Passive multi-throw all-optical switch based on optical multistable state

Abstract

The invention discloses a passive multi-throw optical multistable all-optical switch based on an annular cavity system and a control method thereof, and the passive multi-throw optical multistable all-optical switch is characterized in that the passive multi-throw optical multistable all-optical switch comprises a one-way annular optical cavity and a rubidium bubble, the rubidium bubble is a cylindrical glass bubble which is located at the central position of the axis of the left upper cavity mirror and the central position of the axis of the right upper cavity mirror and filled with rubidium 85 atomic gas, and a monochromatic light field in the cavity can penetrate through the left side and the right side of the cylindrical glass bubble. Under the strong coupling condition of an atom-cavity system, the monochromatic cavity mode can excite multiple transition energy levels of rubidium atoms at the same time, so that strong optical nonlinear interaction is caused, and multiple different transmitted light intensity values can be achieved by modulating the light intensity of signal light. The multi-throw all-optical switch disclosed by the invention is based on an optical multistable state excited by signal light, does not need an additional auxiliary light field, a magnetic field and the like, and has the advantages of wide band, passivity, low power consumption, multiple channels, simple structure, easiness in integration and miniaturization and the like.

Description

Technical Field

[0001] The present invention relates to the technical fields of all-optical switches and all-optical communication, and relates to a passive multi-throw all-optical switch based on optical multistability. Background Art

[0002] Traditional signal transmission networks are mainly established based on electronic signals or the optical-electric-optical backbone network propagation mode. When performing signal transmission work, since it is necessary to involve the conversion and processing processes of optical and electrical signals, the signal transmission speed and accuracy are greatly limited. An all-optical communication network refers to a network in which signals are transmitted and operate in an all-optical signal mode from the time they are sent to the time they are received by users, thereby greatly improving the signal transmission speed and efficiency and meeting the requirements for establishing a fast and large-data all-optical information network in the future. In an optical communication network, an all-optical switch can be used for optical path routing and switching to achieve flexible optical signal transmission and routing operations, improve the network capacity and efficiency, and the all-optical switch is of crucial significance and important application value for the establishment of future all-optical communication networks. For example, optical cross-connect devices and optical add-drop multiplexing devices are the core components of all-optical networks, and optical cross-connect devices and optical add-drop multiplexing devices mainly operate based on all-optical switch operations and all-optical switch arrays. Therefore, an all-optical switch is one of the core components for establishing an all-optical network and realizing high-speed optical communication in the future. In addition, in the field of fiber optic sensing, an all-optical switch can be used for modulating and controlling optical signals in a fiber optic sensing system to achieve highly sensitive fiber optic sensing; in photon computing, an all-optical switch can be used for controlling and modulating photon logic gates, and it is an essential key device for realizing optical quantum computing, processing, and transmission; in an optical imaging system, an all-optical switch can be used for switching and controlling optical devices to achieve adjustment and optimization of imaging parameters; in the research and development of quantum computers and the field of quantum cryptography, an all-optical switch is a basic control component for realizing data transmission and control. It can be seen that all-optical switches play an important and key role in the fields of optical communication, optical sensing, quantum computing, etc. Therefore, how to realize an efficient, fast, easily miniaturized and integrated all-optical switch to better apply it to the above-mentioned fields has become an important problem currently faced.

[0003] Traditional all-optical switches mainly rely on the nonlinear interaction between the optical field and a specific medium to achieve switching. Currently, the more promising solutions mainly fall into three categories: waveguide-based, fiber-loop-based, and atomic-medium-based. Traditional multi-throw all-optical switches based on atomic systems are mainly made based on the electromagnetically induced transparency (EIT) effect or quantum coherence effect. The signal light needs to interact with an additional strong control light beam or multiple beams with atomic energy levels and must simultaneously satisfy the two-photon resonance condition. This results in the fact that traditional all-optical switches can only achieve switching operations at a certain and single frequency and cannot achieve all-optical switching operations in multiple frequencies or wide frequency bands. In addition, since the above all-optical switches require multiple light fields and additional lasers to assist in operation, this greatly increases the usage cost and power consumption, limits their practicality, makes it difficult to carry out large-scale industrial production and integrated applications, and makes it difficult to achieve multi-throw all-optical switches for practical applications. Summary of the Invention

