An integrated electro-optic modulator and method of manufacturing thereof

Abstract

An integrated electro-optic modulator (1) comprising: - an electro-optic layer (11) comprising an electro-optic material being a uniaxial material with an extraordinary axis (110), comprising at least: o a first region (101) in which the extraordinary axis (110) is oriented along a first direction (111); o a second region (102) in which the extraordinary axis (110) is oriented along a second direction (112) opposite to the first direction (111); - a first electrode (21); - a second electrode (22); - a first optical waveguide (31); and - a second optical waveguide (32); and wherein the first optical waveguide (31) and the second optical waveguide (32) are provided between the first electrode (21) and the second electrode (22) along the extraordinary axis (110).

Description

[0001] AN INTEGRATED ELECTRO-OPTIC MODULATOR AND METHOD OF MANUFACTURING THEREOF

[0002] Technical field

[0003]

[0001] The present invention generally relates, amongst others, to an integrated electro-optic modulator and to a method of manufacturing thereof. The present invention further generally relates to an integrated electro-optic modulator comprising an electro-optic material demonstrating the Pockels effect and to a method of manufacturing thereof.

[0004] Background

[0005]

[0002] The Pockels effect, also known as the Pockels electro-optic effect, in optics, is a directionally-dependent linear variation in the refractive index of an optical medium that occurs in response to the application of an electric field. In optical media, the Pockels effect causes changes in birefringence that vary in proportion to the strength of the applied electric field.

[0006]

[0003] When the Pockels effect is used in a uniaxial material, such as for example x-cut lithium niobate, also known as x-cut LN, to create an electro-optic phase modulator, the electric field applied between the electrodes of the electro-optic phase modulator needs to have a specific orientation with reference to the orientation of the crystal axis, also known as the extraordinary axis, of the material of the electro-optic phase modulator such that the modulation achieves the desired phase change. Applying an electric field in the opposite direction induces the opposite phase change in the electro-optic phase modulator. This effect is often used for example in Mach-Zehnder interferometer structures to achieve what is called Push-Pull interaction. The fields are oriented specifically to achieve opposite phase changes in the two arms of the Mach-Zehnder interferometer. This way the total phase change is doubled for a device with the same length where only one arm is experiencing a phase change.

[0007]

[0004] To create high-speed Mach-Zehnder modulators, the electrodes applying the voltage must be designed to support the high-speed electrical signals. There are several conventional designs for such high-speed electrodes. The electrodes are named with a combination of G and S letters signaling the sequence of electrodes that are placed next to each other and whether they function as a Signal (S) or Ground (G) electrode. For example, a GSG electrode consists of a signal electrode carrying the signal accompanied by two ground electrodes, one on each side of the signal electrode. Two other examples are the GSSG and GSGSG electrodes where two signal electrodes each carry opposite but identical signals flanked on each side by a ground electrode and in the case of GSGSG electrodes even with a ground electrode in the middle of the signal electrodes. Fig. 1 illustrates these three conventional electrode designs and how the fields are oriented between them. Note that in the GSSG electrode configuration the voltage between the two signal electrodes is twice that of the voltage between two electrodes in other configurations. In Fig. 1 , the field is depicted but it is the voltage that is doubled, the field still depending on the distance between the electrodes and on the material configuration.

[0008]

[0005] Fig. 2 depicts the same electrodes when creating for example a Mach-Zehnder amplitude modulator using a uniform piece of uniaxial material. In the GSSG case, the electric field and the two arms are oriented in the same direction with reference to the extraordinary axis of the material, resulting in an identical phase change in both arms of the modulators and thus in the lack of phase change between the two arms of the modulators. This design does not work. In the designs with the GSG and GSGSG electrodes the fields in both arms are opposite to each other and thus the phase changes in both arms are opposite and the device functions with a Push-Pull interaction.

[0009]

[0006] It is therefore impossible to use GSSG electrode designs with a uniform uniaxial material and using two signal electrodes and differential signals to achieve Push-Pull interaction. It is also impossible to take advantage of the higher voltage drop between the S+ and S- electrodes in this configuration since both arms would achieve the same phase change and thus no phase difference would be achieved. However, this GSSG design, thanks to its differential electrode configuration, remains interesting for electronics applications as the effective voltage drop is doubled without requiring more power.

[0010] Summary

[0011]

[0007] One could think of placing the waveguide in the strong field region of the GSSG design, in two different ways as shown in Fig. 3, in order to take advantage of the inherent double voltage drop between the S+ and the S- electrodes in GSSG electrode configurations. However, the configuration on the left of Fig. 3, labelled as A with reference number 88, causes an asynchronous phase change which will distort the signal. On the other hand, the configuration on the right of Fig. 3, labelled C with reference number 90, requires twice the driving power.

[0008] The optical and the electrical losses induced in current electro-optic modulators are therefore the current limitations of electro-optic modulators for high-speed applications. Minimizing the electronic losses in the electrodes in the current designs of electro-optic modulators focusses for example on changing the substrate of the chip onto which the electrooptic modulator is manufactured, for example by adopting a high-resistivity silicon substrate, thereby increasing the costs of manufacturing.

[0012]

[0009] It is thus an object of embodiments of the present invention to propose an integrated electro-optic modulator and a method of manufacturing thereof which do not show the inherent shortcomings of the prior art. More specifically, it is an object of embodiments of the present invention to propose an integrated electro-optic modulator which is shorter, faster, experiencing less optical and electrical losses, thereby reducing the voltage required to achieve the desired modulation, or even better reducing the length of the device required to achieve the modulation. It is a further object of embodiments of the present invention to propose a method of manufacturing the integrated electro-optic modulator demonstrating such improved performance.

[0013]

[0010] The scope of protection sought for various embodiments of the invention is set out by the independent claims.

[0014]

[0011] The embodiments and features described in this specification that do not fall within the scope of the independent claims, if any, are to be interpreted as examples useful for understanding various embodiments of the invention.

[0015]

[0012] There is a need for an integrated electro-optic modulator for which the voltage length product of the modulator is reduced, thereby reducing the form factor of the modulator, but more importantly rendering the modulator faster and experiencing less optical and electrical losses, two of which are the current limitations of high-speed electro-optic modulators for, for example, high-speed applications. More particularly, there is a need for an electro-optic modulator with which the double voltage in the GSSG configuration, which is always present in a driver chip of an electro-optic modulator, is exploited to achieve a more efficient modulation.

