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

Abstract

The invention relates to the technical field of optical communication, in particular to a device and method 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 present invention relates to the field of optical communication technology, and in particular to a device and method 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 smart terminals, the demand for large data transmission has also shown explosive growth. However, traditional electrical interconnection is limited by its high power consumption and high loss, and cannot meet the needs of large data capacity and high-speed transmission. In order to solve the "bottleneck" problem of electrical interconnection, light, as a new information carrier, gradually replaces electricity in interconnection scenarios. Compared with electrical interconnection, optical interconnection can realize high-speed modulation of signals, greatly reducing the delay of signals in interconnection, and there is no crosstalk between signals of different frequencies, nor is it affected by external electromagnetic interference. Therefore, optical interconnection is a promising solution. Silicon is a mature electronic 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 idea of ​​silicon-based optical interconnection was proposed, using silicon complementary metal oxide semiconductor technology to simultaneously produce photonic and electronic devices on silicon materials to achieve miniaturized, low-cost and high-performance large-scale optoelectronic integrated circuits, and ultimately achieve high-speed and broadband interconnection.

[0003] Optical switches are the core devices in optical interconnection. They are widely used in optical information exchange and signal processing. They have the advantages of small size and low power consumption, faster response speed and lower driving voltage. Research on silicon-based integrated optical switch technology is of great significance for the future construction of all-optical high-speed optical communication networks. Optical switches have one or more selectable transmission windows, which can convert or perform logical operations on optical signals in optical transmission lines or integrated optical circuits. The basic form of optical switches includes 2×2 optical switches, that is, there are two optical fibers at the input and output ends, which can complete two connection states, parallel connection and cross connection. Larger optical switch arrays can be composed of basic 2×2 optical switches and corresponding 1×2 optical switches cascaded and combined. The working principle of optical switches is to change the phase of transmitted light by adjusting the refractive index of the waveguide at a specific position, thereby controlling the transmission path of light in the waveguide device. For silicon-based optical switches, thermo-optical effect and plasma dispersion effect are mainly used, and the corresponding switch units are thermo-optical and electro-optical switches.

[0004] Integrating a single optical switch into an N×N large-scale high-speed optical switch array can realize multi-port information exchange function, 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, some light will be output from an output port in the closed state. 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 invention

[0005] In view of this, the embodiments of the present invention provide a device and method 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 optical switches 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, wherein the optical switch includes at least two output ports, and the device includes: at least two adjustable optical attenuators, which are respectively arranged at the at least two output ports of the optical switch and connected to the output ports, and are used to be in a working state when the connected output ports are in a closed state, and attenuate the optical signal output by the output ports in the optical switch that are in a closed state; or at least two optical amplifiers, which are respectively arranged at the at least two output ports of the optical switch and connected to the output ports, and are used to be in a working state when the connected output ports are in an open state, and amplify the optical signal output by the output ports in the optical switch that are in an open state.

[0008] The device for increasing the extinction ratio of an optical switch provided in this embodiment is configured by arranging an adjustable optical attenuator or an optical amplifier at the output port of the optical switch. When the adjustable optical attenuator is configured, the adjustable optical attenuator connected to the output port of the optical switch in a closed state is in a working state, and the optical signal output from the output port of the optical switch in a closed state is attenuated; when the optical amplifier is configured, the optical amplifier connected to the output port of the optical switch in an open state is in a working state, and the optical signal output from the output port of the optical switch in an open state is amplified. Thus, the device reduces the optical energy output from the output port in a closed state, or increases the optical energy output from the output port in an open state, thereby increasing the extinction ratio of the optical switch.

[0009] In an optional implementation, the optical attenuator is an adjustable optical attenuator made of semiconductor materials.

[0010] In this embodiment, the adjustable optical attenuator is made of semiconductor materials, so that the adjustable optical attenuator and the optical switch can be integrated on the same chip.

[0011] In an optional implementation, the adjustable 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 used to receive externally inputted carriers so that the adjustable optical attenuator is in a working state.

[0012] In this embodiment, by setting the structure of the adjustable optical attenuator, when the adjustable optical attenuator is working, by applying voltage to the PN junction or PIN structure, the concentration distribution of carriers (electrons and holes) is controlled, the optical properties of the waveguide region are changed, such as the change of the absorption coefficient, and then the light intensity passing through the waveguide is adjusted. This makes the adjustable optical attenuator have the advantages of fast response rate and low power consumption, and conforms to the development trend of high-speed and green silicon-based photonic integration.