[0004] The object of the present invention is to overcome the practical problems of the existing all-optical switches, such as complex structure, high cost, narrow bandwidth, and difficulty in miniaturization and integration, and to propose a passive, broadband, and multi-throw all-optical switch.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A passive multi-throw all-optical switch based on optical multistability, comprising an upper left cavity mirror (1), an upper right cavity mirror (2), a lower left cavity mirror (3), a lower right cavity mirror (4), a rubidium glass bubble (5), a four-level rubidium-85 atomic gas cluster (6), a signal light (7), a monochromatic cavity field (8), a transmitted light (9), a light source (10), and a photodetector (11).

[0007] The characteristics of this passive multi-throw all-optical switch are as follows:

[0008] The upper left cavity mirror (1), the upper right cavity mirror (2), the lower left cavity mirror (3), and the lower right cavity mirror (4) are symmetrically distributed and fixed in a square ring shape to form an annular optical cavity.

[0009] The reflectivities of the lower left cavity mirror (3) and the lower right cavity mirror (4) are approximately 1, and the reflection coefficients and transmission coefficients of the upper left cavity mirror (1) and the upper right cavity mirror (2) are R and T respectively, where R + T = 1;

[0010] The rubidium glass bubble (5) is made of cylindrical sealed and light-transmitting glass material and is located at the axial center position between the upper left cavity mirror (1) and the upper right cavity mirror (2).

[0011] The four-level rubidium-85 atomic gas cluster (6) is enclosed in the rubidium glass bubble (5).

[0012] The four-level rubidium-85 atomic gas cluster (6) contains approximately 10 to the 28th power of four-level rubidium-85 atoms. The four-level rubidium-85 atoms contain four electron energy levels, namely the ground state |2 S 1 / 2 , F = 2>, excited state | 2 P 3 / 2 , F = 1>, excited state | 2 P 3 / 2 , F = 2>, excited state | 2 P 3 / 2 , F = 3>.

[0013] The signal light (7) generated by the light source (10) vertically enters the ring optical cavity from the left outside of the upper left cavity mirror (1) and excites the monochromatic cavity field (8) in the cavity.

[0014] The frequency of the signal light (7) is ω p , ω p relative to the D2 line of the four-level rubidium-85 atom (6) | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 3 transition detuning is ω p -ω 41 .

[0015] The intensity of the signal light (7) can be adjusted and can act on the ring optical cavity with light pulses of instantaneous high light intensity or low light intensity.

[0016] The monochromatic cavity field (8) is located in the ring optical cavity, first passes through the rubidium cell (5) and interacts with the four-level rubidium-85 atomic gas group (6), exciting three transition paths of the atoms | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 1> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 2 and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 3>, and then is reflected by the upper right cavity mirror (2), the lower right cavity mirror (4), the lower left cavity mirror (3), and the upper left cavity mirror (1) in turn. Since the upper left cavity mirror (1), the upper right cavity mirror (2), the lower left cavity mirror (3), and the lower right cavity mirror (4) are high-quality plane mirrors, the number of interactions between the signal light (8) located in the ring optical cavity and the four-level rubidium-85 atomic gas group (6) is greatly increased, which is called the collective strong coupling effect.

[0017] Due to the optical feedback effect of the ring cavity and the nonlinear optical interaction between the atoms and the monochromatic cavity field (8), the optical intensity of the input signal light (7) and the optical intensity of the transmitted light (9) at the output end show a nonlinear correspondence, that is, optical multistability.

[0018] In optical multistability, there is a non - linear correspondence between the optical intensity of the input signal light (7) and the transmitted light (9) at the output end. One optical intensity of the input signal light (7) can correspond to multiple optical intensities of the transmitted light (9), and each corresponds to several jump threshold points.

