A device capable of quickly and flexibly regulating the central wavelength of an ultrashort light pulse
Through a device consisting of a mode-locked laser and a Mach-Zehnder interferometer, the problem that optical devices are difficult to quickly and flexibly control the central wavelength of ultrashort light pulses was solved, and efficient and precise control of the central wavelength of the spectrum was achieved, reducing environmental interference.
Patent Information
- Application Number
- CN202510207934.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2045-02-24
AI Technical Summary
Existing optical devices find it difficult to achieve rapid and flexible control of the central wavelength of ultrashort optical pulses. Optical filters lack flexibility, and optical parametric oscillators are affected by environmental factors.
The device, which consists of a mode-locked laser, a phase-modulated Mach-Zehnder interferometer, an arbitrary waveform generator, and a polarization-dependent isolator, achieves precise control of the center wavelength of the spectrum by adjusting components such as the polarization controller, fiber delay line, and variable optical attenuator.
It achieves fast, flexible and efficient regulation of the center wavelength of the spectrum, reduces interference from environmental factors, and improves the accuracy and stability of regulation.
Smart Images
Figure CN120049262B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of optical technology, in particular to a device capable of quickly and flexibly regulating the center wavelength of ultrashort optical pulses. BACKGROUND
[0002] In the fields of optical communication and photonics, it is often necessary to precisely and flexibly regulate the center wavelength of the spectrum according to specific requirements to meet different requirements.
[0003] Currently, common means to achieve this adjustment function include using optical filters and optical parametric oscillators. Optical filters can filter out specific wavelength components from the spectrum of optical pulses, but they lack the ability to flexibly regulate the center wavelength of the spectrum. Optical parametric oscillators are optical devices that use nonlinear effects in optical fibers to achieve wavelength conversion, which can convert input laser into output light of different wavelengths, but the output wavelength is disturbed by environmental temperature and other factors. SUMMARY
[0004] The present application is based on the above technical deficiencies, and provides a device capable of quickly and flexibly regulating the center wavelength of ultrashort optical pulses, which can improve the efficiency and flexibility of regulating the center wavelength of the spectrum.
[0005] To solve the above technical problems, the technical solutions of the present application are as follows:
[0006] In a first aspect, a device capable of quickly and flexibly regulating the center wavelength of ultrashort optical pulses is composed of a mode-locked laser, a phase-modulation-based Mach-Zehnder interferometer, an arbitrary waveform generator, and a polarization-dependent isolator.
[0007] The mode-locked laser is used to provide stable single pulses.
[0008] The phase-modulation-based Mach-Zehnder interferometer is used to regulate the relative phase between pulses.
[0009] The arbitrary waveform generator is used to provide an electrical signal for modulation.
[0010] The polarization-dependent isolator is used to make the polarization states of the two pulses consistent.
[0011] Further, the phase-modulation-based Mach-Zehnder interferometer includes a first optical coupler, a variable optical attenuator, a phase modulator, a fiber delay line, a polarization controller, and a second optical coupler.
[0012] The output port of the mode-locked laser is connected with the input port of the first optical coupler; one of the output ports of the first optical coupler is connected with one end of the fiber delay line, and the other end of the fiber delay line is connected with the input end of the variable optical attenuator; the input end of the phase modulator is connected with the other output port of the first optical coupler through the polarization controller; the output end of the phase modulator and the output end of the variable optical attenuator are respectively connected with two input ends of the second optical coupler;
[0013] The phase modulator is a phase modulator made of a linear electro-optic effect material; the input and output optical fibers of the phase modulator are polarization maintaining optical fibers.
[0014] Further, the output end of the arbitrary waveform generator is connected with the voltage input electrode of the phase modulator through a radio frequency line.
[0015] Further, the input end of the polarization dependent isolator is connected with the output end of the second optical coupler.
