CN217903674U - Tunable fiber laser - Google Patents
Tunable fiber laser Download PDFInfo
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- CN217903674U CN217903674U CN202222174752.2U CN202222174752U CN217903674U CN 217903674 U CN217903674 U CN 217903674U CN 202222174752 U CN202222174752 U CN 202222174752U CN 217903674 U CN217903674 U CN 217903674U
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Abstract
The utility model discloses a tunable fiber laser. The device comprises a pumping source, a wavelength division multiplexer, an active optical fiber, a polarization modulation unit, a wavelength tunable filter and a coupler; the wavelength division multiplexer comprises a pumping input end, an output end and a public input end; the wavelength division multiplexer, the active optical fiber, the polarization modulation unit, the wavelength tunable filter and the coupler are connected to form an annular resonant cavity, wherein the output end and the common input end are connected into the annular resonant cavity; the coupler comprises an input end, a first output end and a second output end, the input end and the first output end are connected into the annular resonant cavity, and the second output end of the coupler is the output end of the tunable fiber laser. By the scheme, the polarization modulation unit can effectively improve the polarization extinction ratio of the laser, the output wavelength of the laser can be controlled by the wavelength tunable filter, the wavelength adjusting range of the output laser is expanded, and the laser output by the optical fiber laser can be continuously adjusted in a wider wavelength range.
Description
Technical Field
The embodiment of the utility model provides a relate to laser technical field, especially relate to a tunable fiber laser.
Background
Tunable laser refers to a laser that can continuously vary the laser output wavelength over a range. The laser has wide application, and can be used in the fields of spectroscopy, photochemistry, medicine, biology, integrated optics, pollution monitoring, semiconductor material processing, information processing, communication and the like. Compared with other traditional solid-state lasers, the tunable fiber laser has a wider tuning range of a wave band, and has small size, narrow line width and high optical efficiency, so that the tunable fiber laser has important application prospects in the fields of single-chip laboratories, medical diagnosis, dermatology and the like.
Currently, tunable lasers are mainly semiconductor tunable lasers, which can be classified into current control technology, temperature control technology, mechanical control technology, and the like according to principles. The current control technology is to realize the wavelength tuning by changing the injection current, and the output power is small, so that the use requirement of a high-power output laser is difficult to meet. The temperature control technology changes the output wavelength of the laser by changing the refractive index of the active region of the laser, and has the following defects: the tuning speed is slow, the adjustable bandwidth is narrow, and the bandwidth is only a few nm generally. The mechanical control is mainly based on the selection of the wavelength by the MEMS (micro electro mechanical system) technology, and the disadvantage is the wide output line width.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a tunable fiber laser realizes the wavelength regulatory function of laser instrument through full fiber structure, has optimized tunable fiber laser's performance to the defect of above prior art.
The embodiment of the utility model provides a tunable fiber laser, including pumping source, wavelength division multiplexer, active optical fiber, polarization modulation unit, wavelength tunable filter and coupler;
the wavelength division multiplexer comprises a pumping input end, an output end and a common input end; the pumping input end is connected with the pumping source, the wavelength division multiplexer, the active optical fiber, the polarization modulation unit, the wavelength tunable filter and the coupler are connected to form a ring-shaped resonant cavity, and the output end and the common input end are connected into the ring-shaped resonant cavity;
the coupler comprises an input end, a first output end and a second output end; the input end and the first output end are connected into the annular resonant cavity, and the second output end is the output end of the tunable fiber laser.
The embodiment of the utility model provides an among the tunable fiber laser, the polarization extinction ratio of laser can effectively be improved in the existence of polarization modulation unit, through the output wavelength of the steerable laser of wavelength tunable filter, enlarges the wavelength control range of output laser, makes the laser of fiber laser output continuously adjustable in broad wavelength range.