[0019] By adjusting the optical intensity (or photon flux) of the signal light (7), when an instantaneous signal pulse light with different optical intensities is applied to the optical ring - cavity system, according to the principle of the corresponding multiple optical intensity values of the transmitted light (9) in optical multistability, the transmitted light (9) will exhibit different and stable optical intensity values of the transmitted light 9, that is, the multi - throw all - optical switch operation is realized. In addition, since the above - mentioned multi - throw all - optical switch operation does not rely on additional auxiliary light fields or magnetic fields, etc., the passive multi - throw all - optical switch operation is realized.

[0020] Under the condition of collective strong coupling, the monochromatic cavity field (8) has a strong non - linear interaction with the four - level rubidium - 85 atomic gas group (6). The monochromatic cavity field (8) can simultaneously excite three independent rubidium - 85 atomic transition paths | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 1> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 2> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 3>.

[0021] During the interaction between the monochromatic cavity field (8) and the four - level rubidium - 85 atomic gas group (6), part of the transmitted light (9) vertically exits from the outer right side of the upper - right cavity mirror (2).

[0022] The light source (10) is located on the outer left side of the upper - left cavity mirror (1).

[0023] The light source (10) has the function of adjusting the intensity of the signal light (7), and outputs optical pulses with the same frequency and high or low optical intensity on the basis of the original optical intensity of the signal light (7).

[0024] The photodetector (11) is located on the outer right side of the upper - right cavity mirror (2).

[0025] A passive multi - throw all - optical switch based on optical multistability, the implementation steps of which include:

[0026] 1) At the initial moment, the optical intensity (or photon flux, representing the number of photons passing through per unit time) of the signal light (7) corresponds to a specific optical intensity value of the transmitted light (9), and the all-optical switch is in the state "1".

[0027] 2) By the circuit control module of the light source (10), a short pulsed light with the same frequency and higher optical intensity is added to the signal light (7). The action time of the optical pulse can be approximately ignored. Due to the input-output characteristics of optical multistability, at this time, the optical intensity of the transmitted light (9) undergoes a sudden change and quickly responds to the "2" state.

[0028] 3) By the circuit module of the light source 10, a short pulsed light with the same frequency and lower optical intensity is added to the signal light (7). At this time, the optical intensity of the transmitted light 9 undergoes a sudden change again and quickly responds to the "1" state.

[0029] 4) Since there are multiple nonlinear regions in the said ring cavity-atom system, by repeating similar operations in different nonlinear regions, multiple discrete optical intensity values of the transmitted light (9) can be achieved, that is, the multi-throw all-optical switch operation is realized.

[0030] Compared with the prior art, the present invention has the following advantages and positive effects:

[0031] 1) Passive, easy to miniaturize and integrate. Due to the natural nonlinear enhancement characteristics of the multi-level excitation effect in the cavity QED system, the all-optical switch scheme based on monochromatic cavity field excitation optical multistability proposed in this project does not require additional optical fields or magnetic fields for assistance, that is, no additional lasers or magnetic field devices are needed. Therefore, this all-optical switch scheme greatly simplifies the physical system and realizes a passive all-optical switch, that is, it does not require additional equipment to assist in working, which greatly saves resource investment, reduces power consumption, and simplifies the operation process. The advantages of being passive, miniaturized and easy to integrate will make the application fields and scenarios of this all-optical switch scheme extremely broad.

[0032] 2) Realization of the multi-throw all-optical switch. The main innovation of the present invention is to utilize the atom-cavity system formed by coupling a four-level rubidium-85 atomic cluster with a unidirectional ring optical cavity, that is, the cavity quantum electrodynamics (cavity QED) system. By using its multi-level excitation characteristics and the principle of quantum interference destruction, the present invention can realize the simultaneous excitation of four-level atoms by a monochromatic cavity field. By adjusting the optical intensity of the signal light, tunable optical multistability can be achieved at the output end of the cavity QED system. It is superior to the traditional "single-pole single-throw" unidirectional all-optical switch based on quantum coherence effects.

