WO2003016957A2 - Index tuned multimode interference coupler - Google Patents

Index tuned multimode interference coupler Download PDF

Info

Publication number
WO2003016957A2
WO2003016957A2 PCT/US2002/025099 US0225099W WO03016957A2 WO 2003016957 A2 WO2003016957 A2 WO 2003016957A2 US 0225099 W US0225099 W US 0225099W WO 03016957 A2 WO03016957 A2 WO 03016957A2
Authority
WO
WIPO (PCT)
Prior art keywords
index
multimode interference
interference coupler
refraction
coupler
Prior art date
Application number
PCT/US2002/025099
Other languages
French (fr)
Other versions
WO2003016957A3 (en
Inventor
Srinath Kalluri
Timothy A. Vang
David C. Scott
Original Assignee
Srinath Kalluri
Vang Timothy A
Scott David C
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Srinath Kalluri, Vang Timothy A, Scott David C filed Critical Srinath Kalluri
Priority to AU2002326560A priority Critical patent/AU2002326560A1/en
Publication of WO2003016957A2 publication Critical patent/WO2003016957A2/en
Publication of WO2003016957A3 publication Critical patent/WO2003016957A3/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12083—Constructional arrangements
    • G02B2006/12097—Ridge, rib or the like
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/217—Multimode interference type

