An ultra-compact right-angled bend waveguide modulator based on phase change material

Abstract

The application discloses an ultra-compact right-angle bending waveguide modulator based on a phase change material, belongs to the technical field of photoelectric modulation, and solves the problem of how to design a bending waveguide photoelectric modulator with good modulation performance and small floor area; a right-angle is inverted at the outer right-angle bending of a right-angle bending silicon waveguide; one side of a cuboid vanadium dioxide is closely attached to a plane formed by the inverted right-angle; when the cuboid vanadium dioxide works in a metal phase, a mirror structure is formed on the plane formed by the inverted right-angle at the outer right-angle bending of the right-angle bending silicon waveguide, so that the transmittance of an input optical signal at the bending is enhanced; when the cuboid vanadium dioxide works in a semiconductor phase, the input optical signal leaks into the cuboid vanadium dioxide at the outer right-angle of the right-angle bending silicon waveguide, and the transmittance of the input optical signal at the outer right-angle of the right-angle bending silicon waveguide is very low due to huge bending loss; the structure of the application is extremely simple, easy to realize, and the floor area of a modulation layer can reach nanometer level.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optoelectronic modulation, and relates to an ultra-compact right-angle bent waveguide modulator based on a phase change material. BACKGROUND

[0002] Optoelectronic modulators with high modulation efficiency and nanoscale size are important components of photonic communication networks, as they connect electrical signals with optical data. Silicon optical modulators have become a research hotspot in recent decades due to their high device integration, negligible propagation loss, fast transmission speed, and large data carrying capacity.

[0003] To date, a large number of silicon optical modulators have been developed. They exhibit good performance in terms of modulation depth and modulation speed. Surface phonons generated and propagated between the metal and dielectric interfaces can compress light to far below the diffraction limit, making it possible to reduce the size of the device to subwavelength size. In addition, as a surface wave, the characteristics of surface phonons are closely related to the dielectric parameters of the interface material. This means that a strong electro-optic coefficient can be obtained by replacing silicon with a phase change material.

[0004] Vanadium dioxide is a solid-state phase change material that exhibits a transition from a semiconductor phase to a metal phase under certain conditions, resulting in a large refractive index contrast at a working wavelength of 1.55 μm, with a semiconductor phase refractive index of n = 3.24 + 0.3i and a metal phase refractive index of n = 2.03 + 2.64i. The phase change of vanadium oxide can be induced by doping, thermal excitation (68℃), high electric field (6.5×107 V / m), optical excitation, and strain engineering. The outstanding phase change performance and various methods of achieving refractive index changes make vanadium oxide a choice for modulators with shorter device lengths and higher modulation efficiency.

[0005] Depending on the actual application, ultra-fast modulation time, ultra-low control power, ultra-high modulation efficiency, and ultra-compact footprint are the most important four performance indicators of optoelectronic modulators. In recent years, there have been great advances in the research of optoelectronic modulators in terms of device structure, modulation performance, and trigger modulation methods. However, the problem of balancing the footprint and modulation performance of the modulator still needs to be addressed. SUMMARY

[0006] The technical problem to be solved by the application is how to design a bent waveguide optoelectronic modulator with good modulation performance and small footprint.

[0007] The application solves the above technical problems by the following technical solutions:

[0008] The application discloses an ultra-compact right-angle bending waveguide modulator based on phase change material, which comprises, from top to bottom, a silica upper cladding layer (1), a modulation layer (2), a silica buried layer (3) and a silicon substrate layer (4); the modulation layer (2) comprises a metal electrode (21), a silica adhesive layer (22), a cuboid vanadium dioxide (23) and a right-angle bending silicon waveguide (24); the outer right-angle bending of the right-angle bending silicon waveguide (24) is straight-chamfered, and one side of the cuboid vanadium dioxide (23) is closely attached to a plane formed by the straight-chamfering; the silica adhesive layer (22) is attached to the upper surface of the wedge-shaped vanadium dioxide (231), and the metal electrode (21) is arranged on the upper surface of the silica adhesive layer (22) and used for loading a rectangular pulse voltage signal.

[0009] The modulator of the application adopts a cuboid vanadium dioxide (23) and a right-angle bending silicon waveguide (24), the outer right-angle bending of the right-angle bending silicon waveguide (24) is straight-chamfered, and one side of the cuboid vanadium dioxide (23) is closely attached to a plane formed by the straight-chamfering; when the cuboid vanadium dioxide (23) works in a metal phase, a mirror structure is formed on the plane formed by the straight-chamfering of the outer right-angle bending of the right-angle bending silicon waveguide (24), so that the transmittance of the input optical signal at the bending is enhanced; when the cuboid vanadium dioxide (23) is in a semiconductor phase, the input optical signal leaks into the cuboid vanadium dioxide (23) at the outer right-angle bending of the right-angle bending silicon waveguide (24), and the transmittance of the input optical signal at the outer right-angle bending of the right-angle bending silicon waveguide (24) is very low due to the huge bending loss; the structure of the application is extremely simple and easy to process and realize, the footprint of the modulation layer can reach nanometer level, and the application has great potential in the construction of on-chip fast optical communication networks.

