Optical switching device based on germanium-antimony phase change material

Abstract

The application discloses a kind of optical switch devices based on germanium antimony phase change material, the overall structure of the optical switch device is five layers, from bottom to top in turn is substrate, waveguide dielectric layer, waveguide protection layer, phase change layer and top protection layer.The material of the phase change layer of the optical switch device is germanium antimony phase change material, chemical formula is Ge x Sb 100‑x Wherein 10≤x≤30.The crystallization temperature of the germanium antimony phase change material is higher than 230 DEG C, and the amorphous thermal stability is good, and the optical constant difference between amorphous state and crystalline state is large, and the transmittance difference is more than 50%, and the optical contrast is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phase change optical switch devices, and particularly relates to an optical switch device based on a germanium-antimony phase change material. BACKGROUND

[0002] There is a significant difference in optical properties between the amorphous phase and the crystal phase of the phase change material, and the difference has good adjustability. The change can be used to regulate the intensity and phase of optical signals, so that the phase change material has great application potential in the field of optics, and can be used in optical switches, optical phase change memories, display devices, filters and other new optical applications. The phase change material can be integrated into an optical waveguide to form an optical switch. The switching between the amorphous state and the crystal state of the phase change material unit can realize the on-off control of the transmission signal in the integrated optical system.

[0003] At present, the traditional optical switch is mainly a mechanical control optical switch, and the switching rate is in the millisecond level, which is not conducive to high-speed optical applications, and the device has a large volume, which is not conducive to large-scale integration. Compared with the traditional optical switch, the switching speed of the phase change optical switch is faster, which can reach nanoseconds, and the device has a small volume. The phase change optical switch can realize non-volatile programming, and the static power consumption is almost zero. However, the current phase change optical switch is mainly based on the traditional phase change material germanium-antimony-tellurium, and still has problems such as insufficient optical contrast and low stability.

[0004] Sb is a typical phase change material, which has a superfast crystallization speed, which can reach the order of picoseconds, and has a large optical contrast window, and has great potential in optical switch applications. However, the amorphous thermal stability of Sb is low, and crystallization easily occurs in the actual application of the chip, thereby causing the optical switch to fail. Previous studies have shown that reducing the thickness of the Sb functional layer to 5 nm can effectively improve the amorphous thermal stability, but this method will also significantly reduce the optical contrast window, resulting in a very low switching ratio. At the same time, the over-thin functional layer will significantly increase the production cost. Therefore, it is necessary to improve the thermal stability of the amorphous phase while maintaining a large optical contrast window. SUMMARY

[0005] In order to overcome the defects of the prior art, the present application provides an optical switch device based on a germanium-antimony phase change material. The device uses germanium-doped antimony material for alloying. The germanium element can effectively inhibit the crystallization behavior of antimony within a specific proportion range, greatly improve the amorphous thermal stability of the material, and maintain a sufficient optical contrast window.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0007] The application discloses a kind of germanium antimony phase change material-based optical switch device, the overall structure of the optical switch device is five layers, from bottom to top in turn is substrate, waveguide medium layer, waveguide protection layer, phase change layer and top protection layer, the material of the phase change layer is germanium antimony phase change material, chemical formula is Ge x Sb 100-x Wherein 10≤x≤30, x is the atomic percentage of elements.

[0008] The germanium antimony phase change material is prepared by doping germanium elements in antimony thin film, and the doping amount is 10% to 30% of the total amount of germanium and antimony. The crystallization temperature of the thin film is higher than 230 DEG C, and the amorphous thermal stability is good, which effectively improves the thermal stability of the optical switch device.

[0009] The germanium antimony phase change material has a refractive index and an extinction coefficient greater than that of the amorphous phase in the optical communication wavelength band of 1530-1565 nm, so that the transmittance difference between the crystal phase and the amorphous phase is more than 50%, effectively improving the switching ratio of the optical switch device.

[0010] The switching between the amorphous phase and the crystal phase of the germanium antimony phase change material is realized by external excitation, which includes heating, light pulse or electric pulse.

[0011] The device unit length of the optical switch device is 1-50 μm; the waveguide medium layer is a ridge waveguide, and the thickness of the waveguide medium layer is 10-300 nm, and the width is 10-1000 nm.

[0012] The thickness of the waveguide protection layer is 5-150 nm.

[0013] The thickness of the phase change layer is 2-100 nm; the thickness of the top protection layer is 5-100 nm; and the length of the phase change layer and the top protection layer is 0.5-20 μm.

[0014] The material of the substrate is one of SiO2 and Si; the material of the waveguide medium layer is one of Si and Si3N4; and the materials of the waveguide protection layer and the top protection layer are one of SiO2 and ITO.

[0015] The preparation method of the phase change layer includes but is not limited to magnetron sputtering, vacuum evaporation, atomic layer deposition and chemical vapor deposition. When the phase change layer is in amorphous phase, the extinction coefficient of the germanium antimony phase change material is low, the transmittance of the device is high, the device is in open state, and the incident light normally passes through;

[0016] When the phase change layer is in crystal phase, the extinction coefficient of the germanium antimony phase change material is high, the transmittance of the device is low, the device is in closed state, the incident light is blocked, and the transmittance difference between the amorphous phase and the crystal phase of the device is more than 50%.

[0017] The amorphous phase and the crystal phase of the phase change layer are switched by external excitation, which includes but is not limited to laser pulse, electrical pulse or heating.

[0018] The optical switch device is used for the transmission or switching of optical signals.

[0019] The optical switch device is used for optical sensing systems, integrated photonic memories, optical switches in fiber communication systems or signal receivers and transmitters in time-division systems, modulators.

[0020] The present application has the following advantages:

[0021] The present application provides an optical switch device based on germanium-antimony phase change material, wherein the crystallization speed of the germanium-antimony phase change material as a functional layer reaches several nanoseconds, and the amorphization speed is in the order of picoseconds, and the switching speed of the optical switch device is much faster than the millisecond order of traditional mechanical optical switch devices. At the same time, the optical constants of the amorphous and crystalline states of the germanium-antimony phase change material are quite different, and the transmittance contrast of the optical switch device to the optical signal exceeds 50%, which is much higher than that of traditional mechanical optical switch devices.

[0022] The present application provides an optical switch device based on germanium-antimony phase change material, wherein the crystallization temperature and amorphous stability of the germanium-antimony phase change material as a functional layer are significantly improved compared with Sb, reaching more than 230 DEG C, which is much higher than the ~ 150 DEG C of traditional phase change material germanium-antimony tellurium, and has excellent thermal stability. The transmittance contrast of the optical signal under the crystal and amorphous phase of germanium-antimony tellurium is about 40%, and the germanium-antimony material can improve it to more than 50%. In addition, the optical switch device provided by the present application has simple structure and compact size, which can effectively improve the integration density of the chip, and its preparation process is compatible with the existing CMOS process, and is easy to mass-produce. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a phase change optical switch device.

[0024] Figure 2 It is a resistance-temperature curve of germanium-antimony phase change material.

[0025] Figure 3 It is a curve of the refractive index n of germanium-antimony phase change material in amorphous state and crystalline state with wavelength.

[0026] Figure 4 It is a curve of the extinction coefficient k of germanium-antimony phase change material in amorphous state and crystalline state with wavelength.

[0027] Figure 5 It is the transmittance spectrum of the germanium-antimony optical switch device in amorphous state (on state) and crystalline state (off state).

[0028] Figure 6The simulated electric field intensity distribution of the Ge-Sb optical switch device in amorphous state (on state).

[0029] Figure 7 The simulated electric field intensity distribution of the Ge-Sb optical switch device in crystalline state (off state). DETAILED DESCRIPTION

[0030] The application will be further described in detail below with reference to the accompanying drawings.

[0031] Figure 1 The structural schematic diagram of the phase-change optical switch device. The device is sequentially from bottom to top 1-substrate, 2-waveguide medium layer, 3-waveguide protective layer, 4-phase-change layer and 5-top protective layer.

[0032] Figure 2 The resistance-temperature curve of the Ge-Sb phase-change material. The deposited thin film is in amorphous state and has high resistance value. With the temperature rising at a rate of 10 ℃ / min, the resistance of the amorphous thin film linearly decreases with the temperature rising. When the temperature rises to about 270 ℃, the resistance rapidly decreases, indicating that the thin film starts to crystallize. After heating to 400 ℃ and cooling to room temperature, the thin film is in crystalline state and has low resistance value. The resistance change window between the amorphous state and the crystalline state is large.

[0033] Figure 3 The curves of the refractive index n of the Ge-Sb phase-change material in amorphous state and crystalline state changing with wavelength. In the wavelength range of 200-935 nm, the refractive index n of the amorphous state is greater than that of the crystalline state. In the wavelength range of 935-2100 nm, the refractive index n of the amorphous state is less than that of the crystalline state.

[0034] Figure 4 The curves of the extinction coefficient k of the Ge-Sb phase-change material in amorphous state and crystalline state changing with wavelength. In the wavelength range of 200-280 nm, the extinction coefficient k of the amorphous state is greater than that of the crystalline state. In the wavelength range of 280-2100 nm, the extinction coefficient k of the amorphous state is less than that of the crystalline state. The greater the extinction coefficient k, the stronger the absorption of the optical signal, and the lower the transmittance of the device. The difference of the extinction coefficient between the amorphous state and the crystalline state of Ge-Sb is large in the communication waveband (1530-1565 nm).

[0035] Figure 5 The transmittance spectrum of the Ge-Sb optical switch device when the phase-change layer is in amorphous state and crystalline state. The transmittance is defined as the ratio of the output optical power to the input optical power. When the phase-change layer is in amorphous state, the absorption is low, the transmittance is high, and the optical switch is in on state. When the phase-change layer is in crystalline state, the absorption is high, the transmittance is low, and the optical switch is in off state. The transmittance difference window between the amorphous state and the crystalline state is over 50%.

[0036] Figure 6The simulation electric field intensity distribution of Ge-Sb optical switch device in amorphous state (on state). The TE mode (λ=1550nm) is used, and the electric field intensity distribution is |E|(x, y). The higher the electric field intensity is, the higher the optical signal intensity is. When the Ge-Sb phase change material is in amorphous state, the transmittance is high, the optical signal is normally transmitted through the waveguide, and the optical switch is in on state.

[0037] Figure 7 The simulation electric field intensity distribution of Ge-Sb optical switch device in crystalline state (off state). The TE mode (λ=1550nm) is used, and the electric field intensity distribution is |E|(x, y). When the Ge-Sb phase change material is in crystalline state, the transmittance is low, the optical signal transmission in the waveguide is interrupted, and the optical switch is in off state.

[0038] The present application is further illustrated below by taking specific examples as examples.

[0039] Example 1

[0040] This example is based on Ge 15 Sb 85 optical switch device.

[0041] The Ge 15 Sb 85 phase change material has a crystallization temperature of about 270℃.

[0042] The Ge 15 Sb 85 based phase change material optical switch device structure is shown in Figure 1 , and the specific device structure is:

[0043] (1) The material selection of each layer of the device is: the substrate is SiO2; the waveguide medium layer is Si; the waveguide protection layer is SiO2; the phase change layer is Ge 15 Sb 85 ; and the top protection layer is ITO.

[0044] (2) The waveguide medium layer is a ridge waveguide, the center thickness of the waveguide medium layer is 220nm, the center width is 450nm, and the thickness of both sides is 70nm; the thickness of the waveguide protection layer is 150nm; the thickness of the phase change layer is 20nm, and the length is 2μm; the thickness of the top protection layer is 20nm, and the length is 2μm.

[0045] (3) The light source uses TE mode, the incident direction is along the x direction of the waveguide, and the boundary conditions of x, y and z directions are all set as perfect matching layer.

[0046] The Ge 15 Sb 85The optical switch device of the phase change material, when the phase change layer is in amorphous state, the absorption is low, the transmittance is close to 60%, the optical signal is normally transmitted through the waveguide, and the optical switch is in open state; when the phase change layer is in amorphous state, the absorption is high, the transmittance is less than 10%, the transmission of the optical signal in the waveguide is interrupted, and the optical switch is in closed state. The transmittance difference window between the amorphous state and the crystalline state is more than 50%, and the Ge 15 Sb 85 The switching between the amorphous state and the crystalline state of the phase change layer can realize the on-off control of the transmitted optical signal.

[0047] Embodiment 2

[0048] This embodiment is based on Ge 20 Sb 80 The optical switch device of the phase change material.

[0049] The Ge 20 Sb 80 The crystallization temperature of the phase change material is about 290°C.

[0050] The Ge 20 Sb 80 The structure of the optical switch device of the phase change material is shown in Figure 1 The specific device structure is as follows:

[0051] (1) The material selection of each layer of the device is as follows: the substrate is SiO2; the waveguide medium layer is Si; the waveguide protection layer is SiO2; the phase change layer is Ge 15 Sb 85 ; and the top protection layer is ITO.

[0052] (2) The waveguide medium layer is a ridge waveguide, the center thickness of the waveguide medium layer is 220 nm, the center width is 450 nm, and the thickness of both sides is 70 nm; the thickness of the waveguide protection layer is 150 nm; the thickness of the phase change layer is 30 nm, and the length is 2 μm; the thickness of the top protection layer is 20 nm, and the length is 2 μm.

[0053] (3) The light source adopts TE mode, the incident direction is along the x direction of the waveguide, and the boundary conditions of x, y and z directions are all set as perfect matching layer.

[0054] The Ge 20 Sb 80 The optical switch device of the phase change material, when the phase change layer is in amorphous state, the absorption is low, the transmittance is close to 60%, the optical signal is normally transmitted through the waveguide, and the optical switch is in open state; when the phase change layer is in amorphous state, the absorption is high, the transmittance is less than 10%, the transmission of the optical signal in the waveguide is interrupted, and the optical switch is in closed state. The transmittance difference window between the amorphous state and the crystalline state is more than 50%, and the Ge 20 Sb 80The switching between amorphous and crystalline states of the phase change layer can inhibit the switching control of the transmitted optical signal.

Claims

1. An optical switch device based on germanium antimony phase change material, characterized in that: The overall structure of the optical switch device comprises five layers, which are, from bottom to top, a substrate (1), a waveguide dielectric layer (2), a waveguide protection layer (3), a phase change layer (4), and a top protection layer (5). The material of the phase change layer (4) is a germanium antimony phase change material, and the chemical formula is Ge x Sb 100-x , where 10≤x≤30, and x is the atomic percentage of the element.

2. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: The germanium-antimony phase change material is prepared by doping germanium into an antimony film, with the doping amount being 10% to 30% of the total germanium-antimony content. The crystallization temperature of the film is higher than 230° C., effectively improving the thermal stability of the optical switch device.

3. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: In the optical communication band of 1530-1565nm, the refractive index and extinction coefficient of the crystalline phase of the germanium antimony phase change material are greater than those of the amorphous phase, and the transmittance difference between the crystalline phase and the amorphous phase exceeds 50%, effectively improving the switching ratio of the optical switch device.

4. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: The switching between the amorphous phase and the crystalline phase of the germanium antimony phase change material is achieved by external excitation, which includes heating, light pulse or electric pulse.

5. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: The device unit length of the optical switch device is 1 to 50 μm; the waveguide medium layer (2) is a ridge waveguide, the thickness of the waveguide medium layer (2) is in the range of 10 to 300 nm, and the width is in the range of 10 to 1000 nm; The thickness of the waveguide protection layer (3) ranges from 5 to 150 nm; The thickness of the phase change layer (4) ranges from 2 to 100 nm; the thickness of the top protective layer (5) ranges from 5 to 100 nm; and the lengths of the phase change layer (4) and the top protective layer (5) range from 0.5 to 20 μm.

6. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: The material of the substrate (1) is one of SiO2 and Si materials, the material of the waveguide dielectric layer (2) is one of Si and Si3N4 materials, and the material of the waveguide protection layer (3) and the top protection layer (5) is one of SiO2 and ITO materials.

7. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: The preparation method of the phase change layer (4) includes but is not limited to magnetron sputtering, vacuum evaporation, atomic layer deposition, and chemical vapor deposition.

8. The optical switch device based on germanium antimony phase change material according to claim 1, characterized in that: When the phase change layer (4) is in an amorphous phase, the extinction coefficient of the germanium antimony phase change material is low, the transmittance of the device is high, and the device is in an open state, and incident light passes normally; When the phase change layer (4) is in a crystalline phase, the extinction coefficient of the germanium antimony phase change material is high, the transmittance of the device is low, the device is in a closed state, the incident light is blocked, and the difference in device transmittance between the amorphous phase and the crystalline phase exceeds 50%; The phase change layer switches between the amorphous phase and the crystalline phase by external excitation, and the external excitation includes but is not limited to laser pulses, electrical pulses or heating.

9. Application of an optical switch device based on germanium antimony phase change material according to any one of claims 1 to 8, characterized in that: The optical switch device is used for transmission or switching of optical signals.

10. Application of an optical switch device based on germanium-antimony phase change material according to any one of claims 1 to 8, characterized in that: The optical switch device is used for an optical sensor system, an integrated photon memory, an optical switch in an optical fiber communication system, or a signal receiver, transmitter, and modulator in a time segmentation system.

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