Definitions

  • This invention relates to optical couplers.
  • the present invention relates to ultimode interference couplers.
  • MMI couplers and splitters are important devices in integrated optical circuits, such as those used in fiber optic communication systems.
  • MMI couplers can be built in a variety of material systems including SOI, semiconductors, LiNb0 3 , and polymers.
  • MMI couplers are important because they can accomplish various functions such as lxN and Nxl optical splitting and combining and be integrated with other optical devices, such as modulators, semiconductor lasers, optical amplifiers, or other optoelectronic circuits.
  • NxM MMI couplers (where N and M are the number of input and output ports, respectively) are used for many different types of photonic circuits.
  • the 1x2 MMI coupler is particularly useful when used at the input of an integrated waveguide Mach-Zehnder modulator or optical switch because light is always evenly split between the two output channels.
  • MMI based NxM optical splitters or combiners described in the prior art are difficult to manufacture reliably. This is particularly true for the high port count devices where the performance of the device depends critically on the precise control of the coupler's geometry. MMI coupler performance is extremely sensitive to width variations, which can increase the insertion loss.
  • MMI couplers can be very sensitive to reflections when used as 2x1 power combiners in Mach-Zehnder modulators. This is particularly an issue for MMI couplers of non-optimum length.
  • the solution to variations in width has been to fabricate several MMI coupler designs of varying geometry.
  • the MMI coupler designs have widths and lengths that have been varied around a nominal value in the hope that at least one device will have the desired performance.
  • the problem with this solution is that the non-optimum devices will not be used. This is a very inefficient and costly solution.
  • a further object of the invention is to provide a new and improved multimode interference coupler which has an improved throughput.
  • a further object of the invention is to provide a new and improved multimode interference coupler which has electrodes that can provide positive feedback and actively control the insertion loss at the output.
  • an index tuned MMI coupler is disclosed.
  • the index can be tuned by several different methods.
  • the MMI coupler consists of a pin diode structure that acts as a waveguide and is positioned between electrodes. The electrodes allow an electric field to be created within the pin diode structure so that the index of refraction can be controllably varied in the multimode region.
  • the substrate material is n-type doped InP.
  • a subsequent InGaAsP quantum well structure is epitaxially grown on the InP substrate.
  • a p- type doped InP layer is then epitaxially grown on the InGaAsP quantum well structures.
  • the InP layer is then etched so as to form a multi-mode waveguide cavity to guide the light signal. The width of this waveguide cavity defines the width W of the multimode region.
  • Narrower access waveguides are similarly defined at the input to couple light into the multimode region and at the output to couple light out.
  • the substrate is subsequently lapped on the backside.
  • ohmic metal contacts to the p-type doped InP and n-type doped InP layers of the multimode region are defined.
  • the metal contacts are not required over the access waveguides since the index of these waveguides need not be varied.
  • the n-type doped InP substrate, the InGaAsP quantum well's, and the p-type doped InP. region form a pin diode structure.
  • the index of refraction of the MMI coupler material By varying the index of refraction of the MMI coupler material, the effective length and width of the MMI coupler device can be controlled and the insertion loss can be minimized. This is important because the performance of an MMI coupler is extremely sensitive to the geometry of the device. Also, the device performance can be actively tuned and the throughput increased. In the prior art, variations in the device geometry caused the need to fabricate many devices. These devices would be tested until one was found that had the desired performance. This process is expensive and inefficient because many devices were being fabricated and tested and then were never used in actual applications.
  • FIG. 1 is a top plan view of an index tuned 1x2 multimode interference coupler in accordance with the present invention.
  • FIG. 2 is a sectional view as seen from the line 2-2 of FIG. 1.
  • Index tuned 1x2 multimode interference coupler 5 contains an input optical light path 30 for receiving incident light.
  • input optical light path 30 is connected to index tuned MMI waveguide 20.
  • Index tuned MMI waveguide 20 acts as a power splitter that evenly distributes the optical power between an optical light path 40 and an optical light path
  • Index tuned MMI waveguide 20 receives an incident light signal from input optical light path 30 and splits the incident light signal into two equal light signals. The split light signals are then evenly outputted through optical light path 40 and optical light path 50.
