Device for increasing extinction ratio of optical switch and optical switch chip

Abstract

The utility model relates to the technical field of optical communication, in particular to a device for increasing the extinction ratio of an optical switch and an optical switch chip. The device comprises at least two variable optical attenuators which are respectively arranged at at least two output ports of an optical switch, are connected with the output ports and are used for attenuating optical signals output by the output ports in the closed state in the optical switch when the connected output ports are in the closed state and are in a working state; or the at least two optical amplifiers are respectively arranged at the at least two output ports of the optical switch, are connected with the output ports and are used for amplifying the optical signals output by the output ports in the open state in the optical switch when the connected output ports are in the open state and are in the working state. According to the device, the light energy output from the output port in the closed state is reduced, or the light energy output from the output port in the open state is increased, so that the extinction ratio of the optical switch is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of optical communication, and particularly relates to a device for increasing the extinction ratio of an optical switch and an optical switch chip. Background Art

[0002] With the rapid development of the Internet and intelligent terminals, the demand for large data volume transmission has also shown an explosive growth. However, traditional electrical interconnections are limited by their high power consumption and high loss, and cannot meet the requirements of large data capacity and high-speed transmission. To solve the "bottleneck" problem of electrical interconnections, light, as a new information carrier, has gradually replaced electricity in interconnection scenarios. Compared with electrical interconnections, optical interconnections can achieve high-speed modulation of signals, greatly reducing the signal delay in interconnections, and there is no crosstalk between signals of different frequencies, nor is it affected by external electromagnetic interference. Therefore, optical interconnection is a solution with bright prospects. Silicon is a mature electronics material and has been widely used in the preparation of large-scale integrated circuit chips. At the same time, silicon is also an ideal optical material and is almost completely transparent to light in the communication band. Therefore, the concept of silicon-based optical interconnection was proposed, using silicon complementary metal oxide semiconductor technology to fabricate both photonic and electronic devices on silicon materials to achieve miniaturization, low cost, and high-performance large-scale optoelectronic integrated circuits, and ultimately achieve high-speed and broadband interconnections.

[0003] In optical interconnection, the optical switch is its core device, which has a wide range of applications in optical information exchange and signal processing, with the advantages of small size, low power consumption, faster response speed, and lower driving voltage. Studying silicon-based integrated optical switch technology is of great significance for building a future all-optical high-speed optical communication network. The optical switch has one or more selectable transmission windows and can perform mutual conversion or logical operations on optical signals in optical transmission lines or integrated optical paths. The basic form of the optical switch includes a 2×2 optical switch, that is, there are two optical fibers at both the input end and the output end, and two connection states, parallel connection and cross connection, can be completed. Larger optical switch arrays can be formed by cascading and combining basic 2×2 optical switches and corresponding 1×2 optical switches. The working principle of the optical switch is to change the refractive index of the waveguide at a specific position, which can change the phase of the transmitted light, and then control the transmission path of light in the waveguide device. For silicon-based optical switches, the thermo-optic effect and the plasma dispersion effect are mainly used, and the corresponding switching units are thermo-optic and electro-optic switches respectively.

[0004] Integrating a single optical switch into an N×N large-scale high-speed optical switch array can realize multi-port information exchange functions, which is of great significance for both optical fiber communication systems and on-chip integration. However, in an optical switch, when light is output from an output port in the open state, there will be some light output from the output port in the closed state, and the light output from the output port in the closed state becomes noise, thereby reducing the extinction ratio of the optical switch. Summary of the Utility Model

[0005] In view of this, an embodiment of the present invention provides a device for increasing the extinction ratio of an optical switch and an optical switch chip, so as to solve the problem of low extinction ratio of the optical switch in the prior art.

[0006] The technical solution provided by the embodiment of the present invention is as follows:

[0007] A first aspect of an embodiment of the present invention provides a device for increasing the extinction ratio of an optical switch. The optical switch includes at least two output ports. The device includes: at least two variable optical attenuators, which are respectively arranged at at least two output ports of the optical switch and are connected to the output ports, and are used for being in a working state when the connected output ports are in a closed state, and attenuating the optical signal output from the output ports of the optical switch that are in the closed state; or at least two optical amplifiers, which are respectively arranged at at least two output ports of the optical switch and are connected to the output ports, and are used for being in a working state when the connected output ports are in an open state, and amplifying the optical signal output from the output ports of the optical switch that are in the open state.

[0008] For the device for increasing the extinction ratio of the optical switch provided in this embodiment, by arranging a variable optical attenuator or an optical amplifier at the output port of the optical switch, when the variable optical attenuator is arranged, the variable optical attenuator connected to the output port of the optical switch in the closed state is in a working state, and the optical signal output from the output port of the optical switch in the closed state is attenuated; when the optical amplifier is arranged, the optical amplifier connected to the output port of the optical switch in the open state is in a working state, and the optical signal output from the output port of the optical switch in the open state is amplified. Thus, the device realizes that the optical energy output from the output port in the closed state is reduced, or the optical energy output from the output port in the open state is increased, thereby realizing an increase in the extinction ratio of the optical switch.

[0009] In an optional embodiment, the optical attenuator is a variable optical attenuator prepared from a semiconductor material.

[0010] In this embodiment, the variable optical attenuator is a variable optical attenuator prepared from a semiconductor material. Thus, it is convenient to integrate the variable optical attenuator and the optical switch on the same chip.

[0011] In an optional embodiment, the variable optical attenuator includes a waveguide and P-type and N-type regions on both sides of the waveguide. The waveguide is used to receive externally input carriers, so that the variable optical attenuator is in a working state.

[0012] In this embodiment, by setting the structure of the variable optical attenuator, when the variable optical attenuator is working, an external voltage is applied to the PN junction or PIN structure to control the concentration distribution of carriers (electrons and holes), change the optical properties of the waveguide region, such as the change in the absorption coefficient, and then adjust the light intensity passing through the waveguide. This makes the variable optical attenuator have the advantages of fast response rate and low power consumption, meeting the development trend of high-speed and green silicon-based photon integration.

[0013] In an alternative embodiment, the variable optical attenuator is further configured to be in a non-operating state or at the minimum value of the adjustable range when the connected output port is in an open state.

[0014] In this embodiment, when the output port of the optical switch is an open output port, the variable optical attenuator connected to this output port is in a non-operating state or at the minimum value of the adjustable range, so that the optical power output from the open output port remains almost unchanged, ensuring normal optical power output and improvement of the extinction ratio.

[0015] In an alternative embodiment, the optical amplifier is an optical amplifier prepared from semiconductor materials.

[0016] In this embodiment, the optical amplifier is an optical amplifier prepared from semiconductor materials. Thus, it is convenient to integrate the optical amplifier and the optical switch on the same chip.

[0017] In an alternative embodiment, the optical amplifier includes a stacked P-type layer, an active layer, and an N-type layer, and the active layer is used to receive externally input carriers to make the optical amplifier in an operating state.

[0018] In this embodiment, through the setting of the optical amplifier structure, the optical amplifier can realize the injection of electrons and holes by injecting current during operation, and realize optical amplification by electrons jumping from the high-energy conduction band to the low-energy valence band.

[0019] In an alternative embodiment, the optical amplifier is further configured to be in a non-operating state when the connected output port is in a closed state, and attenuate the optical signal output from the closed output port.

[0020] In this embodiment, when the output port of the optical switch is a closed output port, the optical amplifier connected to this output port is in a non-operating state. Since the semiconductor material itself has certain light absorption characteristics, in the case where there is no current injection into the optical amplifier of the closed output port (i.e., this optical amplifier is in a non-operating state), there will be some losses such as absorption and scattering when photons pass through the optical amplifier, which will lead to the attenuation of the light intensity. Thus, by making the optical amplifier of the closed output port in a non-operating state, the ratio of the light intensity of the open output port to the leakage light intensity output from the closed output port can be further increased.

[0021] In an alternative embodiment, when multiple optical switches form an optical switch array, a tunable optical attenuator is provided at the output port of each optical switch in the optical switch array, or an optical amplifier is provided at the output port of each optical switch in the optical switch array.

[0022] In this embodiment, by providing a tunable optical attenuator or an optical amplifier in the optical switch array, the effects of reducing optical leakage and improving the extinction ratio can also be achieved in application scenarios such as data transmission and high-performance computing.

[0023] The second aspect of the embodiment of the present utility model provides an optical switch chip, an optical switch, and a device for increasing the extinction ratio of the optical switch according to the first aspect and any one of the first aspects of the embodiment of the present utility model. The optical switch and the device are integrated on the same chip.

[0024] In this embodiment, by integrating the tunable optical attenuator or the optical amplifier in the device and the optical switch on the same chip, the optical switch chip can not only achieve the purpose of increasing the extinction ratio of the optical switch, but also has the advantages of simple structure, good stability, and easy integration.

[0025] The third aspect of the embodiment of the present utility model provides a method for increasing the extinction ratio of an optical switch. The optical switch includes at least two output ports. The method includes: respectively providing a connection to a tunable optical attenuator at at least two output ports of the optical switch. When the output port connected to the tunable optical attenuator is in a closed state, controlling the corresponding tunable optical attenuator to be in an operating state to attenuate the optical signal output from the closed output port of the optical switch; or respectively providing a connection to an optical amplifier at at least two output ports of the optical switch. When the output port connected to the optical amplifier is in an open state, controlling the corresponding optical amplifier to be in an operating state to amplify the optical signal output from the open output port of the optical switch. Description of the Drawings

[0026] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic structural diagram of an optical switch in the prior art;

[0028] Figure 2 It is a structural block diagram of a device for increasing the extinction ratio of an optical switch in an embodiment of the present utility model;

[0029] Figure 3 It is a schematic diagram of the principle of an adjustable optical attenuator in an embodiment of the present utility model;

[0030] Figure 4 It is a schematic diagram of the principle of a semiconductor optical amplifier in an embodiment of the present utility model;

[0031] Figure 5 It is a structural block diagram of a device for increasing the extinction ratio of an optical switch in another embodiment of the present utility model;

[0032] Figure 6 It is a structural block diagram of a device for increasing the extinction ratio of an optical switch for an optical switch array in an embodiment of the present utility model;

[0033] Figure 7 It is a structural block diagram of a device for increasing the extinction ratio of an optical switch in another embodiment of the present utility model;

[0034] Figure 8 It is a structural block diagram of a device for increasing the extinction ratio of an optical switch for an optical switch array in another embodiment of the present utility model. Specific embodiments

[0035] As in the background art, there is a problem of low extinction ratio in optical switches. For example, for Figure 1For the shown 2×2 optical switch, when the first output port 21 of the optical switch is set to the "on" state and the output port 2 is set to the "off" state, ideally, when a light beam is input from the input end, the light beam should be completely output from the first output port 21, and there is no light output from the second output port 22. However, in actual situations, due to problems such as device structure, process errors in the manufacturing process, and bias regulation, in the optical switch, when the input light is output from the set first output port 21, a part of the light will leak into the output path corresponding to the second output port 22 and be output from the second output port 22 in the closed state, thus resulting in the problem of "incomplete on and incomplete off". At this time, this part of the leaked light becomes noise, and larger noise will deteriorate the bit error rate of the system signal transmission. The ratio of the optical power output when the optical switch is in the on state to the optical power output when it is in the off state is the extinction ratio. The larger the extinction ratio, the better the performance of the optical switch, and the smaller the impact of the leaked light on the performance of the optical switch device, which is particularly important for the application of the optical switch.

[0036] The optical switch is the functional core of the optical interconnection system, and its performance will directly affect the performance of the entire device. Moreover, a high-performance optical switch requires a relatively complex structure and more external control ports. Optimizing the optical switch is an important way to improve the overall performance of the system, and this problem will become more prominent with the increase in the number of ports, causing noise superposition of different optical switches and restricting the development of silicon-based optical switch array chips towards larger ports. Therefore, how to improve the extinction ratio of the optical switch has become an important problem to be solved urgently at present.

[0037] In view of this, this embodiment provides a device for increasing the extinction ratio of an optical switch. By setting an adjustable optical attenuator or an optical amplifier at the output port of the optical switch, when the adjustable optical attenuator is set, the adjustable optical attenuator connected to the output port in the closed state of the optical switch is in the working state to attenuate the optical signal output from the output port in the closed state of the optical switch; when the optical amplifier is set, the optical amplifier connected to the output port in the open state of the optical switch is in the working state to amplify the optical signal output from the output port in the open state of the optical switch. Thus, this device realizes a reduction in the optical energy output from the output port in the closed state or an increase in the optical energy output from the output port in the open state, thereby realizing an increase in the extinction ratio of the optical switch.

[0038] Next, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0040] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0041] In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0042] An embodiment of the present utility model provides a device for increasing the extinction ratio of an optical switch, as Figure 2 shown. The optical switch includes at least two output ports. The device includes: at least two variable optical attenuators, which are respectively arranged at at least two output ports of the optical switch and are connected to the output ports. When the connected output port is in the closed state, the corresponding connected variable optical attenuator is in the working state to attenuate the optical signal output from the output port of the optical switch in the closed state; or at least two optical amplifiers, which are respectively arranged at at least two output ports of the optical switch and are connected to the output ports. When the connected output port is in the open state, the corresponding connected optical amplifier is in the working state to amplify the optical signal output from the output port of the optical switch in the open state.

[0043] Specifically, for an optical switch, it includes a plurality of input ports and a plurality of output ports. For example, for a 2×2 optical switch, it includes two input ports and two output ports, and for an 8×8 optical switch, it includes eight input ports and eight output ports. In actual applications, multiple output ports may not output optical signals simultaneously, that is, some of the output ports may be selected according to the actual situation to output optical signals. At this time, the output port that outputs the optical signal is the output port in the open state, and the unselected output port is the output port in the closed state.

[0044] Among them, the selection of the output port can be achieved by inputting a control signal to the optical switch. That is, the optical switch can determine whether the output port is open or closed by receiving a control signal. This signal can be an electrical signal (such as voltage or current) or a digital control signal (such as through I2C, SPI protocols). After receiving the control signal, the internal mechanism of the optical switch is activated. There are certain differences in the internal mechanisms of different types of optical switches. For example, in a MEMS optical switch, this control signal can drive the micro mirror; in a liquid crystal (LC) optical switch, this control signal can change the arrangement of the LC to control the passage of light; in a waveguide optical switch, this control signal can guide light to different ports by changing the refractive index distribution of the waveguide structure. Thus, according to the instructions of the control signal, the optical switch will select the corresponding output port, and the input optical signal will be output from the open output port.

[0045] According to the above analysis, when the optical signal of the optical switch is output from the open output port, light may leak from the closed output port. Therefore, in this embodiment, adjustable optical attenuators can be preset at all output ports of the optical switch. Thus, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is a closed output port, the adjustable optical attenuator connected to this output port can be activated to make it in a working state, and at the same time, it can be adjusted to the maximum value within its adjustable range, so that the light at the closed output port is attenuated to the maximum extent.

[0046] In addition to setting adjustable optical attenuators, optical amplifiers can also be preset at all output ports of the optical switch. Thus, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is an open output port, the optical amplifier connected to this output port can be activated to make it in a working state, so that the light at the open output port is amplified.

[0047] In an optional implementation manner, the adjustable optical attenuator is an adjustable optical attenuator prepared from semiconductor materials. The adjustable optical attenuator includes a waveguide and P-type and N-type regions on both sides of the waveguide. The waveguide is used to receive externally input carriers to make the adjustable optical attenuator in a working state. The adjustable optical attenuator is also used to be in a non-working state or at the minimum value within the adjustable range when the connected output port is open.

[0048] Specifically, in practical applications, tunable optical attenuators can be preset at all output ports of the optical switch. During the operation of the optical switch, the output ports in the off state may not be fixed. For example, in one signal transmission, a certain output port may be in the on state, while in the next signal transmission, this output port may be in the off state. Thus, when a certain output port is determined to be in the off state, the tunable optical attenuator connected to this output port can be activated to make the tunable optical attenuator enter the working state and attenuate the optical signal output from the output port.

[0049] Moreover, the tunable optical attenuator can be a tunable optical attenuator prepared from semiconductor materials, which is convenient for co-integration with the optical switch on the same chip. Among them, as Figure 3 shown, the tunable optical attenuator can be a silicon-based tunable optical attenuator. The tunable optical attenuator specifically includes a waveguide and P-type and N-type regions on both sides of the waveguide. The P-type and N-type regions on both sides need to be precisely aligned and in close contact with the waveguide (the contact part can be used as the modulation region) to facilitate the effective control of charge carriers. When the tunable optical attenuator is working, by applying an external voltage to the PN junction or PIN structure, the concentration distribution of carriers (electrons and holes) is controlled, and the optical properties of the waveguide region are changed, such as the change in the absorption coefficient, thereby adjusting the light intensity passing through the waveguide.

[0050] In this embodiment, by using a silicon-based tunable optical attenuator and utilizing the plasma dispersion effect of silicon to change the optical intensity of the transmitted light, that is, to adjust the light intensity passing through the waveguide. Among them, when the concentration of free carriers in the material changes, the corresponding refractive index and the absorption coefficient of the material will change accordingly. By changing the carrier concentration in the silicon optical waveguide and increasing the absorption coefficient, the attenuation of the transmitted light can be achieved. And the tunable optical attenuator has the advantages of fast response rate, low power consumption, etc., which is in line with the development trend of high-speed and green silicon-based photon integration.

[0051] After tunable optical attenuators are connected to all output ports of the optical switch, when the input light is output from one of the output ports in the on state through the optical switch, carriers are injected into the waveguide of the tunable optical attenuator connected to the output port in the off state to make the tunable optical attenuator in the working state. At this time, due to the change in the carrier concentration, the light absorption coefficient of the waveguide of this tunable optical attenuator increases, and the light intensity passing through the waveguide decreases. Thus, the optical power of the leakage light at the output port in the off state can be greatly reduced. At the same time, for the tunable optical attenuator connected to the output port in the on state, it is controlled to be in the non-working state or at the minimum value within the tunable range, so that the optical power at the output port in the on state remains almost unchanged. Thus, the optical power at the output port in the off state decreases, and the light at the output port in the on state remains almost unchanged, thereby achieving the purpose of increasing the extinction ratio of the optical switch.

[0052] In an alternative embodiment, the optical amplifier is an optical amplifier made of semiconductor material. The optical amplifier includes a P-type layer, an active layer, and an N-type layer stacked thereon. The active layer is configured to receive externally input carriers to enable the optical amplifier to be in an operating state. The optical amplifier is further configured to be in a non-operating state and attenuate the optical signal output from the output port in the closed state when the connected output port is in the closed state.

[0053] Specifically, in practical applications, optical amplifiers can be pre-set at all output ports of the optical switch. During the operation of the optical switch, the output port in the open state may not be fixed. For example, during one signal transmission, a certain output port may be in the closed state, while during the next signal transmission, this output port may be in the open state. Thus, when a certain output port is determined to be in the open state, the optical amplifier connected to this output port can be activated to enable the optical amplifier to enter the operating state and amplify the optical signal output from the output port.

[0054] Moreover, the optical amplifier can be an optical amplifier made of semiconductor material, which facilitates co-integration with the optical switch on the same chip. As shown in Figure 4 , the optical amplifier includes a P-type layer, an active layer, and an N-type layer stacked thereon, that is, the optical amplifier is a semiconductor optical amplifier including a passive region and an active region (gain region, i.e., the active layer). The active layer is configured to receive externally input carriers to enable the optical amplifier to be in an operating state. When the optical amplifier operates, electrons and holes are injected by injecting current, and optical amplification is achieved by electrons jumping from the high-energy conduction band to the low-energy valence band. Specifically, the optical amplifier provides carriers for the active region by injecting current. When the injected current meets a certain value, population inversion will be formed in the active region. At this time, if an optical signal is injected into it, due to the excitation of the carriers provided by the current, the carriers inside the optical amplifier generate stimulated emission in the gain medium and release photons. Since the photons generated by stimulated emission are the same as the incoming photons, that is, they have the same information such as phase, polarization energy, etc., the function of optical amplification is thus achieved.

[0055] After connecting optical amplifiers to all output ports of the optical switch, when the input light is output from one of the open output ports via the optical switch, a current is injected into the optical amplifier connected to the open output port to excite the optical amplifier, providing carriers for the active region. When the optical signal passes through the active region, high-energy electrons return to the ground state and emit photons, enhancing the optical signal. Therefore, the optical intensity of the light output from the open output port increases, improving the ratio of the optical intensity of the open output port to the leakage light intensity of the closed output port, thereby achieving the purpose of increasing the extinction ratio of the optical switch. In addition, due to the light absorption characteristics of the semiconductor material itself, when there is no current injection into the optical amplifier at the closed output port (i.e., the optical amplifier is in a non-operating state), there will be some losses such as absorption and scattering during the process of photons passing through the optical amplifier, resulting in attenuation of the optical intensity. Thus, by setting an optical amplifier at the closed output port and keeping it in a non-operating state, the ratio of the optical intensity of the light output from the open output port to the leakage light intensity of the closed output port can be further improved.

[0056] In an alternative embodiment, when multiple optical switches form an optical switch array, a tunable optical attenuator is provided at the output port of each optical switch in the optical switch array, or an optical amplifier is provided at the output port of each optical switch in the optical switch array. Specifically, in current data transmission and high-performance computing, large-scale, array-form optical switches are often required. For array forms, they are usually implemented by connecting several 1×2 or 2×2 optical switches in a certain arrangement, that is, integrating individual optical switches into a large-scale N×N optical switch array. At this time, the overall performance of the optical switch array can also be improved by setting a tunable optical attenuator and / or an optical amplifier to achieve the effect of reducing light leakage.

[0057] In an alternative embodiment, taking a 2×2 optical switch and an N×N optical switch as examples, the working principle when a tunable optical attenuator is provided at all output ports of the optical switch is described as follows:

[0058] As Figure 5As shown, when the optical switch is a 2×2 optical switch, light is input from the first input port 11 or the second input port 12, and is coupled and transmitted to the intermediate long waveguide. During the transmission of light in the intermediate long waveguide, a large number of carriers are injected by heating or applying a bias voltage, changing the refractive index of the material, thereby causing a phase difference between the two beams of light, and then entering the output port in the open state after re-coupling. Among them, when the two beams of light after passing through the intermediate long waveguide are coupled and enter the output port in the open state, a small amount of leakage light enters the other output port. To reduce the leakage light, the adjustable optical attenuator located at the output port in the closed state is made to work through electrical adjustment (at this time, the adjustable optical attenuator at the output port in the open state is in a non-working state), that is, the carrier concentration of the waveguide of the adjustable optical attenuator at the output port in the closed state is changed through electrical adjustment, and the corresponding refractive index and absorption coefficient will also change, weakening the light intensity and greatly weakening the leakage light output from the output port in the closed state. Thus, the light energy output from the output port in the open state remains almost unchanged, and the light energy output from the output port in the closed state is greatly reduced, realizing an increase in the extinction ratio of the optical switch.

[0059] As Figure 6 shown (it should be noted that Figure 6 a possible example of an N×N optical switch is given, and in practical applications, the number of ports and the connection method between optical switches can be changed according to the situation), in Figure 6 the switch array shown, multiple optical switch units 100 are connected between multiple input ports and multiple output ports, and the optical switch units 100 are connected by waveguides. Each optical switch unit includes an optical switch and two adjustable optical attenuators connected to the output port of the optical switch. In this embodiment, it is set that light is input from the first input port 11, and the output port in the open state is the first output port 21. Specifically, after the light is input from the first input port 11 into the first optical switch 101, most of the light enters the first waveguide 301 through the first adjustable optical attenuator 201 in the non-working state by electrically modulating or thermally modulating the first optical switch 101. The light output from the first waveguide 301 enters the second optical switch 102, and after being modulated by the second optical switch 102, most of the modulated light enters the second waveguide 302 through the third adjustable optical attenuator 202 in the non-working state. The light output from the second waveguide 302 enters the third optical switch 103, and after being modulated by the third optical switch 103, most of the modulated light enters the third waveguide through the fifth adjustable optical attenuator 203 in the non-working state, and so on. Finally, the light beam enters the nth optical switch 106 through the (n - 1)th waveguide, and after being modulated by the nth optical switch 106, most of it passes through the 2nth adjustable optical attenuator 212 in the non-working state and is output from the first output port 21.

[0060] Meanwhile, in addition to most of the light passing through the first optical switch 101 entering the first waveguide 301 via the first variable optical attenuator 201, a small portion of the leaked light also enters the second variable optical attenuator 207. At this time, a voltage is applied to the second variable optical attenuator 207 to change the carrier concentration therein, causing changes in the refractive index and absorption coefficient within the second variable optical attenuator 207, and thus greatly reducing the optical intensity of the light entering the second variable optical attenuator 207. Similarly, in addition to most of the light passing through the second optical switch 102 entering the second waveguide 302 via the third variable optical attenuator 202, a small portion of the leaked light also enters the fourth variable optical attenuator 208. At this time, a voltage is applied to the fourth variable optical attenuator 208 to change the carrier concentration therein, causing changes in the refractive index and absorption coefficient within the fourth variable optical attenuator 208, and thus greatly reducing the optical intensity of the light entering the fourth variable optical attenuator 208. By analogy, voltages are applied to the sixth variable optical attenuator 209, the eighth variable optical attenuator 210, the tenth variable optical attenuator 211... the (2n - 1)-th variable optical attenuator 206 to activate and reduce the leaked light. Finally, the purpose of making the light output from the first output port 21 in the open state while greatly reducing the leaked light from other output ports is achieved.

[0061] In an alternative embodiment, taking a 2×2 optical switch and an N×N optical switch as examples, the working principle when optical amplifiers are arranged at all output ports of the optical switch will be described:

[0062] As Figure 7 shown, when the optical switch is a 2×2 optical switch, light is input from the first input port 11 or the second input port 12 and is coupled and transmitted to the intermediate long waveguide. During the transmission of light in the intermediate long waveguide, a large number of carriers are injected by heating or applying a bias voltage to change the refractive index of the material, thereby causing a phase difference between the two beams of light. After re-coupling, the light enters the output port in the open state. Among them, the two beams of light after passing through the intermediate long waveguide are coupled and enter the output port in the open state, and a small amount of leaked light is output from the output port in the closed state. To increase the extinction ratio of the optical switch, an optical amplifier at the output port in the open state is excited by injecting current to increase the optical intensity output from the output port in the open state. At the same time, for the optical amplifier at the other output port in the closed state, in the absence of current injection, due to the inherent light absorption characteristics of the semiconductor material, there will be some losses such as absorption and scattering when photons pass through the optical amplifier, thereby resulting in the attenuation of the optical intensity, and increasing the ratio of the optical intensity of the light output from the output port in the open state to the leaked light from the output port in the closed state. Thus, the optical energy output from the output port in the open state increases, and the optical energy output from the output port in the closed state decreases, effectively achieving an increase in the extinction ratio of the optical switch.

