JP2003530580A - Piezoelectric switch device - Google Patents

Abstract

(57) Abstract: A piezoelectric optical switch (10) comprises a planar Mach having a piezoelectric rib (40) disposed on one or both waveguide structures (20, 30). -Including a zender optical device. The piezoelectric ribs (40) deform the waveguide structure and create strain vectors that change the optical path of the waveguide (20). The piezoelectric rib (40) is offset from the propagation path of the waveguide (20). By arranging the piezoelectric ribs 40 away from the waveguide, distortion components in the propagation path of the waveguide in directions perpendicular to the propagation direction, for example, in the x and y directions, are negligibly small. Eliminating distortions in the direction perpendicular to the direction of propagation will result in birefringence, so eliminating these distortions will minimize birefringence. The piezoelectric switch of the present invention provides a high extinction ratio and low power consumption and short switching time expected for a piezoelectric device.

Description

Detailed Description of the Invention

1. TECHNICAL FIELD The present invention relates generally to a piezoelectric optical switch, and more particularly to a planar Mach-Zehnder piezoelectric optical switch having weak birefringence and a high extinction ratio.

2. BACKGROUND OF THE INVENTION As the demand for bandwidth expansion increases, so does the driving force for high capacity, low cost, dynamically reconfigurable fiber optic networks. In order to achieve this, network designers, etc. are looking for a method for replacing a certain kind of network function that has been conventionally performed in the electrical domain with a substitute in the optical domain as far as cost and system design allow. ing. Designers have found that 4-port optical devices have fault tolerance in fiber networks,
It has been recognized for some time that there may be widespread applications for providing signal modulation and signal routing. Integrated optical devices using thermo-optical and electro-optical technologies are currently available. However, these devices suffer from high power consumption and low switching speeds.

Four-port piezoelectric optical devices are of particular interest because of their low power consumption, short switching times, and suitability for high volume manufacturing techniques such as photolithography. One approach that has been investigated is an optical phase modulator made by coating a fiber with a coaxial piezoelectric lead zirconate titanate thick film. In this circularly symmetric in-line fiber phase modulator, phase modulation is obtained in the frequency range of 100 kHz to 25 MHz. Unfortunately, this device was inefficient due to its high attenuation and low piezoelectricity due to the difficulty of depositing the PZT thick film around the optical fiber.

In another approach that has been studied, Mach Zehnder made of optical fiber was used to construct an optical switch. In this structure, each leg of the optical fiber was placed in contact with the piezoelectric strip. This structure also has some drawbacks. First, the switching required a high voltage on the piezoelectric strip. Second, the placement of the strip with respect to the fiber disturbed the polarization in the interference arm, thus creating asymmetric stresses along the fiber axis that strengthen birefringence and degrade crosstalk performance. As a result, polarization is required when using this switch.

In another approach, modulators have been made by stacking piezoelectric strips on planar waveguide devices. The piezoelectric strip was formed by sandwiching a piezoelectric material layer between a lower electrode and an upper electrode. The piezoelectric strip is then
It was attached directly to the overcladding layer of the device on the waveguide. However, when the piezoelectric strip was actuated, the resulting strain vector caused a strong birefringence effect that significantly reduced the extinction ratio at the device output.

That is, there is a need for a 4-port piezoelectric optical device with weakened birefringence, high extinction ratio, low power consumption, and short switching time. The switch must be cost effective and the structure must be suitable for mass production techniques.

SUMMARY OF THE INVENTION The present invention substantially solves the birefringence problem discussed above and addresses other problems,
It is a 4-port piezoelectric optical switch. As such, the piezoelectric switch of the present invention provides a high extinction ratio in addition to the low power consumption and short switching times possible with piezoelectric technology. The planar structure of the present invention is well suited for high volume manufacturing techniques such as photolithography, and has a promising low cost for both the signal routing and fault tolerant functions required to realize high throughput fiber optic networks. Provide a solution.

One aspect of the present invention is an optical device for selectively directing an optical signal in a certain propagation direction, and the optical device has a propagation path and an output port for the optical signal. The present optical device includes a piezoelectric element for directing an optical signal to the output port by creating a plurality of mutually orthogonal distortion components in the optical device, the piezoelectric element being a plurality of mutually orthogonal distortion components, The components are arranged with respect to the propagation path such that only one component matching the propagation direction can be substantially present in the propagation path.

In another aspect, the invention is a Mach-Zehnder optical device for directing an optical signal of wavelength λ in a propagation direction. The optical device comprises a first waveguide having a first propagation path, a refractive index n, a first length L ₁ and a first output port, and a first waveguide.
A first piezoelectric rib for directing an optical signal by creating a first plurality of mutually orthogonal distortion components in the waveguide of the optical signal, the optical signal being propagated along the first propagation path, The rib has a first offset from the first propagation path such that only a component of the first plurality of mutually orthogonal distortion components that matches the propagation direction may be substantially present in the first propagation path. It is arranged on the first waveguide.

In another aspect, the invention provides a first propagation path, a refractive index n, a first length L ₁ ,
And a first waveguide having a first output port, wherein the optical signal is propagated along the first propagation path, and a method for directing an optical signal having a wavelength λ in the propagation direction. . A method for directing an optical signal is: providing first piezoelectric ribs for producing a first plurality of mutually orthogonal strain components in a first waveguide, the first piezoelectric ribs comprising: A first offset is taken from the first propagation path such that only a component of the first plurality of mutually orthogonal distortion components that matches the propagation direction may be substantially present in the first propagation path. A second propagation path, a refractive index n, a second length L ₂ , and a second output port, which are arranged in proximity to the first waveguide. A step of preparing a second waveguide having; and a step of operating the first piezoelectric rib to selectively deform the first waveguide, wherein the deformation of the first waveguide is the first plurality. Causing mutually orthogonal distortion components in the first waveguide;

In another aspect, the invention discloses a method of making an optical device used to direct an optical signal. This manufacturing method includes: a step of forming a substrate; a step of disposing a waveguide core layer on the substrate; a step of forming a first waveguide structure from the waveguide core layer, the first waveguide structure comprising: First propagation path, refractive index n, first length L ₁ , and first
And having a first axis, the first axis being substantially perpendicular to the first length and the first propagation path; forming a second waveguide structure from the waveguide core layer. Wherein the second waveguide structure has a second propagation path, a refractive index n, a second length L ₂ , and a second axis parallel to the first axis. A step of disposing a first piezoelectric rib on the first waveguide structure, the first piezoelectric rib being substantially parallel to the first axis and having an offset from the first axis. Having a first rib axis disposed at a second piezoelectric rib on the second waveguide structure; and a step of disposing a second piezoelectric rib on the second waveguide structure. Having a second rib axis that is substantially parallel and offset from the second axis, said offset being a multiple in an optical device. Including; steps as chosen to keep the folding to a minimum.

In another aspect, the invention includes at least one waveguide having at least one core connected to a first output port, the optical signal propagating in the propagation direction along the at least one waveguide. Disclosed is a method for selectively directing an optical signal to a first output port or a second output port of an optical device, the method for selectively directing an optical signal comprises: A step of preparing at least one piezoelectric element for switching an optical signal from the first output port to the second output port by inducing a plurality of mutually orthogonal distortion components in the waveguide. One piezoelectric element on the at least one waveguide such that only a first component of the plurality of mutually orthogonal strain components is substantially present in the at least one core. Arranging at a predetermined position, wherein the first component is a strain component matching the propagation direction; and actuating the at least one piezoelectric element, and thus a plurality of mutually orthogonal strain components. Causing the deformation of the at least one waveguide in the at least one waveguide.