  • the device illustrated in FIG. 1 is a 1x2 index tuned MMI coupler. However, a 2x1 index tuned MMI coupler or in general an NxM index tuned MMI coupler can also be fabricated in order to distribute light signals.
  • FIG. 2 illustrates a simplified sectional view of an index tuned multimode interference coupler 10 as seen from Line 2-2 of FIG. 1.
  • Index tuned multimode interference coupler 10 consists of an n-type doped substrate 80. It will be understood that in this preferred embodiment, the n-type doped substrate includes InP, but it could include any material that is compatible with layers subsequently grown or deposited thereon.
  • An intrinsic region 90 which in this preferred embodiment includes neutrally doped InGaAsP quantum wells, is epitaxially grown on the n-type doped substrate 80. It will be understood that the intrinsic region 90 can include other material structures, such as quantum dots, or other structures known to those skilled in the art. A p-type doped region 100 is then epitaxially grown on intrinsic region 90. It will be understood that p-type doped region 100 used in this preferred embodiment includes a layer of InP. However, this region could include another material system compatible with the other layers and can also include other material structures, such as quantum wells, quantum dots, or other material structures known to those skilled in the art. Also, it will be understood that the use of the word "intrinsic" indicates that intrinsic region 90 is less conductive when compared to n-type doped substrate 80 and p-type doped region 100.
  • P-type doped region 100 used in the preferred embodiment is etched so as to form a ridge of width W and provides lateral confinement for the optical path.
  • the films are epitaxially grown using MOCVD, but it will be understood that there are many other growth methods, such as MBE, that can be used to epitaxially grow the regions. These different growth methods are well known to those skilled in the art.
  • n-type doped substrate 80 is lapped.
  • a p- type doped electrode 70 is formed on p-type doped region 100 to form a p-type ohmic contact and an n-type doped electrode 60 is formed on n-type doped substrate 80 to form an n-type ohmic contact.
  • p-type doped electrode 70 and n-type doped electrode 60 are formed from materials and by fabrication techniques well known to those skilled in the art. Also, p-type doped region 100, intrinsic region 90, and n-type doped substrate 80 are made to form a pin diode structure whose function is well known to those skilled in the art.
  • n-type doped electrode 60 and p-type doped electrode 70 allow the application of an electric field across a pin region 110 so that the index of refraction of this region can be actively tuned.
  • the index of refraction of pin region 110 can be actively tuned by other means, such as by using a resistive electrode heater that allows the index of refraction to be changed by using thermal effects and that the use . of an electric field in this preferred embodiment is only for illustrative purposes.
  • the index of refraction of pin region 110 can be actively tuned by injecting a current into this region and changing the index of refraction via the free carrier effect. However, this current injection technique increases the insertion loss of the device.
  • the multimode interference coupler is sandwiched between two electrodes. These electrodes can be used to apply a small DC voltage across the MMI region to tune its effective index slightly and thus compensate for manufacturing errors in it's width. Finally, these electrodes can also be used to provide a feedback signal to actively stabilize the contrast ratio and insertion loss in the MZ modulator. Tuning the index of refraction changes the effective width of the MMI coupler. Index tuning can be most easily achieved in electro-optic materials via the Pockels effect described in Equation 1:
  • n the refractive index of the material
  • r e ff the effective electro-optic coefficient
  • V the DC voltage applied across the electrodes
  • d the separation between the electrodes.
  • III-V semiconductors such as GaAs and InP
  • dielectric materials such as nonlinear polymers and LiNb0 3 .
  • the index tuned MMI coupler can be implemented in any of these material systems.
  • Actively tuning the index of refraction of pin region 110 improves the overall device yield and reduces the cost when compared to alternate designs and methods.
  • the advantage of this method is a lower insertion loss when compared to alternate techniques such as Y branch splitters and combiners.
  • a low insertion loss is particularly important for MMI couplers used in Mach- Zehnder modulators since these devices require high throughputs.
  • the conventional MMI coupler's sensitivity to width variations places stringent requirements on the dimensions of the multimode waveguide region. This is a difficulty for the reliable and low cost manufacturing of these devices. It is known to those skilled in the art that the width of the multimode waveguide region must be controlled to within 0.3 ⁇ m in an InP MMI coupler design to keep the insertion losses within acceptable limits.
  • 2x1 MMI combiners of non- optimum widths and lengths are known to be sensitive to reflections. By tuning the index of refraction, these tolerances are relaxed.

