A narrow linewidth fiber laser that alternately emits continuous wave and pulsed wave

Abstract

The present invention discloses a narrow-linewidth fiber laser that alternately emits continuous waves and pulsed waves, which includes: a narrow-linewidth seed light source, a laser pre-amplification unit, a continuous and pulsed light switching unit, and a laser power amplification unit; the output end of the narrow-linewidth seed light source is connected to the input end of the laser pre-amplification unit through an optical fiber jumper, the output end of the laser pre-amplification unit is respectively connected to the continuous light input end and the pulsed light input end of the continuous and pulsed light switching unit through a first beam splitter, the continuous light output end and the pulsed light output end of the continuous and pulsed light switching unit are coupled through a first coupler, the output end of the first coupler is connected to the input end of the laser power amplification unit, and the output end of the laser power amplification unit is connected to a large-mode-field optical fiber. The structure of the present invention is compact, highly reliable, and has low optical noise, and can be applied to fields such as laser detection, lidar, industrial inspection, and laser sensing to improve the detection accuracy and sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber lasers and relates to a narrow-linewidth fiber laser that alternately emits continuous waves and pulsed waves. Background Art

[0002] The narrow-linewidth fiber laser is a new type of laser developed in recent years. Compared with gas lasers and solid lasers, the narrow-linewidth fiber laser has the advantages of narrow laser linewidth, high frequency stability, small size, light weight, long life, etc., and can achieve laser output with high frequency stability. In the time-domain modulation technology of narrow-linewidth fiber lasers, there are various forms of internal modulation and external modulation technologies, which can achieve pulsed and continuous-wave modulation outputs; in the optical parameter modulation technology, there are various modulation methods such as frequency modulation, phase modulation, amplitude modulation, and polarization modulation.

[0003] The narrow-linewidth fiber laser that alternately emits continuous waves and pulsed waves has an all-fiber optical path. A semiconductor narrow-linewidth laser is used as a narrow-linewidth small-signal light source, which is injected into a pre-amplifier for small-signal amplification, and then injected into a continuous and pulsed light switching system. Among them, the continuous and pulsed light switching system is composed of an optical switch and an optical modulator, and can realize the switching of continuous-wave and pulsed-wave amplification optical paths or simultaneous output under electrical control. For the optical modulator, in addition to modulating the continuous wave into pulsed light with required parameters in the time domain; it can also be replaced with a frequency modulation, phase modulation, or polarization modulation device to realize the modulation output of the frequency, phase, and polarization state of the output laser, while maintaining the narrow linewidth of the injected optical signal, and has great application potential in lidar, laser sensing, optical fiber communication, and industrial monitoring. Summary of the Invention

[0004] (1) Object of the Invention

[0005] The object of the present invention is to provide a narrow-linewidth fiber laser that alternately emits continuous waves and pulsed waves in view of the defects of the prior art. Since the continuous and pulsed light switching system has multiple optical path switching channels for continuous and pulsed waves, the alternate / simultaneous output of continuous and pulsed lasers can be realized on one laser.

[0006] (2) Technical Solution

[0007] To solve the above technical problems, the present invention provides a narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves, which includes: a narrow linewidth seed light source, a laser pre-amplification unit, a continuous and pulsed light switching unit, and a laser power amplification unit; the output end of the narrow linewidth seed light source is connected to the input end of the laser pre-amplification unit through an optical fiber jumper, the output end of the laser pre-amplification unit is respectively connected to the continuous light input end and the pulsed light input end of the continuous and pulsed light switching unit through a first beam splitter 6, the continuous light output end and the pulsed light output end of the continuous and pulsed light switching unit are coupled through a first coupler 11, the output end of the first coupler 11 is connected to the input end of the laser power amplification unit, and the output end of the laser power amplification unit is connected to a large mode field fiber 22..

[0008] Among them, the narrow linewidth seed light source includes a narrow linewidth semiconductor laser 1, and the narrow linewidth semiconductor laser 1 outputs seed laser with narrow linewidth and low noise under the rated operating voltage, and the seed laser is injected into the laser pre-amplification unit through a single-mode output optical fiber.

