Tunable laser and wavelength adaptive control method thereof

Abstract

The invention provides a tunable laser and a wavelength adaptive control method thereof.The wavelength adaptive control is performed in real time through a microcontroller arranged in the tunable laser, the control method comprises the steps that real-time monitoring is performed, specifically, the voltage feedback value ADC of an etalon and the DAC value of heating power are monitored in real time, and a calculated value is obtained through calculation according to the formula a1 * ADC + a2 * DAC + a3; comparing the calculated value with a target value m lambda of the tunable laser; and calculating and judging whether a difference value delta between the test value and the target value is within a preset interval, if so, continuing monitoring, and if not, adjusting the input voltage and / or the heating power of the etalon and then continuing monitoring until the difference value delta between the calculated value of the formula a1 * ADC + a2 * DAC + a3 and the target value m lambda is within the preset interval, ending adjustment and continuing monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of tunable lasers, and in particular to a tunable laser and a wavelength adaptive control method thereof. Background Art

[0002] With the advancement of technology, tunable lasers are increasingly being used in fields such as communications, biomedicine, and sensing. However, the wavelength stability of tunable lasers is affected by a variety of factors, such as ambient temperature and device aging, which can cause wavelength drift and, in turn, affect their performance. However, there are currently no effective measures in the industry to eliminate wavelength drift. Therefore, it is of great significance to develop a tunable laser that can adaptively control the wavelength of the tunable laser according to changes in environmental factors to improve the stability of the tunable laser and ensure its performance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a tunable laser and a wavelength adaptive control method thereof, which can adaptively control the wavelength of the tunable laser according to changes in environmental influencing factors, so as to improve the stability of the tunable laser and ensure its performance.

[0004] In a first aspect, the present invention provides a tunable laser having an etalon therein, capable of real-time wavelength adaptive control, wherein the wavelength adaptive control method comprises the following steps:

[0005] S1. Real-time monitoring of the voltage feedback value ADC of the standard instrument and the DAC value of the heating power, and the calculated value is obtained according to formula 1:

[0006] Calculated value = a1 × ADC + a2 × DAC 2 +a3 formula 1;

[0007] Among them, a1, a2, and a3 are all experimental constants;

[0008] S2. Calculate the difference δ between the calculated value and the target value according to Formula 2:

[0009] δ=calculated value-target value formula 2;

[0010] Wherein, target value = mλ, m is the interference order of the etalon, and λ is the target wavelength of the tunable laser;

[0011] S3. Determine whether the difference δ is within a preset allowable range. If so, return directly to step S1. If not, adjust the input voltage and / or heating power of the etalon and then return to step S1.

[0012] In a second aspect, the present invention provides a wavelength adaptive control method for a tunable laser, comprising the following steps:

[0013] S1. Real-time monitoring of the voltage feedback value ADC of the standard instrument and the DAC value of the heating power, and the calculated value is obtained according to formula 1:

[0014] Calculated value = a1 × ADC + a2 × DAC 2 +a3 formula 1;

[0015] Among them, a1, a2, and a3 are all experimental constants;

[0016] S2. Calculate the difference δ between the calculated value and the target value according to Formula 2:

[0017] δ=calculated value-target value formula 2;

[0018] Wherein, target value = mλ, m is the interference order of the etalon, and λ is the target wavelength of the tunable laser;

[0019] S3. Determine whether the difference δ is within a preset allowable range. If so, return directly to step S1. If not, adjust the input voltage and / or heating power of the etalon and then return to step S1.

[0020] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages: the tunable laser can automatically adjust the voltage value and heating power value of the etalon according to the changes in environmental factors, so that the formula a1×ADC+a2×DAC 2 The calculated value of +a3 is always close to the target value of mλ, which means that the actual wavelength of the tunable laser is always controlled to be close to the target wavelength, eliminating or reducing the impact of environmental factors on the wavelength. Because this monitoring and control is performed in real time, it can greatly improve the stability of the tunable laser and ensure its performance. Moreover, during control, since the calculated value is composed of two variables, U and DAC, an iterative approach can be used to gradually reduce the deviation between the calculated value and the target value until the deviation is within the preset range, which greatly reduces the difficulty of control.

[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 Schematic diagram of the structure of the tunable laser of the present invention;

[0024] Figure 2Schematic diagram of the flow of the wavelength adaptive control method of the present invention;

[0025] Figure 3 Schematic diagram of the iterative adjustment process of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present application provide a tunable laser and a method for adaptively controlling its wavelength, which can adaptively control the wavelength of the tunable laser according to changes in environmental factors, thereby improving the stability of the tunable laser and ensuring its performance.