Abstract

Index tuned multimode interference coupler epitaxially grown on an n-type doped substrate. The index tuned multimode interference coupler includes an intrinsic region epitaxially grown on the substrate and a p-type doped region grown on the insulating region. The semiconductor regions are formed so as to act as a pin diode. Ohmic contacts are formed on the p-type doped region and the n-type doped substrate. The ohmic contacts allow the application of an electric field so that the index of refraction of the pin diode can be tuned. This allows the active control of the device performance.

Description

INDEX TUNED MULTIMODE INTERFERENCE COUPLER
TECHNICAL FIELD This invention relates to optical couplers.
More particularly, the present invention relates to ultimode interference couplers.
BACKGROUND ART Multimode interference (hereinafter referred to as "MMI") couplers and splitters are important devices in integrated optical circuits, such as those used in fiber optic communication systems. MMI couplers can be built in a variety of material systems including SOI, semiconductors, LiNb03, and polymers. MMI couplers are important because they can accomplish various functions such as lxN and Nxl optical splitting and combining and be integrated with other optical devices, such as modulators, semiconductor lasers, optical amplifiers, or other optoelectronic circuits.
NxM MMI couplers (where N and M are the number of input and output ports, respectively) are used for many different types of photonic circuits. For example, the 1x2 MMI coupler is particularly useful when used at the input of an integrated waveguide Mach-Zehnder modulator or optical switch because light is always evenly split between the two output channels.
The problem with MMI based NxM optical splitters or combiners described in the prior art is that they are difficult to manufacture reliably. This is particularly true for the high port count devices where the performance of the device depends critically on the precise control of the coupler's geometry. MMI coupler performance is extremely sensitive to width variations, which can increase the insertion loss.
Also, MMI couplers can be very sensitive to reflections when used as 2x1 power combiners in Mach-Zehnder modulators. This is particularly an issue for MMI couplers of non-optimum length. The MMI coupler's sensitivity to width variations, and the difficulty in manufacturing MMI couplers to precise widths, particularly in the III-V material systems, implies that the length of the fabricated MMI coupler is often not optimum. In the prior art, the solution to variations in width has been to fabricate several MMI coupler designs of varying geometry.
The MMI coupler designs have widths and lengths that have been varied around a nominal value in the hope that at least one device will have the desired performance. The problem with this solution is that the non-optimum devices will not be used. This is a very inefficient and costly solution.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide a new and improved multimode interference coupler. It is another object of the present invention to provide a new and improved multimode interference coupler which has a smaller insertion loss.
It is another object of the present invention to provide a new and improved multimode interference coupler which allows the device performance to be actively tuned.
A further object of the invention is to provide a new and improved multimode interference coupler which has an improved throughput. A further object of the invention is to provide a new and improved multimode interference coupler which has electrodes that can provide positive feedback and actively control the insertion loss at the output.
DISCLOSURE OF THE INVENTION To achieve the objects and advantages specified above and others, an index tuned MMI coupler is disclosed. The index can be tuned by several different methods. In the preferred embodiment, the MMI coupler consists of a pin diode structure that acts as a waveguide and is positioned between electrodes. The electrodes allow an electric field to be created within the pin diode structure so that the index of refraction can be controllably varied in the multimode region.
In a preferred embodiment, the substrate material is n-type doped InP. A subsequent InGaAsP quantum well structure is epitaxially grown on the InP substrate. A p- type doped InP layer is then epitaxially grown on the InGaAsP quantum well structures. The InP layer is then etched so as to form a multi-mode waveguide cavity to guide the light signal. The width of this waveguide cavity defines the width W of the multimode region. Narrower access waveguides are similarly defined at the input to couple light into the multimode region and at the output to couple light out. The substrate is subsequently lapped on the backside. Finally, ohmic metal contacts to the p-type doped InP and n-type doped InP layers of the multimode region are defined. The metal contacts are not required over the access waveguides since the index of these waveguides need not be varied. The n-type doped InP substrate, the InGaAsP quantum well's, and the p-type doped InP. region form a pin diode structure. By varying the index of refraction of the MMI coupler material, the effective length and width of the MMI coupler device can be controlled and the insertion loss can be minimized. This is important because the performance of an MMI coupler is extremely sensitive to the geometry of the device. Also, the device performance can be actively tuned and the throughput increased. In the prior art, variations in the device geometry caused the need to fabricate many devices. These devices would be tested until one was found that had the desired performance. This process is expensive and inefficient because many devices were being fabricated and tested and then were never used in actual applications.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and further and more specific objects and advantages of the instant invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof taken in conjunction with the following drawings:
FIG. 1 is a top plan view of an index tuned 1x2 multimode interference coupler in accordance with the present invention; and
FIG. 2 is a sectional view as seen from the line 2-2 of FIG. 1.