Drawings
Fig. 1 is a schematic structural diagram of a tunable fiber laser according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another tunable fiber laser provided in an embodiment of the present invention;
fig. 3 is a schematic diagram of an output spectrum of a tunable fiber laser according to an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating a variation in output power stability of a tunable fiber laser according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of a tunable fiber laser provided in an embodiment of the present invention, and referring to fig. 1, the tunable fiber laser includes a pump source 1, a wavelength division multiplexer 2, an active fiber 3, a polarization modulation unit 4, a wavelength tunable filter 5, and a coupler 6; the wavelength division multiplexer 2 comprises a pumping input end a, an output end b and a common input end c; the pump input end a is connected with a pump source 1, the wavelength division multiplexer 2, the active optical fiber 3, the polarization modulation unit 4, the wavelength tunable filter 5 and the coupler 6 are connected to form an annular resonant cavity, and the output end b and the common input end c are connected into the annular resonant cavity; the coupler 6 comprises an input d, a first output e and a second output f; the input end d and the first output end e are connected into the annular resonant cavity, and the second output end f is the output end of the tunable fiber laser.
Specifically, as shown in fig. 1, a pump source 1 is connected to a pump input end a of a wavelength division multiplexer 2, and the wavelength division multiplexer 2, an active fiber 3, a polarization modulation unit 4, a wavelength tunable filter 5, and a coupler 6 are connected to form a ring resonator. In the embodiment shown in fig. 1, the wavelength division multiplexer 2, the active optical fiber 3, the polarization modulation unit 4, the wavelength tunable filter 5, and the coupler 6 are sequentially connected, but the actual connection mode is not limited thereto, and in the actual application process, a person skilled in the art can adjust the relative position relationship between the above components according to actual requirements.
The embodiment of the utility model provides a tunable fiber laser sets up polarization modulation unit 4 and wavelength tunable filter 5 in the ring resonator. The polarization modulation unit 4 can effectively improve the polarization characteristic in the cavity, so that the polarization extinction ratio of the output laser is high. The wavelength tunable filter 5 is used as a frequency selecting device, which can filter laser in a certain wavelength range, retain laser in a required wavelength range, and control the output wavelength of the laser through the wavelength tunable filter 5, thereby enlarging the wavelength adjusting range of the output laser and enabling the laser output by the fiber laser to be continuously adjustable in a wider wavelength range.
Wherein, technicians in the field can set the working wavelength range of the wavelength tunable filter 5 according to the application scenario of the actual device, so that the laser wavelength output by the tunable fiber laser meets the requirements of the actual scenario.
With continued reference to fig. 1, the coupler 6 includes an input d, a first output e, and a second output f; the input end d and the first output end e are connected into the annular resonant cavity, and the second output end f is used as the output end of the tunable fiber laser. The laser beam entering the coupler 6 enters the wavelength division multiplexer 2 from the first output end e of the coupler 6, continues to vibrate in the ring resonator, and exits from the second output end f of the coupler 6.
Exemplarily, in the specific embodiment shown in fig. 1, the output end b of the wavelength division multiplexer 2 is connected to the first end of the active optical fiber 3; the second end of the active optical fiber 3 is connected with the first end of the polarization modulation unit 4, and the second end of the polarization modulation unit 4 is connected with the first end of the wavelength tunable filter 5; the second end of the wavelength tunable filter 5 is connected with the input end d of the coupler 6, and the first output end e of the coupler 6 is connected with the common input end c of the wavelength division multiplexer 2, so as to form a ring-shaped resonant cavity of the tunable fiber laser.
The operation of a tunable fiber laser can be described as follows: under the excitation of a pumping source, the population of laser energy level particles in the active optical fiber is reversed, laser with high polarization extinction ratio is obtained through a polarization modulation unit, and then the laser with specific wavelength range is output through the filtering function of a wavelength tunable filter, wherein one part of the laser with specific wavelength range enters a coupler, the other part of the laser with specific wavelength range enters a wavelength division multiplexer through a second output end of the coupler, and the other part of the laser with specific wavelength range enters the wavelength division multiplexer through a first output end of the coupler and continues to vibrate in a resonant cavity.
The embodiment of the present invention does not limit the specific types of the wavelength division multiplexer, the polarization modulation unit, the wavelength tunable filter, and the coupler, and those skilled in the art can select the wavelength tunable filter according to actual needs.
