CN203069943U - Stimulated raman scattering based wavelength converter - Google Patents

Abstract

The utility model discloses a wavelength converter based on stimulated Raman scattering, which comprises a first laser, a second laser, a wave combiner and an optical filter, a modulator is connected to the first laser, and the output end of the first laser passes through The first optical fiber is connected with an erbium-doped fiber amplifier, the output end of the erbium-doped fiber amplifier is connected with the first input end of the multiplexer through the first optical fiber, and the output end of the second laser is connected with the second input end of the multiplexer through the second optical fiber end connection, the output end of the wave combiner is connected to the optical filter through the third optical fiber for wavelength conversion through the stimulated Raman scattering amplification process, the central wavelength of the second laser is greater than the central wavelength of the first laser, and the optical filter The central wavelength of the laser is equal to the central wavelength of the second laser. The utility model has fast wavelength conversion rate, wide tuning bandwidth, transparent wavelength conversion, cross-band and tunable wavelength conversion, and strong practicability.

Description

Wavelength Converter Based on Stimulated Raman Scattering

technical field

The utility model belongs to the technical field of optical communication, in particular to a wavelength converter based on stimulated Raman scattering.

Background technique

Wavelength division multiplexing technology is the preferred technology for high-speed broadband and large-capacity optical fiber communication technology. In an optical cross-connect node of a wavelength division multiplexing communication system, when two signals of the same wavelength in different optical fibers enter the same optical fiber, the problem of wavelength blocking occurs. Due to the limitations of various factors in the system, the number of wavelengths that can be multiplexed by each optical fiber is limited, so this situation will inevitably occur at the optical cross node. An effective way to solve this problem is to use wavelength conversion technology to convert one signal wavelength to other wavelengths, so as to avoid wavelength blocking in OXC. Another important use of wavelength conversion devices is to achieve wavelength matching between different optical networks. It can unify products of different wavelength series produced by different manufacturers and in different eras to the same wavelength standard to realize communication between networks. In addition, the flexibility and reliability of network reconfiguration and network management can be enhanced through the wavelength converter, and functions such as wavelength routing can be realized with the wavelength division switch.

The tunable all-optical wavelength converter can realize the conversion between multiple groups of different wavelengths. It has the following advantages in the all-optical network: (1) It can reuse wavelengths more effectively and further improve the wavelength utilization rate. (2) Dynamic wavelength routing can be formed, which is conducive to the improvement of transmission rate. (3) The number of wavelength converters placed in optical network nodes can be reduced, which is beneficial to reduce system costs.

At present, there are two main methods to achieve wavelength conversion:

(1) Optical/electrical-electrical/optical method. This method is relatively mature in technology and works stably. It has been widely used in optical fiber communication systems and has mature commercial products. But its disadvantages are that the device structure is complex, the cost increases with the rate and the number of components, the power consumption is high, and the reliability is poor, which limits its application in multi-wavelength channel systems, and it does not have the transparency of the transmission pattern and rate. When the system needs to be upgraded, the equipment must be replaced.

(2) The all-optical wavelength conversion method is to use the nonlinear effect of some media to directly transfer the input optical signal to a new wavelength, which is conducive to system upgrade and expansion. At present, the physical effects mainly used in all-optical wavelength conversion devices are: cross-gain modulation effect, cross-phase modulation, four-wave mixing in semiconductor optical amplifier (SOA), gain saturation effect in semiconductor laser, semiconductor material, lithium niobate crystal Difference frequency and four-wave mixing effects of nonlinear materials such as optical fibers and optical fibers. However, they all have disadvantages such as complex implementation process, high cost, slow conversion speed, and limited wavelengths to be converted. Moreover, when a network node needs to perform wavelength conversion on multiple wavelength channels, multiple wavelength converters must be installed at the same time, which greatly increases the cost.

Utility model content

The technical problem to be solved by the utility model is to provide a wavelength converter based on stimulated Raman scattering, which has a simple structure, reasonable design, low implementation cost, fast wavelength conversion rate and wide bandwidth in view of the above-mentioned deficiencies in the prior art , capable of transparent wavelength conversion and tunable wavelength conversion, strong practicability, good use effect, and convenient popularization and use.

