High-power super-continuum spectrum laser device based on full polarization maintaining optical fiber

Abstract

The invention discloses a high-power super-continuum spectrum laser device based on an all-polarization-maintaining optical fiber, belongs to the technical field of high-power optical fiber laser, aims to solve the problems in the prior art, and comprises a first single-mode semiconductor laser, a mode-locked optical fiber oscillator, a second single-mode semiconductor laser, a third single-mode semiconductor laser, a fourth single-mode semiconductor laser and a fourth single-mode semiconductor laser, the second single-mode semiconductor laser is connected with the first-stage amplifier, the first-stage amplifier is connected with the optical fiber repetition frequency multiplier, the optical fiber repetition frequency multiplier is connected with the second-stage amplifier, and the second-stage amplifier is connected with the third-stage amplifier. The first multi-mode semiconductor laser and the second multi-mode semiconductor laser are respectively connected with the second-stage amplifier and the third-stage amplifier, the third-stage amplifier is connected with the mode field adapter, the mode field adapter is respectively connected with the first fluorinated liquid single-point heat dissipation unit and the electric refrigeration sheet, the first fluorinated liquid single-point heat dissipation unit is connected with the photonic crystal fiber, and the electric refrigeration sheet is connected with the photonic crystal fiber. The photonic crystal fiber is connected with the second fluorinated liquid single-point heat dissipation unit, and the second fluorinated liquid single-point heat dissipation unit is connected with the collimator.

Description

Technical Field

[0001] This invention belongs to the field of high-power fiber laser technology, specifically relating to a high-power supercontinuum laser device based on fully polarization-maintaining fiber, which is suitable for industrial detection, biomedical imaging and military optoelectronic countermeasures. Background Technology

[0002] Supercontinuum lasers are a special type of laser source with a wider spectral range than tunable lasers. They offer advantages such as high brightness, broad spectral width, and good spatial coherence, making them important for applications in biomedicine, optical frequency measurement, and military fields. However, existing supercontinuum lasers suffer from the following technical drawbacks: 1) Insufficient polarization stability: Non-polarization-maintaining fiber links can cause polarization drift due to mechanical vibration or temperature changes, affecting spectral consistency; 2) The conflict between heat dissipation and size: High-power supercontinuum lasers face difficulties in thermal management, often employing water-cooling solutions, resulting in bulky systems and severely limiting their application scenarios.

[0003] Chinese patent publication number "CN 103022867 A" and patent title "A High-Power, High-Efficiency Supercontinuum Light Source" proposes an all-fiber supercontinuum light source consisting of a pump laser with an output pigtail and a photonic crystal fiber. High average output power can be achieved by pumping the specially designed photonic crystal fiber with a 1.06-micron laser with a pulse width of 20 picoseconds and a repetition frequency of 500 MHz. However, while this specially designed photonic crystal fiber improves conversion efficiency, its spectral broadening range is only 700-1700 nm, which severely limits the spectral broadening range of high-power supercontinuum light sources. Summary of the Invention

[0004] To address the problem of insufficient spectral broadening capability of high-power supercontinuum light sources in the prior art, this invention provides a high-power supercontinuum laser device using all-polarization-maintaining fiber.

[0005] The solution to the technical problem of this invention is:

[0006] A high-power supercontinuum laser device based on polarization-maintaining fiber comprises: a first single-mode semiconductor laser, a mode-locked fiber oscillator, a second single-mode semiconductor laser, a first-stage amplifier, a frequency multiplier, a first multimode semiconductor laser, a second-stage amplifier, a third-stage amplifier, a second multimode semiconductor laser, a mode field adapter, an electrocooler, a first fluorinated liquid single-point heat dissipation unit, a photonic crystal fiber, a second fluorinated liquid single-point heat dissipation unit, and a collimator;

[0007] The first single-mode semiconductor laser is connected to a mode-locked fiber oscillator, which is connected to a first-stage amplifier. The second single-mode semiconductor laser is connected to the first-stage amplifier, which is connected to a fiber repetition rate multiplier. The fiber repetition rate multiplier is connected to a second-stage amplifier, which is connected to a third-stage amplifier. The first multimode semiconductor laser and the second multimode semiconductor laser are connected to the second-stage amplifier and the third-stage amplifier, respectively. The third-stage amplifier is connected to a mode field adapter, which is connected to a first fluorinated liquid single-point heat dissipation unit and an electrocooler, respectively. The first fluorinated liquid single-point heat dissipation unit is connected to a photonic crystal fiber, which is connected to a second fluorinated liquid single-point heat dissipation unit, which is connected to a collimator.