In one embodiment, the wavelength division multiplexer can be a PM 980/1064nm wavelength division multiplexer, and the coupler can be a PM 1064nm50/50 coupler, but is not limited thereto.
The embodiment of the utility model provides an in, the device in the tunable fiber laser is whole to be the optic fibre structure, and the side mode of tunable fiber laser suppresses than higher, and is small, and life is longer to laser output power is higher, and adjustable bandwidth is higher, can compensate among the prior art a great deal of not enough of the tunable laser of semiconductor, as the preferred product of seed laser, has important use value in the scientific research field.
The embodiment of the utility model provides a tunable fiber laser, including pumping source, wavelength division multiplexer, active optical fiber, polarization modulation unit, wavelength tunable filter and coupler; the wavelength division multiplexer comprises a pumping input end, an output end and a common input end; the wavelength division multiplexer, the active optical fiber, the polarization modulation unit, the wavelength tunable filter and the coupler are connected to form an annular resonant cavity, wherein the output end and the common input end are connected into the annular resonant cavity; the coupler comprises an input end, a first output end and a second output end; the input end and the first output end are connected into the annular resonant cavity, and the second output end is the output end of the tunable fiber laser. In the technical scheme, the polarization modulation unit can effectively improve the polarization extinction ratio of the laser, the output wavelength of the laser can be controlled through the wavelength tunable filter, the wavelength adjusting range of the output laser is expanded, and the laser output by the optical fiber laser can be continuously adjusted in a wider wavelength range.
Optionally, in order to ensure unidirectional transmission of laser in the resonant cavity, an isolator may be further disposed in the tunable fiber laser. To the setting position of isolator and the type etc. that sets up quantity and isolator, the embodiment of the utility model provides a do not all do the restriction, technical personnel in the field can set up according to actual need.
Exemplarily, fig. 2 is a schematic structural diagram of another tunable fiber laser provided in an embodiment of the present invention, as shown in fig. 2, the tunable fiber laser may further include a first isolator 7, and the first isolator 7 is located on a connection path between the wavelength division multiplexer 2 and the coupler 6.
Referring to fig. 2, in the embodiment of the present invention, a first isolator 7 may be disposed in the connection path between the wavelength division multiplexer 2 and the coupler 6, and the existence of the first isolator 7 can ensure that the oscillating beam in the resonant cavity is in a traveling wave state, so as to avoid forming a standing wave to cause spatial hole burning.
Optionally, a person skilled in the art may set the first isolator 7 between any two devices of the wavelength division multiplexer 2, the polarization modulation unit 4, the wavelength tunable filter 5, and the coupler 6 according to actual requirements, so as to ensure that the input end of the first isolator 7 is close to the output end b of the wavelength division multiplexer 2, and the output end of the first isolator 7 is close to the input end d of the coupler 6.
Illustratively, and still referring to fig. 2, in a possible embodiment, the input end of the first isolator 7 may be connected to the second end of the active fiber 3, and the output end of the first isolator 7 is connected to the first end of the polarization modulation unit 4.
Specifically, as shown in fig. 2, the first isolator 7 may be disposed between the active optical fiber 3 and the polarization modulation unit 4. The second end of the active optical fiber 3 is connected with the input end of the first isolator 7, and the output end of the first isolator 7 is connected with the first end of the polarization modulation unit 4.
Optionally, and still referring to fig. 1, in one possible embodiment of the present invention, the tunable fiber laser may further comprise a second isolator 8; the input end of the second isolator 8 is connected with the second output end f of the coupler 6; part of the beam is output from the output of the second isolator 8 via the input d and the second output f of the coupler 6.
As shown in fig. 1, a second isolator 8 may also be provided in the fiber laser, the second isolator 8 being provided outside the ring resonator and on the output path of the laser light. Specifically, the input end of the second isolator 8 may be connected to the second output end f of the coupler 6, and at this time, the output end of the second isolator 8 is the output end of the tunable fiber laser. The existence of the second isolator 8 can further improve the isolation of the output laser and avoid the returned return light from damaging the tunable fiber laser.