In order to solve the above technical problems, the technical solution adopted by the utility model is: a wavelength converter based on stimulated Raman scattering, which is characterized in that it includes a first laser for outputting signal light and a laser for outputting continuous detection light The second laser, and a multiplexer for coupling the amplified signal light and continuous detection light and an optical filter for filtering out the wavelength-converted detection light, the first laser is electrically connected to A modulator that modulates the amplitude and phase of the output light of the first laser, and the output end of the first laser is connected to a doped fiber for power amplifying the signal light output by the first laser and forming a pump signal light through the first optical fiber. An erbium fiber amplifier, the output end of the erbium-doped fiber amplifier is connected to the first input end of the multiplexer through the first optical fiber, and the output end of the second laser is connected to the first input end of the multiplexer through the second optical fiber. The two input terminals are connected, the output terminal of the multiplexer is connected to the optical filter through the third optical fiber for wavelength conversion through the stimulated Raman scattering amplification process, and the central wavelength λ _i of the second laser is greater than the specified The central wavelength λ ₁ of the first laser, the central wavelength of the optical filter is equal to the central wavelength λ _i of the second laser.

The above-mentioned wavelength converter based on stimulated Raman scattering is characterized in that: the central wavelength λ _i of the second laser and the central wavelength λ ₁ of the first laser satisfy the frequency shift calculation formula Δv=(1/λ ₁ )—(1/λ _i ), where Δv is the frequency shift and the value of Δv ranges from 200cm ⁻¹ to 500cm ⁻¹ .

The above-mentioned wavelength converter based on stimulated Raman scattering is characterized in that: the third optical fiber is a highly nonlinear optical fiber, and the nonlinear coefficient range of the highly nonlinear optical fiber is 10W ^-1 in the wavelength range of 1370nm to 1700nm km ^-1 ~ 37W ^-1 km ^-1 , the nonlinear coefficient of the highly nonlinear optical fiber at a wavelength of 1550nm is 36.2W ^-1 km ^-1 , and the dispersion value of the highly nonlinear optical fiber in the wavelength range of 1370nm ~ 1700nm The range is 0-0.6 ps/(nm·km), and the dispersion slope range of the highly nonlinear optical fiber is -0.2-0.2 in the wavelength range of 1370nm-1700nm.

The above-mentioned wavelength converter based on stimulated Raman scattering is characterized in that: the second laser is a tunable laser, the optical filter is a tunable optical filter, and the tuning range of the second laser is the same as that of the The tuning range of the optical filter is the same.

Compared with the prior art, the utility model has the following advantages:

1. The utility model has the advantages of simple structure, reasonable design and convenient realization.

2. Compared with ordinary optical-electrical-optical wavelength converters, the utility model retains the phase and amplitude information of signal light waves during wavelength conversion, and has strict transmission transparency.

3. The implementation cost of the utility model is low, and the cost is much lower than that of ordinary optical-electrical-optical wavelength converters. By adjusting the tunable laser, the information carried by the signal light can be converted to different continuous detection lights, which can complete Tunable wavelength conversion.

4. During the wavelength conversion process of the utility model, the spontaneous noise of the wavelength converter is low, and chirp reversal can be realized.

5. The wavelength conversion rate of the utility model is fast, the wavelength conversion bandwidth is wide, the output signal extinction ratio is good, and cross-band conversion can be realized.

6. The utility model realizes the amplification of the wavelength signal to be converted while performing the wavelength conversion, and the amplification factor can be controlled by adjusting the pump light power and the length of the optical fiber.

7. The utility model has strong practicability, good use effect, and is convenient for popularization and use.

In summary, the utility model has simple structure, reasonable design, low implementation cost, high wavelength conversion rate, wide tuning bandwidth, can realize transparent wavelength conversion, cross-band wavelength conversion and tunable wavelength conversion, strong practicability and good use effect , which is convenient for promotion and use.

The technical solutions of the present utility model will be further described in detail through the drawings and embodiments below.

Description of drawings

Fig. 1 is a functional block diagram of the utility model.

Fig. 2 is a schematic diagram of the optical power of the pumping signal light.

Fig. 3 is a schematic diagram of the optical power of the continuous detection light output by the second laser of the present invention.

Fig. 4 is a schematic diagram of the optical power of the pump signal light after wavelength conversion.

FIG. 5 is a schematic diagram of the optical power of the probe light after wavelength conversion.

Explanation of reference signs:

1—modulator; 2—the first laser; 3—erbium-doped fiber amplifier;

4—second laser; 5—multiplexer; 6—third optical fiber;

7—optical filter; 8—the first optical fiber; 9—the second optical fiber.