Additional features and advantages of the invention are set forth in the detailed description which follows, and those of ordinary skill in the art will appreciate.
It will be readily apparent to some extent from the description and will be appreciated by practicing the invention as described herein, including the following detailed description and claims, and the accompanying drawings.

It should be understood that the foregoing general description and the following detailed description are merely illustrative of the present invention and are intended to provide an overview or framework for understanding the nature and features of the claimed invention. Is. The accompanying drawings are included to provide a further understanding of the invention and are incorporated herein and made a part of the specification. The drawings illustrate various embodiments of the invention and, together with the detailed description, serve to explain the principles and operation of the invention.

[0015] DETAILED DESCRIPTION Examples of the invention are illustrated in the accompanying drawings, referring in detail to the present preferred embodiments of the invention herein. Wherever possible, the same reference numbers will be used for the same or like elements throughout the drawings. An exemplary embodiment of a piezoelectric optical switch of the present invention is shown in FIG. 1 and designated generally by the reference numeral 10.

According to the present invention, an optical device 1 for directing an optical signal to a desired output port.
0 includes piezoelectric ribs 40. The piezoelectric ribs 40 direct the optical signal by deforming the core of at least one waveguide, thus changing the optical path length. The transformation creates a three-dimensional strain vector having components in each of the dimensions x, y, and z of the Cartesian coordinate system. The z direction corresponds to the propagation direction. By disposing the piezoelectric rib 40 on the waveguide at a position where a predetermined offset is taken from the core, strain components in the x and y directions orthogonal to the propagation direction can be reduced to a negligible level. Since strains in these directions cause birefringence, reducing these strains would have a similar effect on reducing birefringence. The rest is only distortion in the propagation direction, and distortion in the z direction does not cause birefringence. Elimination or reduction of birefringence is highly desirable because it reduces the extinction ratio at the output of the optical device.

That is, by solving the birefringence problem, the present invention provides an optical switch having a high extinction ratio. Another advantage of the present invention is low power consumption and fast switching time due to piezoelectric effect. Moreover, the planar structure of the present invention is well suited for high volume manufacturing techniques such as photolithography, and thus has promising low performance for both the signal routing and fault tolerance functions required to realize high throughput fiber optic networks. Provide a cost solution.

As embodied herein and shown in FIG. 1, the configuration of the piezoelectric optical switch 10 according to the first embodiment of the present invention includes a waveguide 20 and a waveguide 30. A planar directional coupler 110 is included. The piezoelectric rib 40 is used for the waveguide core 2
It is arranged on the waveguide structure 20 at a position separated by a predetermined offset distance “d” from 2 (see FIG. 2). The piezoelectric rib 40 has a length L _π , which is long enough to create a phase difference of π radians between the waveguide 20 and the waveguide 30.

As embodied herein and shown in FIG. 2, a detailed view of the placement of piezoelectric ribs 40 on a waveguide structure 20 according to the present invention is disclosed. A Cartesian coordinate system is provided in FIG. 2 as a convenient means of representing the orientation of the device and is used throughout.
The piezoelectric rib 40 includes upper electrodes 42 and 44. Electrodes 42 and 44 are connected to actuator 50. The piezoelectric rib 40 is located at an offset distance “d” from the waveguide axis that bisects the waveguide core 22, and the overclad layer 24 of the waveguide structure 20.
Placed on top. The waveguide structure 20 includes an overclad layer 24 and a core 22.
Note that the propagation direction is the z direction.

The waveguide structure 20 and the waveguide structure 30 may be of any suitable and well known type, with a waveguide made using silica glass having a refractive index of about 1.45 as an example. Shown. One of ordinary skill in the art will appreciate that polymeric or other similar materials may be used. The geometric shape of the core 22 may be square, rectangular, trapezoidal or semi-circular. The core size depends on the signal light wavelength and is designed to ensure that the waveguide is single mode at the signal wavelength. The core 22 is covered with an overclad layer 24 having a thickness designed to confine modes and suppress propagation losses.

The piezoelectric ribs 40 may be of any suitable well-known type, with a thickness range of approximately 3 μm to 300 μm, a width range of approximately 20 μm to 300 μm, and a length range of approximately 2 mm. A 3 cm layer of lead zirconate titanate (PZT) or zinc oxide (ZnO) is shown as an example. The dimensions of the piezoelectric ribs will vary depending on several factors, including the amount of phase shift the piezoelectric ribs 40 must produce. The piezoelectric ribs 40 are made by spin coating deposition and annealing of a PZT or ZnO sol-gel solution. A more detailed discussion of the dimensions and placement of the piezoelectric ribs 40 will be presented later.

The actuator 50 may be of any suitable well known type,
A voltage source capable of supplying two separate voltages to the piezoelectric rib 40 is shown as an example. First
The individual voltage of is in the range of several volts. The exact voltage depends on the required phase shift. The second voltage is approximately at ground level. As will be appreciated by those skilled in the art, there is virtually no Mach-Zender with a perfect 3dB combiner. Therefore, the actual voltage supplied to the piezoelectric ribs 40 by the actuator 50 can include a bias voltage for compensating for small phase fluctuations caused by imperfections of the Mach-Zehnder. This "tuning" can be made permanent by UV exposing the waveguide to complete the desired phase difference.

The network interface 60 allows the optical device 10 to be adapted to any network environment with respect to line level and logical protocols. The network interface 60 can also be configured to send failure information back to the network.

The operation of the optical device 10 according to the first embodiment of the present invention, as shown in FIGS. 1 and 2, is as follows. In the first operating state, the optical signal is transmitted to the waveguide 30.
The network interface receives commands for directing to the output port of. The network interface 60 drives the actuator 50, and the piezoelectric rib 40 is cut off. The optical signal is directed to the directional coupler 110 and the signal power is transferred to the waveguide 30, as shown. In the second state, the network interface receives a command that directs the optical device 10 to direct all optical signals to the output port of the waveguide 20. In response to this command, the network interface 60 drives the actuator 50 to supply the piezoelectric rib 40 with the appropriate voltage. The piezoelectric ribs 40 expand to deform the waveguide structure 20 and induce strain in the waveguide 20. The induced strain caused by the deformation will change the refractive index and length of the waveguide 20. All of these factors contribute to the change in the optical path length of the waveguide 20. A phase difference of π radians is established between the waveguide 20 and the waveguide 30, and light is no longer coupled to the waveguide 30. As a result, the optical device 10 is switched and the optical signal exits the optical device 10 from the waveguide 20. As discussed above, those skilled in the art will appreciate that the magnitude of the voltage depends on the magnitude of the strain needed to create the index variation that produces the desired phase difference.

The principle of operation of the present invention that establishes the relationship between the dimensions, the power requirements and the placement of the piezoelectric ribs 40 with respect to deformation, strain and the resulting phase shift induced in the waveguides 20 and 30 is as follows. . E _input is the electric field of the input optical signal, and ΔΦ is the waveguides 20 and 3
Assuming the phase difference between 0 and E _output as the electric field of the output optical signal, the following relational expression (1):

[Equation 11] Is established. The transmission of Mach-Zehnder 110 is defined as the ratio of output intensity to input intensity. Therefore, from equation (1):

[Equation 12] Is obtained. The phase difference ΔΦ between the waveguides 20 and 30 is:

[Equation 13] Is expressed as Where λ is the wavelength, n is the effective index of refraction for the modes propagating through device 10, and L is the length of waveguides 20 and 30 between coupler 112 and coupler 114. The term d (nL) is the nL difference between the waveguide 20 and the waveguide 30.

