waveguide 9. [44] The widths (W ) and thickness (d) of the first, third, fourth, fifth and sixth single-
SM mode waveguides 1, 4, 5, 8 and 9 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide. Also, the width (W MMl ), thickness (d) and length (L MMl ) of the first multi-mode waveguide 3 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (5) in the case of the symmetric interference. The width (W MM2 ), thickness (d) and leng °th (L MM2 ) of the second multi-mode waveg °uide 7 are determined by the wavelength (λ) of the applied optical signal and the refractive index (n) of the waveguide and by Equations (2) and (4) in the case of the paired i nterference. [45] In the case of the symmetric interference, the optical signal is inputted to the first multi-mode waveguide 3 through the first single-mode waveguide 1 directly coupled to W MMl /2 of the width direction of the first multi-mode waveguide 3. The o xp-tical sigσnal gets to have a phase difference of O°by the symmetric interference while proceeding in the first multi-mode waveguide 3 and are distributed in a rate of 50:50 and then are transferred to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 directly coupled to W /4 and 3W /4 of the width direction of the first
MMl MMl multi-mode waveguide 3. The temperature control heater 6 is attached to the third single-mode waveguide 4 and the fourth single-mode waveguide 5 so as to vary an effective refractive index by a thermo-optic effect. The optical signal proceeding in the third single-mode waveguide 4 and the fourth single-mode waveguide 5 has a predetermined phase variation of 0°to 180°due to the varied effective refractive index. The optical signal having the varied phase is directly coupled to W /3 and 2W /3 of the width direction of the second multi-mode waveguide 7, and the respective input optical signals have a phase difference of 270°by the paired interference while proceeding in the second multi-mode waveguide 7 and are distributed in a rate of 50:50 and then are transferred to the fifth single-mode waveguide 8 and the sixth single-
mode waveguide 9 directly coupled to W /3 and 2W /3 of the width direction of
MM2 MM2 the second multi-mode waveguide 7. The optical signals that are transferred to the output terminal make a desired optical power distribution in such a manner that the phase of 0°to 180°varied by the thermo-optic effect and a phase of 270°varied by the multi-mode interference are offset or added up.
[46] As shown in FIG. 5, in an optical distributor according to a fifth embodiment of the present invention, the optical distributor of the first embodiment is added in series and in parallel to the output terminal of the optical distributor of the first embodiment, so that the optical power can be distributed to a plurality of output terminals.
[47] While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.
Claims
[1] An optical distributor having a strong guiding multi-mode waveguide structure with a predetermined width, a predetermined length, and a predetermined thickness, comprising: a first multi-mode waveguide (3) receiving an optical signal at one side thereof, wherein the received optical signal is distributed in one or more self-images at periodic intervals in a proceeding direction, and a predetermined optical power is outputted to the other side of the first multi-mode waveguide (3); one or more transmission lines to which a temperature control heater (6) is attached; and a second multi-mode waveguide (7) receiving the optical signal at one side thereof through the one or more transmission lines, wherein the received optical signal is distributed in one or more self-images at periodic intervals in a proceeding direction, and a predetermined optical power is outputted through the other side of the second multi-mode waveguide (7).
[2] The optical distributor of claim 1, wherein a predetermined number of the optical distributors are added in series and in parallel.
[3] The optical distributor of claim 1, wherein one or more optical signals are directly inputted to the first multi-mode waveguide (3) or are inputted through a transmission line coupled to the first multi-mode waveguide 3.
[4] The optical distributor of claim 1, wherein one or more optical signals are directly outputted from the second multi-mode waveguide (7) or are outputted through a transmission line coupled to the second multi-mode waveguide (7).
[5] The optical distributor of claim 1, wherein the temperature control heater (6) attached to one or more transmission lines for connecting the first multi-mode waveguide (3) and the second multi-mode waveguide (7) varies phases of the respective optical signals proceeding in the one or more transmission lines to 0-180°by a thermo-optic effect.
[6] The optical distributor of any one of claims 1 to 5, wherein the length, width, and thickness of the first multi-mode waveguide (3) or the second multi-mode waveguide (7) and input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and interference on the waveguide.
[7] The optical distributor of claim 6, wherein the length (L ), width(W ), and
MMl MMl thickness (d) of the first multi-mode waveguide (3) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and general interference.
[8] The optical distributor of claim 6, wherein the length (L ), width(W ), and thickness (d) of the first multi-mode waveguide (3) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and paired interference.
[9] The optical distributor of claim 6, wherein the length (L ), width(W ), and thickness (d) of the first multi-mode waveguide (3) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and symmetric interference.
[10] The optical distributor of claim 6, wherein the length (L ), width(W ), and thickness (d) of the second multi-mode waveguide (7) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and general interference. [11] The optical distributor of claim 6, wherein the length (L ), width(W ), and thickness (d) of the second multi-mode waveguide (7) and the input/output position of the optical signal are determined by wavelength (λ) of the applied optical signal, refractive index (n) of the waveguide, and paired interference.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/KR2005/002634 WO2007021041A1 (en) | 2005-08-12 | 2005-08-12 | Variable optical distributors using multi-mode interference |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/KR2005/002634 WO2007021041A1 (en) | 2005-08-12 | 2005-08-12 | Variable optical distributors using multi-mode interference |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2007021041A1 true WO2007021041A1 (en) | 2007-02-22 |
Family
ID=37757684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2005/002634 WO2007021041A1 (en) | 2005-08-12 | 2005-08-12 | Variable optical distributors using multi-mode interference |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2007021041A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017116735A1 (en) * | 2015-12-31 | 2017-07-06 | Alcatel-Lucent Usa Inc. | Photonic integrated circuit using chip integration |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000241644A (en) * | 1998-12-22 | 2000-09-08 | Nippon Telegr & Teleph Corp <Ntt> | Multi-mode interference optical coupler |
| US6631223B2 (en) * | 2000-03-03 | 2003-10-07 | Hitachi Cable, Ltd. | Optical multiplexer/demultiplexer |
-
2005
- 2005-08-12 WO PCT/KR2005/002634 patent/WO2007021041A1/en active Application Filing
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000241644A (en) * | 1998-12-22 | 2000-09-08 | Nippon Telegr & Teleph Corp <Ntt> | Multi-mode interference optical coupler |
| US6631223B2 (en) * | 2000-03-03 | 2003-10-07 | Hitachi Cable, Ltd. | Optical multiplexer/demultiplexer |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017116735A1 (en) * | 2015-12-31 | 2017-07-06 | Alcatel-Lucent Usa Inc. | Photonic integrated circuit using chip integration |
| US9762334B2 (en) | 2015-12-31 | 2017-09-12 | Alcatel-Lucent Usa Inc. | Photonic integrated circuit using chip integration |
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