Detailed ways

As shown in Figure 1, the utility model includes a first laser 2 for outputting signal light and a second laser 4 for outputting continuous detection light, and a laser for coupling the amplified signal light and continuous detection light a multiplexer 5 and an optical filter 7 for filtering out wavelength-converted probe light, the first laser 2 is electrically connected to a modulator 1 for modulating the amplitude and phase of the output light of the first laser 2, The output end of the first laser 2 is connected with an erbium-doped fiber amplifier 3 for power amplifying the signal light output by the first laser 2 and forming a pump signal light through the first optical fiber 8, and the erbium-doped fiber amplifier 3 The output end is connected with the first input end of the described multiplexer 5 through the first optical fiber 8, and the output end of the second laser 4 is connected with the second input end of the described multiplexer 5 through the second optical fiber 9, so The output end of the multiplexer 5 is connected to the optical filter 7 through the third optical fiber 6 used for wavelength conversion through the stimulated Raman scattering amplification process, and the central wavelength λ _i of the second laser 4 is greater than that of the first laser. The central wavelength λ ₁ of a laser 2 , the central wavelength of the optical filter 7 is equal to the central wavelength λ _i of the second laser 4 .

In this embodiment, the central wavelength λ _i of the second laser 4 and the central wavelength λ ₁ of the first laser 2 satisfy the frequency shift calculation formula Δv=(1/λ ₁ )—(1/λ _i ), where , Δv is the frequency shift and the value range of Δv is 200cm ^-1 ~ 500cm ^-1 , in this frequency shift range can get a higher Raman gain, making wavelength conversion easy to happen, not only can realize the same communication band Tunable all-optical wavelength conversion, and can realize all-optical wavelength conversion across communication bands.

In this embodiment, the third optical fiber 6 is a highly nonlinear optical fiber, and the nonlinear coefficient of the highly nonlinear optical fiber ranges from 10W ^-1 km ^-1 to 37W ^-1 km ^-1 in the wavelength range of 1370nm to 1700nm, The nonlinear coefficient of the highly nonlinear optical fiber at a wavelength of 1550nm is 36.2W ^-1 km ^-1 , and the dispersion value of the highly nonlinear optical fiber ranges from 0 to 0.6 ps/(nm·km) in the wavelength range of 1370nm to 1700nm ), the dispersion slope of the highly nonlinear optical fiber ranges from -0.2 to 0.2 in the wavelength range of 1370nm to 1700nm, and the dispersion of the optical fiber is almost flat, which can effectively avoid the walk-off between signals caused by different group velocities corresponding to different lights, It is beneficial to the synchronous transmission of pumping signal light and continuous detection light; the Raman gain spectrum of the optical fiber is continuous and wide up to 40THz.

In this embodiment, the second laser 4 is a tunable laser, the optical filter 7 is a tunable optical filter, and the tuning range of the second laser 4 is the same as that of the optical filter 7; By adjusting the tunable laser, the information carried by the signal light can be converted to different continuous detection lights, and the tunable wavelength conversion can be completed. Since the Raman gain spectrum of the third optical fiber 6 is continuous and wide as 40THz, the effective tuning range is also Very wide and can reach 50nm.

The method for performing wavelength conversion using the wavelength converter based on stimulated Raman scattering described in the present invention comprises the following steps:

Step 1, first select the first laser 2 with a center wavelength of _λ1 , then modulate the amplitude and phase of the output light of the first laser 2 through the modulator 1, so that the first laser 2 outputs signal light and transmit it through the first optical fiber 8 Give erbium-doped fiber amplifier 3; In the present embodiment, select the first laser device 2 of central wavelength λ ₁ =1550nm;

Step 2, amplifying the power of the signal light output by the first laser 2 through the erbium-doped fiber amplifier 3 to form a pump signal light, so that the power of the pump signal light reaches or exceeds the threshold of the stimulated Raman scattering effect, and The pump signal light is transmitted to the multiplexer 5 through the first optical fiber 8; in the present embodiment, the optical power schematic diagram of the pump signal light is as shown in Figure 2; in Figure 2, the abscissa represents the time t, and the unit It is picosecond p s; the ordinate indicates optical power P, and the unit is watt W; "1" code power is 0.5W;