[0010] Further, when the rectangular pulse voltage signal is in a low level state, the cuboid vanadium dioxide (23) is in a metal phase, a mirror structure is formed on the plane formed by the straight-chamfering of the outer right-angle bending of the right-angle bending silicon waveguide (24), so that the transmittance of the input optical signal at the bending is enhanced, and at this time, the modulator is in an "on" state; when the rectangular pulse voltage signal is in a high level state, the cuboid vanadium dioxide (23) is in a semiconductor phase, the input optical signal leaks into the cuboid vanadium dioxide (23) at the outer right-angle bending of the right-angle bending silicon waveguide (24), and the transmittance of the input optical signal at the outer right-angle bending of the right-angle bending silicon waveguide (24) is very low due to the huge bending loss, and at this time, the modulator is in an "off" state.

[0011] Further, the silica upper cladding layer (1) is processed with grooves matching the modulation layer (2), the modulation layer (2) is covered by the silica upper cladding layer (1) in the grooves, the lower surface of the modulation layer (2) is arranged on the upper surface of the silica buried layer (3), the modulation layer (2) is clamped between the silica upper cladding layer (1) and the silica buried layer (3), and the lower surface of the silica buried layer (3) is attached to the upper surface of the silicon substrate layer (4).

[0012] Further, the upper surface of the metal electrode (21) is flush with the upper surface of the silica upper cladding layer (1), and the metal electrode (21) is exposed outside.

[0013] Further, the inner right angle of the right-angle curved silicon waveguide (24) is curved into a rounded angle.

[0014] Further, the thickness of the cuboid vanadium dioxide (23) is the same as the thickness of the right-angle curved silicon waveguide (24).

[0015] The advantages of the present application are as follows:

[0016] The modulator of the present application adopts a cuboid vanadium dioxide (23) and a right-angle curved silicon waveguide (24), the outer right-angle of the right-angle curved silicon waveguide (24) is curved into a rounded angle, one side of the cuboid vanadium dioxide (23) is tightly attached to the plane formed by the rounded angle; when the cuboid vanadium dioxide (23) works in a metal phase, a mirror structure is formed on the plane formed by the rounded angle of the outer right-angle of the right-angle curved silicon waveguide (24), thereby enhancing the transmittance of the input optical signal at the curved position; when the cuboid vanadium dioxide (23) is in a semiconductor phase, the input optical signal leaks into the cuboid vanadium dioxide (23) at the outer right-angle of the right-angle curved silicon waveguide (24), and at the same time, the transmittance of the input optical signal at the outer right-angle of the right-angle curved silicon waveguide (24) is very low due to the huge bending loss; the structure of the present application is extremely simple and easy to process and realize, the footprint of the modulation layer can be in the order of nanometers, and has great potential in the construction of on-chip fast optical communication networks. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the front perspective view of the super-compact right-angle curved waveguide modulator structure based on phase change material of the embodiment of the present application;

[0018] Figure 2 is the exploded view of the super-compact right-angle curved waveguide modulator structure based on phase change material of the embodiment of the present application;

[0019] Figure 3 is the front view of the modulation layer structure of the super-compact right-angle curved waveguide modulator of the embodiment of the present application;

[0020] Figure 4 is a top view of a modulation layer structure of a phase change material based ultra-compact right-angle bent waveguide modulator according to an embodiment of the present application;

[0021] Figure 5 is a working principle diagram of a modulation of a phase change material based ultra-compact right-angle bent waveguide modulator according to an embodiment of the present application;

[0022] Figure 6 is a top view of simulated optical characteristics of a phase change material based ultra-compact right-angle bent waveguide modulator according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings and specific embodiments of the present application. Obviously, the described embodiments are some, but not all of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0024] The technical solutions of the present application will be further described below in conjunction with the accompanying drawings and specific embodiments of the present application:

[0025] Embodiment one

[0026] As shown in Figures 1 to 4 , a phase change material based ultra-compact right-angle bent waveguide modulator comprises: a silica upper cladding layer 1, a modulation layer 2, a silica buried layer 3, and a silicon substrate layer 4. The modulation layer 2 comprises: a metal electrode 21, a silica adhesion layer 22, a cuboid vanadium dioxide 23, and a right-angle bent silicon waveguide 24.

[0027] The silica upper cladding layer 1 is processed with a groove matched with the modulation layer 2. The modulation layer 2 is coated in the groove by the silica upper cladding layer 1. The lower surface of the modulation layer 2 is arranged on the upper surface of the silica buried layer 3. The modulation layer 2 is clamped between the silica upper cladding layer 1 and the silica buried layer 3. The lower surface of the silica buried layer 3 is attached to the upper surface of the silicon substrate layer 4.

[0028] As shown in Figure 2 and Figure 3 , the upper surface of the metal electrode 21 is flush with the upper surface of the silica upper cladding layer 1. The metal electrode 21 is exposed outside. The metal electrode 21 is used for loading a rectangular pulse voltage signal. The silica adhesion layer 22 is pasted on the upper surface of the cuboid vanadium dioxide 23. The metal electrode 21 is arranged on the upper surface of the silica adhesion layer 22.