[0016] The second aspect is a method for quickly and flexibly regulating the center wavelength of an ultrashort optical pulse, comprising the following steps:
[0017] S1: turn on the pump source of the mode-locked laser to obtain a stable single pulse;
[0018] S2: input the stable single pulse into the first optical coupler, and the first optical coupler divides the stable single pulse into two pulses; one of the two pulses reaches the phase modulator through the polarization controller, and the other pulse reaches the variable optical attenuator through the fiber delay line;
[0019] S3: the two pulses are injected into the second optical coupler through the output ends of the phase modulator and the variable optical attenuator for beam combination, and finally the two combined pulses are input into the polarization dependent isolator, and the output end of the polarization dependent isolator is set as the output port of the total device;
[0020] S4: adjust the polarization controller to ensure that the light input into the phase modulator is linearly polarized light and the polarization direction is parallel to the fast axis or the slow axis of the polarization maintaining optical fiber;
[0021] S5: adjust the knob of the fiber delay line to regulate the optical path difference of the two arms of the phase modulated Mach-Zehnder interferometer; rotate the knob on the variable optical attenuator to accurately control the power of the two optical pulses until the peak powers of the two pulses output from the output end of the polarization dependent isolator are completely equal;
[0022] S6: the electrical signal emitted by the arbitrary waveform generator acts on the voltage input electrode of the phase modulator to change the relative phase between the pulses.
[0023] The above scheme of the present application at least has the following beneficial effects:
[0024] The present invention uses a phase modulator in conjunction with a Mach-Zehnder interferometer to jointly act on the pulse transmission process, so that parameters such as the relative phase can be accurately adjusted as expected, and the central wavelength of the spectrum can be flexibly and efficiently controlled in the spectrum. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 A schematic diagram of the overall structure of a device provided by the present invention that can quickly and flexibly adjust the central wavelength of ultrashort optical pulses.
[0026] Figure 2 Schematic diagram of the autocorrelation trace of the double pulse provided by the present invention.
[0027] Figure 3 The present invention provides a schematic diagram of the spectrum evolution of the relative phase change presenting a sinusoidal waveform. Figure (a): relative phase change curve; Figure (b): corresponding spectrum evolution schematic diagram.
[0028] Figure 4 The present invention provides a schematic diagram of the spectrum evolution in which the relative phase change presents a square waveform, wherein Figure (a) represents a curve diagram of the relative phase change; Figure (b) represents a schematic diagram of the corresponding spectrum evolution.
[0029] Figure 5 The present invention provides a curve diagram showing the relationship between the change in the center wavelength of the spectrum and the peak-to-peak voltage applied to the phase modulator electrode. DETAILED DESCRIPTION
[0030] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.
[0031] like Figure 1 As shown, an embodiment of the present invention proposes a device that can quickly and flexibly adjust the central wavelength of ultrashort optical pulses, including: a mode-locked laser 1, a first 1×2 optical coupler (OC-1) 2, a polarization controller (PC) 3, a phase modulator (PM) 4, an optical fiber delay line (ODL) 5, a variable optical attenuator (VOA) 6, a second 1×2 optical coupler (OC-2) 7, a polarization-dependent isolator (PS-ISO) 8, and an arbitrary waveform generator (AWG) 9.
[0032] The key part of the device is composed of a first optical coupler 2, a polarization controller 3, a phase modulator 4, a fiber delay line 5, a variable optical attenuator 6 and a second optical coupler 7, which together form a phase modulation based Mach-Zehnder interferometer.
[0033] Stable single pulse output can be obtained from the mode-locked fiber laser 1.
[0034] The stable single pulse is split into two equal pulses in the first optical coupler 2 (coupling ratio 50:50). One of the pulses passes through the polarization controller 3 to the phase modulator 4, and the other pulse passes through the fiber delay line 5 to the variable optical attenuator 6.
[0035] The two pulses are further injected into the second optical coupler 7 (coupling ratio 50:50) through the outputs of the phase modulator 4 and the variable optical attenuator 6 for beam combination, and finally the two combined pulses are input into the polarization-dependent isolator 8, and the output end of the polarization-dependent isolator 8 is set as the total output port of the device.
[0036] The polarization-dependent optical isolator 8 can effectively make the polarization states of the two pulses consistent. Such a setup can avoid optical signal interference caused by different polarization states.
[0037] Further, the voltage input electrode of the phase modulator 4 is connected to the output end of the arbitrary waveform generator 9 through a radio frequency line.
[0038] Since the input and output fibers of the phase modulator 4 are both polarization-maintaining fibers, the light input into the phase modulator 4 is linearly polarized light with the polarization direction parallel to the fast axis or slow axis of the polarization-maintaining fiber by adjusting the bias state of the polarization controller 3.
[0039] Further, the optical path difference of the two arms of the phase modulation based Mach-Zehnder interferometer is controlled by adjusting the knob of the fiber delay line 5, and the number of spectral interference fringes decreases as the optical path difference of the two arms decreases. In order to make the intensities of the two pulses output from the output end of the polarization-dependent isolator 8 consistent, the power of the two optical pulses is precisely controlled by rotating the knob on the variable optical attenuator 6 until the peak powers of the two output pulses are exactly equal, and at the same time, an interference spectrum with high contrast can also be obtained.
[0040] When the electrical signal emitted by the arbitrary waveform generator 9 acts on the voltage input electrode of the phase modulator 4, it will change the phase delay of the pulse after passing through the phase modulator 4, and further change the relative phase between the pulses.
[0041] Since the phase modulator 4 is a phase modulator made of a linear electro-optic effect material, the change of the relative phase is proportional to the input voltage.
[0042] Through the above-mentioned use method, two identical pulses with a certain relative phase and time interval can be obtained from the output end of the polarization-dependent isolator 8.
[0043] Further, the spectral intensity expression at the total output port after phase modulation is:
[0044]
[0045] Wherein, R represents the modulation coefficient of the phase modulator, and V(t) represents the electrical signal applied to the voltage input electrode of the phase modulator.
[0046] According to the spectral intensity expression, if the pulse relative interval τ is small enough, the change of the relative phase (i.e. the change of the voltage applied to the input electrode of the phase modulator) can cause the change of the spectral center wavelength. The change of the spectral center wavelength is consistent with the form of the change of the voltage applied to the input electrode of the phase modulator; and the change range of the spectral center wavelength increases with the increase of the peak-to-peak voltage.
[0047] Further, by Fourier transforming the interference spectrum, the corresponding autocorrelation trace curve can be obtained, as shown in Figure 2 From the figure, it can be seen that the time interval of the pulse is 1.9 ps, and the peak power is basically consistent, further verifying the reliability of the device.
[0048] Further, through the above-mentioned operation, various types of modulation are performed on the relative phase of the pulse:
[0049] Example 1
[0050] If the electrical signal applied to the phase modulator 4 by the arbitrary waveform generator 9 is a sinusoidal electrical signal, as shown in Figure 3 (a), the repetition frequency of the sinusoidal electrical signal is 100 KHz, and the spectral evolution diagram as shown in Figure 3 (b) can be obtained. The spectral center wavelength changes sinusoidally with the change of the electrical signal, and the change frequency is consistent with the repetition frequency of the electrical signal.
[0051] Example 2
[0052] Change the waveform of the electrical signal to a square wave signal, as shown in Figure 4 (a), the repetition frequency of the signal is 50 KHz, and the spectral evolution diagram as shown in Figure 4 (b) can be obtained. The spectral center wavelength changes with the change of the electrical signal, and the change frequency is consistent with the repetition frequency of the electrical signal.
[0053] It should be noted that the pulse time interval in the second embodiment is the same as that in the first embodiment, both of which are Figure 2 The 1.9 ps shown in FIG; the relative phase change is proportional to the input voltage.
[0054] As described in the first and second embodiments, if the time interval τ of the pulses is small enough, the relative phase Changes in the voltage applied to the phase modulator's input electrode cause the center wavelength of the spectrum to shift. Changing the waveform of the electrical signal causes a corresponding change in the center wavelength of the spectrum, and the frequency of the change matches the frequency of the electrical signal. Because the spectrum's response to the electrical signal is instantaneous, the device exhibits rapid response characteristics.