[0008] The beneficial effects of this invention are:

[0009] This invention employs a fully polarization-maintaining fiber structure. After repetition rate multiplication, the passively mode-locked fiber laser outputs linearly polarized picosecond pulses with wavelengths of 1.06 micrometers, 60 picoseconds, and 100 MHz. These pulses are then passed through a three-stage fully polarization-maintaining ytterbium-doped fiber amplifier to achieve a high-power pump laser with high environmental stability. Finally, the laser is fused with a polarization-maintaining photonic crystal fiber via a mode field adapter, thus achieving full polarization-maintaining supercontinuum laser.

[0010] This invention utilizes an all-fiber dual-coupler multiplier to achieve frequency repetition rate multiplication; the semiconductor pump sources in the second and third stage amplifiers have a wavelength of 915 nm, and the wide absorption peak of ytterbium-doped fiber at 915 nm is utilized to improve the stability of output laser power and environmental adaptability; active cooling is used for temperature-sensitive devices such as the mode field adapter and the 976 nm semiconductor pump source using an electrothermal cooler, and passive heat dissipation is used for the photonic crystal fiber splice using a fluorinated liquid single-point heat dissipation unit, enabling the laser to maintain high power output for a long time under air-cooled conditions.

[0011] Using polarization-maintaining fiber can effectively suppress polarization state changes caused by fiber bending, temperature changes or other environmental factors, thereby ensuring the stability and consistency of the supercontinuum.

[0012] This invention employs multiple heat dissipation methods, including fan cooling, a single-point fluorinated liquid heat dissipation unit, and an electrothermal cooling chip, to meet the heat dissipation requirements of high-power supercontinuum laser devices and improve their environmental stability. This invention is applicable to fields such as industrial inspection, biomedical imaging, and military optoelectronic countermeasures. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a high-power supercontinuum laser device based on fully polarization-maintaining fiber according to the present invention.

[0014] Figure 2This is a schematic diagram of the single-point heat dissipation unit structure of the fluorinated liquid described in this invention.

[0015] Figure 3 This is the output spectrum of the supercontinuum light source described in this invention.

[0016] Figure 4 This is a power jitter diagram when the output power of the supercontinuum light source described in this invention is 30W. Detailed Implementation

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] like Figure 1 As shown, a high-power supercontinuum laser device based on polarization-maintaining fiber comprises: a first single-mode semiconductor laser 1, a mode-locked fiber oscillator 2, a second single-mode semiconductor laser 3, a first-stage amplifier 4, a frequency multiplier 5, a first multimode semiconductor laser 6, a second-stage amplifier 7, a third-stage amplifier 8, a second multimode semiconductor laser 9, a mode field adapter 10, an electrocooler 11, a first fluorinated liquid single-point heat dissipation unit 12, a photonic crystal fiber 13, a second fluorinated liquid single-point heat dissipation unit 14, and a collimator 15.

[0019] The operating wavelength of the first single-mode semiconductor laser 1 and the second single-mode semiconductor laser 3 is 976 nm.

[0020] The operating wavelength of both the first multimode semiconductor laser 6 and the second multimode semiconductor laser 9 is 915nm.