As discussed above, when actuator 50 applies a voltage to piezoelectric rib 40,
The piezoelectric rib 40 expands or contracts depending on the magnitude and polarity of the voltage. Expansion and contraction of the piezoelectric ribs 40 deforms the waveguide 20 and causes changes in the refractive index and length of the waveguide 20. The change in refractive index is strain and the following equations (4) and (5):

[Equation 14]

[Equation 15] Related by. Here, n _x is the refractive index of light polarized in the x direction (see FIG. 2), n _y is the refractive index of light polarized in the y direction, and ε _x , ε _y, and ε _z = dL / L are x. ，
These distortion components are orthogonal to each other in the y and z directions. The terms p ₁₁ and p ₁₂ are photoelastic coefficients and vary depending on the material used to make the waveguide. The phase difference ΔΦ between the waveguides 20 and 30 is generally the difference between the polarization components of the optical signal in the x and y directions, and thus equations (6) and (7):

[Equation 16]

[Equation 17] Is. From Equations (6) and (7), it is possible to calculate the length of the piezoelectric rib 40 required to generate the phase difference of π radian, and Equation (8):

[Equation 18] To get

Depending on the materials used and the wavelength of the optical signal, L _π will be in the range of approximately 2 mm to 3 cm. The width and thickness tolerances of the piezoelectric ribs 40 are determined by comparing the strain ε _{z in the} propagation direction for PZT ribs with different widths and thicknesses and for waveguide structures with different overcladding layer thicknesses. . That is, as an acceptable result, the thickness of the piezoelectric rib 40 is approximately in the range of 3 μm to 300 μm and the width thereof is approximately 2 μm.
It is in the range of 0 μm to 300 μm. The thickness of the over cladding layer depends on the signal wavelength,
It should be sufficient to confine modes and suppress propagation losses.

From equations (6) and (7), the polarization dependence of the phase difference due to birefringence is also clear. The main effect of birefringence is to reduce the extinction ratio. The extinction ratio refers to the ratio of the light intensity at the output of the waveguide 20, for example, in the “on state” to the “off state”. In theory, there should be no light exiting the waveguide 20 in the "off state". That is, the extinction ratio is a measure of light leakage. Obviously, the output of waveguide 30 could also be used to obtain this measure. A low extinction ratio means that a significant amount of light is leaking out of the device 10 from the waveguide output port, which should have been blocked.
The extinction ratio is also improved by reducing the birefringence of the device.

FIG. 3 is a graph showing the relationship between birefringence and extinction ratio. One of the measures of birefringence is the Q value. The highest curve is Mach without birefringence corresponding to infinity Q value.
Shows Zender. The bottom curve shows a device with an extinction ratio of 10 dB, corresponding to a Q value of about 5. The Q value must be greater than 16 to obtain an extinction ratio of at least 20 dB. The Q value is given by equation (9):

[Formula 19] Is related to the difference in refractive index for light polarized in the x and y directions.

The parameters dn _x and dn _y are the refractive index changes caused by the strain induced by the piezoelectric ribs 40. Equations (6) and (7) show that the change in waveguide length dL / L and the deformation-induced refractive index change compensate for the strain ε _{z in the} propagation direction. That is, birefringence can be obtained by removing the strain components ε _x and ε _y in the x and y directions, respectively.
It can be kept quite small. This is accomplished in the present invention by placing the piezoelectric ribs 40 at a predetermined offset distance from the central axis of the core 22 (see FIG. 2) and the propagation path. In operation, the geometrical position of the piezoelectric rib acts to minimize the strain components ε _x and ε _y , but the switching function is maintained by changing the refractive index and length of the waveguide using ε _z. It

The optimum range of the offset distance is L _π in length, about 100 μm in width, and 20 μm in thickness.
It was determined by plotting the Q value (inversely proportional to birefringence) as a function of offset distance using a Mach-Zehnder with m PZT ribs. Under the above conditions, the optimum value of the offset distance in the above configuration is about 100 μm. Generally speaking, the offset distance is approximately equal to λ / 4n.

As embodied herein and shown in FIG. 4, a configuration of a piezoelectric optical switch 10 according to a second embodiment of the present invention includes a planar formed by a waveguide 20 and a waveguide 30. A model Mach-Zehnder 110 is included. Piezoelectric ribs 40 are disposed on the waveguide structure 20 at an offset distance “d” from the waveguide core 22 (see FIG. 2). The length of the piezoelectric rib 40 is equal to L _π . The piezoelectric rib 40 is an actuator 50.
Electrically connected to. The actuator 50 is connected to a network interface 60 that receives network commands and drives the actuator 50 accordingly.

The operation of the optical device 10 according to the second embodiment of the present invention as shown in FIG. 4 is as follows. In the first operating state, the network interface receives a command to direct the optical signal to the output port of the waveguide 30. The network interface 60 drives the actuator 50, and the piezoelectric rib 40
Is brought into a non-driving state. The optical signal is Mach-Zender 110 as shown in the figure.
Directed to. Half of the optical signal is coupled to the waveguide 30 by the 3 dB coupler 112. As will be appreciated by those skilled in the art, a symmetric Mach-Zehnder with a perfect 3 dB coupler will operate in the crossed state when there is no phase difference between the waveguides 20 and 30 and the optical signal will conduct. The device 10 will exit from the output port of the waveguide 30.

In the second state, the network interface receives a command that directs the optical signal to exit the optical device 10 from the output port of the waveguide 20. In response, network interface 60 drives actuator 50 to provide piezoelectric ribs 40 with a voltage sufficient to induce a phase difference of π radians. The piezoelectric ribs 40 expand and deform the waveguide structure 20 to induce strain in the waveguide 20.
The induced strain caused by the deformation will change the refractive index and length of the waveguide 20.
All of these factors contribute to the change in optical path length that an optical signal takes when propagating in the waveguide 20. One of ordinary skill in the art will appreciate that the magnitude of the voltage required depends on the magnitude of the strain required to cause the change in refractive index that will produce the desired phase difference. The phase difference determines the magnitude of the electric field required to drive the piezoelectric element 40.
The voltage applied to the piezoelectric rib 40 establishes a phase difference of π radian between the waveguide 20 and the waveguide 30. As a result, the optical switch 10 is switched and the optical signal exits the device 10 from the waveguide 20.

In a third embodiment of the present invention, as embodied herein and shown in FIG. 5, a piezoelectric Mach-Zehnder optical switch 10 comprises a waveguide 20 and a waveguide 30. A planar Mach-Zehnder 110 is included. The piezoelectric ribs 40 are offset from the waveguide 20 by a distance "d" to provide the waveguide structure 20.
Placed on top. Another piezoelectric rib 70 is placed on the waveguide structure 30, also offset by "d". Piezoelectric ribs 40 and 70 may also be disposed on the inner edges of each of waveguides 20 and 30. It should be noted that FIG. 2 and the discussion about the offset distance “d” apply to this embodiment as well as the first embodiment.
The piezoelectric rib 40 is electrically connected to the actuator 50, and the piezoelectric rib 70 is electrically connected to the actuator 52. The actuators 50 and 52 are tandem driven by the network interface 60.

Those skilled in the relevant art will appreciate that modifications and variations can be made to the piezoelectric ribs 40 and 70 depending on the amount of phase shift each of the piezoelectric ribs 40 and 70 must provide. In the third embodiment of the present invention, the waveguide 3
By arranging the second piezoelectric ribs 70 on the waveguide 20,
And the waveguide 30. Similar to the first embodiment, the optical signal is transmitted to the waveguide 2
In order to switch to the 0 output port, the total phase difference of π radians must be provided between the waveguide 20 and the waveguide 30. However, the use of piezoelectric ribs 70 makes it possible to use the "push-pull" effect in which piezoelectric ribs 40 provide a positive phase shift and piezoelectric ribs 70 provide a negative phase shift. That is, the piezoelectric ribs 40 must provide a phase shift of + π / 2 radians, and the piezoelectric ribs 70 have a −
A phase shift of π / 2 radians must be given. Since the phase shift that each piezoelectric rib must provide is reduced from π radians to π / 2 radians, the length of each rib can also be reduced to approximately 1/2, and α ≈ 0.5
):

[Equation 20] It is represented by. To avoid problems with mechanical crosstalk, piezoelectric ribs 40
And 70 should be separated by at least 500 μm. Recommended separation distance is 50
It is in the range of 0 μm to 1000 μm. This is a trade-off between device size and crosstalk.

Another embodiment of the present invention, embodied herein and shown in FIG. 6, may include an etched groove 80 between the waveguide 20 and the waveguide 30. The etching groove 80 is provided to reduce the mechanical crosstalk by separating the arms 20 and 30 of the Mach-Zehnder 110.

The principle of operation of the present invention establishing the width, thickness, power requirements and placement of the piezoelectric ribs 40 and 70 with respect to the strains and phase shifts induced in the waveguides 20 and 30 is illustrated in FIGS. It is essentially the same as the operating principle discussed above for one embodiment.

The operation of the optical device 10 according to the third embodiment of the present invention as shown in FIG. 5 is as follows. In the first operating state, the need for the network requires that the optical signal be directed to the output port of the waveguide 30. Half of the optical signal entering the Mach-Zehnder 110 is coupled to the waveguide 30 by the 3 dB coupler 112. A symmetric Mach-Zehnder with perfect 3 dB couplers 112 and 114 operates in the crossed state when there is no phase difference between the waveguides 20 and 30,
The optical signal will be the output of the waveguide 30. That is, in processing the network command, the network interface 60 causes the actuators 50 and 52 to
Driving, the voltage supplied to the piezoelectric ribs 40 and 70 drops to approximately zero volts. As discussed above and as will be appreciated by those skilled in the art, there is virtually no Mach-Zehnder with a perfect 3dB coupler. In each switch state, the actuators 50 and 52 apply a small bias voltage to the piezoelectric ribs 40 and 70, respectively, in addition to the nominal voltage to compensate for the small phase variations caused by Mach-Zehnder imperfections.

In the second operating state, the network interface 60 is commanded to direct the optical signal to the output port of the waveguide 20. The network interface 60 drives the actuators 50 and 52 according to the command. Actuator 5
0 supplies a positive voltage to the piezoelectric rib 40, and the actuator 52 supplies a negative voltage having substantially the same absolute value to the piezoelectric rib 70. The piezoelectric ribs 40 extend and thus the waveguide structure 20.
Will transform. The piezoelectric ribs 70 will contract and thus deform the waveguide structure 30. The deformation distorts the waveguides 20 and 30, thus changing their respective path lengths. A change in the path length of the waveguide 20 causes a phase shift of approximately + π / 2 radians, while a change in the path length of the waveguide 30 causes a phase shift of approximately −π / 2 radians. That is, π radians or π between the waveguide 20 and the waveguide 30.
A phase difference of odd radians is established and the optical signal is directed to the output port of waveguide 20. Of course, the same result can be obtained by reversing the polarity of the voltage. However, the voltages must have opposite polarities.

In yet another embodiment of the present invention, as embodied herein and shown in FIG. 7, piezoelectric ribs 40 include an outer edge piezoelectric strip 46 and an outer edge piezoelectric strip 46 disposed on the outer edge of the waveguide 20. It consists of an inner edge piezoelectric strip 48 located on the inner edge of the waveguide 20.
The piezoelectric rib 70 is composed of an outer edge piezoelectric strip 72 arranged on the outer edge of the waveguide 30 and an inner edge piezoelectric strip 74 arranged on the inner edge of the waveguide 30. Inner edge piezoelectric strip 48 and inner edge piezoelectric strip 74 are separated by at least 500 μm and are within the recommended separation range of 500 μm to 1000 μm, as discussed above and shown in FIG. This is a trade-off between crosstalk and device size. The etching groove shown in FIG. 6 can also be used in this embodiment. The actuator 50 is connected to the piezoelectric strips 46 and 48 and supplies the same voltage to each. The actuator 52 is connected to the piezoelectric strips 72 and 74 and supplies the same voltage to each. A network interface 60 is connected to the actuator 50 and the actuator 52, and drives the actuators 50 and 52 in tandem.

It will be apparent to those skilled in the relevant art that modifications and variations can be made to the piezoelectric ribs 40 and 70 of the present invention depending on the amount of phase shift each must provide. By arranging the piezoelectric strips 46, 48, 72 and 74 on both sides of the waveguides 20 and 30, respectively, the length of the piezoelectric rib is ½ of that of the second embodiment, and for the first embodiment, It can be shortened to 1/4. That is, in equation (10), α≈0.25.

Except for the changes discussed above, the optical switch 10 of FIG. 7 operates in the same manner as the embodiment shown in FIG. 5, so its operation will not be repeated.

In yet another embodiment of the present invention, as embodied herein and shown in FIG. 8, the configuration of the piezoelectric optical switch 10 includes a Mach formed by a waveguide 20 and a waveguide 30. -Zender 110 is included. The piezoelectric ribs 40 are arranged on the waveguide structure 20 with an offset distance from the waveguide core 22. Another piezoelectric rib 70 is also disposed on the waveguide structure 30 at an offset distance from the core of the waveguide 30. The discussion of offset distance with respect to FIG. 2 applies to this embodiment as well. The piezoelectric rib 40 is electrically connected to the actuator 50. The piezoelectric rib 70 is electrically connected to the actuator 52. The actuators 50 and 52 are connected to the network interface 60 and driven in tandem.

The actuators 50 and 52 may be of any suitable and well known type, but a voltage source capable of supplying three distinct voltage values to the piezoelectric ribs 40 and 70 is shown as an example. This embodiment uses a "push-pull" effect similar to the approach discussed above with respect to the embodiments shown above. Switching is performed by driving the piezoelectric ribs 40 and 70 with voltages having opposite polarities. That is, the voltage source operates in tandem such that actuator 52 supplies -V when actuator 50 supplies + V. Actuator 50-
When supplying V, the actuator 52 supplies + V. When the actuator 50 is at about ground voltage, the actuator 52 is also at about ground voltage. As discussed above, the nominal voltage V depends on various factors such as the desired phase difference and piezoelectric rib size. It will be apparent to those skilled in the relevant art that multiple voltage combinations may be used to split the optical signal between the waveguides 20 and 30 as desired.

It will be apparent to those skilled in the relevant art that modifications and variations can be made to the present invention depending on the amount of phase shift each rib must provide. In FIG. 8, the waveguide 20 is shorter than the waveguide 30 by a length ΔL = L ₂ −L ₁ ,
ΔL is about 250 μm when λ = 1.55 μm and n≈1.5. Waveguide 2
This path length difference between 0 and the waveguide 30 is π / between the waveguide 20 and the waveguide 30.
Establish a phase difference of 2 radians. That is, the phase shift that each of the piezoelectric elements 40 and 70 must produce to obtain a phase difference of π radians or a zero phase difference between the waveguides 20 and 30 is only π / 4 radians. Piezoelectric rib 4
0 and the phase shift that the piezoelectric rib 70 must provide is from π radian to π / 4.
Since it is reduced to radians, the lengths of the piezoelectric ribs 40 and the piezoelectric ribs 70 can be reduced to about 1/4. That is, the equation (10) in which α≈0.25 can be used to calculate the length L _{π / 4} of the piezoelectric rib 40 and the piezoelectric rib 70. If you are a person skilled in the art,
It will also be appreciated that this embodiment can be realized using one piezoelectric rib or four piezoelectric ribs.

It will be apparent to those skilled in the relevant art that modifications and variations can be made to the invention shown in FIG. Instead of configuring the path length difference to provide a phase difference of π / 2 radians, the path length difference can be configured to provide a permanent phase difference of π radians. In this case, when the piezoelectric ribs are not operating, the optical device 10 is in the orthogonal state instead of the intersecting state. This configuration is important when the switch is likely to be used in the orthogonal state rather than in the crossed state.

As discussed above with respect to the embodiments shown above, the piezoelectric ribs 40 and 70 should be spaced by at least 500 μm to avoid problems with mechanical crosstalk. The recommended separation distance range is 500 μm to 1000 μm.
As discussed above, separation is a tradeoff between crosstalk and device size. An etching groove as shown in FIG. 6 can also be used in this embodiment.

The operation of the optical device 10 according to the present invention as shown in FIG. 8 is as follows. In the first operating state, the network commands the optical device 10 to direct the optical signal to the output port of the waveguide 20. Network interface 6
0 drives the actuators 50 and 52 accordingly. Actuator 50
Supplies a positive predetermined voltage to the piezoelectric ribs 40. Actuator 5
2 supplies a negative voltage having the same absolute value to the piezoelectric rib 70. The piezoelectric rib 40 is the waveguide 2
It deforms 0 and causes a phase shift of approximately + π / 4 radians. The piezoelectric rib 70 deforms the waveguide 30 and a phase shift of approximately −π / 4 radian is generated. As one of ordinary skill in the art will appreciate, the actual phase shift depends on the inherent imperfections of the MZI (Mach-Zehnder interferometer). The phase change can be slightly different for each MZI. It is a requirement that a total phase difference of π radians is established between the waveguide 20 and the waveguide 30. In doing so, the optical device 10 is switched and the optical signal can exit the device from the output port of the waveguide 20.

In the second actuated state shown in FIG. 8, the actuators 50 and 52 supply approximately zero volts to their respective piezoelectric ribs 40 and 70. As discussed above,
The asymmetric Mach-Zehnder shown in FIG. 8 has approximately π / 2 between the waveguide 20 and the waveguide 30.
It is manufactured with a phase difference of radian. That is, when the piezoelectric ribs 40 and 70 do not deform the waveguides 20 and 30, respectively, an optical signal is generated between the output port of the waveguide 20 and the output port of the waveguide 30 due to the inherent phase difference of π / 2 radians. Are equally divided by. In this state, the optical device 10 is a 3 dB divider.

In the third operating state, the network interface 60 is commanded to direct the optical signal to the output port of the waveguide 30. The network interface 60 drives the actuator 50 to supply the piezoelectric rib 40 with a negative voltage. Similarly, the actuator 52 supplies a positive voltage having substantially the same absolute value to the piezoelectric rib 70.
The piezoelectric ribs 40 deform the waveguide 20 to produce a phase shift of approximately -π / 4 radians. The piezoelectric ribs 70 deform the waveguide 30 to produce a phase shift of approximately + π / 4 radians. In this operating state, the phase shift generated by the piezoelectric ribs 40 and 70 is caused by the path length difference between the waveguide 20 and the waveguide 30, and the phase shift between the waveguide 20 and the waveguide 30 is π / 2. Cancel the characteristic phase difference of radian. That is, there is no phase difference between the waveguide 20 and the waveguide 30, and the optical signal is directed to the output port of the waveguide 30 as instructed.

In yet another embodiment, as embodied herein and shown in FIG. 9, the configuration of the piezoelectric variable attenuator 10 includes a Mach-Zehnder formed of a waveguide 20 and a waveguide 30. 110 are included. The piezoelectric ribs 40 are arranged on the waveguide 20 with an offset distance from the waveguide core 22. The discussion of offset distances with respect to FIG. 2 applies equally to this embodiment as well. The piezoelectric rib 40 is electrically connected to the actuator 50.

The actuator 50 may be of any suitable and well known type known, but a variable voltage source for dynamically changing the voltage over a continuous voltage range is shown as an example. Those skilled in the art will appreciate that the power level of the optical signal at the output port of the waveguide 20 or 30 is dynamically controlled in proportion to the voltage level provided by the actuator 50. That is, the variable attenuator 10 is realized by changing the voltage over a continuous range.

The operation of the variable attenuator 10 according to the present invention, as shown in FIG. 9, is as follows. As discussed with respect to the first embodiment, the optical signal propagating through the symmetric Mach-Zehnder 110 would be directed to the output port of the waveguide 30 if the piezoelectric ribs 40 were unactuated. When a command is received that orders the light output from the waveguide 30 to be attenuated to a certain level, the network interface 60 interprets the command and translates it into a voltage level within the range provided by the actuator 50. The actuator 50 supplies its voltage level to the piezoelectric ribs 40 as commanded. In response to this, the piezoelectric rib 40 expands, deforms the waveguide structure 20, and changes the refractive index and the length of the waveguide 20. Thus, a portion of the optical signal is diverted from the output port of waveguide 30 and redirected to the output port of waveguide 20. As the voltage is increased, more and more signal is diverted from the waveguide 30 and thus attenuated. When the actuator 50 supplies a predetermined voltage to the piezoelectric rib 40, a phase difference of π radian is established between the waveguide 20 and the waveguide 30. In this state, the output from the waveguide 30 is completely attenuated. That is, the voltage supplied by the actuator 50 is proportional to the amount of attenuation.

In yet another embodiment as embodied herein and shown in FIG. 10, a piezoelectric tunable filter 10 may be configured with a Mach-Zehnder waveguide 20 and a waveguide 30. 110 are included. Note that the waveguide 20 is shorter than the waveguide 30 by the distance ΔL = L ₂ −L ₁ , which is approximately 200 μm. The piezoelectric ribs 40 are arranged on the waveguide structure 20 with an offset distance from the waveguide core 22. The discussion of offset distances with respect to FIG. 2 applies equally to this embodiment as well. The piezoelectric rib 40 is electrically connected to the actuator 50.

The operation of the tunable filter 10 according to the present invention as shown in FIG. 10 is as follows. The phase change between the two arms is given by the following equation (11):

[Equation 21] Given in. Since the refractive index n depends on the wavelength, the product nΔL also depends on the wavelength. ΔL
Is large, a large phase difference can be obtained between different wavelengths. For example,
In the first operating state in which the piezoelectric ribs 40 are not activated, λ ₁ = 1554.5n
The light of m has no phase difference, and the light of λ ₂ = 1558.5 nm has a phase difference of π radian. That is, λ ₁ will not be interfered and λ ₂ will be subject to destructive interference. In the second operating state, the piezoelectric ribs 40 induce a phase difference of π radians between the waveguide 20 and the waveguide 30. Due to the wavelength dependence discussed above, the attenuation at different wavelengths will change, λ ₂ will not interfere and λ ₁ will disappear due to destructive interference.

11A-Q are schematic diagrams sequentially illustrating successive fabrication steps of the piezoelectric optical switch of the present invention. The substrate 100 is formed in FIG. 11A. Substrate 100 may be of any suitable well-known type, but a substrate formed of silicon glass is shown as an example. FIG. 11B shows the buffer layer 102 deposited on the substrate 100.
Buffer layer 102 may be of any suitable well known type, but a layer formed of fused silica is shown as an example. FIG. 11C shows the core layer 104 deposited on the buffer layer 102. The core layer 104 may be of any suitable well-known type, but a layer formed of fused silica having a refractive index n higher than that of the buffer layer 102 is shown as an example. Those skilled in the relevant art will appreciate that the fabrication process illustrated in Figures 11A-11C can also be accomplished with polymers, copolymers, monomers or other suitable materials. 11D-1
1H indicates a photolithography process for forming the waveguide structure 20 and the waveguide structure 30. A mask 116 is disposed on the core layer 104 and the waveguide structures 20 and 30.
Pattern is transferred to the core layer 104 by exposure through a mask. Unnecessary core material is removed by the etching process shown in FIG. 11G. In FIG. 11H, an overclad layer 24 is deposited over the waveguide structures 20 and 30. Figure 11
I to 11N indicate piezoelectric ribs 40 formed on the waveguide structure 20. PZT
Alternatively, a layer of ZnO is deposited on the bottom electrode 44. The dimensions of PZT ribs will vary within the ranges given in the discussion above. In FIG. 11P, pigtail 18 is connected to waveguides 20 and 30 to provide optical coupling. Finally, in FIG. 11Q, the piezoelectric rib electrode is connected to the connector arranged in the optical unit package 108.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[Brief description of drawings]

[Figure 1]   Schematic diagram of a piezoelectric optical switch according to a first embodiment of the present invention

[Fig. 2]   Detailed view of the arrangement of piezoelectric ribs on a waveguide structure according to the invention.

[Figure 3]   Graph showing the relationship between birefringence and extinction ratio for the present invention

[Figure 4]   Schematic diagram of a piezoelectric optical switch according to a second embodiment of the present invention.

[Figure 5]   Schematic diagram of a piezoelectric optical switch according to another embodiment of the present invention.

FIG. 6 is a detailed view of the etching groove used to mechanically separate the Mach-Zehnder arms to reduce crosstalk.

[Figure 7]   Schematic diagram of a piezoelectric optical switch according to yet another embodiment of the invention.

[Figure 8]   Schematic diagram of a piezoelectric optical switch according to yet another embodiment of the invention.

FIG. 9 is a schematic diagram of a piezoelectric optical device, which is a variable attenuation controller according to yet another embodiment of the present invention.

FIG. 10 is a schematic diagram of a piezoelectric optical device, which is an optical modulator according to yet another embodiment of the present invention.

FIG. 11a   Schematic diagram sequentially showing successive fabrication steps of the piezoelectric optical switch of the present invention

FIG. 11b   Schematic diagram sequentially showing successive fabrication steps of the piezoelectric optical switch of the present invention

[Explanation of symbols]

      10 Piezoelectric optical device       20,30 Waveguide       40 Piezo rib       50 actuators       60 network interface       110 Mach-Zender

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), AE, AL, A M, AT, AU, AZ, BA, BB, BG, BR, BY , CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, H U, ID, IL, IN, IS, JP, KE, KG, KP , KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, N Z, PL, PT, RO, RU, SD, SE, SG, SI , SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (67)