[0009] Among them, the laser pre-amplification unit includes a first pre-amplification drive and power control circuit, a first wavelength division multiplexer 2, a first pump laser source 3, a first gain fiber 4, a first filter, and a first isolator 5; the first pre-amplification drive and power control circuit is connected to the pump laser source 3, the output end of the narrow linewidth semiconductor laser 1 is connected to the input end of the first wavelength division multiplexer 2, the output end of the first wavelength division multiplexer 2 is connected to the input end of the first gain fiber 4, the output end of the first pump laser source 3 is connected to the connection between the first wavelength division multiplexer 2 and the first gain fiber 4, the output end of the first gain fiber 4 is connected to the input end of the first filter, the output end of the first filter is connected to the input end of the first isolator 5, and the output end of the first isolator 5 is connected to the input end of the first beam splitter 6.

[0010] Among them, the first pre-amplification drive and power control circuit controls the first pump laser source 3 to output a set laser wavelength with stable power; the central wavelength of the laser output by the first pump laser source 3 is consistent with the absorption laser central wavelength of the first gain fiber 4; the first gain fiber 4 absorbs the pump energy output by the first pump laser source 3 and is excited by the seed laser signal of the narrow linewidth semiconductor laser 1 to complete radiative transition, and emits continuous laser with the same frequency, phase, polarization direction as the narrow linewidth seed laser and amplified optical power; the first wavelength division multiplexer 2 couples the pump light output by the first pump laser source 3 into the first gain fiber 4; the first filter completes the optical filtering of the continuous laser; the first isolator 5 completes the laser isolation in the first pump laser source 3, the first wavelength division multiplexer 2 and the first gain fiber 4, protects the first pump laser source 3 and the first wavelength division multiplexer 2, and at the same time isolates the reflected light of the laser pre-amplification unit from the continuous and pulsed light switching unit to protect the laser pre-amplification unit.

[0011] Among them, the continuous and pulsed light switching unit includes a first optical switch 7, a second optical switch 8, a first optical modulator 9, and a second optical modulator 10. The first optical switch 7 and the second optical switch 8 are connected in parallel, and one end of each is connected to the first beam splitter 6. The first optical switch 7, the first optical modulator 9, and the second optical modulator 10 are connected in sequence. The input end of the first coupler 11 is connected to the second optical modulator 10 and the second optical switch 8. The first optical switch 7 and the second optical switch 8 alternately inject continuous laser into the laser power amplification unit and the first optical modulator 9 and the second optical modulator 10. The first optical modulator 9 and the second optical modulator 10 complete the pulsed wave modulation of the continuous laser and inject it into the laser power amplification unit through the single-mode output optical fiber.

[0012] Among them, the laser power amplification unit includes a second drive and power control circuit, a third drive and power control circuit, a fourth drive and power control circuit, a second wavelength division multiplexer 12, a second pump laser source 13, a second gain fiber 14, a second filter 15, a second isolator 16, a beam combiner 19, a third pump laser source 17, a fourth pump laser source 18, a third gain fiber 20, and a third isolator 21. The input end of the second wavelength division multiplexer 12 is connected to the first coupler 11. The second wavelength division multiplexer 12, the second gain fiber 14, the second filter 15, the second isolator 16, the beam combiner 19, the third gain fiber 20, and the third isolator 21 are connected in sequence. The connection between the second wavelength division multiplexer 12 and the second gain fiber 14 is connected to the output end of the second pump laser source 13. The second pump laser source 13 is driven by the second drive and power control circuit. The input end of the beam combiner 19 is connected to the third pump laser source 17 and the fourth pump laser source 18. The third pump laser source 17 and the fourth pump laser source 18 are respectively driven by the third drive and power control circuit and the fourth drive and power control circuit.

[0013] Among them, the second drive and power control circuit controls the second pump laser source 13 to output a set laser wavelength with stable power; the central wavelength of the laser output by the second pump laser source 13 is consistent with the absorption wavelength of the second gain fiber 14; the second wavelength division multiplexer 12 couples the pump light output by the second pump laser source 13 into the second gain fiber 14; the second gain fiber 14 absorbs the pump energy output by the second pump laser source 13, and is excited by the continuous / pulse laser injected by the continuous and pulse light switching system to complete radiative transition, emitting continuous / pulse laser with the same frequency, phase, polarization direction as the injected continuous / pulse laser and amplified optical power; the second filter 15 filters the continuous / pulse laser; the second isolator 16 isolates the laser within the second wavelength division multiplexer 12, the second pump laser source 13, and the second gain fiber 14. The second pump laser source 13 and the second wavelength division multiplexer 12 also isolate the reflected light from the laser power amplification system and the output fiber end face to protect the laser power amplification system; the beam combiner 19 combines the continuous / pulse laser and the pump light input by the third pump laser source 17 and the fourth pump laser source 18, and merges them into the third gain fiber 20. After the isolation of the combined laser is completed by the third isolator 21, it is output.

[0014] Among them, the narrow-linewidth fiber laser that alternately emits continuous wave and pulse wave in this embodiment further includes a temperature control unit. The temperature control unit includes a temperature sensor, a TEC component, a cooling fan, and a control circuit. The TEC component keeps each pump laser source at a stable operating temperature. The cooling fan performs air cooling on the overall laser. The temperature sensor collects the temperature value in real time. The control circuit receives the data of the temperature sensor and automatically controls the operation of the TEC component and the cooling fan to keep each optical element within the operating temperature range.

[0015] (III) Beneficial Effects

[0016] The narrow-linewidth fiber laser that alternately emits continuous wave and pulse wave provided by the above technical solution provides a solution for alternately emitting continuous wave and pulse wave output on one laser, and can quickly modulate optical parameters such as power, repetition frequency, and pulse width for the same narrow-linewidth light source to meet the needs of different optical systems. This laser has a compact structure, high reliability, and low optical noise, and can be applied in fields such as laser detection, lidar, industrial inspection, and laser sensing to improve detection accuracy and sensitivity. Description of the Drawings

[0017] Figure 1 It is a schematic optical path diagram of the narrow-linewidth fiber laser that alternately emits continuous wave and pulse wave in the embodiment of the present invention. Detailed Embodiments

[0018] To make the objectives, contents, and advantages of the present invention clearer, the following further describes the detailed embodiments of the present invention in conjunction with the drawings and embodiments.

[0019] Referring to Figure 1 As shown, the narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves in this embodiment includes: a narrow linewidth seed light source, a laser pre-amplification unit, a continuous and pulsed light switching unit, and a laser power amplification unit; the output end of the narrow linewidth seed light source is connected to the input end of the laser pre-amplification unit through an optical fiber jumper, the output end of the laser pre-amplification unit is respectively connected to the continuous light input end and the pulsed light input end of the continuous and pulsed light switching unit through a first beam splitter 6, the continuous light output end and the pulsed light output end of the continuous and pulsed light switching unit are coupled through a first coupler 11, the output end of the first coupler 11 is connected to the input end of the laser power amplification unit, and the output end of the laser power amplification unit is connected to a large mode field fiber 22.

[0020] The narrow linewidth seed light source includes a narrow linewidth semiconductor laser 1. The narrow linewidth semiconductor laser 1 outputs seed laser with a narrow linewidth and low noise under the rated operating voltage, and the seed laser is injected into the laser pre-amplification unit through a single-mode output optical fiber.

[0021] The laser pre-amplification unit includes a first pre-amplification drive and power control circuit, a first wavelength division multiplexer 2, a first pump laser source 3, a first gain fiber 4, a first filter, and a first isolator 5; the first pre-amplification drive and power control circuit is connected to the pump laser source 3, the output end of the narrow linewidth semiconductor laser 1 is connected to the input end of the first wavelength division multiplexer 2, the output end of the first wavelength division multiplexer 2 is connected to the input end of the first gain fiber 4, the output end of the first pump laser source 3 is connected to the connection between the first wavelength division multiplexer 2 and the first gain fiber 4, the output end of the first gain fiber 4 is connected to the input end of the first filter, the output end of the first filter is connected to the input end of the first isolator 5, and the output end of the first isolator 5 is connected to the input end of the first beam splitter 6.