[0033] 3) The bandwidth of the all-optical switch is greatly increased. Experiments show that the monochromatic cavity field based on strong coupling can simultaneously excite multiple energy levels of atoms, greatly expanding the excitation frequency region, overcoming the limitations of the two-photon resonance condition in optics, and greatly enhancing the spectral operation bandwidth. Based on this principle, the present invention designs a broadband, high-efficiency, multi-channel all-optical switch, thus greatly improving the practicality of the all-optical switch and reducing the difficulty of its large-scale industrial manufacturing at the same time.

[0034] 4) High compatibility. The cavity QED scheme is one of the current ideal quantum hardware design schemes. In quantum communication and quantum computing, with the continuous increase in data transmission volume, it is inevitable to require quantum devices to meet the need for multi-channel parallel data transmission. Therefore, how to efficiently increase the output spectral bandwidth of cavity QED and implement a multi-channel cavity QED output scheme is a very important cutting-edge research topic. The passive multi-throw all-optical switch of the present invention provides a possible solution to the above problems. Quantum communication and quantum computing mainly rely on atoms or optical fields as media to carry and store information. The series connection of the system of the present invention and the quantum communication system does not require additional signal conversion devices, demonstrating the strong compatibility and practicality of the present invention.

[0035] In summary, the invention design has outstanding advantages such as high efficiency, broadband, passive, multi-channel, low power consumption, fast response, easy miniaturization and integration, easy cascading and expansion, and high compatibility, and can meet many application requirements. It is expected to greatly expand the applicable fields of the optical multistable all-optical switch based on monochromatic cavity field excitation. Brief Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art.

[0037] Figure 1 It is a schematic structural diagram of a passive multi-throw all-optical switch based on optical multistability disclosed in an embodiment of the present invention.

[0038] In the figure, 1, upper left cavity mirror; 2, upper right cavity mirror; 3, lower left cavity mirror; 4, lower right cavity mirror; 5, rubidium glass bubble; 6, four-level rubidium-85 atomic gas group; 7, signal light; 8, monochromatic cavity field; 9, transmitted light; 10, light source; 11, photodetector.

[0039] Figure 2 It is a schematic diagram of the four energy levels of rubidium-85 atoms excited by the monochromatic cavity field 8. Under the strong coupling condition of the atom-cavity system, the three energy level transition paths of the atom are | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 1> and | 2S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 2> and | 2 S 1 / 2 , F = 2 → | 2 P 3 / 2 , F=3> is excited at the same time, and the coupling strengths of the monochromatic cavity field 8 and the three energy level transition paths of the atom are Ω1, Ω2, Ω3, δ 23 and δ 34 is the energy level distance between adjacent excited states.

[0040] Figure 3 Describes the transmitted light intensity I of the all-optical switching system T With input signal light 7 light intensity I in There are three nonlinear regions in the input-output curve, where the blue solid line, green dotted line and red dashed line correspond to C = 80, 160 and 240 respectively. The other parameters are δ 34 =2δ 23 =10Γ,Δ p =-12.5Γ. Γ = γ i (i = 2-3) is the spontaneous emission rate of the excited state of rubidium-85. i (i=2-3) is the excited state | 2 P 3 / 2 , the spontaneous radiation rate of F=i>.

[0041] Figure 4 The intensity of the transmitted light 9 of the system when changing the atomic decoherence rate is I T With input signal light 7 light intensity I in The relationship between 34 =2δ 23 =10Γ,Δ p =-12.5Γ, C=80.

[0042] Figure 4 In (a), γ2=γ3, the blue solid line, green dotted line and red dashed line correspond to γ4=γ2, γ4=0.9γ2 and γ4=0.8γ2, respectively.

[0043] Figure 4 In (b), the blue solid line, green dotted line, and red dashed line correspond to γ4=γ3=γ2, γ4=γ3=0.9γ2,

[0044] γ3=0.9γ2 and γ4=0.8γ2.