Alternatively, the second isolator may be a dual stage isolator. Through experimental tests, the second isolator is set to be a double-stage isolator, the isolation of the output laser can reach 60dB, and the isolation of the output laser is effectively improved.
Alternatively, in a possible embodiment, the polarization modulation unit may comprise a polarizer.
Specifically, in the embodiment of the present invention, the polarization modulation unit may be a polarizer, an input end of the polarizer is connected to the second end of the source optical fiber, and an output end of the polarizer is connected to the first end of the wavelength tunable filter. The polarizer is simple in arrangement mode, low in arrangement cost and capable of effectively improving polarization characteristics in the cavity.
For the type and specification of polarizer, the embodiment of the present invention is not limited, and those skilled in the art can set the polarizer according to actual requirements, and in a specific embodiment, the polarizer can be an online 1064nm PM/PM polarizer, but is not limited thereto.
Optionally, in the practical application process, a person skilled in the art may also set the polarization modulation unit as a polarization device such as a polarization beam splitter according to practical requirements.
Optionally, in a possible embodiment, the operating wavelength range of the wavelength tunable filter may be 1019nm to 1098nm.
Specifically, the embodiment of the present invention provides a tunable fiber laser, which has a wavelength tunable filter with a working wavelength ranging from 1019nm to 1098nm, and an adjustable range of the output laser wavelength of the tunable fiber laser reaches 79nm and is continuously adjustable within the wavelength range from 1019nm to 1098nm.
Optionally, active fiber is polarization maintaining gain fiber, to active fiber's specific doping element, doping concentration and fiber length etc, the embodiment of the utility model provides a do not do the restriction, technical personnel in the field can set up according to actual need. For example, in one possible embodiment, the active fiber may be a polarization-maintaining ytterbium-doped fiber, and the polarization-maintaining ytterbium-doped fiber is configured to effectively improve the amplification characteristic of the fiber and also improve the polarization extinction ratio of the output laser.
In one embodiment, the length of the polarization maintaining ytterbium-doped fiber may be 7m, the peak absorption coefficient of the polarization maintaining ytterbium-doped fiber at a wavelength of 976nm is 250dB/m, and the emission wavelength range is 1015 nm-1115 nm.
Optionally, the embodiment of the present invention does not limit the number and specific types of the pump sources, and the like, and those skilled in the art can set the number of the pump sources according to actual requirements, for example, in one possible embodiment, the number of the pump sources may be greater than or equal to 1. That is, one or more pump sources can be set according to the actual laser output power requirement, and in the embodiments of the present invention, one pump source is exemplarily shown, and the actual set number is not limited thereto.
In one embodiment, the pump source may be a single-mode output laser diode with a center wavelength of 976nm, and the maximum pumping power of the pump source may be 650mW.
Optionally, in the embodiment of the present invention, the optical fiber used in the tunable fiber laser is a polarization maintaining fiber, and the used device is a polarization maintaining device.
Specifically, in the tunable fiber laser provided in this embodiment, all the used fibers may adopt polarization maintaining fibers, and the polarization maintaining fibers can improve the polarization performance of the output single-frequency laser and improve the polarization extinction ratio. Furthermore, in order to realize stable single-frequency output, all the devices used by the whole optical fiber laser can be full polarization maintaining devices so as to avoid mode hopping caused by unstable polarization. Through experimental tests, the polarization extinction ratio of output laser of the tunable optical fiber laser composed of the full polarization maintaining device is larger than 30dB.
Optionally, the connection mode of each device in the tunable fiber laser can be set according to actual need by technical personnel in the art, for example adopt modes such as welding to connect, the embodiment of the utility model provides an it is this unreinforced and also not limited.
Illustratively, the measurements herein can be performed using a YOKOGAWA AQ6370D spectrometer with a maximum accuracy of 0.02nm. When the pumping optical power is 100mW, the tunable optical fiber laser starts to start oscillation. As the pumping power increases, the laser line tends to stabilize. When the pumping power was 300mW, stable spectral lines began to be obtained, and the 3dB linewidth of the spectral line was not affected by the increase in pumping light power. Because the gain of the ytterbium-doped fiber at different wavelengths is different, when the pumping is the same, the power and the signal-to-noise ratio at different wavelengths are different, the laser output with the same power at the full wavelength can be realized through a constant power output mode (APC), and the output power of 30mW can be satisfied at the full-wave band of 1019-1098 nm through the APC. Fig. 3 is a schematic diagram of an output spectrum of the tunable fiber laser provided by the embodiment of the present invention, and fig. 4 is a schematic diagram of a change in output power stability of the tunable fiber laser provided by the embodiment of the present invention. In the tunable fiber laser shown in fig. 3 and 4, the pumping source is a single-mode output laser diode with a central wavelength of 976nm, the number of the pumping sources is 1, the active fiber is a polarization-maintaining ytterbium-doped fiber, and the polarization modulation unit is a polarizer. The tunable fiber laser can output laser wavelength required in the wavelength range of 1019-1098 nm, fig. 3 exemplarily shows output spectrograms with central wavelengths of 1019.32nm, 1030.26nm, 1050.01nm, 1064.15nm, 1075.43nm and 1098.06nm, according to practical tests, the edge-mode suppression ratio and the signal-to-noise ratio of the output laser under the wavelengths shown in fig. 3 can be both larger than 60dB, the power stability of the output laser is good, and the power stability in 13h is smaller than 1%.
It should be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles applied thereto. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments illustrated herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (10)
1. A tunable fiber laser is characterized by comprising a pumping source, a wavelength division multiplexer, an active fiber, a polarization modulation unit, a wavelength tunable filter and a coupler;
the wavelength division multiplexer comprises a pumping input end, an output end and a common input end; the pumping input end is connected with the pumping source, the wavelength division multiplexer, the active optical fiber, the polarization modulation unit, the wavelength tunable filter and the coupler are connected to form a ring-shaped resonant cavity, and the output end and the common input end are connected into the ring-shaped resonant cavity;
the coupler comprises an input end, a first output end and a second output end; the input end and the first output end are connected into the annular resonant cavity, and the second output end is the output end of the tunable fiber laser.
2. The tunable fiber laser of claim 1, further comprising a first isolator located on a connection path of the wavelength division multiplexer and the coupler.
3. The tunable fiber laser of claim 2, wherein an input end of the first isolator is connected to the second end of the active fiber, and an output end of the first isolator is connected to the first end of the polarization modulation unit.
4. The tunable fiber laser of claim 1, further comprising a second isolator; the input end of the second isolator is connected with the second output end of the coupler; part of the light beam is output from the output end of the second isolator through the input end of the coupler and the second output end.
5. The tunable fiber laser of claim 4, wherein the second isolator is a dual stage isolator.
6. The tunable fiber laser of claim 1, wherein the polarization modulation unit includes a polarizer.
7. The tunable fiber laser of claim 1, wherein the wavelength tunable filter has an operating wavelength in the range of 1019nm to 1098nm.
8. The tunable fiber laser of claim 1, wherein the active fiber is a polarization-maintaining ytterbium-doped fiber.
9. The tunable fiber laser of claim 1, wherein the number of pump sources is greater than or equal to 1.
10. The tunable fiber laser of claim 1, wherein the fiber used in the tunable fiber laser is a polarization maintaining fiber and the device used is a polarization maintaining device.
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| CN202222174752.2U CN217903674U (en) | 2022-08-18 | 2022-08-18 | Tunable fiber laser |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117578173A (en) * | 2023-10-27 | 2024-02-20 | 北京大学长三角光电科学研究院 | Full polarization-maintaining O-shaped ultrashort pulse mode-locked fiber laser |
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- 2022-08-18 CN CN202222174752.2U patent/CN217903674U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117578173A (en) * | 2023-10-27 | 2024-02-20 | 北京大学长三角光电科学研究院 | Full polarization-maintaining O-shaped ultrashort pulse mode-locked fiber laser |
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