Step 3. According to the frequency shift calculation formula Δv=(1/λ ₁ )—(1/λ _i ), select the second laser 4 with a center wavelength of λ _i , and the second laser 4 outputs continuous detection light and transmits it through the second optical fiber 9 For the multiplexer 5; wherein, Δv is the frequency shift and the value range of Δv is 200cm ^-1 ~ 500cm ^-1 ; that is, the value range of the central wavelength λ _i of the second laser 4 is 1599.6nm ~ 1680.2nm; In the embodiment, take Δv=440cm ^-1 , the Raman gain coefficient of the frequency shift is the largest, and the wavelength conversion effect is optimal, then the center wavelength λi of the selected second laser 4 is λ _i =1663.5nm, and the output of the second laser 4 is The schematic diagram of the optical power of the continuous probing light is as shown in Figure 3; in Figure 3, the abscissa represents the time t, and the unit is picosecond p s; the ordinate represents the optical power P, and the unit is Watt W; The optical power of the light is a constant value of 1×10 ^-6 W;

Step 4, coupling the pump signal light transmitted by the first optical fiber 8 and the continuous detection light transmitted by the second optical fiber 9 into the third optical fiber 6 through the multiplexer 5;

Step five, the third optical fiber 6 according to the formula

c为光速且值c=3×10⁸m/s，

为第一信道的波数且

为第i信道的波数且

为第一信道的泵浦信号光的波长与第i信道的连续探测光的波长之间的频移且

的取值范围为0～500cm^-1，

为第一信道的泵浦信号光中的平均光子频率，P₁(t-z/u)为泵浦信号光在第三光纤6传输了距离z后的光功率，L为第三光纤6的有效作用长度，i为信道数，N为信道总数且为整数；本实施例中，所述

的取值为440cm^-1，所述L的取值为10km，所述α的取值为0.2dB/km，所述A的取值为5.0×10^-11m²，所述M的取值为2，所述u的取值为2.0×10⁸m/s。由于第三光纤6上传输的泵浦信号光的“1”码有很大功率，达到或超过了受激拉曼散射效应的阈值，与连续探测光进行作用，而泵浦信号光的“0”码不与连续探测光作用或作用很小，这样就把泵浦信号光上携带的信息透明转换到了连续探测光上，泵浦信号光的能量由于受激拉曼散射放大将一部分能量传递给了连续探测光；进行波长转换后泵浦信号光的光功率示意图如图4所示，图4中，横坐标表示时间t，单位为皮秒p s；纵坐标表示光功率P，单位为瓦特W;与图2泵浦信号光的光功率相比，其“1”码功率减小到0.32W左右，“0”码没有改变，这是由于受激拉曼散射效应，其“1”码将一部分能量传递给了连续探测光，“0”码不作用或作用很小；And carry out wavelength conversion through the stimulated Raman scattering amplification process, convert the information carried on the pump signal light to the continuous detection light and transmit it to the optical filter 7; wherein, P _1i is the continuous detection light in the third optical fiber 6 α is the attenuation coefficient of the optical power in the third optical fiber 6, z is the distance of the light transmitted in the third optical fiber 6, and t is the time used for the transmission distance z , u is the group velocity of light in the third optical fiber 6, G _1i is the gain between the first channel and the i-th channel, P _i (tz/u) is the gain of the probe light after it travels the distance z in the third optical fiber 6 Optical power, e is the natural logarithm, λ ₁ is the central wavelength of the pump signal light, M is the polarization maintaining coefficient and the value range of M is 1≤M≤2, A is the effective active area of the third optical fiber 6, k is a constant and takes k=1.80×10 ^-16 m·cm/w, v ₁ is the optical frequency of the pump signal light and

c is the speed of light and the value c=3×10 ⁸ m/s,

is the wavenumber of the first channel and

is the wavenumber of the i-th channel and

is the frequency shift between the wavelength of the pump signal light of the first channel and the wavelength of the continuous detection light of the i-th channel and

The value range of is 0～500cm ^-1 ,

is the average photon frequency in the pump signal light of the first channel, P ₁ (tz/u) is the optical power of the pump signal light after the distance z is transmitted in the third optical fiber 6, and L is the effective effect of the third optical fiber 6 length, i is the number of channels, N is the total number of channels and is an integer; in this embodiment, the