[0021] The first single-mode semiconductor laser 1 is connected to the mode-locked fiber oscillator 2, the mode-locked fiber oscillator 2 is connected to the first-stage amplifier 4, the second single-mode semiconductor laser 3 is connected to the first-stage amplifier 4, the first-stage amplifier 4 is connected to the fiber repetition rate multiplier 5, the fiber repetition rate multiplier 5 is connected to the second-stage amplifier 7, the second-stage amplifier 7 is connected to the third-stage amplifier 8, the first multimode semiconductor laser 6 and the second multimode semiconductor laser 9 are connected to the second-stage amplifier 7 and the third-stage amplifier 8, respectively, the third-stage amplifier 8 is connected to the mode field adapter 10, the mode field adapter 10 is connected to the first fluorinated liquid single-point heat dissipation unit 12 and the electrocooler 11, the first fluorinated liquid single-point heat dissipation unit 12 is connected to the photonic crystal fiber 13, the photonic crystal fiber 13 is connected to the second fluorinated liquid single-point heat dissipation unit 14, and the second fluorinated liquid single-point heat dissipation unit 14 is connected to the collimator 15.

[0022] like Figure 2 As shown, the two fluorinated liquid single-point heat dissipation units have the same structure, consisting of upper and lower covers 16 and a quartz cavity 17 sealed within the upper and lower covers 16. The quartz cavity 17 is filled with fluorinated liquid.

[0023] The working process of this invention:

[0024] The first single-mode semiconductor laser 1 pumps a mode-locked fiber oscillator 2, which uses SESAM passive mode-locking technology to output linearly polarized pulses with a center wavelength of 1.06 micrometers, a pulse width of 60 picoseconds, and a repetition frequency of 50 MHz. Simultaneously, the second single-mode semiconductor laser 3 pumps the first-stage amplifier 4, amplifying the seed pulse generated by the mode-locked fiber oscillator 2 and initially increasing the laser power. After the first-stage amplification, the seed pulse passes through a fiber repetition rate multiplier 5, doubling the repetition frequency from 50 MHz to 100 MHz, further reducing the peak power density in the amplification stage and increasing the Raman effect threshold, thereby reducing stimulated Raman scattering in subsequent processes. The linearly polarized pulse with a center wavelength of 1.06 micrometers, after the repetition frequency is doubled, is further amplified by the second-stage amplifier 7 and the third-stage amplifier 8. These two amplification stages are pumped by the first multimode semiconductor laser 6 and the second multimode semiconductor laser 9, respectively, achieving an average power output in the hundreds of watts range for the pump pulse. The mode field adapter 10 connects the third-stage amplifier 8 to the photonic crystal fiber 12, improving the transmission efficiency between them. An electrothermal cooler 11 actively cools and controls the temperature of the mode field adapter 10. At the two fusion splices before and after the mode field adapter 10, collimator 15, and photonic crystal fiber 13, a first fluorinated liquid single-point heat dissipation unit 12 and a second fluorinated liquid single-point heat dissipation unit 14 are used for heat dissipation, respectively. The fusion splices are immersed in fluorinated liquid (3M Fluorinert FC-40). The low freezing point, high boiling point, and high thermal conductivity of the fluorinated liquid ensure that the fusion splices remain stable over a wide temperature range. The high-power pump pulse light undergoes dramatic spectral broadening in the photonic crystal fiber 13, ultimately outputting supercontinuum laser light through the connected collimator 15.

[0025] like Figure 3 As shown, the output spectrum of the high-power supercontinuum laser device based on fully polarization-maintaining fiber of the present invention reaches the range of 430nm-2400nm.

[0026] like Figure 4 As shown, the power jitter curve of the high-power supercontinuum laser device based on full polarization-maintaining fiber of the present invention at an output of 30W is less than 3%.