[0063] As Figure 8 shown (it should be noted thatFigure 8 A possible example of an N×N optical switch is given. In practical applications, the number of ports and the connection manner between optical switches can be changed according to the situation. In Figure 6 In the switch array shown, multiple optical switch units 100 are connected between multiple input ports and multiple output ports. The optical switch units 100 are connected by waveguides. Each optical switch unit includes an optical switch and two optical amplifiers connected to the output port of the optical switch. In this embodiment, it is assumed that light enters from the first input port 11, and the output port in the open state is the first output port 21. When light enters the first optical switch 101 from the first input port 11, most of the light enters the first optical amplifier 401 by electrically modulating or thermally modulating the first optical switch 101. A current is injected into the first optical amplifier 401 to make it in the working state. The light amplified by the first optical amplifier 401 enters the first waveguide 301. The light output from the first waveguide 301 enters the second optical switch 102 and is modulated by the second optical switch 102. Most of the modulated light passes through the third optical amplifier 402. A current is injected into the third optical amplifier 402 to make it in the working state. The light amplified by the third optical amplifier 402 enters the second waveguide 302. The light output from the second waveguide 302 enters the third optical switch 103 and is modulated by the third optical switch 103. Most of the modulated light passes through the fifth optical amplifier 403. A current is injected into the fifth optical amplifier 403 to make it in the working state. The light amplified by the fifth optical amplifier 403 enters the third waveguide 303. And so on. Finally, the light beam enters the nth optical switch 106 through the (n - 1)th waveguide and is modulated by the nth optical switch 106. Most of the modulated light passes through the 2nth optical amplifier 412. A current is injected into the 2nth optical amplifier 412 to make it in the working state. The light amplified by the 2nth optical amplifier 412 is output from the first output port 21.

[0064] Meanwhile, in addition to most of the light passing through the first optical switch 101 entering the first optical waveguide 301 via the first optical amplifier 401, a small portion of the leaked light will enter the second optical amplifier 407 in the non-operating state. Due to the light absorption characteristics of the semiconductor material and the optical transmission loss, the light intensity of the light passing through the second optical amplifier 407 is attenuated. Similarly, in addition to most of the light passing through the second optical switch 102 entering the second optical waveguide 302 via the third optical amplifier 402, a small portion of the leaked light will enter the fourth optical amplifier 408. Due to the light absorption characteristics of the semiconductor material and the optical transmission loss, the light intensity of the light passing through the fourth optical amplifier 408 is attenuated. By analogy, the light passing through the third optical switch 103, the fourth optical switch 104, the fifth optical switch 105... the nth optical switch 106 is attenuated by the sixth amplifier 409, the eighth amplifier 410, the tenth amplifier 411... the (2n - 1)th amplifier 406 in the non-operating state respectively, and finally the purpose of outputting the light from the first output port 21 in the open state while greatly reducing the leaked light of other output ports is achieved.

[0065] The embodiment of the present invention also provides an optical switch chip, which includes an optical switch and the device for increasing the extinction ratio of the optical switch in the above embodiment, and the optical switch and the device are integrated on the same chip. Among them, by integrating the tunable optical attenuator or optical amplifier in the device and the optical switch on the same chip, the optical switch chip can not only achieve the purpose of increasing the extinction ratio of the optical switch, but also has the advantages of simple structure, good stability, and easy integration.

[0066] The embodiment of the present invention also provides a method for increasing the extinction ratio of an optical switch. The optical switch includes at least two output ports, and the method includes the following steps:

[0067] Step S101: Connect tunable optical attenuators to at least two output ports of the optical switch respectively. When the output ports connected to the tunable optical attenuators are in the closed state, control the corresponding tunable optical attenuators to be in the operating state to attenuate the optical signal output from the closed output ports in the optical switch.

[0068] Or, step S102: Connect optical amplifiers to at least two output ports of the optical switch respectively. When the output ports connected to the optical amplifiers are in the open state, control the corresponding optical amplifiers to be in the operating state to amplify the optical signal output from the open output ports in the optical switch.

[0069] Specifically, the output ports in the open state and the output ports in the closed state of the optical switch can be determined according to the actual situation. After determining the output ports in the open state, a control signal can be input to the optical switch, and the optical switch controls the input optical signal to be output from the output ports in the open state. At this time, the ports not designated as output optical signals are in the closed state.

[0070] According to the above analysis, when the optical signal of the optical switch is output from the output ports in the open state, light may leak to the output ports in the closed state. Therefore, in this embodiment, adjustable optical attenuators can be preset at all output ports of the optical switch. Thus, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is in the closed state, the adjustable optical attenuator connected to this output port can be activated to make it in the working state, and at the same time, it can be adjusted to the maximum value within its adjustable range, so that the light at the output port in the closed state is attenuated to the maximum extent.