[0013] In an optional implementation, the adjustable optical attenuator is further configured to be in a non-operating state or in a minimum value of an 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 in an open state, the adjustable optical attenuator connected to the output port is in a non-working state or in a minimum value of an adjustable range, so that the optical power output by the output port in the open state remains almost unchanged, thereby ensuring normal optical power output and improvement of the extinction ratio.

[0015] In an optional implementation, the optical amplifier is an optical amplifier made of semiconductor materials.

[0016] In this embodiment, the optical amplifier is made of semiconductor materials, which makes it easy to integrate the optical amplifier and the optical switch on the same chip.

[0017] In an optional implementation, the optical amplifier includes a P-type layer, an active layer, and an N-type layer that are stacked, and the active layer is used to receive externally inputted carriers, so that the optical amplifier is in an operating state.

[0018] In this embodiment, the optical amplifier structure is set so that the optical amplifier can inject electrons and holes by injecting current when working, and realize light amplification by electrons transitioning from a high-energy conduction band to a low-energy valence band.

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

[0020] In this embodiment, when the output port of the optical switch is in a closed state, the optical amplifier connected to the output port is in a non-working state. Since the semiconductor material itself has certain light absorption characteristics, when no current is injected into the optical amplifier of the closed output port (that is, the optical amplifier is in a non-working state), there will be some absorption and scattering losses in the process of photons passing through the optical amplifier, which will lead to the attenuation of light intensity. Therefore, by making the optical amplifier of the closed output port in a non-working state, the ratio of the light intensity of the open output port to the leakage light intensity output by the closed output port can also be further improved.

[0021] In an optional implementation, when a plurality of optical switches form an optical switch array, an output port of each optical switch in the optical switch array is provided with an adjustable optical attenuator, or an output port of each optical switch in the optical switch array is provided with an optical amplifier.

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

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

[0024] In this embodiment, by integrating the adjustable optical attenuator or optical amplifier and the optical switch in the device 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, easy integration, etc.

[0025] A third aspect of an embodiment of the present invention provides a method for increasing the extinction ratio of an optical switch, wherein the optical switch includes at least two output ports, and the method includes: respectively setting an adjustable optical attenuator connected to the at least two output ports of the optical switch, and when the output port connected to the adjustable optical attenuator is in a closed state, controlling the corresponding adjustable optical attenuator to be in a working state to attenuate an optical signal output from the output port in the optical switch that is in a closed state; or respectively setting an optical amplifier connected to the at least two output ports of the optical switch, and when the output port connected to the optical amplifier is in an open state, controlling the corresponding optical amplifier to be in a working state to amplify an optical signal output from the output port in the optical switch that is in an open state. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a structural schematic 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 invention;

[0029] Figure 3 It is a schematic diagram of the principle of an adjustable optical attenuator according to an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the principle of a semiconductor optical amplifier according to an embodiment of the present invention;

[0031] Figure 5 A structural block diagram of a device for increasing the extinction ratio of an optical switch according to another embodiment of the present invention;

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

[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 invention;

[0034] Figure 8 This is a structural block diagram of a device for increasing the extinction ratio of optical switches in an optical switch array according to another embodiment of the present invention. DETAILED DESCRIPTION

[0035] As mentioned in the background art, there is a problem of low extinction in optical switches. Figure 1In the 2×2 optical switch shown, 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, in an ideal state, when a light beam is input from the input end, the light beam should be completely output from the first output port 21, and no light is output from the second output port 22. However, in actual situations, due to problems such as device structure, process error in the manufacturing process, and bias control, 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 off state, thereby causing the problem of "incomplete opening and continuous closing". At this time, this part of the leaked light becomes noise, and a large 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 output optical power 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 optical switches.

[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. In addition, high-performance optical switches require more complex structures and more external control ports. Optimizing optical switches is an important way to improve the overall performance of the system. This problem will become more prominent as the number of ports increases, causing noise superposition from different optical switches and limiting the development of silicon-based optical switch array chips towards larger ports. Therefore, how to improve the extinction ratio of optical switches has become an important issue that needs to be solved urgently.

[0037] In view of this, the present 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 of the optical switch in a closed state is put into a working state, and the optical signal output from the output port of the optical switch in a closed state is attenuated; when the optical amplifier is set, the optical amplifier connected to the output port of the optical switch in an open state is put into a working state, and the optical signal output from the output port of the optical switch in an open state is amplified. In this way, the device reduces the optical energy output from the output port in a closed state, or increases the optical energy output from the output port in an open state, thereby increasing the extinction ratio of the optical switch.