[0022] The first pre-amplification drive and power control circuit controls the first pump laser source 3 to output a set laser wavelength with stable power; the central wavelength of the laser output by the first pump laser source 3 is consistent with the absorption laser central wavelength of the first gain fiber 4; the first gain fiber 4 absorbs the pump energy output by the first pump laser source 3, is excited by the seed laser signal of the narrow linewidth semiconductor laser 1 to complete radiative transition, and emits continuous laser with the same frequency, phase, polarization direction as the narrow linewidth seed laser and amplified optical power; the first wavelength division multiplexer 2 couples the pump light output by the first pump laser source 3 into the first gain fiber 4; the first filter completes the optical filtering of the continuous laser; the first isolator 5 completes the laser isolation in the first pump laser source 3, the first wavelength division multiplexer 2 and the first gain fiber 4, protects the first pump laser source 3 and the first wavelength division multiplexer 2, and at the same time isolates the reflected light between the laser pre-amplification unit and the continuous and pulsed light switching unit to protect the laser pre-amplification unit.

[0023] The continuous and pulsed light switching unit includes a first optical switch 7, a second optical switch 8, a first optical modulator 9, and a second optical modulator 10. The first optical switch 7 and the second optical switch 8 are in parallel, and one end of each is connected to the first beam splitter 6. The first optical switch 7, the first optical modulator 9, and the second optical modulator 10 are connected in sequence. The input end of the first coupler 11 is connected to the second optical modulator 10 and the second optical switch 8. The first optical switch 7 and the second optical switch 8 alternately inject continuous laser into the laser power amplification unit and the first optical modulator 9 and the second optical modulator 10. The first optical modulator 9 and the second optical modulator 10 complete the pulsed wave modulation of the continuous laser and inject it into the laser power amplification unit through the single-mode output optical fiber.

[0024] The laser power amplification unit includes a second drive and power control circuit, a third drive and power control circuit, a fourth drive and power control circuit, a second wavelength division multiplexer 12, a second pump laser source 13, a second gain fiber 14, a second filter 15, a second isolator 16, a beam combiner 19, a third pump laser source 17, a fourth pump laser source 18, a third gain fiber 20, and a third isolator 21. The input end of the second wavelength division multiplexer 12 is connected to the first coupler 11. The second wavelength division multiplexer 12, the second gain fiber 14, the second filter 15, the second isolator 16, the beam combiner 19, the third gain fiber 20, and the third isolator 21 are connected in sequence. The connection between the second wavelength division multiplexer 12 and the second gain fiber 14 is connected to the output end of the second pump laser source 13, and the second pump laser source 13 is driven by the second drive and power control circuit. The input end of the beam combiner 19 is connected to the third pump laser source 17 and the fourth pump laser source 18, and the third pump laser source 17 and the fourth pump laser source 18 are respectively driven by the third drive and power control circuit and the fourth drive and power control circuit.

[0025] The second driving and power control circuit controls the second pump laser source 13 to output a set laser wavelength with stable power; the central wavelength of the laser output by the second pump laser source 13 is consistent with the absorption wavelength of the second gain fiber 14; the second wavelength division multiplexer 12 couples the pump light output by the second pump laser source 13 into the second gain fiber 14; the second gain fiber 14 absorbs the pump energy output by the second pump laser source 13, and is excited by the continuous / pulse laser injected by the continuous and pulse light switching system to complete the radiation transition, and emits a continuous / pulse laser with the same frequency, phase and polarization direction as the injected continuous / pulse laser and amplified optical power. Pulse laser; the second filter 15 completes continuous / pulse laser filtering; the second isolator 16 completes laser isolation in the semi-second wavelength division multiplexer 12, the second pump laser source 13, and the second gain fiber 14, and the second pump laser source 13 and the second wavelength division multiplexer 12, while isolating the laser power amplification system from the reflected light of the output fiber end face to protect the laser power amplification system; the combiner 19 combines the continuous / pulse laser and the pump light input by the third pump laser source 17 and the fourth pump laser source 18, and merges them into the third gain fiber 20, and outputs them after the isolation of the combined laser is completed by the third isolator 21.

[0026] The narrow-linewidth fiber laser that alternately emits continuous waves and pulse waves in this embodiment further includes a temperature control unit for adjusting the operating temperature of the environment in which each optical element is located.

[0027] The temperature control unit includes a temperature sensor, a TEC component, a cooling fan, and a control circuit. The TEC component maintains each pump laser source at a stable operating temperature, and the cooling fan cools the laser as a whole. The temperature sensor collects temperature values ​​in real time, and the control circuit receives the temperature sensor data, automatically controls the TEC component and the cooling fan, and keeps each optical element within the operating temperature range.