[0045] Figure 5 To change the frequency detuning Δ of the signal light 7 p and the atomic energy level spacing δ 23 , δ 34Transmitted light intensity I of the system at a certain time T And the intensity I of the input signal light in Relationship. C = 80.

[0046] Figure 5 In (a), δ 34 = 2δ 23 = 10Γ, the blue solid line, the green dotted line and the red dashed line respectively correspond to Δ p = -10Γ, -12.5Γ, -15Γ.

[0047] Figure 5 In (b), the blue solid line, the green dotted line and the red dashed line respectively correspond to δ 34 = 2δ 23 = 10Γ, Δ p = -12.5Γ, δ 23 = 4Γ, δ 34 = 6Γ, Δ p = -8Γ and δ 34 = 2δ 23 = 4Γ, Δ p = -5Γ.

[0048] Figure 6 Is the experimental spectrogram of the monochromatic cavity field exciting four energy levels of rubidium - 85 atoms simultaneously measured in the experiment, and 4 transmitted spectral peaks can be clearly seen.

[0049] Figure 6 In figure (a), Δ p = -5Γ.

[0050] Figure 6 In figure (b), Δ p = -15Γ.

[0051] Figure 7 Is the input - output schematic diagram of the passive multi - throw all - optical switch based on optical multistability.

[0052] Figure 7 In (a), the abscissa is time, and the ordinate is the intensity (photon flux) I of the input signal light in .

[0053] Figure 7 In (b), the abscissa is time, and the ordinate represents the transmitted light intensity I T value, that is, the switch state. Specific implementation mode

[0054] Example 1:

[0055] The present invention will be described in detail below with reference to the drawings and examples.

[0056] The present invention provides a passive multi-throw all-optical switch based on optical multistability, as Figure 1 shown, which consists of four cavity mirrors fixedly distributed in a square ring shape and a transparent rubidium glass bubble 5. The rubidium glass bubble 5 is made of transparent and sealed glass material, and the inside of the rubidium glass bubble 5 is filled with a four-level rubidium-85 atomic gas group 6, and the four-level rubidium-85 atomic gas group 6 contains about 10 to the 28th power of rubidium-85 gaseous atoms. There are four rubidium atom energy levels participating in the interaction, which are | 2 S 1 / 2 , F = 2>, | 2 P 3 / 2 , F = 1>, | 2 P 3 / 2 , F = 2>, | 2 P 3 / 2 , F = 3>.

[0057] γi (i = 2 - 3) is the spontaneous emission rate of the excited state | 2 P 3 / 2 , F = i>. The spontaneous emission rates of the three excited states of rubidium-85 atoms can be approximately considered equal, Γ = γ i (i = 2 - 3) = 6 MHz.

[0058] A light source 10 is provided on the left outside of the upper left cavity mirror 1, and a light detector 11 is provided on the right outside of the upper right cavity mirror 2.

[0059] The lower left cavity mirror and the lower right cavity mirror are high-reflection plane mirrors, and the reflectivity of the mirror surface is approximately 1. R and T respectively represent the reflection coefficient and transmission coefficient of the mirror surface of the upper left cavity mirror and the upper right cavity mirror, and R + T = 1. The four cavity mirrors are placed and fixed at an angle of 45° to each other, and the distance B between each two is 8 cm, and the four form an annular optical cavity.

[0060] The light source 10 is a Toptica Pro semiconductor laser, which can provide a signal light 7 with a stable intensity, and can obtain an instantaneously increased or decreased light pulse intensity by modulating through an internal circuit module.

[0061] The signal light 7 is coupled into the ring optical cavity from the left side outside the upper left mirror 1, exciting the monochromatic cavity field 8 in the cavity. The monochromatic cavity field 8 acts on the four-level rubidium-85 atomic gas group 6 inside the rubidium cell 5 in sequence, and then is reflected by the upper right mirror 2, the lower right mirror 4, the lower left mirror 3, and the upper left mirror 1 in sequence. Since the upper left mirror 1, the upper right mirror 2, the lower left mirror 3, and the lower right mirror 4 are all high-quality mirrors with a reflectivity exceeding 99.99%, the probability of the monochromatic cavity field 8 running out of the cavity is very low and can be regarded as being trapped in the ring optical cavity. After the monochromatic cavity field 8 travels back and forth in the cavity about hundreds of thousands of times, there is a certain probability of being emitted from the right side outside the upper right mirror 2 and being detected by the photodetector 11 on the right side outside the upper right mirror 2. Compared with free space, the interaction intensity between the optical field and the atoms in the ring optical cavity is greatly improved, which is called the collective strong coupling condition of the atom-cavity system.

[0062] Under the collective strong coupling condition, the monochromatic cavity field 8 has a strong non-linear interaction with the four-level rubidium-85 atomic gas group 6, and the monochromatic cavity field 8 can simultaneously excite three independent rubidium-85 atomic transition paths| 2 S 1 / 2 ,F = 2> → | 2 P 3 / 2 ,F = 1> and | 2 S 1 / 2 ,F = 2> → | 2 P 3 / 2 ,F = 2> and | 2 S 1 / 2 ,F = 2> → | 2 P 3 / 2 ,F = 3>, as Figure 2 shown. Due to the quantum coherence effect of multi-path excitation, the atom-cavity system exhibits a strong optical non-linear effect. At this time, one input signal light 7 intensity corresponds to multiple transmitted light 9 intensities, that is, optical multistability, as Figure 3 、 4 、5 shown.

[0063] Figure 3 、 4 、5 show the variation of the non-linear input-output (optical multistability) region of the system light intensity with parameters (such as the detuning Δp of the signal light 7, the coupling coefficient C, etc.). By adjusting the corresponding system parameters, the position and area of the optical multistability region can be flexibly adjusted, providing conditions for realizing a broadband multi-throw all-optical switch.

[0064] The frequency of the signal light 7 is ω p ,ω 41 is the energy level| 2 S 1 / 2 ,F = 2> and the energy level| 2 P 3 / 2, the spacing between F = 3>. The signal light 7 is relative to the D2 line of rubidium-87 atoms| 2 S 1 / 2 , F = 2> →| 2 P 3 / 2 , the negative detuning (red detuning) of the F = 3> transition is 25 MHz, and its detuning is defined as Δ p = ω p -ω 41 . Scan (adjust) the frequency of the incident signal light 7 in the range of [-25 MHz, +10 MHz]. At this time, four absorption peaks appear in the corresponding absorption spectrum, representing the four eigenvalues of the cavity QED system, as Figure 6 shown.

[0065] The transmitted signal detector 8 is a silicon avalanche detector of model PDA36A2 produced by Thorlabs, and is used to collect the transmitted light 9 signal.

[0066] As Figure 7 shown, initially the light intensity (photon flux, representing the number of photons passing through per unit time) of the signal light 7 is 30, and at this time the transmitted light 9 is in the "1" state. At 1 μs, a high light intensity pulse is obtained for the signal light 7 through the circuit module of the light source 10, and the pulse light intensity is 40. At this time, the light intensity of the transmitted light 9 changes suddenly and quickly responds to the "2" state. At 2 μs, a low light intensity pulse is obtained for the signal light 7 through the circuit module of the light source 10, and the pulse light intensity is 20. At this time, the light intensity of the transmitted light 9 changes suddenly and quickly responds to the "1" state. At 3 μs, the light intensity of the signal light 7 is 250, and at this time the transmitted light 9 is in the "3" state. At 4 μs, a high light intensity pulse is obtained for the signal light 7 through the circuit module of the light source 10, and the pulse light intensity is 500. At this time, the light intensity of the transmitted light 9 changes suddenly and quickly responds to the "4" state. At 5 μs, a low light intensity pulse is obtained for the signal light 7 through the circuit module of the light source 10, and the pulse light intensity is 200. At this time, the light intensity of the transmitted light 9 changes suddenly and quickly responds to the "3" state. At 6 μs, the light intensity of the signal light 7 is 450, and at this time the transmitted light 9 is in the "4" state. At 7 μs, a high light intensity pulse is obtained for the signal light 7 through the circuit module of the light source 10, and the pulse light intensity is 650. At this time, the light intensity of the transmitted light 9 changes suddenly and quickly responds to the "5" state. At 8 μs, a low light intensity pulse is obtained for the signal light 7 through the circuit module of the light source 10, and the pulse light intensity is 250. At this time, the light intensity of the transmitted light 9 changes suddenly and quickly responds to the "4" state.

[0067] As can be seen from the above demonstration process, by adjusting the light intensity of the signal light 7, without relying on external auxiliary strong light fields or magnetic fields, etc., and only through the ring cavity-atom system, the transmitted light 9 can achieve a total of "1", "2", "3", "4", "5" independent states, and the switching response time is on the order of microseconds. This is a fast, passive, multi-throw all-optical switch.

[0068] The working principle of the present invention is based on the strong coupling characteristics of the atom-cavity system to simultaneously excite multiple transition energy levels of the D2 line of rubidium-85 atoms by a single-color cavity field 8. Four cavity mirrors form a confocal cavity, and a four-level rubidium-85 atomic gas cluster 6 and this confocal cavity form a so-called cavity quantum electrodynamics (cavity QED) physical system. The incident signal light 7 is coupled into the cavity from the left side of the confocal cavity. Due to the strong coupling effect of the cavity QED system, the atoms and the cavity field have a strong interaction. The frequency of the incident signal light 7 is adjusted to simultaneously excite the atomic ground state energy level and three excited state energy levels, that is, three atomic transition paths are simultaneously excited. During this process, a part of the single-color cavity field 8 passes through the cavity QED system and is emitted from the right side of the cavity, which is called the transmitted light 9.

[0069] Table 1 shows a specific design value of a passive multi-throw all-optical switch based on optical multistability. Its specific numerical value can be optimized and adjusted according to product requirements and applications, and is not used as a limitation to the embodiments of the present invention. In the "label" column of the table, the components are numbered according to the size spacing of each component.

[0070] A and B are respectively the lengths between the rubidium bubble 5 and the cavity mirror.

[0071] Label A B Length (cm) 5 8

[0072] Through the above specific embodiments, a passive multi-throw all-optical switch based on optical multistability can be obtained.

[0073] The above are only the preferred examples of the present invention and are not used to limit the present invention. Parameter changes and adjustments can be made to the structure of the present invention to obtain more other embodiments, and it is not necessary and impossible to list all the embodiments here. Therefore, the protection scope of the present invention is only determined by the scope of the appended claims.

