A kind of manufacturing method of high repetition frequency optical fiber green light and 15w uv laser

1. The present invention relates to the technical field of lasers, in particular to a high repetition frequency, sub-nanosecond all-fiber green light and ultraviolet laser.

Background technique:

2. In recent years, solid-state lasers have developed rapidly, and green lasers have attracted more and more attention. The green laser has a short output wavelength and high processing accuracy, so it has a very wide range of applications in the cutting and drilling of ceramics, glass, pcb boards, solar cells and other materials, especially the sub-nanosecond green laser in the laser There are significant applications in micromachining, laser detection and display lights.

3. In the prior art, a kind of high repetition frequency narrow pulse width green light single-mode laser disclosed in the patent document with application number cn201410295146.3 and a sub-nanosecond green laser disclosed in the patent document with application number cn201810974644.9 Optical lasers are all solid-state green lasers with a full-space structure; 1. Since solid-state green lasers have a full-space structure, they have relatively high requirements for stability and environmental cleanliness, and cannot be long-term stable and reliable in practical industrial applications. Work, maintenance-free; 2. The laser pulse repetition frequency of solid-state lasers can only be up to several hundred khz, so applications with higher processing efficiency (repetition frequencies of several mhz to tens of hundreds of mhz) cannot meet the demand; 3. Solid state At present, the pulse width of the laser can only be as narrow as 10ns, which cannot meet the needs of more precise processing (generally 100ps to 1ns). It can output signal light of no more than 100 watts, which cannot meet the increasing power improvement requirements of the industry.

uv laser | green laser | Ultraviolet lasers | uv dpss laser | nanosecond laser | UV laser source | Solid State Lasers

Technical implementation elements:

4. The purpose of the present invention is to provide a high repetition frequency, sub-nanosecond all-fiber green light and ultraviolet laser to solve the problems raised in the above background technology.

5. In order to achieve the above object, the present invention provides the following technical solutions:

6. A high repetition frequency, sub-nanosecond all-fiber green and ultraviolet laser, including single frequency continuous narrow linewidth dfb

‑

ld semiconductor seed laser, the dfb

‑

A circulator, a grating msg and a Mach are arranged on the axis of the output end of the ld semiconductor seed source laser in sequence

‑

Zehnder intensity modulator;

7. Two Machs in cascade

‑

After modulation by the Zehnder intensity modulator, an adjustable sub-nanosecond seed source optical pulse signal is obtained, and the sub-nanosecond seed source optical pulse signal undergoes first-level amplification, second-level amplification, third-level amplification and cascaded frequency conversion to achieve high efficiency times. frequency.

8. Preferably, the single-frequency continuous narrow linewidth dfb

‑

The power of ld semiconductor seed source laser is 30mw

‑

100mw, the sub-nanosecond seed source light pulse signal is an adjustable pulse signal with a high extinction ratio of 50-60db and a pulse width of 150ps-2ns.

9. Preferably, the first-stage amplification comprises a polarization-maintaining isolator filter, a ytterbium-doped fiber, a pump source 1d with a locked wavelength of 976 nm, and an amplification structure of double-ended single-mode wdm arranged in sequence, and the core of the ytterbium-doped fiber is is 5μm, cladding 130μm;

10. The secondary amplification includes an all-fiber analog adapter mfa, a polarization-maintaining isolator filter, a ytterbium-doped fiber, a (2+1) combiner, and a pump source ld with a locked wavelength of 976 nm, which are arranged in sequence. The core of the fiber is 12μm and the cladding is 130μm;

11. The three-stage amplification includes an all-fiber analog adapter mfa, a polarization-maintaining isolator filter, a large mode field ytterbium-doped chiral fiber, a (6+1) combiner, an fbg fiber grating, and a locked wavelength of 976 nm. The pump source ld and polarization analyzer, the core of the large mode field ytterbium-doped chiral fiber is 33um, and the cladding is 125um.

12. Preferably, the cascaded frequency conversion comprises a double-stage spatial optical isolator, a collimating lens, a focusing lens and a lithium triborate crystal which are arranged in sequence.

13. Preferably, the single-frequency continuous narrow linewidth dfb

‑

ld semiconductor seed laser 113 is cascaded by two Mach

‑

The Zehnder intensity modulator performs two consecutive modulations. The modulation bandwidth of the two lithium niobate Mach-Zehnder intensity modulators is 10ghz, and the rising edge time is 70ps. The RF input of the two cascaded intensity modulators The signal, the input voltage amplitude and the modulation pulse width are all the same, and the generated pulse has a rectangular waveform with sharp rising and falling edges. The pulse width and repetition frequency are τ and 1/t, respectively. The static extinction ratio (ser) is measured at When no electrical signal is input to the RF port of the Mach-Zehnder intensity modulator, the extinction ratio of the signal light after passing through the modulator is:

[0014] [0015]

where p

min

is the minimum output obtained to adjust the dc bias voltage of the dc port, p

max

is the maximum output, der is measured using the RF signal sent to the mzim’s RF port, the dc bias voltage is set to the minimum drive point of the mzim’s transfer function, the optical average power p

ave

, expressed as follows:

[0016] [0017]

where p

max

6.22 mW, h

min

obtained as h

min

= 57.9nw, which is equivalent to when p

max

=h

max

When the der is 50.3db, and the der of 44db is ensured in the cascade modulation, the optical pulse contains 90% of the total energy, and the excess of 10db is the standard of pulse quality.

[0018]

Preferably, the Mach

‑

The feedback bias method of the Zehnder intensity modulator is as follows: the function generator generates a signal plus a DC bias voltage from the DC input terminal of the Mach-Zehnder modulator, and a rectangular wave voltage signal is added to the RF signal terminal, The modulated optical pulse signal passes through a coupler, one end is split to the pd detector, the other end is output to the lock-in amplifier circuit (lia), and the y component of the signal vs is used as the input of a bias controller (bc), as the bias The feedback signal of the control, based on this configuration, for a single-stage Mach-Zehnder intensity modulation, the calculated static extinction ratio ser is 32.7db, and the dynamic extinction ratio der is 32.3db, using bipolar cascaded Mach-Zehnder intensity modulation , the obtained static extinction ratio ser is 55.4db, and the dynamic extinction ratio der is 50.3db. Through the cascade modulation scheme, the improvement of the seed source extinction ratio is more than 20db.

[0019]

Preferably, the cascading frequency conversion further includes an external cavity frequency doubling module, the external cavity frequency doubling module connects multiple groups of lithium triborate crystals 111 in series and controls the temperature respectively, and the temperature of the first group of crystals in the two groups of crystals in series is 149.5°C , the crystal length is 14mm; the temperature of the second group of crystals is 148.5°C and the length of the crystal is 9mm. In the series of three groups of crystals, the temperature of the first group of crystals is 150°C and the length of the crystal is 14mm; the temperature of the second group of crystals is 149°C and the length of the crystal is 9mm; the third group of crystals The temperature is 148°C, and the crystal length is 7mm.

[0020]

Preferably, after the seed source laser is divided into beams, after three-stage amplification and multi-stage cascade frequency doubling, the laser beams are combined to realize higher power fiber green light and ultraviolet lasers.

[0021]

The working steps of the high repetition frequency, sub-nanosecond all-fiber green light and ultraviolet laser are as follows:

[0022]

1) First use a single-frequency continuous narrow linewidth dfb

‑

The ld semiconductor seed source laser 113, the seed source signal it emits is coupled and output by the polarization maintaining fiber and then enters the port 1 of the circulator 101, and then outputs from the port 2 and passes through a

After the mode selects a high-inversion grating msg and a polarization controller, it is output from port 3 and passes through two cascaded Machs.

‑

After modulation by the Zehnder intensity modulator 114, an adjustable sub-nanosecond seed light pulse signal is obtained;

[0023]

2) The sub-nanosecond seed source light pulse signal first undergoes first-level amplification, and the first-level amplification adopts the amplification structure of double-ended single-mode wdm103, and then enters the second-level amplification after passing through the all-fiber analog adapter mfa;

[0024]

3) The second-stage amplification adopts the reverse pumping method to realize the second-stage amplification, and the power of the incoming seed light is increased to the level of 0.5-1w, and then enters the third-stage amplification through the all-fiber analog adapter mfa;

[0025]

4) The large-mode field ytterbium-doped chiral fiber 106 is used in the three-stage amplification, and a tilted fbg fiber grating is integrated at the tail end of the large-mode field ytterbium-doped chiral fiber 106 for mode control and adjustment, In the three-stage amplification, the 6+1) combiner beam combiner 117 is used for reverse pumping, and five groups of 130w 976nm-locked pump sources are used for pumping, and a pigtail is left for the polarization state of the signal light. Monitoring and analysis, while actively feeding back to the polarization controller at the seed source;

[0026]

5) According to the monitoring and analysis of the polarization state of the fundamental frequency light of the three-stage amplification, real-time self-adaptive feedback and regulation of the polarization state of the seed source end, to achieve the fundamental frequency light amplification of the best extinction ratio, through the three-stage all-fiber The amplified fundamental frequency light of hundreds of watts passes through the double-stage spatial optical isolator 108 , the collimating lens 109 and the focusing lens 110 and then undergoes an external cavity frequency doubling module. The external cavity frequency doubling module uses multiple groups of lithium triborate crystals 111 in series and cascade frequency doubling to further improve the frequency doubling efficiency of the fundamental frequency light. By optimizing the external cavity frequency doubling structure and parameters, and multiple groups of The optimized design of lithium triborate crystal 111 achieves the final high efficiency and frequency doubling of more than 65%, and obtains green lasing with high power, high beam quality and high peak power;

[0027]

6) Finally, a dichromatic mirror is set at the output end to filter out the participating infrared fundamental frequency light to obtain the final output green light.