[0038] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

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

[0042] The embodiment of the present invention provides a device for increasing the extinction ratio of an optical switch, such as Figure 2 As shown, the optical switch includes at least two output ports, and the device includes: at least two adjustable optical attenuators, which are respectively arranged at the at least two output ports of the optical switch and connected to the output ports, and are used for attenuating the optical signal output from the output port in the optical switch in the closed state when the connected output port is in the closed state; or at least two optical amplifiers, which are respectively arranged at the at least two output ports of the optical switch and connected to the output ports, and are used for amplifying the optical signal output from the output port in the optical switch in the open state when the connected output port is in the open state.

[0043] Specifically, an optical switch includes multiple input ports and multiple output ports. For example, a 2×2 optical switch includes two input ports and two output ports. An 8×8 optical switch includes eight input ports and eight output ports. In practical applications, multiple output ports may not output optical signals at the same time, that is, some of the output ports may be selected to output optical signals according to actual conditions. At this time, the 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 in an open or closed state 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 protocol). After receiving the control signal, the mechanism inside 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, the control signal can drive the micro-mirror; in a liquid crystal (LC) optical switch, the control signal can change the arrangement of LC to control the passage of light; in a waveguide optical switch, the control signal can guide light to different ports by changing the refractive index distribution of the waveguide structure. Therefore, according to the instruction of the control signal, the optical switch will select the corresponding output port so that the input optical signal is output from the output port in the open state.

[0045] According to the above analysis, when the optical signal of the optical switch is output from the output port in the open state, the light may leak from the output port in the closed state. Therefore, in this embodiment, an adjustable optical attenuator can be pre-set at all the output ports of the optical switch. Therefore, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is an output port in the closed state, the adjustable optical attenuator connected to the output port can be started to be in the working state, and it can be adjusted to the maximum value of its adjustable range, so that the light of the output port in the closed state reaches the maximum attenuation.

[0046] In addition to setting the adjustable optical attenuator, optical amplifiers can also be set in advance at all output ports of the optical switch. Therefore, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is an output port in an open state, the optical amplifier connected to the output port can be started to be in an operating state, thereby amplifying the light of the output port in the open state.

[0047] In an optional embodiment, the adjustable optical attenuator is an adjustable optical attenuator made of semiconductor materials. The adjustable 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 used to receive external input carriers so that the adjustable optical attenuator is in a working state. The adjustable optical attenuator is also used to be in a non-working state or in a minimum value of an adjustable range when the connected output port is in an open state.

[0048] Specifically, in practical applications, an adjustable optical attenuator can be pre-set at all output ports of the optical switch. During the operation of the optical switch, the output port in the closed state may not be fixed. During one signal transmission, a certain output port may be in an open state, and during the next signal transmission, the output port may be in a closed state. Therefore, when a certain output port is determined to be in a closed state, the adjustable optical attenuator connected to the output port can be started, so that the adjustable optical attenuator enters the working state and attenuates the optical signal output by the output port.

[0049] Furthermore, the adjustable optical attenuator can be an adjustable optical attenuator made of semiconductor materials, so that it is convenient to integrate it with the optical switch on the same chip. Figure 3 As shown, the adjustable optical attenuator can be a silicon-based adjustable optical attenuator. The adjustable optical attenuator specifically includes a waveguide and a P-type region and an N-type region on both sides of the waveguide. The P-type region and the N-type region on both sides need to be precisely aligned and closely contact the waveguide (the contact portion can be used as a modulation region) to facilitate effective control of charge carriers. When the adjustable 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, the optical properties of the waveguide region, such as the change in the absorption coefficient, are changed, and the light intensity passing through the waveguide is adjusted.

[0050] In this embodiment, a silicon-based variable optical attenuator is used to change the intensity of the transmitted light by utilizing the plasma dispersion effect of silicon, that is, to adjust the intensity of the light passing through the waveguide. When the free carrier concentration 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. In addition, the variable optical attenuator has the advantages of fast response rate and low power consumption, and conforms to the development trend of high-speed and green silicon-based photonic integration.