[0055] Figure 5 A graph shows the relationship between the change in the center wavelength of the spectrum and the peak-to-peak voltage applied to the phase modulator electrodes. The change in the center wavelength position of the ultrashort pulse is directly proportional to the peak-to-peak voltage. The dots represent the experimental results, and the solid line represents the linear fit.
[0056] With the technical solution designed above, the flexible adjustment of the central wavelength position of the ultrashort pulse can be achieved accurately and effectively. In the implementation process of this technical solution, various technical links work closely together to act together on the regulation of the central wavelength position of the spectrum. Although the present invention has been explained in detail with reference to specific embodiments, it should be clear that the scope of the present invention is by no means limited to the disclosed implementation methods and corresponding embodiments. For those technical personnel who have a certain amount of knowledge and practical experience in their professional fields, based on the core idea of the present invention, improvements or appropriate changes can be implemented according to the above description. As long as such improvements and changes do not deviate from the principles and essence of the present invention, all these changes should be included in the protection scope of the present invention.
Claims
1. A device for quickly and flexibly adjusting the central wavelength of ultrashort optical pulses, characterized in that: It consists of a mode-locked laser, a phase-modulated Mach-Zehnder interferometer, an arbitrary waveform generator, and a polarization-dependent isolator. The mode-locked laser is used to provide a stable single pulse; The phase-modulated Mach-Zehnder interferometer is used to control the relative phase between pulses; The arbitrary waveform generator is used to provide an electrical signal for modulation; The polarization-dependent isolator is used to make the polarization states of the two pulses consistent; the phase-modulated Mach-Zehnder interferometer includes a first optical coupler, a variable optical attenuator, a phase modulator, an optical fiber delay line, a polarization controller and a second optical coupler; The output port of the mode-locked laser is connected to the input port of the first optical coupler; one of the output ports of the first optical coupler is connected to one end of the optical fiber delay line, and the other end of the optical fiber delay line is connected to the input end of the variable optical attenuator; the input end of the phase modulator is connected to the other output end of the first optical coupler through a polarization controller; the output end of the phase modulator and the output end of the variable optical attenuator are respectively connected to the two input ends of the second optical coupler; The phase modulator is made of a linear electro-optical effect material; the input and output optical fibers of the phase modulator are both polarization-maintaining optical fibers; the output end of the arbitrary waveform generator is connected to the voltage input electrode of the phase modulator via a radio frequency line; the input end of the polarization-dependent isolator is connected to the output end of the second optical coupler.
2. A method for quickly and flexibly regulating the central wavelength of ultrashort optical pulses, characterized in that: The method is used to execute the apparatus according to claim 1, comprising the following steps: S1: Turn on the pump source of the mode-locked laser to obtain a stable single pulse; S2: A stable single pulse is input to the first optical coupler, which splits the stable single pulse into two pulses; one pulse passes through the polarization controller to the phase modulator, and the other pulse passes through the optical fiber delay line to the variable optical attenuator; S3: The two pulses are injected into the second optical coupler through the output ends of the phase modulator and the variable optical attenuator for beam combining. Finally, the two combined pulses are input into the polarization-dependent isolator, and the output end of the polarization-dependent isolator is set as the output port of the overall device. S4: Adjust the polarization controller to ensure that the light input to the phase modulator is linearly polarized light and the polarization direction is parallel to the fast axis or slow axis of the polarization-maintaining fiber; S5: The optical path difference between the two arms of the phase-modulated Mach-Zehnder interferometer is controlled by adjusting the knob of the fiber delay line. The power of the two optical pulses is precisely controlled by rotating the knob on the variable optical attenuator until the peak powers of the two pulses output from the polarization-dependent isolator are exactly equal. S6: The electrical signal from the arbitrary waveform generator acts on the voltage input electrode of the phase modulator to change the relative phase between pulses.