[0027] The technical solution in the embodiment of the present application has the following general idea: Since the wavelength of the tunable laser may be affected by changes in environmental factors, the present invention adjusts the voltage value U of the etalon in the tunable laser and the value of the heating power value DAC so that the formula a1×ADC+a2×DAC 2 The calculated value of +a3 is always close to the target value of mλ, which means that the actual wavelength of the tunable laser is always controlled to be close to the target wavelength, eliminating or reducing the impact of environmental factors on the wavelength. And because this monitoring and control is performed in real time, the stability of the tunable laser is greatly improved and its performance is guaranteed. Furthermore, since the calculated value is composed of two variables, U and DAC, an iterative approach can be used during control, gradually reducing the deviation between the calculated value and the target value until the deviation is within the preset range, greatly reducing the difficulty of control.

[0028] The tunable laser is provided with an etalon, which can output a voltage feedback value ADC and a heating power DAC value. The present invention can be based on the formula a1×ADC+a2×DAC 2 The principle of +a3 controlling the actual wavelength of the tunable laser to be close to the target wavelength is:

[0029] mλ=2n T d T cosθ……(1)

[0030]

[0031] mλ0=2n0d0cosθ……(4)

[0032] Wherein, formulas (1) and (4) are diffraction formulas, formula (2) is the refraction formula, and formula (3) is the expansion coefficient formula. m is the interference order of the etalon, λ is the laser wavelength, λ0 is the laser wavelength at the initial moment, n0 is the refractive index of the etalon (the etalon is made of silicon material) at 25 degrees Celsius, and n t is the refractive index of the etalon at temperature t, d0 and d Tis the expansion coefficient of the standard at the initial moment (the initial moment is time 0) and time T; α and β are both constants, α is 1.84*10^-4, β is 2.4*10^-6, T0 Etalon and T Etalon Indicates the detection resistor temperature on the etalon at the initial time and time T.

[0033] From formula (1), formula (2) and formula (3), we can get:

[0034]

[0035] From formula (4), we can get:

[0036]

[0037] From formula (5) and formula (6), we can get:

[0038]

[0039] From formula (7), we can get:

[0040]

[0041] Dividing both sides of formula (8) by 2n0d0, we can get:

[0042]

[0043] In actual ambient temperature changes, the temperature changes by 1°C, and the frequency (wavelength) changes by 10GHz. However, in the product, the frequency changes by only 1GHz, so the change by 1GHz is only 0.1°C, which can be ignored.

[0044] Very small and can be omitted.

[0045] Then formula (11) can be transformed into formula (12):

[0046]

[0047] After the transformation of formula (12), we can get:

[0048]

[0049] Formula (13), formula (14) and formula (15) give formula (16):

[0050]

[0051] β Etalon Used to express formula (14), That is, the etalon temperature.

[0052] According to the experimental law:

[0053]

[0054] R0 and R are the resistance temperatures used to detect temperature on the standard. T Respectively represent the initial temperature and the resistance of the standard device used to detect temperature at time T.

[0055] From the circuit design:

[0056]

[0057] The initial temperature is equal to the temperature at time T, so:

[0058] R T ≈R0……(19)

[0059] From formula (18) and formula (19), we can get:

[0060]

[0061]

[0062] From formula (17) and formula (21), we can get:

[0063]

[0064] α sensor That is, the temperature variation coefficient of the thermistor, which is the detection resistor temperature on the standard instrument.

[0065]

[0066] From formula (22) and formula (25), we can get:

[0067]

[0068] Substituting equations (27) and (28) into equation (26), we get:

[0069]

[0070] According to Newton's heat transfer formula:

[0071]

[0072] T Env is the ambient temperature.

[0073] From formula (30) and formula (31), we can get:

[0074]

[0075] That is TEtalon -T Env Simplified to coefficient k Etalon , T sensor -T Env Simplified to coefficient k sensor ,

[0076] Objective: The ambient temperature changes, but the wavelength remains unchanged.