[0016]

[0013] This object is achieved, according to a first example aspect of the present disclosure, by an integrated electro-optic modulator comprising: - an electro-optic layer comprising an electro-optic material with an extraordinary axis, the electro-optic layer comprising at least: o a first region in which the extraordinary axis is oriented along a first direction; o a second region in which the extraordinary axis is oriented along a second direction opposite to the first direction;

[0017] - a first electrode on top of or below the first region;

[0018] - a second electrode on top of or below the second region;

[0019] - a first optical waveguide on top of or below the first region; and

[0020] - a second optical waveguide on top of or below the second region; and wherein the first optical waveguide and the second optical waveguide are provided between the first electrode and the second electrode along the extraordinary axis.

[0021]

[0014] This object is achieved, according to a first example aspect of the present disclosure, by an integrated electro-optic modulator comprising:

[0022] - an electro-optic layer comprising an electro-optic material being a uniaxial material with an extraordinary axis, the electro-optic layer comprising at least: o a first region in which the electro-optic layer is poled along a first direction of the extraordinary axis; o a second region in which the electro-optic layer is poled along a second direction of the extraordinary axis opposite to the first direction;

[0023] - a first electrode on top of or below the first region;

[0024] - a second electrode on top of or below the second region;

[0025] - a first optical waveguide on top of or below the first region; and

[0026] - a second optical waveguide on top of or below the second region; and wherein the first optical waveguide and the second optical waveguide are provided between the first electrode and the second electrode along the extraordinary axis.

[0027]

[0015] The integrated electro-optic modulator according to the present disclosure takes advantage of the existing conventional driver electronics designs features to reduce the voltage length product of the integrated electro-optic modulator by implementing a design where both waveguides are positioned in-between the two signal electrodes of the GSSG electrode configuration, also referred to as the S+ signal electrode and the S- signal electrode. The voltage length product of the integrated electro-optic modulator according to the present disclosure can be reduced for example 30% or even more. This way, the voltage required to achieve the desired modulation with the integrated electro-optic modulator according to the present disclosure is reduced. Even better, the length of the integrated electro-optic modulator according to the present disclosure required to achieve the modulation is reduced. Reducing the length of the integrated electro-optic modulator is not just a matter of form factor. Shorter electro-optical modulators are indeed faster and experience less optical and electrical losses.

[0028]

[0016] The integrated electro-optic modulator according to the present disclosure comprises at least two waveguides, both waveguides being placed between the S+ and S- electrodes in for example the GSSG electrode configuration of an integrated electro-optic modulator. The phase shift given to the light entering the integrated electro-optic modulator according to the present disclosure is coming from the doubled voltage between the S+ and S- electrodes in for example the GSSG electrode configuration. A first region of the electro-optic material of the integrated electro-optic modulator according to the present disclosure, for example half of the electro-optic layer, is poled such that the extraordinary z-axis, also referred to as extraordinary axis, of the electro-optic material is oriented in the opposite direction with respect to the orientation of the extraordinary z-axis of the electro-optic material in a second region of the electro-optic material of the integrated electro-optic modulator according to the present disclosure, for example the other half of the electro-optic layer. Otherwise, light propagating in both arms of the integrated electro-optic modulator according to the present disclosure would experience the same phase change and no modulation will occur. By choosing the correct waveguide separation as described in more details below, electrode position and etching pattern, for the integrated electro-optic modulator according to the present disclosure, the integrated electro-optic modulator according to the present disclosure becomes more efficient than existing electro-optic modulators.

[0029]

[0017] One would hope to make the integrated electro-optic modulator according to the present disclosure twice as efficient because the voltage is twice as high. However, there is a need for some separation between the waveguides to ensure that light does not couple between the waveguides. The electrodes should also be placed far enough away from the waveguides to ensure no absorption losses are introduced in the design of the integrated electro-optic modulator according to the present disclosure. From initial simulations, the integrated electro-optic modulator according to the present disclosure demonstrates a factor of for example 25-35% improvement in modulation efficiency, referring to the Half-Wave Votlage-Length product, also referred to as VpiL.

[0030]

[0018] With the present disclosure, the integrated electro-optic modulator according to the present disclosure can be for example 30% shorter than most existing design of integrated electro-optic modulator. This is a drastic improvement in terms of speed and loss. How the waveguides and electrodes configurations according to the present disclosure are used in for example a Mach-Zehnder configuration is completely free and could include multimode interferometers or directional couplers, could be balanced or unbalanced, include heaters or not, etc. Some configurations of rings could use the geometry of the modulator as understood in the first example aspect of the disclosure.

[0031]

[0019] In the context of the present disclosure, an electro-optic material is the host of an electro-optic effect, also referred to as electro-optic effect, corresponding to the modification of the optical phase delay, often described with its refractive index, of the electro-optic material, caused by an electric field. In other words, an electro-optic effectis a group of effects that include any interaction between electrical and optical signals. Most devices in electro-optics are based on the linear electro-optic effect, for example for electro-optic modulation and / or for electro-optic sampling, or for example electro-optical modulators relying on plasma dispersion based Si modulators. In the context of the present disclosure, the electro-optic effect of the integrated electro-optic modulator is the Pockels effect. An electro-optic material in the context of the present disclosure has a crystal axis, also known as the extraordinary axis. In a design of an electro-optic phase modulator made out of an elector-optic material in the context of the present disclosure, an electric field applied between the electrodes of the electro-optic phase modulator needs to have a specific orientation with reference to the orientation of the extraordinary axis of the electro-optic material such that the modulation achieves the desired phase change for the light propagating in the electro-optic phase modulator.

[0032]

[0020] In the context of the present disclosure, the integrated electro-optic modulator according to the present disclosure further optionally comprises a substrate. The substrate provides mechanical strength to the integrated electro-optic modulator according to the present disclosure. Substrate removal is a relevant method for improving the Radio-Frequencies properties of the integrated electro-optic modulator according to the present disclosure. The electro-optic layer of the integrated electro-optic modulator according to the present disclosure is provided on top of the substrate, if present. The substrate is for example comprises one or more of the following: photoresist, e-beam resist, polymethyl methacrylate, benzocyclobutene or divynilsiloxane bis-benzocyclobutene, silicon, amorphous silicon, silicon dioxide, silicon nitride, silicon carbide, aluminium oxide, any suitable polymer, lithium niobate, germanium, germanium-on-insulator, lll-V, silicon-on-insulator, glass, any suitable substrate.

