Optical fiber laser, multi-dimensional optical storage device and performance improvement method thereof

Abstract

The application relates to an optical fiber laser, which comprises a seed source for generating initial pulse laser, a coupler for dividing the initial pulse laser into two pulse lasers, a first acousto-optic modulator for switching the light path of one of the two pulse lasers divided by the coupler, the light path of the pulse laser being a signal light path, a second acousto-optic modulator for switching the light path of the other of the two pulse lasers divided by the coupler, the light path of the pulse laser being a reference light path, and a control unit for controlling the opening and closing of the first acousto-optic modulator and the opening and closing of the second acousto-optic modulator, so that the pulse frequency of the laser when the two light beams are combined is consistent with the pulse frequency of the initial pulse laser generated by the seed source. A multi-dimensional optical storage device and a method for improving the storage performance of the multi-dimensional optical storage device are also provided. The application can realize high-speed pulse switching, and can realize high-frequency pulse optical signal output in any arrangement according to requirements.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a fiber laser and a multidimensional optical storage device. Background Technology

[0002] In ultrafast laser processing such as femtosecond and picosecond lasers, the use of spatial optical modulators (SLMs) combined with external trigger signals for switching control is an advanced technique. This method enables high-precision and highly flexible laser processing, and is particularly suitable for the fabrication of complex micro- and nanostructures. Typically, in fiber acousto-optic modulators are used to down-modulate the optical pulses in the fiber amplification section. The down-modulated pulses are then amplified and further divided using a SLM. However, due to the extremely long rise (fall) times of the SLMs—approximately 250 ns for a laser beam diameter of 1 mm and a sound velocity of 4 km / s—the acousto-optic pulses can only switch at low frequencies, affecting processing efficiency. Furthermore, the diffraction efficiency of SLMs is typically between 80% and 90%, leading to energy loss after amplification. Adding a SLM to the optical path also results in complex optical structure, increased material costs, and poor system stability. Summary of the Invention

[0003] The purpose of this invention is to provide a fiber laser and a multidimensional optical storage device, which can at least solve some of the defects in the prior art.

[0004] To achieve the above objectives, embodiments of the present invention provide the following technical solution: a fiber laser, comprising a seed source and a coupler, and further comprising a first acousto-optic modulator, a second acousto-optic modulator, and a control unit.

[0005] The seed source is used to generate the initial pulse laser.

[0006] The coupler is used to split the initial laser pulse into two laser pulses.

[0007] The first acousto-optic modulator is used to switch one of the pulsed laser paths split off from the coupler; this pulsed laser path is the signal optical path.

[0008] The second acousto-optic modulator is used to switch the optical path of another pulsed laser branched off from the coupler; this pulsed laser optical path serves as the reference optical path.

[0009] The control unit is used to control the opening or closing of the first acousto-optic modulator and the second acousto-optic modulator, so that the laser pulse frequency when the two optical beams are combined and output is consistent with the pulse frequency of the initial pulse laser generated by the seed source.

[0010] Furthermore, the control unit includes a first delay unit and a second delay unit.

[0011] A laser synchronization signal is generated and input to the first delay unit, which then controls the first acousto-optic modulator to turn on or off.

[0012] Simultaneously, a complementary reference signal complementary to the laser synchronization signal pulse sequence is generated and input to the second delay unit, which controls the second acousto-optic modulator to turn on or off.

[0013] Furthermore, it also includes an optical fiber delay line, which adjusts the optical path of the signal optical path and the reference optical path to be consistent.

[0014] Furthermore, it also includes a polarization beam combiner, which combines two beams of light so that the polarization directions of the two beams are perpendicular to each other.

[0015] Furthermore, it also includes an optical fiber amplifier, which amplifies the power of the combined light.

[0016] Furthermore, it also includes an optical fiber isolation collimator that separates and absorbs the reference light to output the signal light and prevent the backlight from returning.

[0017] Furthermore, the fiber optic isolation collimator includes a first polarizing beam splitter prism, a Faraday rotator crystal, and a second polarizing beam splitter prism.