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

[0052] In an optional embodiment, the optical amplifier is an optical amplifier made of semiconductor materials. 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 external input carriers so that the optical amplifier is in a working state. The optical amplifier is also used to be in a non-working state when the connected output port is in a closed state, and attenuate the optical signal output from the output port in the closed state.

[0053] Specifically, in practical applications, optical amplifiers may 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. During one signal transmission, a certain output port may be in the closed state, and during the next signal transmission, the output port may be in the open state. Therefore, when a certain output port is determined to be in the open state, the optical amplifier connected to the output port may be started, so that the optical amplifier enters the working state and amplifies the optical signal output from the output port.

[0054] Furthermore, the optical amplifier can be an optical amplifier made of semiconductor materials, so that it is convenient to integrate it with the optical switch on the same chip. Figure 4 As shown, the optical amplifier includes a stacked P-type layer, an active layer and an N-type layer, that is, the optical amplifier is a semiconductor optical amplifier including a passive region and an active region (gain region, i.e., an active layer). The active layer is used to receive carriers input from the outside, so that the optical amplifier is in a working state. When the optical amplifier is working, the injection of electrons and holes is realized by injecting current, and light amplification is realized by the transition of electrons 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, a 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 radiation in the gain medium and release photons. Because the photons generated by stimulated radiation are the same as the external photons, that is, they have the same phase, polarization energy and other information, thereby realizing the function of light amplification.

[0055] After optical amplifiers are connected to all output ports of the optical switch, when input light is output from one of the output ports in the open state via the optical switch, current is injected into the optical amplifier connected to the output port in the open state to excite the optical amplifier, providing carriers for the active region. When the optical signal passes through the active region, the high-energy electrons return to the ground state and emit photons, so that the optical signal is enhanced. Therefore, the light intensity output from the output port in the open state becomes larger, and the ratio of the light intensity of the output port in the open state to the light intensity of the leakage light output from the output port in the closed state is increased, thereby achieving the purpose of increasing the extinction ratio of the optical switch. In addition, since the semiconductor material itself has certain light absorption characteristics, when there is no current injection into the optical amplifier of the output port in the closed state (that is, the optical amplifier is in a non-working state), there will be some absorption and scattering losses in the process of photons passing through the optical amplifier, thereby causing the attenuation of light intensity. Therefore, by setting an optical amplifier at the output port in the closed state and making it in a non-working state, the ratio of the light intensity output from the output port in the open state to the light intensity of the leakage light output from the output port in the closed state can also be further increased.

[0056] In an optional implementation, when multiple optical switches form an optical switch array, an adjustable 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-type optical switches are often required. For the array type, it is usually realized by connecting a number of 1×2 or 2×2 optical switches in a certain arrangement, that is, a single optical switch is integrated 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 providing an adjustable optical attenuator and / or an optical amplifier to achieve the effect of reducing light leakage.

[0057] In an optional implementation, taking a 2×2 optical switch and an N×N optical switch as examples, the working principle when an adjustable optical attenuator is set at all output ports of the optical switch is described:

[0058] like 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 transmitted to the intermediate long waveguide through coupling. During the transmission of the 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 entering the output port in the open state after re-coupling. Among them, when the two beams of light transmitted through the intermediate long waveguide enter the output port in the open state after coupling, a small amount of leakage light enters the other output port. In order to reduce the leakage light, the adjustable optical attenuator located at the output port in the closed state is in the working state through electrical adjustment (at this time, the adjustable optical attenuator at the output port in the open state is in the 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, so that the light intensity is weakened, and the leakage light output from the output port in the closed state is greatly reduced. As a result, 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, thereby achieving an increase in the extinction ratio of the optical switch.

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

[0060] At the same time, in addition to most of the light passing through the first optical switch 101 passing through the first adjustable optical attenuator 201 and entering the first waveguide 301, a small part of the light will leak into the second adjustable optical attenuator 207. At this time, a voltage is applied to the second adjustable optical attenuator 207 to change the carrier concentration inside the second adjustable optical attenuator 207, so that the refractive index and absorption coefficient inside the second adjustable optical attenuator 207 change, and the light intensity of the light entering the second adjustable optical attenuator 207 is greatly reduced. Similarly, in addition to most of the light passing through the second optical switch 102 passing through the third adjustable optical attenuator 202 and entering the second waveguide 302, a small part of the light will leak into the fourth adjustable optical attenuator 208. At this time, a voltage is applied to the fourth adjustable optical attenuator 208 to change the carrier concentration inside the fourth adjustable optical attenuator 208, so that the refractive index and absorption coefficient inside the fourth adjustable optical attenuator 208 change, and the light intensity of the light entering the fourth adjustable optical attenuator 208 is greatly reduced. By analogy, voltage is applied to the sixth adjustable attenuator 209, the eighth adjustable attenuator 210, the tenth adjustable attenuator 211 ... the 2n-1th adjustable attenuator 206 to activate and reduce leakage light, and finally the purpose of making light output from the first output port 21 in the open state and greatly reducing leakage light from other output ports is achieved.