Claims

1. A high-power supercontinuum laser device based on fully polarization-maintaining fiber, characterized in that its... include: The system consists of a first single-mode semiconductor laser (1), a mode-locked fiber oscillator (2), a second single-mode semiconductor laser (3), a first-stage amplifier (4), a frequency multiplier (5), a first multimode semiconductor laser (6), a second-stage amplifier (7), a third-stage amplifier (8), a second multimode semiconductor laser (9), a mode field adapter (10), an electrocooler (11), a first fluorinated liquid single-point heat dissipation unit (12), a photonic crystal fiber (13), a second fluorinated liquid single-point heat dissipation unit (14), and a collimator (15). The first single-mode semiconductor laser (1) is connected to the mode-locked fiber oscillator (2), the mode-locked fiber oscillator (2) is connected to the first-stage amplifier (4), the second single-mode semiconductor laser (3) is connected to the first-stage amplifier (4), the first-stage amplifier (4) is connected to the fiber repetition rate multiplier (5), the fiber repetition rate multiplier (5) is connected to the second-stage amplifier (7), the second-stage amplifier (7) is connected to the third-stage amplifier (8), and the first multimode semiconductor laser (6) and the second multimode semiconductor laser ( 9) Connected to the second stage amplifier (7) and the third stage amplifier (8) respectively. The third stage amplifier (8) is connected to the mode field adapter (10). The mode field adapter (10) is connected to the first fluorinated liquid single-point heat dissipation unit (12) and the electrocooling chip (11) respectively. The first fluorinated liquid single-point heat dissipation unit (12) is connected to the photonic crystal fiber (13). The photonic crystal fiber (13) is connected to the second fluorinated liquid single-point heat dissipation unit (14). The second fluorinated liquid single-point heat dissipation unit (14) is connected to the collimator (15).

2. The high-power supercontinuum laser device based on fully polarization-maintaining fiber according to claim 1, characterized in that, The first single-mode semiconductor laser (1) pumps a mode-locked fiber oscillator (2), which uses SESAM passive mode-locking technology to output linearly polarized pulses with a center wavelength of 1.06 micrometers, a pulse width of 60 picoseconds, and a repetition frequency of 50 MHz. Simultaneously, the second single-mode semiconductor laser (3) pumps the first-stage amplifier (4) to amplify the seed pulses generated by the mode-locked fiber oscillator (2), thus initially increasing the laser power. After the first-stage amplification, the seed pulses pass through a fiber repetition rate multiplier (5), which doubles the repetition frequency of the seed pulses from 50 MHz to output pulses with a repetition frequency of 100 MHz, further reducing the peak power density in the amplification stage and increasing the Raman effect threshold, thereby reducing stimulated Raman scattering in subsequent processes. The linearly polarized pulses with a center wavelength of 1.06 micrometers after the repetition frequency is doubled pass through the second-stage amplifier (7) and the third-stage amplifier (8). The laser power is further amplified. The two-stage amplification uses the first multimode semiconductor laser (6) and the second multimode semiconductor laser (9) for pumping, so that the pump pulse light reaches an average power output of hundreds of watts. The mode field adapter (10) connects the third stage amplifier (8) and the photonic crystal fiber (12) to improve the transmission efficiency between the two. The mode field adapter (10) is actively cooled and temperature controlled by an electrothermal chip (11). The first fluorinated liquid single-point heat dissipation unit (12) and the second fluorinated liquid single-point heat dissipation unit (14) are used to dissipate heat at the two fusion points before and after the mode field adapter (10), collimator (15) and photonic crystal fiber (13), respectively. The fusion points are immersed in fluorinated liquid to ensure that the fusion points can remain stable in a wide temperature range. The high-power pump pulse light undergoes drastic spectral broadening in the photonic crystal fiber (13) and finally outputs supercontinuum laser through the collimator (15) connected to it.

3. A high-power supercontinuum laser device based on fully polarization-maintaining fiber according to claim 1, characterized in that, The operating wavelength of the first single-mode semiconductor laser (1) and the second single-mode semiconductor laser (3) is 976 nm.

4. A high-power supercontinuum laser device based on fully polarization-maintaining fiber according to claim 1, characterized in that, The operating wavelengths of the first multimode semiconductor laser (6) and the second multimode semiconductor laser (9) are both 915 nm.

5. A high-power supercontinuum laser device based on fully polarization-maintaining fiber according to claim 1, characterized in that, The two fluorinated liquid single-point heat dissipation units have the same structure, including upper and lower covers (16) and a quartz cavity (17) sealed in the upper and lower covers (16), and the quartz cavity (17) is filled with fluorinated liquid.

Images