[0018] The first polarizing beam splitter is used to transmit a pulsed laser signal light with a first polarization direction and to reflect a pulsed laser reference light with a second polarization direction, thereby separating the signal light from the reference light.

[0019] The Faraday rotator crystal is used to convert the transmitted pulsed laser with a first polarization direction into a third polarization direction, and the angle between the third polarization direction and the second and first polarization directions is 45 degrees.

[0020] The second polarizing beam splitter is used to transmit pulsed laser light with a third polarization direction.

[0021] Furthermore, the seed source has a frequency of 40-100MHz, and the first and second acousto-optic modulators have inherent operating frequencies of 200-600MHz, with both rising and falling edges of 10-20ns.

[0022] This invention provides another technical solution: a multidimensional optical storage device, including the above-mentioned fiber laser, wherein the fiber laser is used for laser marking.

[0023] This invention provides another technical solution: a method for improving the storage performance of a multidimensional optical storage device, which uses the aforementioned fiber laser to improve data storage density, data writing speed, and data reading speed.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. By controlling the first and second acousto-optic modulators to turn on or off through the control unit, the laser pulse frequency when the two beams are combined is consistent with the pulse frequency of the initial pulse laser generated by the seed source. Compared with traditional technology, without using a spatial acousto-optic modulator, high-speed pulse switching can be achieved. Under the condition that the single pulse energy remains unchanged, high-frequency pulse light signals can be output in any arrangement as needed without causing the amplification stage to be damaged due to the signal light being too low or too high.

[0026] 2. Applying this fiber laser to multidimensional optical storage technology allows for laser marking. Due to the fast switching speed and low energy loss of the fiber laser, more data can be marked under the same conditions, thereby improving the data storage density, data writing speed, and data reading speed of multidimensional optical storage technology. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a fiber laser provided in an embodiment of the present invention;

[0028] Figure 2 A structural block diagram of a fiber laser provided in an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of a fiber laser outputting a laser pulse signal is provided as an embodiment of the present invention;

[0030] Figure 4 A pulse measurement diagram of a fiber laser provided in an embodiment of the present invention;

[0031] In the attached figures, the following labels are used: 100 - seed source; 200 - coupler; 301 - first acousto-optic modulator; 302 - second acousto-optic modulator; 401 - first fiber delay line; 402 - second fiber delay line; 500 - polarization combiner; 600 - fiber amplifier; 700 - fiber isolation collimator; 901 - first delayer; 902 - second delayer. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figure 1 and Figure 2This invention provides a fiber laser, including a seed source 100, a coupler 200, a first acousto-optic modulator 301, a second acousto-optic modulator 302, and a control unit. The seed source 100 generates an initial pulsed laser; the coupler 200 splits the initial pulsed laser into two pulsed lasers; the first acousto-optic modulator 301 switches the optical path of one of the pulsed lasers split from the coupler 200, and this optical path is a signal optical path, i.e., a trigger signal; the second acousto-optic modulator 302 switches the optical path of the other pulsed laser split from the coupler 200, and this optical path is a reference optical path, i.e., a reference signal; the control unit controls the on / off state of the first acousto-optic modulator 301 and the second acousto-optic modulator 302, so that the laser pulse frequency at the combined output of the two beams is consistent with the pulse frequency of the initial pulsed laser generated by the seed source 100. In this embodiment, the control unit controls the on / off state of the first acousto-optic modulator 301 and the second acousto-optic modulator 302 to ensure that the laser pulse frequency at the output of the two beams is consistent with the pulse frequency of the initial pulse laser generated by the seed source 100. Compared with traditional technology, this method does not use a spatial acousto-optic modulator, enabling high-speed pulse switching. With constant single-pulse energy, it can output high-frequency pulsed light signals in any arrangement as needed without damaging the amplification stage due to excessively low or high signal light levels. Specifically, by generating complementary signals for the two acousto-optic modulators, when the signal light is transformed and combined, the reference light synchronously fills in the corresponding pulse gaps to ensure that the input and output power of the power amplification remain constant, thus preventing changes in single-pulse energy. Traditional technology first uses a high-speed fiber acousto-optic modulator to select the frequency of the high-frequency seed signal, then amplifies it and uses low-speed spatial acousto-optic modulation to further divide the selected frequency. This method results in slow switching speed and high energy loss. This embodiment solves both the problems of slow switching speed and high energy loss. The seed source 100 employs a high repetition rate seed source, generating an initial pulsed laser with a very high frequency, which usually requires frequency downsampling; however, this embodiment does not require downsampling. The coupler 200 uses a polarization-maintaining fiber 50:50 coupler, capable of splitting the initial pulsed laser into two pulsed lasers with equal power and frequency. These two pulsed lasers can be defined as the signal light and the reference light, respectively. The two acousto-optic modulators are polarization-maintaining fiber acousto-optic modulators, which can switch the two light paths on and off respectively.

[0034] Please see Figure 1 and Figure 2To further refine the control unit described above, the control unit includes a first delay unit 901 and a second delay unit 902. A laser synchronization signal is generated and input to the first delay unit 901, which controls the first acousto-optic modulator 301 to turn on or off. Simultaneously, a complementary reference signal, complementary to the laser synchronization signal pulse sequence, is generated and input to the second delay unit 902, which controls the second acousto-optic modulator 302 to turn on or off. In this embodiment, a delay unit is used to turn the acousto-optic modulator on or off. In conjunction with the above embodiments, the laser pulse generated by the high repetition rate seed source serves as the initial pulse laser. After passing through a polarization-maintaining fiber 50:50 coupler, it is split into two pulse lasers with equal power and frequency. Then, the two beams pass through the first acousto-optic modulator 301 and the second acousto-optic modulator 302, respectively, forming two laser outputs with equal frequency and perpendicular polarization direction at the fiber polarization combiner. The laser synchronization signal is input to the first delay unit 901 to generate arbitrarily arranged trigger signals, controlling the first acousto-optic modulator 301 to turn on or off. At the same time, a complementary reference signal based on the inherent frequency of the laser synchronization signal is generated and input to the second delay unit 902, controlling the second acousto-optic modulator 302 to turn on or off. The combination of turning on and off the two acousto-optic beams ensures that the laser repetition rate and power before entering the fiber amplifier 600 remain constant, and the laser pulse frequency satisfies: 10≤f1≤100MHz. This embodiment uses a complementary reference signal to compensate for the pulse loss in the laser synchronization signal. Therefore, regardless of how the laser synchronization signal is programmed, there will be no inconsistency with the pulse sequence of the seed light. This makes the adjustment flexibility of this fiber laser very high, and also overcomes the technical problems of long switching time and high energy loss in the prior art.

[0035] Please see Figure 1 and Figure 2 This fiber laser also includes fiber delay lines, which adjust the optical path lengths of the signal optical path and the reference optical path to be consistent. In this embodiment, fiber delay lines are used to adjust the optical path lengths of the optical paths so that the optical path lengths of the signal optical path and the reference optical path are consistent. Specifically, there can be two fiber delay lines: a first fiber delay line 401 and a second fiber delay line 402. The first fiber delay line 401 adjusts the optical path length of the signal optical path to be consistent with the optical path length of the reference optical path, and the second fiber delay line 402 adjusts the optical path length of the reference optical path to be consistent with the optical path length of the signal optical path. The position of the fiber delay line in the optical path can be before or after the acousto-optic modulator, such as... Figure 1 As shown, the fiber delay line is located after the acousto-optic modulator, as... Figure 2 As shown, the fiber delay line can be placed before the acousto-optic modulator in either of two configurations without affecting the adjustment of the optical path.

[0036] Please see Figure 1 and Figure 2 This fiber laser also includes a polarization combiner 500, which combines two optical beams so that their polarization directions are perpendicular to each other. The polarization combiner 500 is a polarization-maintaining fiber combiner, capable of combining the signal and reference beams to ensure their polarization directions are perpendicular to each other.

[0037] Please see Figure 1 and Figure 2 This fiber laser also includes a fiber amplifier 600, which amplifies the power of the combined light. The fiber amplifier 600 is a polarization-maintaining fiber amplifier used to amplify the power of the combined signal light (reference light).

[0038] Please see Figure 1 and Figure 2 This fiber laser also includes a fiber isolation collimator 700, which separates and absorbs the reference light to output the signal light and prevents backlighting. Preferably, the fiber isolation collimator 700 includes a first polarization beam splitter, a Faraday rotator crystal, and a second polarization beam splitter. The first polarization beam splitter transmits the pulsed laser signal light with a first polarization direction and reflects the pulsed laser reference light with a second polarization direction, thus separating the signal light from the reference light. The Faraday rotator crystal converts the transmitted pulsed laser light with the first polarization direction to a third polarization direction, with the third polarization direction forming a 45-degree angle with the second and first polarization directions. The second polarization beam splitter transmits the pulsed laser signal light with the third polarization direction. After the fiber amplifier 600 amplifies the optical path, the fiber isolation collimator 700 can block and absorb the reference light, allowing the laser signal light to be output in the desired arrangement. Preferably, the combination of the first polarizing beam splitter prism, the Faraday glare crystal, and the second polarizing beam splitter prism also has an isolation function, which can effectively prevent backlight. The first polarizing beam splitter prism is placed horizontally to ensure that light in the horizontal polarization direction is transmitted and light in the vertical polarization direction is reflected. The second polarizing beam splitter prism is rotated 45 degrees along the light propagation direction to maintain the same polarization direction as the signal light emitted from the Faraday glare crystal, and is used as an analyzer. In addition, an opening is provided on the wall of the fiber optic isolation collimator 700, and a light-absorbing tube is provided outside the opening. The reference light is emitted from this opening and absorbed by the light-absorbing tube. Based on the above components, the present invention is a fully polarization-maintaining fiber design with a simple optical path structure and stable and reliable performance.

[0039] Please see Figure 1 and Figure 2 The seed source 100 has a frequency of 40-100MHz, and the first acousto-optic modulator 301 and the second acousto-optic modulator 302 have inherent operating frequencies of 200-600MHz, with both rising and falling edges of 10-20ns.

[0040] The following are specific examples:

[0041] like Figure 2 As shown, a high repetition rate seed source generates a laser pulse with a repetition rate of 45MHz and a power of 8-10mW as the initial pulse laser. This pulse is then coupled 200 times through a polarization-maintaining fiber 50:50, splitting into two laser pulses with a power of 4-5mW and a frequency of 22.5MHz. The two pulses are then adjusted to have equal optical path lengths via a first fiber delay line 401 and a second acousto-optic modulator 302. The two beams then pass through the first and second acousto-optic modulators 301 and 302 respectively, forming two laser outputs with a frequency of 22.5MHz and perpendicular polarization directions at the polarization combiner 500. These outputs are then fed into a first delayer 901 via a laser synchronization signal to generate a... The trigger signal arranged in a baabba pattern (a indicates on, b indicates off) controls the first acousto-optic modulator 301 to turn on or off. At the same time, a complementary reference signal (babaab, a indicates on, b indicates off) based on the inherent frequency of the laser synchronization signal is generated and input to the second delay unit 902, which controls the second acousto-optic modulator 302 to turn on or off. The combination of the on and off of the two acousto-optic signals ensures that the repetition rate and power of the laser entering the main amplification remain unchanged. Finally, before the amplified output, the reference light is reflected and blocked by the polarization beam splitter prism in the fiber optic isolation collimator 700, and the laser signal light is output in the required arrangement.

[0042] like Figure 3 The fiber optic acousto-optic modulator in this embodiment features rapid switching. It avoids the use of spatial acousto-optics, overcoming the problem of output signal changes damaging the main amplifier due to different pulse frequencies and sequence combinations. The two acousto-optic modulators generate complementary signals, which synchronously enter the main amplifier. When the signal light is transformed and combined, the reference light synchronously fills in the corresponding pulse gaps to ensure that the input and output power of the power amplifier remain unchanged, thus preventing changes in single-pulse energy. Finally, in the fiber optic collimating isolator before output, the reference light is reflected by the first polarizing beam splitter prism out of the fiber optic collimating isolator and enters the absorption cylinder, allowing the signal light to be output normally. If the external control signal is 11110101101110 (1 represents high level, 0 represents low level), then the switching state of the first acousto-optic modulator 301 is aaaababaabaaab (a represents on, b represents off). The corresponding measured output pulse diagram is shown below. Figure 4 As shown.

[0043] This invention provides a multidimensional optical storage device, including the aforementioned fiber laser, which is used for laser marking. With the rapid development of information technology, data storage demand is growing exponentially, and traditional storage technologies are gradually facing bottlenecks. Multidimensional optical storage technology, as an emerging high-density storage solution, utilizes multiple dimensions of light (such as wavelength, polarization, and phase) to store information, significantly improving storage capacity and data read speed. However, the practical application of multidimensional optical storage technology still faces many challenges, one of which is how to efficiently and accurately control optical pulses to achieve fast data writing and reading. When this fiber laser is applied in multidimensional optical storage technology, due to its fast switching speed and low energy loss, it can generate ultrashort pulses and control the presence or absence of pulses through high-speed switching, enabling the marking of more data under the same conditions, thereby achieving high-precision control of the storage medium. The application of this fiber laser in multidimensional optical storage can not only significantly increase storage density but also significantly improve data writing and reading speeds.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fiber laser, comprising a seed source and a coupler, characterized in that: It also includes a first acousto-optic modulator, a second acousto-optic modulator, an optical fiber amplifier, and a control unit. The seed source is a high-repetition-rate seed source, used to generate the initial pulse laser. The coupler is used to split the initial laser pulse into two laser pulses. The first acousto-optic modulator is used to switch one of the pulsed laser paths split off from the coupler; this pulsed laser path is the signal optical path. The second acousto-optic modulator is used to switch the optical path of another pulsed laser branched off from the coupler; this pulsed laser optical path serves as the reference optical path. The control unit is used to control the on / off state of the first acousto-optic modulator and the second acousto-optic modulator, so that the laser pulse frequency at the output of the two combined beams is consistent with the pulse frequency of the initial pulse laser generated by the seed source. The fiber amplifier amplifies the power of the combined light beam. The control unit includes a first delay unit and a second delay unit. A laser synchronization signal is generated and input to the first delay unit, which then controls the first acousto-optic modulator to turn on or off. Simultaneously, a complementary reference signal complementary to the laser synchronization signal pulse sequence is generated and input to the second delay unit, which controls the second acousto-optic modulator to turn on or off.

2. The fiber laser as described in claim 1, characterized in that: It also includes an optical fiber delay line, which adjusts the optical path of the signal optical path and the reference optical path to be consistent.

3. The fiber laser as described in claim 1, characterized in that: It also includes a polarization beam combiner, which combines two beams of light so that the polarization directions of the two beams are perpendicular to each other.

4. The fiber laser as described in claim 1, characterized in that: It also includes a fiber optic isolation collimator that separates and absorbs the reference light to output the signal light and prevent the backlight from returning.

5. The fiber laser as described in claim 4, characterized in that: The fiber optic isolation collimator includes a first polarization beam splitter, a Faraday rotator crystal, and a second polarization beam splitter. The first polarizing beam splitter is used to transmit a pulsed laser signal light with a first polarization direction and to reflect a pulsed laser reference light with a second polarization direction, thereby separating the signal light from the reference light. The Faraday rotator crystal is used to convert the transmitted pulsed laser with a first polarization direction into a third polarization direction, and the angle between the third polarization direction and the second and first polarization directions is 45 degrees. The second polarizing beam splitter is used to transmit pulsed laser light with a third polarization direction.

6. The fiber laser as described in claim 1, characterized in that: The seed source has a frequency of 40-100MHz, and the first and second acousto-optic modulators have inherent operating frequencies of 200-600MHz, with both rising and falling edges of 10-20ns.

7. A multidimensional optical storage device, characterized in that: Includes a fiber laser as described in any one of claims 1-6, the fiber laser being used for laser marking.

8. A method for improving the storage performance of a multidimensional optical storage device, characterized in that: The fiber laser described in any one of claims 1-6 is used to improve data storage density, data writing speed, and data reading speed.

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