[0033]

[0021] In the context of the present disclosure, the integrated electro-optic modulator according to the present disclosure comprises a first region and a second region. The second region is for example contiguous to the first region. Alternatively, the second region is adjacent for example to the first region. In other words, the second region is positioned next to the first region along a longitudinal direction perpendicular to the extraordinary axis of the electro-optic material. In otherwords, the second region touches the first region along an interface extending along for example a plane comprising a longitudinal direction perpendicular to the extraordinary axis of the electro-optic material. Alternatively, the first region and the second region are provided such that a recess extends between the first region and the second region, wherein the recess extends through, thereby exposing at least partially for example an underlying substrate. This recess may for example be filled with a high-K material.

[0034]

[0022] In the context of the present disclosure, the integrated electro-optic modulator according to the present disclosure comprises at least a first optical waveguide and at least a second optical waveguide. The first optical waveguide extends preferably substantially along a longitudinal direction substantially traverse to the extraordinary axis. The second optical waveguide extends preferably substantially along a longitudinal direction substantially traverse to the extraordinary axis. Alternatively, the first optical waveguide extends within 0 to 10° with respect to the longitudinal direction traverse to the extraordinary axis. Alternatively, the second optical waveguide extends within 0 to 10° with respect to the longitudinal direction traverse to the extraordinary axis. The first optical waveguide and the second optical waveguide preferably comprise a straight section extending substantially along the longitudinal direction in the integrated electro-optic modulator according to the present disclosure. The first optical waveguide and the second optical waveguide may comprise one or more non-straight sections in the vicinity of the integrated electro-optic modulator according to the present disclosure. The integrated electro-optic modulator according to the present disclosure comprises a first optical waveguide on top of the first region, and a second optical waveguide on top of the second region. Alternatively, the integrated electro-optic modulator according to the present disclosure comprises a first optical waveguide below the first region, and a second optical waveguide below of the second region. Alternatively, the integrated electro-optic modulator according to the present disclosure comprises a first optical waveguide on top of the first region, and a second optical waveguide below of the second region. Alternatively, the integrated electrooptic modulator according to the present disclosure comprises a first optical waveguide below the first region, and a second optical waveguide on top of the second region. Any of these embodiments of the positions of the first optical waveguide and the second optical waveguide along a traverse direction traverse to the longitudinal direction and to the direction of the extraordinary axis may be combined with any of the embodiments below for the positions of the first electrode and the second electrode along a traverse direction traverse to the longitudinal direction and to the direction of the extraordinary axis.

[0035]

[0023] In the context of the present disclosure, the integrated electro-optic modulator according to the present disclosure comprises a first electrode and a second electrode. The first electrode extends preferably substantially along a longitudinal direction substantially traverse to the extraordinary axis. The second electrode extends preferably substantially along a longitudinal direction substantially traverse to the extraordinary axis. Alternatively, the first electrode extends within 0 to 10° with respect to the longitudinal direction traverse to the extraordinary axis. Alternatively, the second electrode extends within 0 to 10° with respect to the longitudinal direction traverse to the extraordinary axis. The integrated electro-optic modulator according to the present disclosure comprises a first electrode on top of the first region, and a second electrode on top of the second region. Alternatively, the integrated electro-optic modulator according to the present disclosure comprises a first electrode below the first region, and a second electrode below of the second region. Alternatively, the integrated electro-optic modulator according to the present disclosure comprises a first electrode on top of the first region, and a second electrode below of the second region. Alternatively, the integrated electro-optic modulator according to the present disclosure comprises a first electrode below the first region, and a second electrode on top of the second region. Any of these embodiments of the positions of the first electrode and the second electrode along a traverse direction traverse to the longitudinal direction and to the direction of the extraordinary axis may be combined with any of the embodiments above for the positions of the first optical waveguide and the second optical waveguide along a traverse direction traverse to the longitudinal direction and to the direction of the extraordinary axis. The first electrode preferably is in direct contact with the first region. The second electrode preferably is in direct contact with the second region. Alternatively, the first electrode is provided on top of a given thickness of cladding provided on top of the first region. Alternatively, the first electrode is provided below a given thickness of cladding provided below the first region. Alternatively, the first electrode is provided within a given thickness of cladding provided on top of or below the first region. Alternatively, the second electrode is provided on top of a given thickness of cladding provided on top of the second region. Alternatively, the second electrode is provided below a given thickness of cladding provided below the second region. Alternatively, the second electrode is provided within a given thickness of cladding provided on top of or below the second region. The cladding related to the first electrode is preferably identical to the cladding related to the second electrode. Alternatively, the cladding related to the first electrode is different from the cladding related to the second electrode.

[0036]

[0024] In the context of the present disclosure, the integrated electro-optic modulator according to the present disclosure complies with a GSSG design and comprises a first signal electrode and a second signal electrode, the first electrode being the first signal electrode and the second electrode being the second signal electrode. In other words, the first electrode is a S+ electrode, and the second electrode is a S- electrode.

[0025] In the context of the present disclosure, the integrated electro-optic modulator according to the present disclosure comprises a first optical waveguide and a second optical waveguide, both provided between the first electrode and the second electrode along the extraordinary axis. In other words, in the context of the present disclosure, an interface between the first region and the second region along the extraordinary axis separates the first optical waveguide and the second optical waveguide from each other along the extraordinary axis. Alternatively, a recess formed between the first region and the second region along the extraordinary axis separates the first optical waveguide and the second optical waveguide from each other along the extraordinary axis. In the context of the present disclosure, the first optical waveguide and the second optical waveguide are both provided between the first electrode and the second electrode along the extraordinary axis. In other words, an interface and / or a recess between the first region and the second region is interposed along the extraordinary axis between the first optical waveguide and the second optical waveguide. An interface and / or a recess between the first region and the second region, and the first optical waveguide and the second optical waveguide, are interposed along the extraordinary axis between the first electrode and the second electrode.

[0037]

[0026] According to example embodiments, the electro-optic material demonstrates the Pockels effect.

[0038]

[0027] In the context of the present invention, the electro-optic material is a uniaxial material. In the context of the present invention, the electro-optic material comprises a uniaxial material. In the context of the present invention, the electro-optic material comprises one or more of:

[0039] - lithium niobate;

[0040] - doped lithium niobate;

[0041] - lead zirconate titanate;

[0042] - barium titanate;

[0043] - lanthanum-doped lead zirconium titanate;

[0044] - barium borate;

[0045] - strontium titanate;

[0046] - lithium tantalate;

[0047] - potassium titanyl phosphate;

[0048] - aluminium nitride;

[0049] - potassium tantalate niobate;

[0050] - organic electro-optic materials.

[0028] According to example embodiments, the first optical waveguide and the second optical waveguide are formed out of the electro-optic material.

[0051]

[0029] According to example embodiments, the first optical waveguide and the second optical waveguide are provided in one or more of the following:

[0052] - silicon;

[0053] - silicon oxide;

[0054] - silicon nitride;

[0055] - one or more polymer;

[0056] - any electro-optic material and different from the electro-optic material comprised in the electro-optic layer.

[0057]

[0030] According to example embodiments, the electro-optic layer further comprises:

[0058] - one or more additional first regions identical to the first region;

[0059] - one or more additional second regions identical to the second region; and the additional first regions and the additional second regions are positioned alternatingly along the longitudinal direction and such that one of the additional second regions is contiguous to one of the additional first regions.

[0060]

[0031] In the event that coupling of light between the first optical waveguide and the second optical waveguide occurs, it might be needed to alternate the poling of two or more consecutive regions of the electro-optic layer along the longitudinal direction. In other words, the integrated electro-optic modulator may comprise a first region comprising a plurality of first sub-regions and a plurality of second sub-regions, wherein the extraordinary axis is oriented in the first subregions along the first direction and wherein the extraordinary axis is oriented in the second sub-regions along the second direction. The first sub-regions extend as much as the second sub-regions along the longitudinal direction in the first region. The first sub-regions and the second sub-regions alternate in the first region along the longitudinal direction, for example periodically. The integrated electro-optic modulator then further comprises a second region, adjacent or contiguous to the first region, or separated by one or more recesses from the first region, the second region comprising a plurality of first sub-regions and a plurality of second sub-regions, wherein the extraordinary axis is oriented in the first sub-regions along the first direction and wherein the extraordinary axis is oriented in the second sub-regions along the second direction. The first sub-regions extend as much as the second sub-regions along the longitudinal direction in the second region. The first sub-regions and the second sub-regions alternate in the second region along the longitudinal direction, for example periodically, such that a first sub-region of the first region is adjacent or contiguous or separated by a recess from a second sub-region of the second region, and such that the second sub-region adjacent or contiguous to the first sub-region of the first region is adjacent or contiguous or separated by a recess from a first sub-region of the second region, wherein this first sub-region is adjacent or contiguous to the second sub-region of the second region.

[0061]

[0032] According to example embodiments, the second region is contiguous to the first region along an interface; and a distance between the first optical waveguide and the interface is substantially equal to a distance between the second optical waveguide and the interface; and / or a distance between the first electrode and the interface is substantially equal to a distance between the second electrode and the interface.

[0062]

[0033] With this symmetric design, the performance of the integrated electro-optic modulator according to the present disclosure is optimized. Alternatively, the integrated electro-optic modulator must not demonstrate a symmetric design.

[0063]

[0034] According to example embodiments, the first electrode is a signal electrode, and the second electrode is a signal electrode, and the integrated electro-optic modulator further comprises:

[0064] - a first ground electrode positioned on top of or below the first region and on the opposite side of the first electrode than the first optical waveguide along the extraordinary axis; and

[0065] - a second ground electrode positioned on top of or below the second region and on the opposite side of the second electrode than the second optical waveguide along the extraordinary axis.

[0066]

[0035] According to example embodiments, the integrated electro-optic modulator is:

[0067] - a Mach-Zehnder modulator;

[0068] - a loop back phase modulator;

[0069] - a double-back phase modulator;

[0070] - a double-back ring modulator;

[0071] - a loop back phase modulator with more loops;

[0072] - any combination thereof.

[0073]

[0036] Some implementations could include a first waveguide or a second waveguide going back and forth between the same electrodes to create a low voltage low speed phase modulator. Any combinations of the designs above is also possible: double backs with more double backs, Mach Zehnder’s with loop backs or double backs, etc.

[0074]

[0037] According to example embodiments, the electro-optic layer further comprises one or more recesses between the first optical waveguide and the second optical waveguide and / or between the first optical waveguide and the first electrode and / or between the second optical waveguide and the second electrode along the extraordinary axis.

[0075]

[0038] The one or more recesses are for example one or more trenches extending along the longitudinal direction. Thanks to the presence of the recesses, the first waveguide may be provided closer to the second waveguide, while keeping the coupling between the first waveguide and the second waveguide low, but still allowing the electric field to enter the waveguide effectively.

[0076]

[0039] According to example embodiments, the integrated electro-optic modulator further comprises a top cladding.

[0077]

[0040] The use of a top cladding improves the optical confinement of the light in the first optical waveguide and the second optical waveguide, thereby reducing the optical losses and improving the performance of the integrated electro-optic modulator.

[0078]

[0041] According to a second example aspect of the present disclosure, there is provided a method for manufacturing an integrated electro-optic modulator, wherein the method comprises the steps of:

[0079] - providing a first optical waveguide;

[0080] - providing a second optical waveguide;

[0081] - providing an electro-optic layer comprising an electro-optic material with an extraordinary axis, the electro-optic layer comprising at least: o a first region in which the extraordinary axis is oriented along a first direction, wherein the first region is provided on top of or below the first optical waveguide; o a second region in which the extraordinary axis is oriented along a second direction opposite to the first direction, wherein the second region is provided on top of or below the second optical waveguide;

[0082] - providing a first electrode on top of or below the first region;

[0083] - providing a second electrode on top of or below the second region; and wherein the first optical waveguide and the second optical waveguide are provided between the first electrode and the second electrode along the extraordinary axis.

[0084]

[0042] There is provided a method for manufacturing an integrated electro-optic modulator, wherein the method comprises the steps of:

[0085] - providing a first optical waveguide;

[0086] - providing a second optical waveguide;

[0087] - providing an electro-optic layer comprising an electro-optic material being a uniaxial material with an extraordinary axis, the electro-optic layer comprising at least: o a first region in which the electro-optic layer is poled along a first direction of the extraordinary axis, wherein the first region is provided on top of or below the first optical waveguide; o a second region in which the electro-optic layer is poled along a second direction of the extraordinary axis opposite to the first direction, wherein the second region is provided on top of or below the second optical waveguide;

[0088] - providing a first electrode on top of or below the first region;

[0089] - providing a second electrode on top of or below the second region; and wherein the first optical waveguide and the second optical waveguide are provided between the first electrode and the second electrode along the extraordinary axis.

[0090]

[0043] The method according to the present disclosure takes advantage of the existing conventional driver electronics designs features to reduce the voltage length product of the integrated electro-optic modulator by implementing a design where both waveguides are positioned in-between the two signal electrodes of the GSSG electrode configuration, also referred to as the S+ signal electrode and the S- signal electrode. The voltage length product of the integrated electro-optic modulator manufactured with the method according to the present disclosure can be reduced for example 30% or even more. This way, the voltage required to achieve the desired modulation with the integrated electro-optic modulator manufactured with the method according to the present disclosure is reduced. Even better, the length of the integrated electro-optic modulator manufactured with the method according to the present disclosure required to achieve the modulation is reduced. Reducing the length of the integrated electro-optic modulator is not just a matter of form factor. Shorter electro-optical modulators are indeed faster and experience less optical and electrical losses.

[0091]

[0044] The method according to the present disclosure comprises providing at least two waveguides, both waveguides being placed between the S+ and S- electrodes in for example the GSSG electrode configuration of an integrated electro-optic modulator. The phase shift given to the light entering the integrated electro-optic modulator manufactured with the method according to the present disclosure is coming from the doubled voltage between the S+ and S- electrodes in for example the GSSG electrode configuration. A first region, for example half of the electro-optic layer, of the electro-optic material of the integrated electro-optic modulator manufactured with the method according to the present disclosure is poled such that the extraordinary z-axis, also referred to as extraordinary axis, of the electro-optic material is oriented in the opposite direction with respect to the orientation of the extraordinary z-axis of the electro-optic material in a second region, for example the other half of the electro-optic layer, of the electro-optic material of the integrated electro-optic modulator manufactured with the method according to the present disclosure. Otherwise, light propagating in both arms of the integrated electro-optic modulator manufactured with the method according to the present disclosure would experience the same phase change and no modulation will occur. By choosing the correct waveguide separation as described in more details below, electrode position and etching pattern, for the integrated electro-optic modulator manufactured with the method according to the present disclosure, the integrated electro-optic modulator manufactured with the method according to the present disclosure becomes more efficient than existing electro-optic modulators.

[0092]

[0045] According to example embodiments, the method further comprises the step of providing one or more poling electrodes on top of the electro-optic layer; and the step of providing the second region comprises the step of applying electrical signals to the poling electrodes, thereby producing an electric field across the electro-optic material of the electro-optic layer and inverting the orientation of the extraordinary axis of the electro-optic material resulting in the formation of the second region.

[0093]

[0046] This way, the first region and the second region are formed from the same electro-optic material within the same electro-optic layer. The electro-optic layer is provided and the poling from the electrodes inverts the orientation of the extraordinary axis of the electro-optic material resulting in the formation of the second region.

[0094]

[0047] Alternatively, the method of manufacturing the integrated electro-optic modulator according to the present disclosure comprises providing a first region of electro-optic material in which the extraordinary axis is oriented along a first direction, providing a second region of electro-optic material identical to the electro-optical material of the first region, wherein the extraordinary axis of the second region is oriented along the first direction of the extraordinary axis, poling the second region to invert the orientation of the extraordinary axis of the electrooptic material in the second region to a second direction opposite to the first direction, and arranging the first region and the second region adjacent to each other, for example using micro-transfer printing, or such that the first region and the second region are contiguous or such that the first region and the second region are separated by one or more recesses along the longitudinal direction of the formed integrated electro-optic modulator. Alternatively, the poling electrodes on the second region may be stripped before arranging the second region next to the first region.

[0095]

[0048] According to example embodiments, the method further comprises the step of stripping the poling electrodes from the electro-optic layer prior to providing a first electrode and a second electrode.

[0096]

[0049] The poling electrodes may be bulky and may cause additional electronic losses to the electro-optic modulator. Stripping the poling electrodes prior to manufacturing the electro-optic modulator saves space and minimizes the electronic losses.

[0097]

[0050] According to example embodiments, the method further comprises the step of cladding the first optical waveguide and / or the second optical waveguide with a high-K material.

[0098]

[0051] Using a long sought after high-K material as a cladding for the optical waveguide, such as for example a material with relatively low refractive index but relatively high dielectric constant, would probably allow further improvement of the performance of the integrated electro-optic modulator. There are some demonstrations with polymers that show improvements in this regard, and for example Hafnium Oxide also seems to be a material of interest for this.

[0099]

[0052] Just like capacitors, electric fields prefer to propagate in low-K materials. However, it is important to have the electric field distributed over the waveguide and not the cladding of the integrated electro-optic modulator to improve its performance. One or more recesses, for example trenches extending along the longitudinal direction, allow placing the first electrode and the second electrode closer by increasing the confinement of the electric field. The use of a low-K cladding is not efficient since the electric field gets confined more in the cladding that in the first waveguide or the second waveguide. With high-K claddings, it becomes possible to increase the efficiency without introducing more losses in the integrated electro-optic modulator. The one or more recesses previously described may be filled with high-K material.

[0053] According to a fourth example aspect of the present disclosure, there is provided a semiconductor device comprising the electro-optic modulator according to a first example aspect of the present disclosure and manufactured using the method according to a third example aspect of the present disclosure.

[0100]

[0054] In the context of the present disclosure, a semiconductor device can therefore comprise one or more of the following: silicon, silicon nitride, silicon oxide, lithium niobate, one or more lll-V semiconductor material such as for example InP, GaN, GaP, one or more ll-VI semiconductor material, other devices based on these thin films, any polymer, any dielectric.

[0101]

[0055] In the context of the present disclosure, a semiconductor device can be an electronic device and / or an optical device. For example, a semiconductor device is a photodetector, a laser, an electro-optic modulator, a mirror, a pump, an amplifier, a grating, a waveguide, etc.

[0102]

[0056] The current disclosure in addition also relates to a computer program comprising software code adapted to perform the method according to the present disclosure. The current disclosure further relates to a computer readable storage medium comprising the computer program according to the present disclosure. The current disclosure further relates to a computer readable storage medium comprising computer-executable instructions which, when executed by a computing system, perform the method according to the present disclosure.

[0103] Brief Description of the Drawings

[0104]

[0057] Some example embodiments will now be described with reference to the accompanying drawings.

[0105]

[0058] Fig. 1 depicts a top view of prior art example embodiment of electrode configurations for an electro-optic modulator.

[0106]

[0059] Fig. 2 depicts a top view of prior art example embodiment of electrode configurations for an electro-optic modulator.

[0107]

[0060] Fig. 3 depicts a top view of prior art example embodiment of electrode configurations for an electro-optic modulator.

[0061] Fig. 4A depicts a side view of an example embodiment of an integrated electro-optic modulator according to the present disclosure. Fig. 4B depicts a top view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0108]

[0062] Fig. 5A depicts a side view of an example embodiment of an integrated electro-optic modulator according to the present disclosure. Fig. 5B depicts a top view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0109]

[0063] Fig. 6 depicts a top view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0110]

[0064] Fig. 7 depicts a side view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0111]

[0065] Fig. 8 depicts a side view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0112]

[0066] Fig. 9 depicts a side view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0113]

[0067] Fig. 10A depicts a side view of an example embodiment of an integrated electro-optic modulator according to the present disclosure. Fig. 10B depicts a top view of an example embodiment of an integrated electro-optic modulator according to the present disclosure.

[0114]

[0068] Fig. 11 depicts a top view of an example embodiment of a Mach-Zehnder layout of an integrated electro-optic modulator according to the present disclosure.

[0115]

[0069] Fig. 12 depicts a top view of an example embodiment of a loop back phase layout of an integrated electro-optic modulator according to the present disclosure.

[0116]

[0070] Fig. 13 depicts a top view of an example embodiment of a loop back phase layout with more loops of an integrated electro-optic modulator according to the present disclosure.

[0117]

[0071] Fig. 14 depicts a top view of an example embodiment of a double-back phase layout of an integrated electro-optic modulator according to the present disclosure.

[0072] Fig. 15 depicts a top view of an example embodiment of a double-back phase layout of an integrated electro-optic modulator according to the present disclosure.

[0118] Detailed Description of Embodiment(s)

[0119]

[0073] Fig. 1 schematically depicts a top view of prior art example embodiment of electrode configurations for an electro-optic modulator. Fig. 1 illustrates three conventional electrode designs, GSG in A referenced as 81 , GSSG in B referenced as 82, GSGSG in C referenced as 83, and how the fields are oriented between them. Note that in the GSSG electrode configuration the voltage between the two signal electrodes is twice that of the voltage between two electrodes in other configurations. In Fig.1 , the field 84 is depicted but it is the voltage that is doubled, the field still depending on the distance between the electrodes and on the material configuration. The arrows indicate the orientation of the electrical fields if the applied voltages are positive to S and S+, and therefore negative to S-. In the GSSG configuration in B referenced 82, the field 84 is stronger than in the other configurations.

[0120]

[0074] Fig. 2 depicts the same electrodes when creating for example a Mach-Zehnder amplitude modulator using a uniform piece of uniaxial material. In the GSSG case, the electric field and the two arms are oriented in the same direction with reference to the extraordinary axis of the material, resulting in an identical phase change in both arms of the modulators and thus in the lack of phase change between the two arms of the modulators. This design does not work. In the designs with the GSG and GSGSG electrodes the fields in both arms are opposite to each other and thus the phase changes in both arms are opposite and the device functions with a Push-Pull interaction.

[0121]

[0075] One could think of placing the waveguide in the strong field region of the GSSG design, in two different ways as shown in Fig. 3, in order to take advantage of the inherent double voltage drop between the S+ and the S- electrodes in GSSG electrode configurations. However, the configuration on the left of Fig. 3 causes an asynchronous phase change which will distort the signal and the configuration on the right of Fig. 3 requires twice the driving power.

[0122]

[0076] Fig. 4A schematically depicts a side view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111 . A first electrode 21 is provided on top of the first region 101. A second electrode 22 is provided on top of the second region 102. A first optical waveguide 31 is provided on top of the first region 101. A second optical waveguide 32 is provided on top of the second region 102. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11 . The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. Fig. 4B schematically depicts a top view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 positioned on top the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode 42 positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110.

[0123]

[0077] Fig. 5A schematically depicts a side view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111 . A first electrode 21 is provided on top of the first region 101. A second electrode 22 is provided on top of the second region 102. A first optical waveguide 31 is provided below the first region 101. A second optical waveguide 32 is provided below the second region 102. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11 . The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. Fig. 5B schematically depicts a top view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 positioned on top of the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode 42 positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110.

[0124]

[0078] Fig. 6 schematically depicts a top view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111. The electro-optic layer 11 further comprises one or more additional first regions 141 ; 151 ; 161 identical to the first region 101 in which the extraordinary axis 110 is oriented along a first direction 111. The electro-optic layer 11 further comprises one or more additional second regions 142; 152; 162 identical to the second region 102 in which the extraordinary axis 110 is oriented along a second direction 112. The additional first regions 141 ;151 ;161 and the additional second regions 142;152;162 are positioned alternatingly along the longitudinal direction 220 and such that one of the additional second regions 142; 152; 162 is contiguous or adjacent to one of the additional first regions 141 ;151 ;161. A first electrode 21 is provided on top of the first region 101 and at least one more of the additional first regions 141 ;151 ;161 . A second electrode 22 is provided on top of the second region 102 and at least one more of the additional second regions 142; 152; 162. A first optical waveguide 31 is provided below or on top of the first region 101 and at least one more of the additional first regions 141 ; 151 ; 161. A second optical waveguide 32 is provided below or on top of the second region 102 and at least one more of the additional second regions 142; 152; 162. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11 . The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 positioned on top of the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode 42 positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110.

[0125]

[0079] Fig. 7 schematically depicts a side view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111 . A first electrode 21 is provided below the first region 101. A second electrode 22 is provided below the second region 102. A first optical waveguide 31 is provided on top of the first region 101 . A second optical waveguide 32 is provided on top of the second region 102. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11 . The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. The integrated electro-optic modulator 1 further optically comprises a first ground electrode positioned on top the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110.

[0126]

[0080] Fig. 8 schematically depicts a side view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111. The first region 101 and the second region 102 are separated from each other along the extraordinary axis by a gap 71 , or recess 71. In other words, the first region 101 and the second region 102 do not contact each other. A first electrode 21 is provided on top of the first region 101 . A second electrode 22 is provided on top of the second region 102. A first optical waveguide 31 is provided on top of the first region 101. A second optical waveguide 32 is provided on top of the second region 102. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11. The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. The integrated electro-optic modulator 1 further comprises a first ground electrode positioned on top the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110.

[0127]

[0081] Fig. 9 schematically depicts a side view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111. The first region 101 and the second region 102 are separated from each other along the extraordinary axis by a gap 71 , or recess 71. In other wors, the first region 101 and the second region 102 do not contact each other. The recess 71 or gap 71 formed between the first region 101 and the second region 102 is filled with a cladding 70, for example a cladding comprising a high-K material. A first electrode 21 is provided on top of the first region 101. A second electrode 22 is provided on top of the second region 102. A first optical waveguide 31 is provided on top of the first region 101. A second optical waveguide 32 is provided on top of the second region 102. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The cladding 70 also extends between the first electrode 21 and the second electrode 22, thereby cladding the first optical waveguide 31 and the second optical waveguide 32. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11 . The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. The integrated electro-optic modulator 1 further comprises a first ground electrode positioned on top the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110.

[0128]

[0082] Fig. 10A schematically depicts a side view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises an electro-optic layer 11 comprising an electro-optic material with an extraordinary axis 110. The integrated electro-optic modulator 1 optionally comprises a substrate 10 onto which the electro-optic layer 11 is provided. The electro-optic layer 11 comprising at least a first region 101 in which the extraordinary axis 110 is oriented along a first direction 111 and a second region 102 in which the extraordinary axis 110 is oriented along a second direction 112 opposite to the first direction 111. A first electrode 21 is provided on top of the first region 101. A second electrode 22 is provided on top of the second region 102. A first optical waveguide 31 is provided on top of the first region 101. A second optical waveguide 32 is provided on top of the second region 102. The first optical waveguide 31 and the second optical waveguide 32 are provided between the first electrode 21 and the second electrode 22 along the extraordinary axis 110. The electro-optic material demonstrates the Pockels effect. The first optical waveguide 31 extends substantially along a longitudinal direction 220 traverse to the extraordinary axis 110 and wherein the second optical waveguide 32 extends substantially along the longitudinal direction 220. The first electrode 21 and the second electrode 22 extend substantially along the longitudinal direction 220. The first optical waveguide 31 and the second optical waveguide 32 are formed out of a material different from the electro-optic material of the electro-optic layer 11 . The second region 102 is contiguous to the first region 101 along an interface; and a distance between the first optical waveguide 31 and the interface is substantially equal to a distance between the second optical waveguide 32 and the interface; and / or a distance between the first electrode 21 and the interface is substantially equal to a distance between the second electrode 22 and the interface. The first electrode 31 is a signal electrode, and the second electrode 32 is a signal electrode. Fig. 10B schematically depicts a top view of an example embodiment of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 positioned on top the first region 101 and on the opposite side of the first electrode 21 than the first optical waveguide 31 along the extraordinary axis 110; and a second ground electrode 42 positioned on top of the second region 102 and on the opposite side of the second electrode 22 than the second optical waveguide 32 along the extraordinary axis 110. A cladding 70 is provided on top of the electro-optic layer 11 and between the first electrode 21 and the second electrode 22, thereby cladding the first optical waveguide 31 and the second optical waveguide 32. Three recesses 33;34;35 visible on Fig. 10A and Fig. 10B, more particularly three trenches 33;34;35 extending along the longitudinal direction 220 are provided: the trench 33 extending between the first electrode 21 and the first optical waveguide 31 along the extraordinary axis 110, the trench 34 positioned between the first region 101 and the second region 102, the trench 35 extending between the first electrode 22 and the first optical waveguide 33 along the extraordinary axis 110. The three trenches 33;34;35 are formed within the electro-optic layer 11 .

[0129]

[0083] Fig. 11 depicts a top view of an example embodiment of a Mach-Zehnder layout of an integrated electro-optic modulator 1 according to the present disclosure. The integrated electro-optic modulator 1 comprises a first electrode 21 , a second electrode 22, a first optical waveguide 31 and the second optical waveguide 32. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 and a second ground electrode 42.

[0130]

[0084] Fig. 12 depicts a top view of an example embodiment of a loop back phase layout of an integrated electro-optic modulator according to the present disclosure. The integrated electro-optic modulator 1 comprises a first electrode 21 , a second electrode 22, a first optical waveguide 31 and the second optical waveguide 32. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 and a second ground electrode 42.

[0131]

[0085] Fig. 13 depicts a top view of an example embodiment of a loop back phase layout with more loops of an integrated electro-optic modulator according to the present disclosure. The integrated electro-optic modulator 1 comprises a first electrode 21 , a second electrode 22, a first optical waveguide 31 and the second optical waveguide 32. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 and a second ground electrode 42.

[0086] Fig. 14 depicts a top view of an example embodiment of a double-back phase layout of an integrated electro-optic modulator according to the present disclosure. The integrated electro-optic modulator 1 comprises a first electrode 21 , a second electrode 22, a first optical waveguide 31 and the second optical waveguide 32. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 and a second ground electrode 42.

[0132]

[0087] Fig. 15 depicts a top view of an example embodiment of a double-back phase layout of an integrated electro-optic modulator according to the present disclosure. The integrated electro-optic modulator 1 comprises a first electrode 21 , a second electrode 22, a first optical waveguide 31 and the second optical waveguide 32. The integrated electro-optic modulator 1 further comprises a first ground electrode 41 and a second ground electrode 42.

[0133]

[0088] Although the present invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied with various changes and modifications without departing from the scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the scope of the claims are therefore intended to be embraced therein.

[0134]

[0089] It will furthermore be understood by the reader of this patent application that the words "comprising" or "comprise" do not exclude other elements or steps, that the words "a" or "an" do not exclude a plurality, and that a single element, such as a computer system, a processor, or another integrated unit may fulfil the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned. The terms "first", "second", third", "a", "b", "c", and the like, when used in the description or in the claims are introduced to distinguish between similar elements or steps and are not necessarily describing a sequential or chronological order. Similarly, the terms "top", "bottom", "over", "under", and the like are introduced for descriptive purposes and not necessarily to denote relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the invention are capable of operating according to the present invention in other sequences, or in orientations different from the one(s) described or illustrated above.

Claims

- 27 -CLAIMS1 . An integrated electro-optic modulator (1) comprising:- an electro-optic layer (11) comprising an electro-optic material being a uniaxial material with an extraordinary axis (110), the electro-optic layer (11) comprising at least: o a first region (101) in which the electro-optic layer (11) is poled along a first direction (111) of the extraordinary axis (110); o a second region (102) in which the electro-optic layer (11) is poled along a second direction (112) of the extraordinary axis (110) opposite to the first direction (111);- a first electrode (21) on top of or below the first region (101);- a second electrode (22) on top of or below the second region (102);- a first optical waveguide (31) on top of or below the first region (101); and- a second optical waveguide (32) on top of or below the second region (102); and wherein the first optical waveguide (31) and the second optical waveguide (32) are provided between the first electrode (21) and the second electrode (22) along the extraordinary axis (110).

2. The integrated electro-optic modulator (1) according to claim 1 , wherein the electrooptic material demonstrates the Pockels effect.

3. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the first optical waveguide (31) extends substantially along a longitudinal direction (220) traverse to the extraordinary axis (110) and wherein the second optical waveguide (32) extends substantially along the longitudinal direction (220).

4. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the first electrode (21) and the second electrode (22) extend substantially along the longitudinal direction (220).

5. The integrated electro-optic modulator (1) according to any of claims 1 to 4, wherein the first optical waveguide (31) and the second optical waveguide (32) are formed out of a material different from the electro-optic material of the electro-optic layer (11).

6. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the electro-optic layer (11) further comprises:- one or more additional first regions (141 ;151 ; 161) identical to the first region (101);- one or more additional second regions (142; 152; 162) identical to the second region (102);and wherein the additional first regions (141 ;151 ;161) and the additional second regions (142; 152; 162) are positioned alternatingly along the longitudinal direction (220) and such that one of the additional second regions (142; 152; 162) is contiguous to one of the additional first regions (141 ;151 ; 161).

7. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the second region (102) is contiguous to the first region (101) along an interface; and wherein a distance between the first optical waveguide (31) and the interface is substantially equal to a distance between the second optical waveguide (32) and the interface; and / or wherein a distance between the first electrode (21) and the interface is substantially equal to a distance between the second electrode (22) and the interface.

8. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the first electrode (31) is a signal electrode, and wherein the second electrode (32) is a signal electrode, and wherein the integrated electro-optic modulator (1) further comprises:- a first ground electrode (41) positioned on top of or below the first region (101) and on the opposite side of the first electrode (21) than the first optical waveguide (31) along the extraordinary axis (110); and- a second ground electrode (42) positioned on top of or below the second region (102) and on the opposite side of the second electrode (22) than the second optical waveguide (32) along the extraordinary axis (110).

9. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the integrated electro-optic modulator (1) is:- a Mach-Zehnder modulator;- a loop back phase modulator;- a double-back phase modulator;- a double-back ring modulator;- a loop back phase modulator with more loops;- any combination thereof.

10. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the electro-optic layer (11) further comprises one or more recesses between the first optical waveguide (31) and the second optical waveguide (32) and / or between the first optical waveguide (31) and the first electrode (21) and / or between the second optical waveguide (32) and the second electrode (22) along the extraordinary axis (110).

11. The integrated electro-optic modulator (1) according to any of the preceding claims, wherein the integrated electro-optic modulator (1) further comprises a top cladding (70).

12. A method of manufacturing an integrated electro-optic modulator (1), wherein the method comprises the steps of:- providing a first optical waveguide (31);- providing a second optical waveguide (32);- providing an electro-optic layer (11) comprising an electro-optic material being a uniaxial material with an extraordinary axis (110), the electro-optic layer (11) comprising at least: o a first region (101) in which the electro-optic layer (11) is poled along a first direction (111) of the extraordinary axis (110), wherein the first region (101) is provided on top of or below the first optical waveguide (31); o a second region (102) in which the electro-optic layer (11) is poled along a second direction (112) of the extraordinary axis (110) opposite to the first direction (111), wherein the second region (102) is provided on top of or below the second optical waveguide (32);- providing a first electrode (21) on top of or below the first region (101);- providing a second electrode (22) on top of or below the second region (102); and wherein the first optical waveguide (31) and the second optical waveguide (32) are provided between the first electrode (21) and the second electrode (22) along the extraordinary axis (110).

13. The method according to claim 12, wherein the method further comprises the step of providing one or more poling electrodes (201 ;202) on top of the electro-optic layer (11); and wherein the step of providing the second region (102) comprises the step of applying electrical signals to the poling electrodes (201 ;202), thereby producing an electric field across the electro-optic material of the electro-optic layer (11) and inverting the orientation of the extraordinary axis (110) of the electro-optic material resulting in the formation of the second region (102).

14. The method according to claim 13, wherein the method further comprises the step of stripping the poling electrodes (201 ;202) from the electro-optic layer (11) prior to providing a first electrode (21) and a second electrode (22).

15. The method according to any of the claims 12 to 14, wherein the method further comprises the step of cladding the first optical waveguide (31) and / or the second optical waveguide (32) with a high-K material.

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