[0071] In addition to setting adjustable optical attenuators, optical amplifiers can also be preset at all output ports of the optical switch. Thus, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is in the open state, the optical amplifier connected to this output port can be activated to make it in the working state, so that the light at the output port in the open state is amplified.

[0072] In an alternative embodiment, the method further includes: inputting a light beam to the input port of the optical switch; heating or applying a voltage to the intermediate waveguide of the optical switch to modulate the input light beam, and the modulated light beam is transmitted to the output ports in the open state. Specifically, during the operation of the optical switch, light is input from the input port and is coupled and transmitted to the intermediate long waveguide. During the transmission of light in the intermediate long waveguide, a large number of carriers are injected by heating or applying a bias voltage, changing the refractive index of the material, thereby causing a phase difference between the two light beams, and after being coupled again, they enter the output ports in the open state.

[0073] The method for increasing the extinction ratio of the optical switch provided by the embodiment of the present invention, by setting adjustable optical attenuators or optical amplifiers at the output ports of the optical switch. When setting adjustable optical attenuators, the adjustable optical attenuators connected to the output ports in the closed state of the optical switch are in the working state, and the optical signals output from the output ports in the closed state of the optical switch are attenuated; when setting optical amplifiers, the optical amplifiers connected to the output ports in the open state of the optical switch are in the working state, and the optical signals output from the output ports in the open state of the optical switch are amplified. Thus, this method realizes the reduction of the optical energy output from the output ports in the closed state, or the increase of the optical energy output from the output ports in the open state, thereby realizing the increase of the extinction ratio of the optical switch.

[0074] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions and modifications to these embodiments without departing from the spirit of the present utility model and the scope of protection defined by the appended claims. Such modifications and variations fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should easily understand that the order of process steps can be changed while maintaining the scope of protection of the present utility model.

[0075] In addition, the scope of application of the present utility model is not limited to the processes, mechanisms, manufacturing, compositions of matter, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present utility model, those of ordinary skill in the art will easily understand that for the processes, mechanisms, manufacturing, compositions of matter, means, methods or steps that already exist or will be developed in the future, and which perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described in the present utility model, they can be applied in accordance with the present utility model. Therefore, the appended claims of the present utility model are intended to include these processes, mechanisms, manufacturing, compositions of matter, means, methods or steps within their scope of protection.

Claims

1. An apparatus for increasing the extinction ratio of an optical switch, characterized in that, The optical switch includes at least two output ports, and the device includes: at least two tunable optical attenuators respectively disposed at at least two output ports of the optical switch and connected to the output ports, and configured to, when the connected output port is in a closed state, the corresponding connected tunable optical attenuator is in an operating state to attenuate the optical signal output from the output port of the optical switch that is in the closed state; Alternatively, at least two optical amplifiers respectively disposed at at least two output ports of the optical switch and connected to the output ports, and configured to, when the connected output port is in an open state, the corresponding connected optical amplifier is in an operating state to amplify the optical signal output from the output port of the optical switch that is in the open state.

2. The device for increasing the extinction ratio of the optical switch according to claim 1, wherein The tunable optical attenuator is a tunable optical attenuator prepared by using a semiconductor material.

3. The device for increasing the extinction ratio of an optical switch according to claim 2, wherein The tunable optical attenuator includes a waveguide and a P-type region and an N-type region on both sides of the waveguide, and the waveguide is configured to receive externally input carriers to enable the tunable optical attenuator to be in an operating state.

4. The device for increasing the extinction ratio of an optical switch according to claim 1, characterized in that, The tunable optical attenuator is further configured to be in a non-operating state or at the minimum value of the tunable range when the connected output port is in an open state.

5. The device for increasing the extinction ratio of an optical switch according to claim 1, wherein The optical amplifier is an optical amplifier prepared by using a semiconductor material.

6. The device for increasing the extinction ratio of the optical switch according to claim 5, characterized in that, The optical amplifier includes a stacked P-type layer, an active layer, and an N-type layer, and the active layer is configured to receive externally input carriers to enable the optical amplifier to be in an operating state.

7. The device for increasing the extinction ratio of an optical switch according to claim 5, characterized in that, The optical amplifier is further configured to be in a non-operating state when the connected output port is in a closed state to attenuate the optical signal output from the output port that is in the closed state.

8. The device for increasing the extinction ratio of an optical switch according to claim 1, characterized in that, When a plurality of optical switches form an optical switch array, a light attenuator is disposed at the output port of each optical switch in the optical switch array, or an optical amplifier is disposed at the output port of each optical switch in the optical switch array.

9. An optical switch chip, characterized in that, An optical switch and the device for increasing the extinction ratio of the optical switch according to any one of claims 1-8, wherein the optical switch and the device are integrated on the same chip.

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