[0061] In an optional implementation manner, taking a 2×2 optical switch and an N×N optical switch as examples, the working principle when optical amplifiers are provided at all output ports of the optical switch is described:

[0062] like Figure 7 As 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 transmitted to the intermediate long waveguide through coupling. During the transmission of the light in the intermediate long waveguide, a large number of carriers are injected by heating or applying a bias voltage, which changes the refractive index of the material, thereby causing a phase difference between the two beams of light, and after re-coupling, they enter the output port in the open state. Among them, the two beams of light transmitted through the intermediate long waveguide enter the output port in the open state after coupling, and a small amount of leakage light is output from the output port in the closed state. In order to increase the extinction ratio of the optical switch, the optical amplifier of the output port in the open state is excited by injecting current to increase the light intensity output from the output port in the open state. At the same time, in the case of no current injection into the optical amplifier of the other output port in the closed state, due to the certain light absorption characteristics of the semiconductor material itself, there will be some absorption and scattering losses in the process of photons passing through the optical amplifier, which will lead to the attenuation of light intensity, thereby increasing the light intensity ratio of the output light of the output port in the open state to the leakage light of the output port in the closed state. As a result, the light energy output from the output port in the open state increases, and the light energy output from the output port in the closed state decreases, thereby effectively increasing the extinction ratio of the optical switch.

[0063] like Figure 8 As shown (it should be noted that Figure 8 A possible N×N optical switch example is given. In practical applications, the number of ports and the connection method between optical switches can be changed according to the situation. Figure 6 In 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 through waveguides. Each optical switch unit includes an optical switch and two optical amplifiers connected to the output ports of the optical switch. In this embodiment, it is assumed that light is input from the first input port 11, and the output port in the open state is the first output port 21. When light is input into 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, and current is injected into the first optical amplifier 401 to put it in a working state, and 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, and current is injected into the third optical amplifier 402 to put it in a working state, and 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. Current is injected into the fifth optical amplifier 403 to put it in a working state. The light amplified by the fifth optical amplifier 403 enters the third waveguide 303. Similarly, the light beam finally enters the nth optical switch 106 through the n-1th waveguide and is modulated by the nth optical switch 106. Most of the modulated light passes through the 2nth optical amplifier 412. Current is injected into the 2nth optical amplifier 412 to put it in a working state. The light amplified by the 2nth optical amplifier 412 is output from the first output port 21.

[0064] At the same time, in addition to most of the light passing through the first optical switch 101 passing through the first optical amplifier 401 and entering the first waveguide 301, a small part of the light will leak into the second optical amplifier 407 in a non-operating state. Due to the light absorption characteristics of semiconductor materials and light transmission loss, the light intensity of the light passing through the second optical amplifier 407 is weakened. Similarly, in addition to most of the light passing through the second optical switch 102 passing through the third optical amplifier 402 and entering the second waveguide 302, a small part of the light will leak into the fourth optical amplifier 408. Due to the light absorption characteristics of semiconductor materials and light transmission loss, the light intensity of the light passing through the fourth optical amplifier 408 is weakened. 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 weakened by the sixth amplifier 409, the eighth amplifier 410, the tenth amplifier 411 ... the 2n-1th amplifier 406 in a non-operating state, respectively, and finally the purpose of outputting the light from the first output port 21 in an open state and greatly reducing the leakage 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 of the above embodiment, and the optical switch and the device are integrated on the same chip. Among them, by integrating the adjustable 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, easy integration, etc.

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

[0067] Step S101, at least two output ports of an optical switch are respectively connected to adjustable optical attenuators, and when the output ports connected to the adjustable optical attenuators are in a closed state, the corresponding adjustable optical attenuators are controlled to be in a working state to attenuate the optical signal output by the output ports in the optical switch that are in a closed state.