Claims

1. A passive multi-throw all-optical switch based on optical multistability, characterized in that: This passive multi-throw all-optical switch includes an upper left cavity mirror (1), an upper right cavity mirror (2), a lower left cavity mirror (3), a lower right cavity mirror (4), a rubidium glass bubble (5), a four-level rubidium-85 atomic gas group (6), a signal light (7), a monochromatic cavity field (8), a transmitted light (9), a light source (10), and a photodetector (11). The upper left cavity mirror (1), the upper right cavity mirror (2), the lower left cavity mirror (3), and the lower right cavity mirror (4) are high-quality plane mirrors. The upper left cavity mirror (1), the upper right cavity mirror (2), the lower left cavity mirror (3), and the lower right cavity mirror (4) are symmetrically distributed and fixed in a square ring shape to form an annular optical cavity. The reflectivities of the lower left cavity mirror (3) and the lower right cavity mirror (4) are 1, and the sum of the reflection coefficient R and the transmission coefficient T of the upper left cavity mirror (1) and the upper right cavity mirror (2) is 1. The rubidium glass bubble (5) is a cylindrical sealed and light-transmitting glass material, located at the axial center position between the upper left cavity mirror (1) and the upper right cavity mirror (2). The four-level rubidium-85 atomic gas group (6) is enclosed in the rubidium glass bubble (5). The four-level rubidium-85 atomic gas group (6) contains approximately 10 to the 28th power of four-level rubidium-85 atoms. The four-level rubidium-85 atoms contain four electron energy levels, namely the ground state, the excited state, the excited state, and the excited state. The signal light (7) is perpendicularly incident from the left side outside the upper left cavity mirror (1). The frequency of the signal light (7) is ω p , ω p is detuned by Δ relative to the | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 3> transition of the four-level rubidium-85 atom (6), p where Δ p is ω - ω41. The single-color cavity field (8) is located in the ring optical cavity, first passes through the rubidium cell (5), and is then reflected successively by the upper right cavity mirror (2), the lower right cavity mirror (4), the lower left cavity mirror (3), and the upper left cavity mirror (1). Under the condition of collective strong coupling, the signal light (8) excites two independent atomic transitions, and the frequency of the control light field emitted by the control laser couples three atomic transition paths | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 1> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 2> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 3>. The transmitted light (9) is perpendicularly emitted from the right side outside the upper right cavity mirror (2). The light source (10) is located on the left side outside the upper left cavity mirror (1). The light source (10) outputs the signal light (7). The light source (10) has the function of adjusting the intensity of the signal light (7), and outputs short light pulses with the same frequency and instantaneous high light intensity or low light intensity on the basis of the original light intensity of the signal light (7). The photodetector (11) is located on the right side outside the upper right cavity mirror (2).

2. The passive multi-throw all-optical switch based on optical multistability according to claim 1, characterized in that, The realization of optical multistability includes the following steps: 1) The signal light (7) is perpendicularly incident from the left side outside the upper left cavity mirror (1) into the annular cavity and excites the generation of a monochromatic cavity field (8) in the cavity. 2) The single-color cavity field (8) is located in the ring optical cavity, first passes through the rubidium cell (5) and interacts with the four-level rubidium-85 atomic gas group (6), exciting three transition paths of the rubidium-85 atoms| 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 1> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 2> and | 2 S 1 / 2 , F = 2> → | 2 P 3 / 2 , F = 3>, and then is reflected by the upper right cavity mirror (2), the lower right cavity mirror (4), the lower left cavity mirror (3), and the upper left cavity mirror (1) in sequence. Since the upper left cavity mirror (1), the upper right cavity mirror (2), the lower left cavity mirror (3), and the lower right cavity mirror (4) are high-quality plane mirrors, the number of times the single-color cavity field (8) located in the ring optical cavity interacts with the four-level rubidium-85 atomic gas group (6) is greatly increased, which is called the collective strong coupling effect. 3) Due to the optical feedback effect of the annular cavity and the optical nonlinear interaction between the atoms and the monochromatic cavity field (8), the light intensity of the input signal light (7) and the light intensity of the transmitted light (9) at the output end show a nonlinear correspondence relationship, that is, optical multistability.

3. The passive multi-throw all-optical switch based on optical multistability according to claim 1, wherein The realization of the passive multi-throw all-optical switch includes the following steps: 1) In optical multistability, the light intensity of the input signal light (7) and the light intensity of the transmitted light (9) at the output end show a nonlinear correspondence relationship. One light intensity of the input signal light (7) can correspond to multiple light intensities of the transmitted light (9) and respectively correspond to several jump threshold points. 2) Adjust the light source (10). When instantaneous signal light (7) pulses with different light intensities are added to the optical annular cavity system, according to the principle of the corresponding multiple light intensity values of the transmitted light (9) in optical multistability, different and stable discrete light intensity values will appear for the transmitted light (9), that is, the operation of the multi-throw all-optical switch is realized. In addition, since the above multi-throw all-optical switch operation does not depend on additional auxiliary light fields or magnetic fields, etc., the operation of the passive multi-throw all-optical switch is realized.

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