The value of 440cm ^-1 , the value of L is 10km, the value of α is 0.2dB/km, the value of A is 5.0×10 ^-11 m ² , the value of M is 2, and the value of u is 2.0×10 ⁸ m/s. Since the "1" code of the pump signal light transmitted on the third optical fiber 6 has a large power, it reaches or exceeds the threshold value of the stimulated Raman scattering effect, and interacts with the continuous detection light, while the "0" code of the pump signal light "The code has no or little effect on the continuous detection light, so that the information carried on the pumping signal light is transparently converted to the continuous detection light, and the energy of the pumping signal light is amplified by stimulated Raman scattering and a part of the energy is transferred to the Continuous probing light; the schematic diagram of the optical power of the pump signal light after wavelength conversion is shown in Figure 4. In Figure 4, the abscissa represents the time t, and the unit is picoseconds p s; the ordinate represents the optical power P, and the unit is watts W ;Compared with the optical power of the pump signal light in Figure 2, its "1" code power is reduced to about 0.32W, and the "0" code does not change. This is due to the stimulated Raman scattering effect, and its "1" code will Part of the energy is transferred to the continuous detection light, and the "0" code has no or little effect;

Step 6: Filter out the wavelength-converted probe light through the optical filter 7; the probe light obtained in this way also carries the information carried by the signal light, and completes the wavelength conversion. The schematic diagram of the optical power of the probe light after wavelength conversion is shown in Figure 5. In Figure 5, the abscissa represents the time t, and the unit is picosecond ps; the ordinate represents the optical power P, and the unit is Watt W; 4 Compared with the optical power of the output continuous detection light, it carries the same information as the signal light, the power of the "1" code becomes 7×10 ^-6 W, and the power of the "0" code remains unchanged.

The above are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the present utility model still belong to Within the scope of protection of the technical solution of the utility model.

Claims (4)

1. A wavelength converter based on stimulated Raman scattering, characterized in that: it includes a first laser (2) for outputting signal light and a second laser (4) for outputting continuous probe light, and for A multiplexer (5) for coupling the amplified signal light and continuous detection light and an optical filter (7) for filtering out the wavelength-converted detection light, the first laser (2) is electrically connected to There is a modulator (1) for modulating the amplitude and phase of the output light of the first laser (2), and the output end of the first laser (2) is connected to the first laser (2) through the first optical fiber (8). 2) The output signal light is amplified to form an erbium-doped fiber amplifier (3) for pumping signal light, and the output end of the erbium-doped fiber amplifier (3) is connected to the multiplexer ( 5), the output end of the second laser (4) is connected to the second input end of the multiplexer (5) through the second optical fiber (9), and the multiplexer (5) ) is connected to an optical filter (7) through a third optical fiber (6) for wavelength conversion through a stimulated Raman scattering amplification process, and the central wavelength λ _i of the second laser (4) is greater than the The central wavelength λ ₁ of the first laser (2), the central wavelength of the optical filter (7) is equal to the central wavelength λ _i of the second laser (4). 2. The wavelength converter based on stimulated Raman scattering according to claim 1, characterized in that: the central wavelength λ _i of the second laser (4) is the same as the central wavelength λ of the first laser (2) ₁ Satisfies the frequency shift calculation formula Δv=(1/λ ₁ )—(1/λ _i ), where Δv is the frequency shift amount, and the value range of Δv is 200cm ^-1 to 500cm ^-1 . 3. The wavelength converter based on stimulated Raman scattering according to claim 1, characterized in that: the third optical fiber (6) is a highly nonlinear optical fiber, and the wavelength of the highly nonlinear optical fiber is between 1370nm and 1700nm The range of nonlinear coefficient is 10W ^-1 km ^-1 ~ 37W ^-1 km ^-1 , the nonlinear coefficient of the high nonlinear fiber at the wavelength of 1550nm is 36.2W ^-1 km ^-1 , the high nonlinear fiber The dispersion value ranges from 0 to 0.6 ps/(nm·km) in the wavelength range of 1370 nm to 1700 nm, and the dispersion slope range of the highly nonlinear optical fiber is -0.2 to 0.2 in the wavelength range of 1370 nm to 1700 nm. 4. The wavelength converter based on stimulated Raman scattering according to claim 1, characterized in that: the second laser (4) is a tunable laser, and the optical filter (7) is a tunable optical filter The tuning range of the second laser (4) is the same as that of the optical filter (7).

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