[Claims] 1. An optical device for selectively directing an optical signal to a first output port or a second output port: at least one having at least one core connected to said first output port At least one waveguide that propagates the optical signal in the propagation direction along the at least one waveguide; and induces a plurality of mutually orthogonal distortion components in the at least one waveguide. Thereby, the at least one piezoelectric element for switching the optical signal from the first output port to the second output port, wherein substantially only the first component of the plurality of mutually orthogonal distortion components is provided. To be present in the at least one core, the first component is disposed at a predetermined position on the at least one waveguide, and the first component is the propagation direction. Optical device characterized in that it comprises a; at least one piezoelectric element such that the distortion components matched to. 2. The optical device according to claim 1, wherein the predetermined position makes the birefringence value of the at least one core so small as to be substantially negligible. 3. The optical device of claim 1, wherein the at least one waveguide comprises a first waveguide and a second waveguide, thus forming an optical coupler. 4. The optical device of claim 1, wherein the at least one waveguide comprises a first waveguide and a second waveguide, thus forming a Mach-Zehnder device. 5. A Mach-Zehnder optical device for directing an optical signal of wavelength λ to a first output port or a second output port, the first core connected to the first output port. A first waveguide having a refractive index n, a first length L ₁ and a first output to propagate the optical signal in a propagation direction within the first core; and the first waveguide. A first piezoelectric rib for switching the optical signal between the first output port and the second output port by creating a first plurality of mutually orthogonal distortion components therein. A first predetermined offset distance from the first core is such that only the first component of the first plurality of mutually orthogonal distortion components is substantially within the first core. Is placed on the first waveguide, and Optical device characterized in that it comprises a; component said first piezoelectric rib the propagation direction such that it is parallel. 6. The first predetermined offset distance is the first offset distance.
6. The optical device according to claim 5, wherein the birefringence value of the core is substantially small enough to be ignored. 7. The optical device of claim 5, wherein the first waveguide has a _second core connected to the second output port, a refractive index n, and a second length L _2. A second waveguide arranged in proximity to the second waveguide for propagating the optical signal in the propagation direction in the second core; and the second waveguide in the first waveguide. A first actuator connected to the first piezoelectric rib for causing a first waveguide deformation in the first piezoelectric rib that creates one of a plurality of mutually orthogonal strain components; An optical device comprising: 8. The first waveguide deformation induces a phase difference between the first waveguide and the second waveguide; dn is a change in the refractive index n, and dL ₁ is the length. As a change in the length L _1, the phase difference is expressed by the following equation: The optical device according to claim 7, wherein: 9. The optical signal includes a first polarization component in the x direction and a second polarization component in the y direction; the x direction, the y direction, and the z direction are orthogonal to each other in an orthogonal coordinate system. The optical device according to claim 5, wherein the optical device is an axis and the z direction is the propagation direction. 10. The first plurality of mutually orthogonal distortion components are dn _x a change in refractive index with respect to the first polarized component, dn _y with a change in refractive index with respect to the second polarized component, Let p ₁₁ and p ₁₂ be photoelastic coefficients, ε _x , ε _y , and ε _z = dL ₁ /
It said L first plurality of orthogonal distortion component together, the dL ₁ as a change in the first length L _1, the formula: ## EQU2 ## And [Equation 3] 10. The optical device according to claim 9, wherein the optical device is related to the change in the refractive index n by. 11. The first waveguide deformation, wherein K _x and K _y are non-dimensional coefficients and is a function of the first plurality of mutually orthogonal distortion components, the equation: And [Equation 5] Accordingly, the first polarization component phase difference ΔΦ _x and the second polarization component phase difference ΔΦ _y are established between the first waveguide and the second waveguide. Item 1
The optical device described in 0. 12. A first birefringence value in the first core is set such that Q is equal to the first birefringence value.
As a value inversely proportional to the birefringence value of, the expression: 11. The optical device according to claim 10, wherein the optical device is associated with the plurality of mutually orthogonal distortion components by. 13. The first predetermined offset distance is λ / 4.
13. The optical device according to claim 12, wherein the optical device is substantially equal to n. 14. The optical device according to claim 12, wherein the extinction ratio at the first output port and the second output port is at least 20 dB when Q is greater than 16. 15. The first waveguide modification establishes a phase difference of π radians between the first waveguide and the second waveguide to direct the optical signal to the first output port. The optical device according to claim 5, characterized in that the optical device is directed toward. 16. The optical device of claim 15, wherein the optical signal is directed to the second output port when there is no deformation of the first waveguide. 17. The first actuator is a voltage source connected to the first piezoelectric rib for supplying a predetermined voltage to the first piezoelectric rib. The optical device described. 18. The first piezoelectric rib has the _equations : K _x and K _y as non-dimensional coefficients and as a function of the first plurality of mutually orthogonal strain components: 16. The optical device according to claim 15, having a first rib length L _π corresponding to a phase shift of π radians according to. 19. The optical device of claim 18, wherein L _π is in the range of approximately 2 mm to 3 cm. 20. The optical device according to claim 18, wherein the width of the first piezoelectric rib is in the range of approximately 20 μm to 300 μm. 21. The optical device according to claim 18, wherein the thickness of the first piezoelectric rib is in the range of approximately 3 μm to 300 μm. 22. An optical device according to claim 7, wherein the optical signal is produced in cooperation with the first piezoelectric rib by creating a second plurality of mutually orthogonal strain components in the second waveguide. A second piezoelectric rib for switching between the first output port and the second output port, wherein only a second component of the second plurality of mutually orthogonal strain components is substantially formed. Is disposed on the second waveguide at a second predetermined offset distance from the second core such that it is within the second core, and the second component is A second piezoelectric rib that is parallel to the direction of propagation; and a second waveguide modification that creates the second plurality of mutually orthogonal strain components in the second waveguide. In order to generate a piezoelectric rib, it is connected to the second piezoelectric rib. It has been the second actuator; and optical devices, which comprises a. 23. The optical device of claim 22, wherein the first length L ₁ is substantially equal to the second length L ₂ . 24. A first predetermined voltage is applied to the first actuator to cause the first waveguide deformation, and a polarity opposite to the first predetermined voltage is applied. 24. The optical device according to claim 23, wherein the second waveguide deformation is caused by supplying a second predetermined voltage that the second actuator has to the second actuator. 25. The first waveguide modification establishes a first phase shift in the first waveguide, and the second waveguide modification establishes a second phase shift in the second waveguide. 25. The optical device of claim 24, wherein the phase difference between the first and second phase shifts established is substantially equal to [pi] radians or an odd multiple of [pi] radians. 26. A phase difference of substantially zero radians exists when the first waveguide and the second waveguide are not deformed, and the optical signal is directed to the second output port. The optical device according to claim 23, wherein: 27. The lengths of the first piezoelectric rib and the second piezoelectric rib are equal to each other, α is a proportional constant approximately equal to 0.5, λ is a wavelength, and K _x and K _y are respectively the above-mentioned. As a dimensionless coefficient related to the first plurality of mutually orthogonal distortion components and the second plurality of mutually orthogonal distortion components of the first waveguide and the second waveguide, the equation: 8] 24. An optical device according to claim 23, having a rib length L [ _{pi] / 2} corresponding to a phase shift of [pi] / 2 radians according to. 28. The first length L ₁ and the second length L ₂ are unequal, and a phase difference of π radians is provided between the first waveguide and the second waveguide. 23. The optical device according to claim 22, wherein a path length difference that establishes is established. 29. The first length L ₁ and the second length L ₂ are unequal, and π / 2 radian is provided between the first waveguide and the second waveguide. 23. The optical device according to claim 22, wherein a path length difference that establishes the phase difference of the optical device is formed. 30. The optical device according to claim 29, wherein the path length difference is approximately 250 nm. 31. The first waveguide deformation is caused by supplying a positive predetermined voltage to the first actuator, and a negative predetermined voltage is supplied to the second actuator. 30. The optical device according to claim 29, wherein the second waveguide deformation is caused thereby. 32. The optical signal is directed to the first output port,
The first waveguide deformation induces a phase shift of approximately + π / 4 radians in the first waveguide, and the second waveguide deformation causes a phase shift of approximately −π / 4 radians in the second waveguide. 32. The optical device according to claim 31, wherein a shift is induced to cause a phase difference of π radian between the first waveguide structure and the second waveguide structure. 33. The first waveguide deformation is caused by supplying a negative predetermined voltage to the first actuator, and a positive predetermined voltage is supplied to the second actuator. 32. The optical device according to claim 31, wherein the second waveguide deformation is caused thereby. 34. The first waveguide deformation is approximately -π in the first waveguide structure.
The second waveguide deformation induces a phase shift of approximately + π / 4 radians in the second waveguide structure and induces a phase shift of / 4 radians, and the first path established by the path length difference. 34. The light of claim 33, wherein the phase difference of π / 2 radians between the second waveguide and the second waveguide is canceled, thus directing the optical signal to the second output port. device. 35. Substantially equal splits in which the first waveguide and the second waveguide are not deformed so that the optical signal is directed to the first output port and the second output port. The optical device according to claim 31, wherein the optical device is divided into optical signals. 36. The first piezoelectric rib and the second piezoelectric rib have α of 0.