BEST MODES FOR CARRYING OUT THE INVENTION Turn now to FIG. 1 in which a top plan view of an index tuned 1x2 multimode interference coupler 5 is illustrated. Index tuned 1x2 multimode interference coupler 5 contains an input optical light path 30 for receiving incident light. In the preferred embodiment, input optical light path 30 is connected to index tuned MMI waveguide 20. Index tuned MMI waveguide 20 acts as a power splitter that evenly distributes the optical power between an optical light path 40 and an optical light path
50. The ability to evenly split an optical signal is an important property of this device. Index tuned MMI waveguide 20 receives an incident light signal from input optical light path 30 and splits the incident light signal into two equal light signals. The split light signals are then evenly outputted through optical light path 40 and optical light path 50. The device illustrated in FIG. 1 is a 1x2 index tuned MMI coupler. However, a 2x1 index tuned MMI coupler or in general an NxM index tuned MMI coupler can also be fabricated in order to distribute light signals. Turn now to FIG. 2, which illustrates a simplified sectional view of an index tuned multimode interference coupler 10 as seen from Line 2-2 of FIG. 1. Index tuned multimode interference coupler 10 consists of an n-type doped substrate 80. It will be understood that in this preferred embodiment, the n-type doped substrate includes InP, but it could include any material that is compatible with layers subsequently grown or deposited thereon.
An intrinsic region 90, which in this preferred embodiment includes neutrally doped InGaAsP quantum wells, is epitaxially grown on the n-type doped substrate 80. It will be understood that the intrinsic region 90 can include other material structures, such as quantum dots, or other structures known to those skilled in the art. A p-type doped region 100 is then epitaxially grown on intrinsic region 90. It will be understood that p-type doped region 100 used in this preferred embodiment includes a layer of InP. However, this region could include another material system compatible with the other layers and can also include other material structures, such as quantum wells, quantum dots, or other material structures known to those skilled in the art. Also, it will be understood that the use of the word "intrinsic" indicates that intrinsic region 90 is less conductive when compared to n-type doped substrate 80 and p-type doped region 100.
P-type doped region 100 used in the preferred embodiment is etched so as to form a ridge of width W and provides lateral confinement for the optical path. In this illustration, the films are epitaxially grown using MOCVD, but it will be understood that there are many other growth methods, such as MBE, that can be used to epitaxially grow the regions. These different growth methods are well known to those skilled in the art. Finally, n-type doped substrate 80 is lapped. A p- type doped electrode 70 is formed on p-type doped region 100 to form a p-type ohmic contact and an n-type doped electrode 60 is formed on n-type doped substrate 80 to form an n-type ohmic contact. It will be understood that p-type doped electrode 70 and n-type doped electrode 60 are formed from materials and by fabrication techniques well known to those skilled in the art. Also, p-type doped region 100, intrinsic region 90, and n-type doped substrate 80 are made to form a pin diode structure whose function is well known to those skilled in the art.
In this preferred embodiment, n-type doped electrode 60 and p-type doped electrode 70 allow the application of an electric field across a pin region 110 so that the index of refraction of this region can be actively tuned. It will be understood that the index of refraction of pin region 110 can be actively tuned by other means, such as by using a resistive electrode heater that allows the index of refraction to be changed by using thermal effects and that the use . of an electric field in this preferred embodiment is only for illustrative purposes. Also, the index of refraction of pin region 110 can be actively tuned by injecting a current into this region and changing the index of refraction via the free carrier effect. However, this current injection technique increases the insertion loss of the device.
In our structure, the multimode interference coupler is sandwiched between two electrodes. These electrodes can be used to apply a small DC voltage across the MMI region to tune its effective index slightly and thus compensate for manufacturing errors in it's width. Finally, these electrodes can also be used to provide a feedback signal to actively stabilize the contrast ratio and insertion loss in the MZ modulator. Tuning the index of refraction changes the effective width of the MMI coupler. Index tuning can be most easily achieved in electro-optic materials via the Pockels effect described in Equation 1:
Figure imgf000008_0001
where An is the achieved index change, n is the refractive index of the material, reff is the effective electro-optic coefficient, V is the DC voltage applied across the electrodes, and d is the separation between the electrodes. Examples of materials that have large Pockels effect are the III-V semiconductors, such as GaAs and InP, and dielectric materials such as nonlinear polymers and LiNb03. In fact, the index tuned MMI coupler can be implemented in any of these material systems.
Actively tuning the index of refraction of pin region 110 improves the overall device yield and reduces the cost when compared to alternate designs and methods. The advantage of this method is a lower insertion loss when compared to alternate techniques such as Y branch splitters and combiners. A low insertion loss is particularly important for MMI couplers used in Mach- Zehnder modulators since these devices require high throughputs. However, the conventional MMI coupler's sensitivity to width variations places stringent requirements on the dimensions of the multimode waveguide region. This is a difficulty for the reliable and low cost manufacturing of these devices. It is known to those skilled in the art that the width of the multimode waveguide region must be controlled to within 0.3 μm in an InP MMI coupler design to keep the insertion losses within acceptable limits. Moreover, 2x1 MMI combiners of non- optimum widths and lengths are known to be sensitive to reflections. By tuning the index of refraction, these tolerances are relaxed.
Various changes and modifications to the embodiments herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof which is assessed only by a fair interpretation of the following claims.
Having fully described the invention in such clear and concise terms as to enable those skilled in the art to understand and practice the same, the invention claimed is:

Claims

1. Index tuned multimode interference coupler comprising: a substrate; a multimode interference coupler positioned on the substrate, the multimode interference coupler having an index of refraction; and a control means positioned on the multimode interference coupler for varying the index of refraction.
2. Index tuned multimode interference coupler as claimed in claim 1 wherein the control means includes an ohmic contact layer positioned on top of the multimode interference coupler and an ohmic contact layer positioned on the substrate layer.
3. Index tuned multimode interference coupler as claimed in claim 2 wherein the control means creates an electric field between the ohmic contacts that varies the index of refraction.
4. Index tuned multimode interference coupler as claimed in claim 2 wherein the control means injects a current between the electrodes that varies the index of refraction.
5. Index tuned multimode interference coupler as claimed in claim 2 wherein the control means includes a resistive electrode positioned on top of the multimode interference coupler and a resistive electrode positioned on the substrate layer.
6. Index tuned multimode interference coupler as claimed in claim 5 wherein the control means heats the resistive electrodes that varies the index of refraction.
7. Index tuned multimode interference coupler comprising: a substrate; a multimode interference coupler positioned on the substrate, the multimode interference coupler having N light input terminals, M light output terminals, an effective width, and an index of refraction; and a control means positioned on the multimode interference coupler for varying the index of refraction to vary the effective width, whereby light entering the input terminal is split substantially equally between the pair of output terminals.
8. ' Index tuned multimode interference coupler as claimed in claim 7 wherein the multimode interference coupler comprises a pin diode.
9. Index tuned multimode interference coupler as claimed in claim 8 wherein the pin diode is comprised of an n-type doped InP substrate, an insulating InGaAsP quantum well region, and a p-type doped InP region.
10. Index tuned multimode interference coupler as claimed in claim 8 wherein the control means creates an electric field between the ohmic contacts that varies the index of refraction.
11. Index tuned multimode interference coupler as claimed in claim 8 wherein the control means injects a current between the electrodes that varies the index of refraction.
12. Index tuned multimode interference coupler as claimed in claim 8 wherein the control means includes a resistive electrode positioned on top of the multimode interference coupler and a resistive electrode positioned on the substrate layer.
13. Index tuned multimode interference coupler as claimed in claim 12 wherein the control means heats the resistive electrodes that varies the index of refraction.
14. A method of actively tuning the performance of an optical power coupler comprising the steps of: receiving a light signal at the optical power coupler having an index of refraction; and actively tuning the performance of the optical power coupler by varying the index of refraction and outputting a light signal.
15. A method as claimed in claim 14 wherein the step of coupling the light signal includes using an index tuned multimode interference coupler that contains ohmic contacts.
16. A method as claimed in claim 15 wherein the active tuning of the index of refraction is accomplished by varying an electric field between the ohmic contacts.
17. A method as claimed in claim 15 wherein the active tuning of the index of refraction is accomplished by injecting a current between the ohmic contacts.
18. A method as claimed in claim 15 wherein the active tuning of the index of refraction includes heating the index tuned multimode interference coupler.
19. A method as claimed in claim 14 wherein the step of actively tuning the performance of the optical power coupler includes using an external photodetector to monitor a light signal at any of the outputs of the optical coupler.
20. A method as claimed in claim 19 wherein the step of actively tuning the index of refraction includes using a feedback control circuit.
PCT/US2002/025099 2001-08-16 2002-08-06 Index tuned multimode interference coupler WO2003016957A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002326560A AU2002326560A1 (en) 2001-08-16 2002-08-06 Index tuned multimode interference coupler

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US93120001A 2001-08-16 2001-08-16
US09/931,200 2001-08-16

Publications (2)

Publication Number Publication Date
WO2003016957A2 true WO2003016957A2 (en) 2003-02-27
WO2003016957A3 WO2003016957A3 (en) 2003-10-30

Family

ID=25460372

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2002/025099 WO2003016957A2 (en) 2001-08-16 2002-08-06 Index tuned multimode interference coupler

Country Status (2)

Country Link
AU (1) AU2002326560A1 (en)
WO (1) WO2003016957A2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008044818A1 (en) 2008-08-28 2010-03-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Multimode interference coupler and method for its structural design
WO2010100489A1 (en) * 2009-03-03 2010-09-10 Oclaro Technology Plc Improved optical waveguide splitters
JP7031082B1 (en) 2021-06-04 2022-03-07 三菱電機株式会社 Semiconductor optical integrated device and optical integrated device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4728167A (en) * 1986-02-24 1988-03-01 The United States Of America As Represented By The Secretary Of The Air Force. Electrically controlled integrated optical switch
US5699468A (en) * 1996-06-28 1997-12-16 Jds Fitel Inc. Bragg grating variable optical attenuator
US6353694B1 (en) * 1999-04-30 2002-03-05 Jds Uniphase Inc. MMI thermo-optic coupler