[0028] In this embodiment, the continuous and pulse light switching unit outputs a light wave in the form of continuous wave, pulse wave, continuous wave-pulse wave mixture, pulse wave-continuous wave mixture, or a combination of the above output forms.

[0029] The output optical paths of the continuous and pulse light switching unit are: one continuous wave and one pulse wave, one continuous wave and multiple pulse waves, multiple continuous waves and one pulse wave, multiple continuous waves and multiple pulse waves are output simultaneously, alternately, or in turn;

[0030] The optical switch used in the continuous and pulse light switching unit is: a mechanical optical switch, an acousto-optic switch, an electro-optic switch, a magneto-optic switch, a polarized light switch, or a combination of two or more of the above optical switches;

[0031] The optical modulators used in the continuous and pulsed light switching unit are: mechanical optical modulators, acousto-optic modulators, electro-optic modulators, magneto-optic modulators, Q-switching crystals, absorption saturation crystals, or the combination of two or more of the above optical modulators.

[0032] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves, characterized in that, Comprising: A narrow linewidth seed light source, a laser pre-amplification unit, a continuous and pulsed light switching unit, and a laser power amplification unit; the output end of the narrow linewidth seed light source is connected to the input end of the laser pre-amplification unit through an optical fiber jumper, the output end of the laser pre-amplification unit is respectively connected to the continuous light input end and the pulsed light input end of the continuous and pulsed light switching unit through a first beam splitter (6), the continuous light output end and the pulsed light output end of the continuous and pulsed light switching unit are coupled through a first coupler (11), the output end of the first coupler (11) is connected to the input end of the laser power amplification unit, and the output end of the laser power amplification unit is connected to a large mode field optical fiber (22); The continuous and pulsed light switching unit includes a first optical switch (7), a second optical switch (8), a first optical modulator (9), and a second optical modulator (10). The first optical switch (7) and the second optical switch (8) are in parallel, and one end of each is connected to the first beam splitter (6). The first optical switch (7), the first optical modulator (9), and the second optical modulator (10) are connected in sequence. The input end of the first coupler (11) is connected to the second optical modulator (10) and the second optical switch (8); the first optical switch (7) and the second optical switch (8) alternately inject continuous laser into the laser power amplification unit and the first optical modulator (9) and the second optical modulator (10), and the first optical modulator (9) and the second optical modulator (10) complete the pulsed wave modulation of the continuous laser, and inject it into the laser power amplification unit through a single-mode output optical fiber; The output optical wave form of the continuous and pulsed light switching unit is: continuous wave, pulsed wave, continuous wave - pulsed wave mixture, pulsed wave - continuous wave mixture, or a combination of the above output forms.

2. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves as claimed in claim 1, wherein The narrow linewidth seed light source includes a narrow linewidth semiconductor laser (1), and the narrow linewidth semiconductor laser (1) outputs seed laser with narrow linewidth and low noise under the rated operating voltage, and the seed laser is injected into the laser pre-amplification unit through a single-mode output optical fiber.

3. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves as claimed in claim 2, wherein The laser pre-amplification unit includes a first pre-amplification drive and power control circuit, a first wavelength division multiplexer (2), a first pump laser source (3), a first gain optical fiber (4), a first filter, and a first isolator (5); the first pre-amplification drive and power control circuit is connected to the first pump laser source (3), the output end of the narrow linewidth semiconductor laser (1) is connected to the input end of the first wavelength division multiplexer (2), the output end of the first wavelength division multiplexer (2) is connected to the input end of the first gain optical fiber (4), the output end of the first pump laser source (3) is connected to the connection point between the first wavelength division multiplexer (2) and the first gain optical fiber (4), the output end of the first gain optical fiber (4) is connected to the input end of the first filter, the output end of the first filter is connected to the input end of the first isolator (5), and the output end of the first isolator (5) is connected to the input end of the first beam splitter (6).

4. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves according to claim 3, characterized in that, The first pre-amplification drive and power control circuit controls the first pump laser source (3) to output a set laser wavelength with stable power; the central wavelength of the laser output by the first pump laser source (3) is consistent with the central wavelength of the laser absorbed by the first gain fiber (4); the first gain fiber (4) absorbs the pump energy output by the first pump laser source (3), and is excited by the seed laser signal of the narrow-linewidth semiconductor laser (1) to complete radiative transition, emitting continuous laser with the same frequency, phase, polarization direction as the narrow-linewidth seed laser and amplified optical power; the first wavelength division multiplexer (2) couples the pump light output by the first pump laser source (3) into the first gain fiber (4); the first filter completes the optical filtering of the continuous laser; the first isolator (5) completes the laser isolation in the first pump laser source (3), the first wavelength division multiplexer (2) and the first gain fiber (4), protects the first pump laser source (3) and the first wavelength division multiplexer (2), and at the same time isolates the reflected light of the laser pre-amplification unit and the continuous and pulsed light switching unit, protecting the laser pre-amplification unit.

5. The narrow linewidth fiber laser that alternately emits continuous wave and pulsed wave according to claim 4, characterized in that, The laser power amplification unit includes a second drive and power control circuit, a third drive and power control circuit, a fourth drive and power control circuit, a second wavelength division multiplexer (12), a second pump laser source (13), a second gain fiber (14), a second filter (15), a second isolator (16), a beam combiner (19), a third pump laser source (17), a fourth pump laser source (18), a third gain fiber (20) and a third isolator (21); the input end of the second wavelength division multiplexer (12) is connected to the first coupler (11), and the second wavelength division multiplexer (12), the second gain fiber (14), the second filter (15), the second isolator (16), the beam combiner (19), the third gain fiber (20) and the third isolator (21) are connected in sequence. The connection between the second wavelength division multiplexer (12) and the second gain fiber (14) is connected to the output end of the second pump laser source (13), and the second pump laser source (13) is driven by the second drive and power control circuit; the input end of the beam combiner (19) is connected to the third pump laser source (17) and the fourth pump laser source (18), and the third pump laser source (17) and the fourth pump laser source (18) are respectively driven by the third drive and power control circuit and the fourth drive and power control circuit correspondingly.

6. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves as described in claim 5, wherein The second drive and power control circuit controls the second pump laser source (13) to output a set laser wavelength with stable power; the central wavelength of the laser output by the second pump laser source (13) is consistent with the absorption wavelength of the second gain fiber (14); the second wavelength division multiplexer (12) couples the pump light output by the second pump laser source (13) into the second gain fiber (14); the second gain fiber (14) absorbs the pump energy output by the second pump laser source (13), and completes radiative transition under the excitation of the continuous / pulse laser injected by the continuous and pulse light switching unit, and emits a continuous / pulse laser with the same frequency, phase, polarization direction as the injected continuous / pulse laser and amplified optical power; the second filter (15) completes the filtering of the continuous / pulse laser; the second isolator (16) completes the isolation of the laser in the second wavelength division multiplexer (12), the second pump laser source (13), and the second gain fiber (14), and at the same time isolates the reflected light from the laser power amplification unit and the output fiber end face to protect the laser power amplification unit; the combiner (19) combines the continuous / pulse laser and the pump light input by the third pump laser source (17) and the fourth pump laser source (18), and merges them into the third gain fiber (20), and outputs after the isolation of the combined laser is completed by the third isolator (21).

7. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves as described in claim 6, wherein, It further includes a temperature control unit, and the temperature control unit includes a temperature sensor, a TEC component, a cooling fan, and a control circuit. The TEC component maintains each pump laser source at a stable operating temperature, the cooling fan performs air cooling on the overall laser, the temperature sensor collects the temperature value in real time, and the control circuit receives the data of the temperature sensor and automatically controls the operation of the TEC component and the cooling fan to keep each optical element within the operating temperature range.

8. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves according to claim 7, characterized in that, The optical switch adopted by the continuous and pulse light switching unit is: a mechanical optical switch, an acousto-optic switch, an electro-optic switch, a magneto-optic switch, a polarization optical switch, or the combination of two or more of the above optical switches.

9. The narrow linewidth fiber laser that alternately emits continuous waves and pulsed waves according to claim 8, wherein The optical modulator adopted by the continuous and pulse light switching unit is: a mechanical optical modulator, an acousto-optic modulator, an electro-optic modulator, a magneto-optic modulator, a Q-switching crystal, an absorption saturation crystal, or the combination of two or more of the above optical modulators.

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