[0077] Substituting equations (16) and (29) into equation (32), we obtain:

[0078]

[0079] Transform formula (33):

[0080]

[0081] in Since all wavelength points are consistent, it can be regarded as a constant term A. Therefore:

[0082]

[0083] T sensor =T Env +k sensor ×P……(35)

[0084]

[0085] U Ref is the reference voltage;

[0086] From formula (36) and formula (37):

[0087]

[0088] make but:

[0089] P=β P ×DAC 2 ……(38)

[0090] From formula (35), we can get:

[0091] T Env =T sensor -k sensor ×P……(39)

[0092] From formula (38) + formula (39), we can get:

[0093] T Env =T sensor -k sensor ×β P×DAC 2 ……(40)

[0094] From formula (29) + formula (40), formula (29) is substituted into formula (40):

[0095]

[0096] β sensor Replace with a1, k sensor ×β P Use a2 instead, Substituting a3, we can get the formula:

[0097] a1×ADC+a2×DAC 2 +a3.

[0098] Example 1

[0099] like Figure 1 As shown, this embodiment provides a tunable laser having an internal etalon. The etalon can output a voltage feedback value ADC and a heating power DAC value. The voltage feedback value ADC is used to feedback the input voltage U of the etalon, so ADC = U. The tunable laser also has a microcontroller, which can be used to perform wavelength adaptive control.

[0100] like Figure 2 As shown, the method for wavelength adaptive control includes the following steps:

[0101] S1. Real-time monitoring of the voltage feedback value ADC of the standard instrument and the DAC value of the heating power, and the calculated value is obtained according to formula 1:

[0102] Calculated value = a1 × ADC + a2 × DAC 2 +a3 formula 1;

[0103] Among them, a1, a2, and a3 are all experimental constants;

[0104] S2. Calculate the difference δ between the calculated value and the target value according to Formula 2:

[0105] δ=calculated value-target value formula 2;

[0106] Wherein, target value = mλ, m is the interference order of the etalon, and λ is the target wavelength of the tunable laser;

[0107] S3. Determine whether the difference δ is within a preset allowable range. If so, return directly to step S1. If not, adjust the input voltage and / or heating power of the etalon and then return to step S1.

[0108] like Figure 3As shown in FIG, the adjustment can be performed using an iterative process, that is, setting the U value and DAC value, the ambient temperature and the target wavelength, and substituting the output ADC and DAC values into Formula 1 for calculation through PID control. If the difference δ between the calculated value and the target value meets the preset allowable range requirement, then continue to set new U value and DAC value, and output new ADC value and DAC value until the difference δ meets the preset allowable range requirement.

[0109] The iterative convergence is mainly based on the experimental results. The ambient temperature, ADC and DAC change, but the wavelength λ remains basically unchanged.

[0110] Example 2

[0111] like Figure 2 As shown, in this embodiment, a wavelength adaptive control method for a tunable laser is provided. The tunable laser is provided with an etalon. The method includes the following steps:

[0112] S1. Real-time monitoring of the voltage feedback value ADC of the standard instrument and the DAC value of the heating power, and the calculated value is obtained according to formula 1:

[0113] Calculated value = a1 × ADC + a2 × DAC 2 +a3 formula 1;

[0114] Among them, a1, a2, and a3 are all experimental constants;

[0115] S2. Calculate the difference δ between the calculated value and the target value according to Formula 2:

[0116] δ=calculated value-target value formula 2;

[0117] Wherein, target value = mλ, m is the interference order of the etalon, and λ is the target wavelength of the tunable laser;

[0118] S3. Determine whether the difference δ is within a preset allowable range. If so, return directly to step S1. If not, adjust the input voltage and / or heating power of the etalon and then return to step S1.

[0119] like Figure 3 As shown in FIG, the adjustment can be performed using an iterative process, that is, setting the U value and DAC value, the ambient temperature and the target wavelength, and substituting the output ADC and DAC values into Formula 1 for calculation through PID control. If the difference δ between the calculated value and the target value meets the preset allowable range requirement, then continue to set new U value and DAC value, and output new ADC value and DAC value until the difference δ meets the preset allowable range requirement.

[0120] The iterative convergence is mainly based on the experimental results. The ambient temperature, ADC and DAC change, but the wavelength λ remains basically unchanged.

[0121] The process of determining a1, a2, and a3 includes:

[0122] S11. Take several tunable lasers of the same model;

[0123] S12, setting multiple sets of voltage values U and heating power values DAC;

[0124] S13, multiple sets of voltage values U and heating power values DAC are calculated according to the formula a1×U+a2×DAC 2 + a3 = mλ to calculate the experimental constant group of each tunable laser, the experimental constant group includes a1, a2 and a3, where m is the interference order of the etalon, λ is the laser target wavelength of the tunable laser, and mλ is a constant value;

[0125] S14. Test each experimental constant group and select the best experimental constant group as the experimental constant group for the tunable laser of the model.