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4728167A (en) * 1986-02-24 1988-03-01 The United States Of America As Represented By The Secretary Of The Air Force. Electrically controlled integrated optical switch
US5699468A (en) * 1996-06-28 1997-12-16 Jds Fitel Inc. Bragg grating variable optical attenuator
US6353694B1 (en) * 1999-04-30 2002-03-05 Jds Uniphase Inc. MMI thermo-optic coupler

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008044818A1 (en) 2008-08-28 2010-03-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Multimode interference coupler and method for its structural design
US8478093B2 (en) 2008-08-28 2013-07-02 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Multimode interference coupler and method for the structural configuration thereof
WO2010100489A1 (en) * 2009-03-03 2010-09-10 Oclaro Technology Plc Improved optical waveguide splitters
US8743371B2 (en) 2009-03-03 2014-06-03 Oclaro Technology Limited Optical waveguide splitters
JP7031082B1 (en) 2021-06-04 2022-03-07 三菱電機株式会社 Semiconductor optical integrated device and optical integrated device
WO2022254687A1 (en) * 2021-06-04 2022-12-08 三菱電機株式会社 Semiconductor optical integrated element and optical integrated device

Also Published As

Publication number Publication date
AU2002326560A1 (en) 2003-03-03
WO2003016957A3 (en) 2003-10-30

Similar Documents

Publication Publication Date Title
USRE48379E1 (en) Electronic-integration compatible photonic integrated circuit and method for fabricating electronic-integration compatible photonic integrated circuit
EP0620475B1 (en) Optical devices and optical communication systems using the optical device
US6310995B1 (en) Resonantly coupled waveguides using a taper
Bowers et al. Recent advances in silicon photonic integrated circuits
US5862276A (en) Planar microphotonic circuits
US4889402A (en) Electro-optic polarization modulation in multi-electrode waveguides
US6282345B1 (en) Device for coupling waveguides to one another
US20030091287A1 (en) Multimode interference (MMI) device
JPH11224970A (en) Electrical isolation of photoelectric device component
US6618179B2 (en) Mach-Zehnder modulator with individually optimized couplers for optical splitting at the input and optical combining at the output
US5991475A (en) Tightly curved digital optical switches
WO2003016957A2 (en) Index tuned multimode interference coupler
US5490226A (en) Zero holding power digital optical switches
US5537497A (en) Optimized electrode geometries for digital optical switches
US6775455B1 (en) Silicon mesa structure integrated in a glass-on-silicon waveguide, and a method of manufacturing it
US11867945B2 (en) Optical waveguide circuits having laterally tilted waveguide cores
Aihara et al. Heterogeneously integrated membrane DFB laser and Si Mach-Zehnder modulator on Si photonics platform
Uitterdijk et al. Integrable Polarization Insensitive InGaAsPLnP Mach-Zehnder S witch
Adhikari et al. Electro‐Optic Switches
US20220326588A1 (en) Phase shift keying modulator
US9979160B2 (en) Integrated optical circulator apparatus, method, and applications
KOMATSU et al. Gb/s-Range Semiconductor and Ti: LiNbO 3 Guided-Wave Optical Modulators.
Yamada et al. Double-pass EA modulator array monolithically integrated with passive-waveguide
Papuchon Recent Progresses On Integrated Optics
Zhang et al. Coplanar lumped electroabsorption modulator fabricated on the common n-type InP substrate

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BY BZ CA CH CN CO CR CU CZ DE DM DZ EC EE ES FI GB GD GE GH HR HU ID IL IN IS JP KE KG KP KR LC LK LR LS LT LU LV MA MD MG MN MW MX MZ NO NZ OM PH PL PT RU SD SE SG SI SK SL TJ TM TN TR TZ UA UG US UZ VC VN YU ZA ZM

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ UG ZM ZW AM AZ BY KG KZ RU TJ TM AT BE BG CH CY CZ DK EE ES FI FR GB GR IE IT LU MC PT SE SK TR BF BJ CF CG CI GA GN GQ GW ML MR NE SN TD TG

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR IE IT LU MC NL PT SE SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP