Method for reducing relative intensity noise of quantum dot laser and quantum communication light source

Abstract

The invention provides a method for reducing relative intensity noise of a quantum dot laser and a quantum communication light source, and belongs to the technical field of quantum dot lasers. The method is realized by reducing external carrier noise of a pumping source, so that the silicon-based quantum dot laser generates light in an amplitude compression state, the relative intensity noise of the quantum dot laser is reduced, and the light source prepared by the method for reducing the relative intensity noise of the quantum dot laser can be used as a quantum communication light source. The silicon-based laser has the beneficial effects that the performance of the silicon-based laser is greatly optimized, and the output stability and reliability of the silicon-based laser are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dot lasers, and in particular to a method for reducing the relative intensity noise of a quantum dot laser, and also to a quantum communication light source obtained by the method for reducing the relative intensity noise of a quantum dot laser. Background Art

[0002] Silicon (Si) occupies a core position in the semiconductor industry, and its mature processing technology and relatively low cost make it popular. Silicon-based quantum dot (QD) lasers have excellent compatibility with existing silicon-based microelectronic technology platforms and can be seamlessly integrated into existing microelectronic and optoelectronic devices. This integration capability is particularly prominent in on-chip integrated optical circuits, which can integrate light sources and other optoelectronic devices on the same silicon wafer, not only significantly improving the functionality and efficiency of the module, but also optimizing the manufacturing process, thereby significantly improving system performance and promoting innovation and development in the optoelectronic industry.

[0003] However, the challenges that come with it cannot be ignored. Due to the problems of mismatch dislocations, microcracks and antiphase domain defects between III-V materials and silicon materials, silicon-based lasers will produce a higher dislocation density during the manufacturing process, which inevitably reduces the luminous efficiency and light output quality of the device, and increases the relative intensity noise (RIN) of the laser output, making it unstable. RIN refers to the square of the ratio of the number of photons that fluctuate in the laser output to the number of photons that are stably output. The smaller the RIN value, the more stable the laser output. Quantum well (QW) lasers are very sensitive to defects caused by lattice mismatch, resulting in relatively large RIN values ​​and poor output light quality. Since the QD structure has a strong three-dimensional quantum confinement effect and is insensitive to dislocations, QD lasers have become the only choice for light sources on silicon.

[0004] In order to further reduce the RIN value, the traditional method is to improve the QD growth technology to make the QD grow uniformly, or use p-type modulation doping to increase the differential gain of the QD laser. Although the above methods are effective, the implementation cost is very high and the technical requirements are relatively complex. In addition to traditional methods, the RIN value of QD lasers can also be reduced by external control means, such as external optical feedback and optical injection.

[0005] First, external optical feedback refers to the reflection of part of the light emitted by the laser back into the laser cavity. In this process, two key parameters, the external cavity round-trip time and the optical feedback intensity, play a decisive role. The distance between the laser and the reflector is defined as the external cavity length, and the external cavity round-trip time is proportional to the external cavity length. In the active region of the laser, the re-injected light causes a disturbance in the photon density, resulting in fluctuations in the carrier density and optical gain, which in turn causes fluctuations in the number of output photons of the silicon-based QD laser. Therefore, the existence of optical feedback causes the laser to exhibit complex nonlinear dynamic behavior, resulting in significant changes in the output light intensity. In the feedback space composed of the external cavity length and the optical feedback intensity, only a very small area can reduce the relative intensity noise of the laser. Although optical feedback is expected to be used to reduce the relative intensity noise of silicon-based QD lasers, its adjustment process is extremely difficult and requires precise control of various parameters to achieve the desired effect.

[0006] Second, the external light injection locking technology is to inject the output light of a tunable laser into the silicon-based QD laser, thereby increasing the photon lifetime in the laser, thereby reducing the relative intensity noise and stabilizing the light source output. By adjusting the injection intensity and frequency detuning, the output characteristics of the silicon-based QD laser can be effectively controlled, and the output light intensity fluctuation can be significantly improved. Compared with the optical feedback method, external light injection is easier to adjust, but the requirements for the tunable laser are extremely high: only when its output light has a high stability can the goal of reducing the relative intensity noise of the silicon-based QD laser be achieved.

[0007] Therefore, in order to make up for the limitations of the above methods, it is necessary to study a method that can significantly reduce the relative intensity noise of silicon-based quantum dot lasers and improve the functionality and efficiency of silicon-based quantum dot lasers. Summary of the invention

[0008] In order to solve the problems in the prior art, the present invention provides a method for reducing the relative intensity noise of a quantum dot laser, and also provides a quantum communication light source obtained by the method for reducing the relative intensity noise of a quantum dot laser.

[0009] The method for reducing the relative intensity noise of a quantum dot laser of the present invention is achieved by reducing the external carrier noise of a pump source, so that the silicon-based quantum dot laser generates light in an amplitude compression state.

[0010] Furthermore, the method of reducing the external carrier noise of the pump source is:

[0011] Adjusting the injection current output by the pump current source so that the pump current electron distribution presents a sub-Poisson or quasi-sub-Poisson distribution;

[0012] The injection current acts on the silicon-based quantum dot laser.

[0013] Furthermore, the specific processing method implemented by reducing the external carrier noise of the pump source includes the following steps:

[0014] S1: Building a quantum dot laser model, which consists of three energy states: a two-dimensional carrier reservoir RS, an excited state ES, and a ground state GS;

[0015] S2: Build the quantum dot laser model with the number of carriers N RS 、N ES 、N GS , photon number S GS and the light field phase φ GS The kinetic rate equations, each of which contains a noise source associated with the corresponding current source;

[0016] S3: determining the autocorrelation of the current source noise within the time period based on the five kinetic rate equations in step S2;

[0017] S4: determining a relationship between the relative intensity noise and the external carrier noise of the pump source based on the autocorrelation relationship and the relative intensity noise function;

[0018] S5: Reduce the relative intensity noise by reducing the external carrier noise of the pump source.

[0019] Furthermore, in step S2, the number of carriers N RS 、N ES 、N GS , photon number S GS and the light field phase φ GS The kinetic rate equation is expressed as:

[0020]

[0021] Where I is the pump current, q is the electron charge, and Γ p is the optical confinement factor, v g is the group velocity, τ p is the photon lifetime, β sp is the spontaneous emission factor, are the capture time, relaxation time and escape time of external carriers, respectively. are the spontaneous radiative recombination time of external carriers in each state, τ SRH is the non-radiative recombination lifetime of silicon-based quantum dot lasers, g RS ,g ES ,g GS are the material gains of each energy state, respectively, and the calculation formula is:

[0022]

[0023] Among them, aRS ,a ES ,a GS is the differential gain, ε is the optical confinement factor, N B is the total number of quantum dots, V B is the volume of the active region, D RS is the number of RS states, V RS is the volume of RS, ρ RS , ES , GS are the carrier occupancy rates of RS, ES, and GS, respectively, and F RS ,F ES ,F GS ,F S ,F φ are the kinetic rate equation noise sources for carriers, photons, and phase, respectively.

[0024] Furthermore, in step S3, the correlation strength relationship of the noise sources at two moments is: <F i (t)F j (t')>=U i,j δ(t-t'), where i, j refers to the correlation intensity U of the noise source of the kinetic rate equation at two times t and t' in RS, ES, GS, S, Φ i,j is δ-related, and the correlation strength is specifically expressed as:

[0025]

[0026] U RS,GS =U RS,S =U RS,φ =U ES,S =U ES,φ =U GS,φ =U S,φ =0

[0027] RS, ES, and GS are respectively H The contribution of factors.

[0028] Furthermore, through small signal analysis, the kinetic rate equation is linearized to:

[0029]

[0030] in,

[0031]

[0032] The calculation formula of the relative intensity noise RIN of the silicon-based quantum dot laser is:

[0033]

[0034] Among them, δS GS (ω) is the photon number fluctuation in the frequency domain, S GS is the number of photons when the laser reaches steady state. According to the calculation formula of relative intensity noise RIN, the correlation intensity U RS,RS It is a key parameter that relates RIN to external carrier noise. By reducing or eliminating the external carrier noise of the pump source, the relative intensity noise is reduced.

[0035] The present invention also provides a quantum communication light source, which is provided by the silicon-based quantum dot laser, and the silicon-based quantum dot laser is used to adopt the method for reducing the relative intensity noise of the quantum dot laser.

[0036] Furthermore, the quantum communication light source is light in an amplitude compression state, and its photons are in a sub-Poisson distribution.

[0037] Compared with the prior art, the present invention has the following beneficial effects: by effectively reducing the external carrier noise of the pump source, the relative intensity noise of the silicon-based QD laser is significantly reduced. The performance of the silicon-based laser is greatly optimized, and the stability and reliability of its output are improved. Compared with external control methods such as optical feedback and external light injection, the present invention does not require precise regulation and has the advantages of being simple and reliable.

[0038] The present invention can generate light in an amplitude compressed state, which is used as a quantum communication light source to meet the demand for a light source in the process of quantum communication quantum key distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the present invention or the solutions in the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 Schematic diagram of silicon-based QD laser working under pump source and energy level diagram of QD active region;

[0041] Figure 2 Schematic diagram of noise power of normal pump and low noise pump with current variation;

[0042] Figure 3 Schematic diagram of the time domain intensity noise and the intensity distribution statistics of the time domain noise of normal pump and low-noise pump.

[0043] Figure 4 A schematic diagram showing the comparison of the RIN spectra of the pump source of the present invention and the QD laser driven by a normal pump;

[0044] Figure 5 A schematic diagram showing the comparison of the low-frequency RIN of a silicon-based QD laser under the pump source of the present invention and normal pumping conditions;

[0045] Figure 6 This is a schematic diagram of the application of the present invention in a quantum communication system. DETAILED DESCRIPTION

[0046] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs; the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0047] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it mutually exclusive, independent, or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0048] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0049] The present invention provides a method for reducing the relative intensity noise of a quantum dot laser, which is achieved by reducing the external carrier noise of a pump source, so that the silicon-based quantum dot laser generates light in an amplitude compression state.

[0050] The present invention significantly reduces the relative intensity noise of silicon-based quantum dot (QD) lasers by effectively reducing the external carrier noise of the laser pump source, greatly optimizes the performance of silicon-based lasers, and improves the stability and reliability of their output. The present invention provides an efficient and stable low relative intensity noise light source solution for fields such as photonic integrated chips, data centers, laser radars, and laser sensors, fully demonstrating its wide application potential in modern optoelectronic systems.

[0051] Specifically, the method of reducing the external carrier noise of the pump source of the present invention is:

[0052] Adjusting the injection current output by the pump current source so that the pump current electron distribution presents a sub-Poisson or quasi-sub-Poisson distribution;

[0053] The injection current acts on the silicon-based quantum dot laser, so that the photons generated by the silicon-based quantum dot laser present a sub-Poisson distribution, and the silicon-based quantum dot laser generates light in an amplitude compression state.

[0054] In this example, the pump current source is referred to as low-noise pump. In the specific implementation process, this example builds a quantum dot laser model and explores the relationship between the pump source noise of the silicon-based quantum dot laser and the relative intensity noise of the QD laser, thereby effectively reducing the relative intensity noise of the silicon-based quantum dot laser.

[0055] The working principle of the present invention is described in detail below.

[0056] Step S1: constructing a quantum dot laser model, wherein the quantum dot laser model consists of three energy states: a two-dimensional carrier reservoir RS, an excited state ES and a ground state GS.

[0057] In this example, when building a quantum dot laser model, two pump current sources with different external carrier noise are represented: a normal pump with a Gaussian carrier distribution (the commonly used pump source) and a low-noise pump with a sub-Poissonian carrier distribution (the pump source of the present invention). The model describes the QD carrier dynamics by considering a three-level system, assuming that the silicon-based QD laser is a single-mode laser and that there is only one QD ensemble in the active region.

[0058] like Figure 1 As shown in Figure 1, the silicon-based QD laser model consists of a two-dimensional carrier reservoir (RS), an excited state (ES), and a ground state (GS). The carriers are first trapped in the Captured from RS into ES, and then with relaxation time Relaxation from ES to GS, stimulated emission finally occurs at GS. Due to the effect of heat, the carrier escapes with a time Return from GS to ES to escape time From ES back to RS, this process is determined by the Fermi distribution of the quasi-equilibrium state. In addition, the carriers will spontaneously radiate and recombine in each state, and the time is respectively Since the laser model is a silicon-based QD laser, the non-radiative recombination lifetime τ SRH .

[0059] Step S2: Build the quantum dot laser model with carrier number N RS 、N ES 、N GS , photon number S GS and the light field phase φ GS The kinetic rate equations each contain a noise source associated with the corresponding current source.

[0060] This example describes the carrier number N RS 、N ES 、N GS , photon number S GS and the light field phase φ GS The kinetic rate equation is expressed as:

[0061]

[0062] Where I is the pump current, q is the electron charge, and Γ p is the optical confinement factor, v g is the group velocity, τ p is the photon lifetime, β sp is the spontaneous emission factor, g RS ,g ES ,g GS are the material gains of each energy state, respectively, and the calculation formula is:

[0063]

[0064] Among them, a RS ,a ES ,a GS is the differential gain, ε is the optical confinement factor, N B is the total number of quantum dots, V B is the volume of the active region, D RS is the number of RS states, V RS is the volume of RS, ρ RS , ES , GS are the carrier occupancies of RS, ES, and GS, respectively, and the calculation formula is: RS, ES, and GS are respectively H The contribution of the factor. Given, where T D is the dephasing time, ω RS,ES,GS is the angular frequency of each energy state.

[0065] Step S3: determining the autocorrelation of the current source noise within the time period based on the five kinetic rate equations in step S2.

[0066] F RS ,F ES ,F GS ,F S ,F φ are the kinetic rate equation noise sources of carriers, photons, and phases, respectively. The correlation intensity relationship of the noise sources at two different times t and t' is: <F i (t)F j (t')>=U i,jδ(t-t'), where i, j refers to the correlation intensity U of the noise source of the kinetic rate equation at two times t and t' in RS, ES, GS, S, Φ i,j is δ-related, and the correlation strength is specifically expressed as:

[0067]

[0068] U RS,GS =U RS,S =U RS,φ =U ES,S =U ES,φ =U GS,φ =U S,φ =0

[0069] Through small signal analysis, the rate equation is linearized to obtain:

[0070]

[0071] in,

[0072]

[0073] where a and a p Considering the gain compression under high photon number, dg = adN GS -a p dS GS The other parameter values ​​of silicon-based QD laser can refer to Table 1.

[0074]

[0075]

[0076] Table 1 Materials and optical parameters of silicon-based QD lasers

[0077] Step S4: Based on the autocorrelation relationship and the relative intensity noise function, determine the relationship between the relative intensity noise and the external carrier noise of the pump source.

[0078] According to Cramer's law, the calculation formula for the RIN of silicon-based QD lasers is:

[0079]

[0080] Among them, δS GS (ω) is the photon number fluctuation in the frequency domain, S GS is the number of photons when the laser reaches steady state. According to the calculation formula of relative intensity noise RIN, the correlation intensity U RS,RS It is a key parameter that relates RIN to external carrier noise. By reducing or eliminating the external carrier noise of the pump source, the relative intensity noise is reduced.

[0081] Step S5: Relative intensity noise is reduced by reducing external carrier noise of the pump source.

[0082] In this example, when a normal pump is used to drive the QD laser, RS,RS Add the pump current source noise term to When a low-noise pump is used to drive a QD laser, the external carrier noise will affect the lasing of the active region of the QD laser. RS,RS Remove the pump current source noise term from It is assumed that external carrier noise has no effect on the laser. By adjusting the external carrier noise, the relative intensity noise can be effectively changed.

[0083] Test verification:

[0084] In order to verify the effect of the present invention, the present invention conducts experimental measurements on the noise power and time domain noise of the low-noise pump of the present invention and the existing ordinary pump, such as Figure 2 As shown in Figure 1, the frequency domain noise power of the low-noise pump is about 30dB lower than that of the ordinary pump. Figure 3 As shown in the time domain diagram on the left, the low-noise pump has a lower noise intensity and shows a narrow range of jitter, indicating that the noise intensity is relatively concentrated. In contrast, the normal pump shows a wider range of jitter values ​​and a higher noise intensity, indicating that the distribution of noise intensity over time is more dispersed. Figure 3 The statistical distribution on the right side more intuitively shows the difference in noise levels between the two pump sources.

[0085] like Figure 4 As shown, in this example, according to the above principles and formulas, the RIN spectra of the QD laser driven by different pump sources at 2.5 times the threshold current are obtained. It can be seen that the present invention can significantly reduce the RIN of the silicon-based QD laser by low-noise pumping that reduces the external carrier noise of the pump source, so that the output optical power of the laser is more stable in the time domain.

[0086] like Figure 5 As shown in the figure, under the two pumping conditions of the low-noise pump of the present invention and the conventional pump of the prior art, the output power of the silicon-based QD laser increases with the increase of the pump current. However, the RIN value of the laser using the low-noise pump in the low-frequency range is always lower than that of the laser using the normal pump. This result proves that the method of reducing the RIN of the laser by reducing the external carrier noise is feasible and effective.

[0087] The special semiconductor QD laser used in the present invention utilizes the special pumping mechanism (electric pumping) of the semiconductor laser while taking into account the three-dimensional quantum confinement effect of the QD structure. Therefore, the current distribution of the pumping current can be regularized to make the output light present an amplitude compression state, and the output of the laser is very stable, is less affected by temperature, and has a small threshold current.

[0088] The present invention also provides a quantum communication light source, which is provided by the silicon-based quantum dot laser, and the silicon-based quantum dot laser is used to implement the method of reducing the relative intensity noise of the silicon-based quantum dot laser.

[0089] With the continuous development of information technology, information security issues have become increasingly prominent. In the fields of military, finance, government, and enterprise, the security and reliability of information are of vital importance, and any information leakage may cause serious economic losses. Traditional communication technologies have been widely used, including the Internet, fiber-optic communications, and radio, but classical communications rely on complex mathematical problems for encryption, which become vulnerable to quantum computing. Quantum computers can quickly crack existing encryption algorithms, so there is a need to find more secure communication methods.

[0090] Quantum communication uses the basic principles of quantum mechanics to provide an information-theoretic unconditional security. Through the quantum key distribution (QKD) protocol, quantum communication ensures that any eavesdropping will introduce detectable disturbances in the quantum state, making it impossible for the eavesdropper to steal information without being discovered. Even an attacker with unlimited computing power cannot crack the key generated by QKD. Quantum communication not only has significant advantages in security, but also provides unprecedented guarantees in the confidentiality and integrity of data transmission. This makes it have broad application prospects in fields with extremely high security requirements such as military, finance, government and enterprises.

[0091] In the QKD process, light in quantum states (such as single photons, entangled states, coherent states, or compressed states) is needed to generate and distribute keys. Once the communicating parties generate and share a secure key through the QKD protocol, they can use classical encryption methods for subsequent communications without the transmitted information being obtained, ensuring the effectiveness and security of information transmission. However, it is not easy to produce high-quality quantum state light used to generate keys. It requires the use of high-quality nonlinear optical crystals without any impurities and defects, as well as precise manipulation of the working dimensions and phase matching conditions. These requirements pose challenges to the use and popularization of quantum communications.

[0092] An important factor that distinguishes semiconductor lasers from other types of lasers is the pumping mechanism. Specifically, the semiconductor is pumped by an injected current delivered through a circuit. Optical pumping relies on photon absorption, follows a Poisson point process, and is constrained by the shot noise limit. However, due to the Coulomb interaction, electrical pumping does not strictly conform to the Poisson point process. The present invention reduces the carrier noise of the pump current so that the pump current electron distribution presents a sub-Poisson distribution, and then introduces this mechanism into the generated laser, so that the generated photons present a sub-Poisson distribution, the photon fluctuations are reduced, and are reduced to below the standard quantum limit, generating light in an amplitude compression state. As a result, the quantum communication light source of the present invention can meet the demand for light sources in the process of quantum communication quantum key distribution, and at the same time does not require precise control, and has the advantages of simplicity and reliability.

[0093] like Figure 6 As shown, as an application of the present invention, this example is applied to a quantum communication system. During the quantum communication process, the sender generates a plaintext message. Then, the sender uses a key to encrypt the plaintext to generate a ciphertext. This key is securely generated through quantum key distribution technology. The specific process is:

[0094] The sender first generates a key and encodes it onto quantum bits, which are implemented by modulating quantum states, such as by changing the polarization state of photons. These modulated quantum bits are then sent to the receiver via a quantum channel. The receiver uses quantum detection technology to measure these quantum bits and extract the key from them. At the same time, the sender and receiver also need to communicate through a classical channel to coordinate and confirm the basis vector of the quantum measurement, ensure that both parties can correctly interpret the state of the quantum bits, and ultimately ensure that the keys obtained by both parties are consistent. After the receiver obtains the key, it uses it to decrypt the ciphertext received through the classical channel and restore the original plaintext information. This process not only ensures the secure transmission of the key, but also ensures the confidentiality and integrity of the information content during the transmission process, reflecting the unique advantages of quantum communication in ensuring the secure transmission of data. The generation of quantum keys must use quantum state light, and quantum state light can be provided by the quantum communication light source of the present invention. The silicon-based QD laser introduced in the present invention can be used as a quantum light source in the quantum communication process to meet the demand for light sources in the quantum communication QKD process.

[0095] The specific implementation modes described above are preferred implementation modes of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the specific implementation modes, and all equivalent changes made according to the present invention are within the protection scope of the present invention.

Claims

1. A method for reducing the relative intensity noise of a quantum dot laser, characterized in that: This is achieved by reducing external carrier noise of a pump source, so that the silicon-based quantum dot laser generates light in an amplitude compression state.

2. The method for reducing relative intensity noise of a quantum dot laser according to claim 1, characterized in that: The method to reduce the external carrier noise of the pump source is: Adjusting the injection current output by the pump current source so that the pump current electron distribution presents a sub-Poisson or quasi-sub-Poisson distribution; The injection current acts on the silicon-based quantum dot laser.

3. The method for reducing relative intensity noise of a quantum dot laser according to claim 1, characterized in that: The steps include: S1: Building a quantum dot laser model, which consists of three energy states: a two-dimensional carrier reservoir RS, an excited state ES, and a ground state GS; S2: Build the quantum dot laser model with the number of carriers N RS 、N ES 、N GS , photon number S GS and the light field phase φ GS The kinetic rate equations, each of which contains a noise source associated with the corresponding current source; S3: determining the autocorrelation of the current source noise within the time period based on the five kinetic rate equations in step S2; S4: determining a relationship between the relative intensity noise and the external carrier noise of the pump source based on the autocorrelation relationship and the relative intensity noise function; S5: Reduce the relative intensity noise by reducing the external carrier noise of the pump source.

4. The method for reducing relative intensity noise of a quantum dot laser according to claim 3, characterized in that: In step S2, the number of carriers N RS 、N ES 、N GS , photon number S GS and the light field phase φ GS The kinetic rate equation is expressed as: Where I is the pump current, q is the electron charge, and Γ p is the optical confinement factor, v g is the group velocity, τ p is the photon lifetime, β sp is the spontaneous emission factor, are the capture time, relaxation time and escape time of external carriers, respectively. are the spontaneous radiative recombination time of external carriers in each state, τ SRH is the non-radiative recombination lifetime of silicon-based quantum dot lasers, g RS ,g ES ,g GS are the material gains of each energy state, respectively, and the calculation formula is: Among them, a RS ,a ES ,a GS is the differential gain, ε is the optical confinement factor, N B is the total number of quantum dots, V B is the volume of the active region, D RS is the number of RS states, V RS is the volume of RS, ρ RS , ES , GS are the carrier occupancy rates of RS, ES, and GS, respectively, and F RS ,F ES ,F GS ,F S ,F φ are the kinetic rate equation noise sources for carriers, photons, and phase, respectively.

5. The method for reducing relative intensity noise of a quantum dot laser according to claim 4, characterized in that: In step S3, the correlation strength relationship between the noise sources at two times t and t' is: <F i (t)F j (t')>=U i,j δ(t-t'), where i, j refers to the correlation intensity U of the noise source of the kinetic rate equation at two times t and t' in RS, ES, GS, S, Φ i,j is δ-related, and the correlation strength is specifically expressed as: IN RS,GS =U RS,S =U RS,φ =U ES,S =U ES,φ =U GS,φ =U S,φ =0 RS, ES, and GS are respectively H The contribution of factors.

6. The method for reducing relative intensity noise of a quantum dot laser according to claim 5, characterized in that: Through small signal analysis, the kinetic rate equation is linearized to: in, The calculation formula of the relative intensity noise RIN of the silicon-based quantum dot laser is: Among them, δS GS (ω) is the photon number fluctuation in the frequency domain, S GS is the number of photons when the laser reaches steady state. According to the calculation formula of relative intensity noise RIN, the correlation intensity U RS,RS It is a key parameter that relates RIN to external carrier noise. By reducing or eliminating the external carrier noise of the pump source, the relative intensity noise is reduced.

7. A quantum communication light source, characterized in that: Provided by the silicon-based quantum dot laser, the silicon-based quantum dot laser is used to adopt the method for reducing the relative intensity noise of the quantum dot laser according to any one of claims 1-6.

8. The quantum communication light source according to claim 7, characterized in that: The quantum communication light source is light in an amplitude compression state, and its photons are in a sub-Poisson distribution.

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