[0126] Furthermore, S13 specifically includes calculating the slope function in Excel using the mλ value and multiple sets of voltage values U and heating power values DAC. During the calculation, the multiple sets of mλ values, voltage values U, and heating power values DAC serve as independent variables of the slope function, while a1, a2, and a3 serve as dependent variables of the slope function. Of course, a1, a2, and a3 can also be solved using other methods, such as programming.

[0127] Furthermore, the S14 specifically includes: taking an adjustable laser of the same model as a test object; performing a cyclic iteration test on each experimental constant group one by one according to the S1 to the S3, selecting the experimental constant group with the least number of cyclic iterations as the best set of experimental constant groups, or selecting the experimental constant group that can make the difference δ fall within the preset allowable range the fastest under the condition of the same number of cyclic iterations as the best set of experimental constant groups.

[0128] The technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: the tunable laser can adjust the values of U and DAC according to changes in environmental factors, thereby adaptively controlling the wavelength of the tunable laser to eliminate or reduce the impact of environmental factors on the wavelength. Because this monitoring and control is performed in real time, the stability of the tunable laser can be greatly improved and its performance can be guaranteed. Moreover, during control, since the calculated value is composed of two variables, U and DAC, an iterative approach can be used to gradually reduce the deviation between the calculated value and the target value until the deviation is within a preset range, greatly reducing the difficulty of control.

[0129] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A tunable laser having an etalon therein, characterized in that: The method can perform wavelength adaptive control in real time, and the wavelength adaptive control method includes the following steps: S1. Real-time monitoring of the voltage feedback value ADC of the etalon and the DAC value of the heating power, and calculations are performed according to Formula 1 to obtain the calculated values: Calculated value = a1 × ADC + a2 × DAC 2 +a3 formula 1; Among them, a1, a2, and a3 are all experimental constants; S2. Calculate the difference δ between the calculated value and the target value according to Formula 2: δ=calculated value-target value formula 2; Wherein, target value = mλ, m is the interference order of the etalon, and λ is the target wavelength of the tunable laser; S3. Determine whether the difference δ is within a preset allowable range. If so, return directly to step S1. If not, adjust the input voltage and / or heating power of the etalon and then return to step S1.

2. A method for adaptively controlling the wavelength of a tunable laser, wherein the tunable laser is provided with an etalon, characterized in that: The steps include: S1. Real-time monitoring of the voltage feedback value ADC of the etalon and the DAC value of the heating power, and calculations are performed according to Formula 1 to obtain the calculated values: Calculated value = a1 × ADC + a2 × DAC 2 +a3 formula 1; Among them, a1, a2, and a3 are all experimental constants; S2. Calculate the difference δ between the calculated value and the target value according to Formula 2: δ=calculated value-target value formula 2; Wherein, target value = mλ, m is the interference order of the etalon, and λ is the target wavelength of the tunable laser; S3. Determine whether the difference δ is within a preset allowable range. If so, return directly to step S1. If not, adjust the input voltage and / or heating power of the etalon and then return to step S1.

3. The wavelength adaptive control method of a tunable laser according to claim 2, characterized in that: The process of determining a1, a2, and a3 includes: S11. Take several tunable lasers of the same model; S12, setting multiple sets of voltage values U and heating power values DAC; S13, multiple sets of voltage values U and heating power values DAC are calculated according to the formula a1×U+a2×DAC 2 + a3 = mλ to calculate the experimental constant group of each tunable laser, the experimental constant group includes a1, a2 and a3, where m is the interference order of the etalon, λ is the laser target wavelength of the tunable laser, and mλ is a constant value; S14. Test each experimental constant group and select the best experimental constant group as the experimental constant group for the tunable laser of the model.

4. The wavelength adaptive control method of a tunable laser according to claim 3, characterized in that: The S13 specifically includes: calculating the mλ value with multiple groups of voltage values U and heating power values DAC using the slope function of Excel. During the calculation, the multiple groups of mλ values, voltage U values, and heating power values DAC are used as independent variables of the slope function, and a1, a2, and a3 are used as dependent variables of the slope function.

5. The wavelength adaptive control method of a tunable laser according to claim 3, characterized in that: The S14 specifically includes: taking an adjustable laser of the same model as a test object; performing a cyclic iterative test on each experimental constant group one by one according to the S1 to S3, selecting the experimental constant group with the least number of cyclic iterations as the best set of experimental constant groups, or selecting the experimental constant group that can make the difference δ fall within the preset allowable range the fastest under the condition of the same number of cyclic iterations as the best set of experimental constant groups.

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