[0029] As shown in Figure 4As shown in the figure, the inner right angle of the right-angle curved silicon waveguide 24 is rounded, and the outer right angle of the right-angle curved silicon waveguide 24 is 45° chamfered; the width of the right-angle curved silicon waveguide 24 is 450 nm, and the thickness of the cuboid vanadium dioxide 23 is the same as the thickness of the right-angle curved silicon waveguide 24, both being 220 nm; one side of the cuboid vanadium dioxide 23 is in close contact with the plane of the 45° chamfered outer right angle of the right-angle curved silicon waveguide 24.

[0030] As shown in the figure, the dashed line represents a rectangular pulse voltage loaded on the metal electrode 21, and the solid line represents an outgoing end optical signal of the modulator. Figure 5

[0031] The working principle of the modulator

[0032] The modulator described in the embodiment works at a transverse electric mode 1550 nm wavelength, and has two states of “on” and “off” when a rectangular pulse voltage is connected to the metal electrode 21 due to the phase transition characteristics of vanadium dioxide under electrical excitation. When the rectangular pulse voltage is in a low level state, the cuboid vanadium dioxide 23 is in a metal phase, and a mirror structure is formed on the plane of the 45° chamfered outer right angle of the right-angle curved silicon waveguide 24, thereby enhancing the transmittance of the input optical signal at the curved portion, and at this time, the modulation layer 2 is in the “on” state; when the rectangular pulse voltage is in a high level state, the cuboid vanadium dioxide 23 is in a semiconductor phase, the input optical signal leaks into the cuboid vanadium dioxide 23 at the outer right angle of the right-angle curved silicon waveguide 24, and at the same time, the transmittance of the input optical signal at the outer right angle of the right-angle curved silicon waveguide 24 is very low due to the huge bending loss, at this time, the modulation layer 2 is in the “off” state.

[0033] As shown in the figure, the dashed line represents a rectangular pulse voltage loaded on the metal electrode 21, and the solid line represents an outgoing end optical signal of the modulator. Figure 6 As shown in the figure, the dashed line represents a rectangular pulse voltage loaded on the metal electrode 21, and the solid line represents an outgoing end optical signal of the modulator.

[0034] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.​

Claims

1. An ultra-compact right-angled bend waveguide modulator based on phase change material, characterized in that, The application relates to a modulator, which comprises: a silica upper cladding layer (1), a modulation layer (2), a silica buried layer (3) and a silicon substrate layer (4) which are stacked in sequence from top to bottom; the modulation layer (2) comprises a metal electrode (21), a silica adhesion layer (22) and a cuboid vanadium dioxide (23), and a right-angle curved silicon waveguide (24); the silica upper cladding layer (1) is processed with a groove matched with the modulation layer (2), the modulation layer (2) is covered in the groove by the silica upper cladding layer (1), the lower surface of the modulation layer (2) is arranged on the upper surface of the silica buried layer (3), the modulation layer (2) is clamped between the silica upper cladding layer (1) and the silica buried layer (3), and the lower surface of the silica buried layer (3) is attached to the upper surface of the silicon substrate layer (4); the inner right-angle of the right-angle curved silicon waveguide (24) is rounded, the outer right-angle of the right-angle curved silicon waveguide (24) is chamfered at 45 degrees, and one side of the cuboid vanadium dioxide (23) is tightly attached to the plane of the outer right-angle of the right-angle curved silicon waveguide (24) which is chamfered at 45 degrees; the silica adhesion layer (22) is pasted on the upper surface of the cuboid vanadium dioxide (23), and the metal electrode (21) is arranged on the upper surface of the silica adhesion layer (22) and used for loading a rectangular pulse voltage signal; the modulator works at a transverse electric mode 1550nm wavelength, when the rectangular pulse voltage signal is in a low level state, the cuboid vanadium dioxide (23) is in a metal phase, a mirror structure is formed on the plane formed by rounding the outer right-angle of the right-angle curved silicon waveguide (24), so that the transmittance of the input light signal at the curved position is enhanced, and at this time, the modulator is in an "on" state; when the rectangular pulse voltage signal is in a high level state, the cuboid vanadium dioxide (23) is in a semiconductor phase, the input light signal leaks into the cuboid vanadium dioxide (23) at the outer right-angle of the right-angle curved silicon waveguide (24), and at the same time, due to the huge bending loss, the transmittance of the input light signal at the outer right-angle of the right-angle curved silicon waveguide (24) is very low, and at this time, the modulator is in an "off" state.

2. The phase change material based ultra-compact right-angled bend waveguide modulator according to claim 1, characterized in that, the upper surface of the metal electrode (21) is flush with the upper surface of the silica upper cladding layer (1), and the metal electrode (21) is exposed outside.

3. The phase change material based ultra-compact right-angled bend waveguide modulator according to claim 1, characterized in that, the inner right-angle of the right-angle curved silicon waveguide (24) is curved to form a rounded corner.

4. The phase change material based ultra-compact right-angled bend waveguide modulator according to claim 1, characterized in that, the thickness of the cuboid vanadium dioxide (23) is the same as the thickness of the right-angle curved silicon waveguide (24).

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