[0068] Alternatively, in step S102, optical amplifiers are respectively connected to at least two output ports of the optical switch, and when the output ports connected to the optical amplifiers are in an open state, the corresponding optical amplifiers are controlled to be in a working state to amplify the optical signal output from the output ports in the open state of the optical switch.

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

[0070] According to the above analysis, when the optical signal of the optical switch is output from the output port in the open state, the light may leak to the output port in the closed state for output. Therefore, in this embodiment, an adjustable optical attenuator can be pre-set at all the output ports of the optical switch. Therefore, 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 the output port can be started to be in the working state, and it can be adjusted to the maximum value of its adjustable range, so that the light of the output port in the closed state reaches the maximum attenuation.

[0071] In addition to setting the adjustable optical attenuator, optical amplifiers can also be set in advance at all output ports of the optical switch. Therefore, during the operation of the optical switch, that is, after determining that a certain output port of the optical switch is in an open state, the optical amplifier connected to the output port can be started to be in an operating state, so that the light of the output port in the open state is amplified.

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

[0073] The method for increasing the extinction ratio of an optical switch provided by an embodiment of the present invention is to set 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 of the optical switch in a closed state is put into a 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 of the optical switch in an open state is put into a working state to amplify the optical signal output from the output port in the open state of the optical switch. Thus, the method reduces the optical energy output from the output port in a closed state or increases the optical energy output from the output port in an open state, thereby increasing 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 may make various changes, substitutions and modifications to these embodiments without departing from the spirit of the present invention and the scope of protection defined by the appended claims, and such modifications and variations all fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should readily understand that the order of the process steps may be changed while maintaining the scope of protection of the present invention.

[0075] In addition, the scope of application of the present invention is not limited to the processes, mechanisms, manufactures, material compositions, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present invention, it will be easily understood by those skilled in the art that the processes, mechanisms, manufactures, material compositions, means, methods or steps that currently exist or will be developed in the future, which perform substantially the same functions as the corresponding embodiments described in the present invention or obtain substantially the same results, can be applied according to the present invention. Therefore, the claims attached to the present invention are intended to include these processes, mechanisms, manufactures, material compositions, means, methods or steps within their scope of protection.

Claims

1. A device for increasing the extinction ratio of an optical switch, characterized in that: The optical switch comprises at least two output ports, and the device comprises: at least two adjustable optical attenuators, which are respectively arranged at the at least two output ports of the optical switch and connected to the output ports, and are used for, when the connected output ports are in a closed state, the corresponding connected adjustable optical attenuators are in a working state, and attenuate the optical signal outputted from the output ports in the optical switch in a closed state; Alternatively, at least two optical amplifiers are respectively arranged at at least two output ports of the optical switch and connected to the output ports, so that when the connected output ports are in an open state, the corresponding connected optical amplifiers are in a working state to amplify the optical signal output from the output ports in the optical switch that are in an open state.

2. The device for increasing the extinction ratio of an optical switch according to claim 1, characterized in that: The adjustable optical attenuator is an adjustable optical attenuator made of semiconductor materials.

3. The device for increasing the extinction ratio of an optical switch according to claim 2, characterized in that: The adjustable optical attenuator comprises a waveguide and a P-type region and an N-type region on both sides of the waveguide. The waveguide is used to receive carriers input from the outside, so that the adjustable optical attenuator is in a working state.

4. The device for increasing the extinction ratio of an optical switch according to claim 1, characterized in that: The adjustable optical attenuator is also used to be in a non-working state or in a minimum value of an adjustable 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, characterized in that: The optical amplifier is an optical amplifier made of semiconductor materials.

6. The device for increasing the extinction ratio of an optical switch according to claim 5, characterized in that: The optical amplifier comprises a P-type layer, an active layer and an N-type layer which are stacked, and the active layer is used to receive externally inputted carriers so that the optical amplifier is in a working state.

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

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

10. A method for increasing the extinction ratio of an optical switch, characterized in that: The optical switch comprises at least two output ports, and the method comprises: At least two output ports of the optical switch are respectively connected to adjustable optical attenuators, and when the output port connected to the adjustable optical attenuator is in a closed state, the corresponding adjustable optical attenuator is controlled to be in a working state to attenuate the optical signal output by the output port in the optical switch that is in a closed state; Alternatively, optical amplifiers are respectively connected to at least two output ports of the optical switch, and when the output ports connected to the optical amplifiers are in an open state, the corresponding optical amplifiers are controlled to be in a working state to amplify the optical signal output from the output ports in the open state of the optical switch.

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