A proportionality constant, K _x and K _y , which is approximately equal to 25, respectively, for the first plurality of mutually orthogonal strain components and the second plurality of mutually orthogonal strains of the first waveguide and the second waveguide, respectively. As a dimensionless coefficient associated with the component, the equation: 32. The optical device of claim 31, having a rib length L [ _{pi] / 4} corresponding to a phase shift of [pi] / 4 radians according to. 37. A first outer edge piezoelectric strip disposed on an outer edge of the first waveguide at a distance substantially equal to the first offset; and 37. 23. The optical device of claim 22, further comprising: a first inner edge piezoelectric strip disposed on an inner edge of the first waveguide at a distance substantially equal to an offset of 1. 38. A second outer edge piezoelectric strip disposed on an outer edge of the second waveguide structure at a distance substantially equal to the second offset; and 38. A second inner edge piezoelectric strip disposed on an inner edge of the second waveguide at a distance substantially equal to a second offset; and including: the first inner edge piezoelectric strip and the second inner edge piezoelectric strip. 38. An optical device according to claim 37, wherein the distance to the strip is substantially in the range between 500 [mu] m and 1,000 [mu] m. 39. The first actuator is a variable voltage source connected to the first piezoelectric rib to provide a voltage proportional to the amount of the optical signal directed to the first output port. The optical device according to claim 5, wherein 40. The optical device of claim 39, wherein the voltage is variable within a continuous range between zero volts and a first predetermined amount of voltage. 41. The optical device of claim 40, wherein zero volts corresponds to maximum attenuation of the optical signal and the first predetermined amount of voltage corresponds to maximum transmission of the optical signal. 42. The method further comprises an etched groove between the first output port and the second output port for mechanically separating the first output port from the second output port. The optical device according to claim 5, wherein: 43. The first length L ₁ and the second length L _{2 are} approximately 200.
The path length difference is μm, and the path length difference is ΔL = L ₁ −L ₂ , and the expression: The optical device according to claim 5, which induces a phase change equal to 44. A first optical signal having a first wavelength is output when the first piezoelectric rib is not activated, and a second wavelength of light is output when the first piezoelectric rib is activated. 44. The second optical signal is output.
The optical device described. 45. An optical signal having a wavelength of λ, a first output port and a second output port, a first core connected to the first output port, a refractive index n and a first length L. ₁ for directing said optical signal to said first output port or said second output port of an optical device in which said optical signal is propagated in a propagation direction by said first core: said first A step of providing a first plurality of piezoelectric ribs for generating first plurality of mutually orthogonal strain components in the waveguide, wherein the first piezoelectric rib comprises the first plurality of mutually orthogonal strain elements. On the first waveguide at a first predetermined offset distance from the first core such that only a first of the components is substantially within the first core. In which the first component is parallel to the propagation direction. ; A second core connected to said second output port for propagating the optical signal in the propagation direction, the refractive index n, the second length L _1, and a second output, the first
Providing a second waveguide disposed adjacent to the first waveguide; and actuating the first piezoelectric ribs, thereby causing a first waveguide deformation to cause the first plurality of orthogonal to each other. Producing a strain component in the first waveguide, the method including: 46. The step of actuating the first piezoelectric rib induces a phase difference of π radians between the first waveguide and the second waveguide. The method described. 47. The optical signal exits the second waveguide when the step of actuating the first piezoelectric rib is not being performed.
The method described. 48. The method according to claim 45, comprising providing a second piezoelectric rib in the second waveguide for generating a second plurality of mutually orthogonal strain components. Two piezoelectric ribs are provided from the second core to the second core such that only the second component of the second plurality of mutually orthogonal strain components is substantially within the second core. Arranging on the second waveguide at a predetermined offset distance such that the second component is parallel to the propagation direction; and actuating the second piezoelectric rib, Producing a second waveguide deformation to produce said second plurality of mutually orthogonal strain components within said second waveguide. 49. Activating the first piezoelectric ribs comprises applying a positive predetermined voltage to the first piezoelectric ribs, and actuating the second piezoelectric ribs comprises: 49. The method of claim 48 including the step of applying a negative predetermined voltage to the second piezoelectric ribs. 50. Activating the first piezoelectric rib establishes a phase shift of approximately + π / 2 radians in the first waveguide structure, and actuating the second piezoelectric rib comprises: 50. The method of claim 49, wherein a phase shift of approximately-[pi] / 2 radians is established in the second waveguide structure. 51. A phase difference of π radians or an odd multiple of π radians is established between the first waveguide and the second waveguide, so that the optical signal is directed to the first output port. 50. The method of claim 49, wherein the method is performed. 52. When the first waveguide and the second waveguide are not deformed, a phase difference is not established between the first waveguide and the second waveguide, and the optical signal 49. The method of claim 48, wherein is directed to the second output port. 53. The first length L ₁ and the second length L ₂ are unequal and approximately π is provided between the first waveguide structure and the second waveguide structure. 49. The method of claim 48, having a path length difference that results in a phase difference of / 2 radians. 54. The step of actuating the first piezoelectric ribs supplies a predetermined positive voltage to the first piezoelectric ribs to drive the optical signal at approximately + π // in the first waveguide structure. 4 radian phase shifts, the step of actuating the second piezoelectric ribs supplying a negative voltage to the second piezoelectric ribs to cause the optical signal to be approximately -π in the second waveguide structure. 54. The method of claim 53 including the step of shifting the phase by / 4 radians. 55. π between the first waveguide structure and the second waveguide structure
There is a phase difference of radian or an odd multiple of π radian, and the optical signal is
55. The method of claim 54, wherein the light is output from the optical device through the waveguide structure of. 56. Activating the first piezoelectric ribs supplies a predetermined negative voltage to the first piezoelectric ribs to drive the optical signal to approximately -π in the first waveguide structure. / 4 radian phase shift, the step of actuating the second piezoelectric rib supplying a positive voltage to the second piezoelectric rib,
54. The method of claim 53 including the step of substantially phase shifting the optical signal in the waveguide structure of + π / 4 radians. 57. The phase difference of π / 2 radians is canceled, there is no phase difference between the first waveguide and the second waveguide, and the optical signal is output by the second output. 57. The method of claim 56, wherein the method is directed to a port. 58. The step of actuating the first piezoelectric rib and the step of actuating the second piezoelectric rib are not performed, so that the optical signal is transmitted to the first output port and the second output port. 54. The method of claim 53, wherein the method is split into substantially equal split optical signals that are each directed to the. 59. A method of fabricating an optical device on a substrate, said optical device being used to direct an optical signal to an object, said method of fabrication comprising: depositing a waveguide core layer on said substrate. Forming a first waveguide from the waveguide core layer, wherein the first waveguide structure comprises a first core, a refractive index n, and a first length L _1. Step; a step of forming a second waveguide from the waveguide core layer, wherein the second waveguide structure includes a second core, the refractive index n, and a second length L ₂ . Such a step; a first predetermined offset distance from the first core that minimizes a birefringence value in the first waveguide, and a first offset on the first waveguide structure. Arranging the piezoelectric ribs, and from the second core to the second waveguide. Arranging a second piezoelectric rib on the second waveguide structure at a second predetermined offset distance that minimizes the birefringence value. 60. The step of disposing a first piezoelectric rib comprises: disposing a first outer edge piezoelectric strip on an outer edge of the first waveguide structure at a distance substantially equal to the first offset. 60. Placing a first inner edge piezoelectric strip on an inner edge of the first waveguide at a distance substantially equal to the first offset, and further comprising: The method described. 61. The step of disposing a second piezoelectric rib comprises: disposing a second outer edge piezoelectric strip on an outer edge of the second waveguide structure at a distance substantially equal to the offset. 61. The method of claim 60, further comprising: and arranging a second inner edge piezoelectric strip on an inner edge of the second waveguide at a distance substantially equal to the offset. 62. Each of the first outer edge piezoelectric strips, the second outer edge piezoelectric strips, the first inner edge piezoelectric strips, and the second inner edge piezoelectric strips is substantially in the range of 50 μm to 200 μm. 62. The method of claim 61, having a width. 63. The method of claim 62, wherein the spacing between the first inner edge piezoelectric strip and the second inner edge piezoelectric strip is substantially in the range of 500 μm to 3,000 μm. 64. The first piezoelectric rib, the second piezoelectric rib, or any one of them is one or more selected from the group consisting of lead zirconate titanate (PZT) and zinc oxide (ZnO). 60. A method according to claim 59, characterized in that it is made from a piezoelectric material made of a substance. 65. The first waveguide structure or the second waveguide structure, or any of these, is made of one or more substances selected from the group consisting of silica, polymers and copolymers. 60. The method of claim 59, wherein the method is made from a material that has been prepared. 66. The first waveguide structure has a first cross-sectional shape and the second waveguide structure
60. The waveguide structure of claim 2 has a second cross-sectional shape, and the first cross-sectional shape and the second cross-sectional shape are square, rectangular, trapezoidal, circular or semi-circular. Method. 67. A first output port and a second output port, the first output port
The first output port of the optical device or the at least one waveguide having at least one core connected to an output port of the optical device, the optical signal propagating in a propagation direction along the at least one waveguide. A method for selectively directing an optical signal to a second output port comprising: directing the optical signal from the first output port by inducing a plurality of mutually orthogonal distortion components in the at least one waveguide. Providing at least one piezoelectric element for switching to the second output port, wherein the at least one piezoelectric element is such that only a first component of the plurality of mutually orthogonal strain components is substantially Disposed on the at least one waveguide at a predetermined location such that it resides in the at least one core, and the first component is A strain component matching the carrying direction; and actuating the at least one piezoelectric element to cause deformation of the at least one waveguide to cause the plurality of mutually orthogonal strain components to move into the at least one Producing in two waveguides;