[0028]

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

[0029]

1) The patent of the present invention proposes an all-fiber, high repetition frequency, high average power green laser solution. The all-fiber solution ensures stability and reliability, which has been verified in the application of high-power continuous fiber lasers;

[0030]

2) Since this technical solution adopts the mopa main oscillation power amplification structure, it is a high-power pulse output realized by multi-stage amplification of a semiconductor seed source whose pulse width and repetition frequency can be adjusted arbitrarily. The frequency has a large adjustment range, and it can also achieve high repetition frequency from hz to 100mhz and ultra-narrow pulse width tuning from 50ps to 2ns;

[0031]

3) Finally, because the gain medium doped gain fiber of the fiber laser has a very large surface area to volume ratio compared with the gain medium bulk crystal used in the solid state, and the heat dissipation capacity is much higher than that of the solid laser, the average power of the fiber laser can be To achieve several kilowatts or even tens of thousands of watts, it can fully meet the increasing power demand in industrial processing.

Description of drawings

[0032]

Figure 1 is a schematic structural diagram of a high repetition frequency, sub-nanosecond all-fiber green and ultraviolet laser.

[0033]

Figure 2 is a schematic structural diagram of a cascaded Mach-Zehnder intensity modulator in a high repetition frequency, sub-nanosecond all-fiber green light and ultraviolet laser.

[0034]

3 is a schematic structural diagram of a 150ps-2ns tunable pulse width waveform in a high repetition frequency, sub-nanosecond all-fiber green light and ultraviolet laser.

[0035]

4 is a schematic structural diagram of a feedback bias control scheme of a Mach-Zehnder intensity modulator mzim in a high repetition frequency, sub-nanosecond all-fiber green and ultraviolet laser.

[0036]

Figure 5 is a schematic structural diagram of a multi-crystal cascade scheme in a high repetition frequency, sub-nanosecond all-fiber green and ultraviolet laser.

[0037]

FIG. 6 is a schematic structural diagram of a power boosting scheme for combining multiple lasers in a high repetition frequency, sub-nanosecond all-fiber green light and ultraviolet laser.

Detailed ways

[0038]

The technical solutions of the present invention will be described in further detail below in conjunction with specific embodiments.

[0039]

See Figure 1, a high-repetition, sub-nanosecond, all-fiber green and ultraviolet laser including a single-frequency CW narrow linewidth dfb

‑

ld semiconductor seed source laser 113, the dfb

‑

The circulator 101, the grating msg and the Mach are arranged on the axis of the output end of the ld semiconductor seed laser 113 in sequence

‑

Zehnder Intensity Modulator 114, two Machs in cascade

‑

After being modulated by the Zehnder intensity modulator 11, an adjustable sub-nanosecond seed source optical pulse signal is obtained, and the sub-nanosecond seed source optical pulse signal is sequentially subjected to first-level amplification, second-level amplification, third-level amplification and cascaded frequency conversion to achieve high efficiency frequency doubling;

[0040]

The single frequency continuous narrow linewidth dfb

‑

The power of ld semiconductor seed source laser 113 is 30mw

‑

100mw, the sub-nanosecond seed source light pulse signal is an adjustable pulse signal with a high extinction ratio of 50-60db and a pulse width of 150ps-2ns.

[0041]

Specifically, the first-stage amplification includes a polarization-maintaining isolator filter 102, a ytterbium-doped fiber 104, a pump source ld115 with a locked wavelength of 976 nm, and an amplification structure of a double-ended single-mode wdm103. The fiber of the ytterbium-doped fiber 104 The core is 5 μm, and the cladding is 130 μm; the second-stage amplification includes an all-fiber analog adapter mfa, a polarization-maintaining isolator filter 102, a ytterbium-doped fiber 104, a (2+1) combiner 103, and a locked wavelength of 976 nm. The pump source ld115 of the ytterbium-doped fiber 104 has a core of 12 μm and a cladding of 130 μm; the three-stage amplification includes an all-fiber analog adapter mfa, a polarization-maintaining isolator filter 102, a large-mode field ytterbium-doped hand A chiral fiber 106, a (6+1) combiner 117, a fbg fiber grating, a pump source ld115 with a locked wavelength of 976 nm, and a polarization analyzer 107, the core of the large mode field ytterbium-doped chiral fiber 106 is 33um, The cladding layer is 125um; the cascaded frequency conversion includes a double-stage spatial optical isolator 108 , a collimating lens 109 , a focusing lens 110 and a lithium triborate crystal 111 arranged in sequence.

[0042]

As a further solution of the embodiment of the present invention, please refer to FIG. 2, the single-frequency continuous narrow linewidth dfb

‑

ld semiconductor seed laser 113 is cascaded by two Mach

‑

The Zehnder intensity modulator performs two consecutive modulations. The modulation bandwidth of the two lithium niobate Mach-Zehnder intensity modulators is 10ghz, and the rising edge time is 70ps. The RF input of the two cascaded intensity modulators The signal, the input voltage amplitude and the modulation pulse width are all the same, see Figure 3, the generated pulse has a rectangular waveform with sharp rising and falling edges, the pulse width and repetition rate are τ and 1/t, respectively, and the static extinction ratio (ser) When no electrical signal is input to the RF port of the Mach-Zehnder intensity modulator, the extinction ratio of the signal light after passing through the modulator is:

[0043] [0044]

where p

min

is the minimum output obtained to adjust the dc bias voltage of the dc port, p