Intracavity frequency doubling laser

Abstract

The utility model relates to an intracavity frequency doubling laser, which comprises a pumping source, a light beam combiner and a bidirectional optical amplifier, and is characterized in that a first optical fiber collimator, a first Wollaston prism, a first roof prism, a first Faraday rotator, a polarizer, a frequency doubling crystal, a first reflection cavity mirror and a second reflection cavity mirror are sequentially arranged on one side of the bidirectional optical amplifier along an optical path; and a second optical fiber collimator, a second Wollaston prism, a second roof prism, a second Faraday rotator and a rectangular prism are sequentially arranged on the other side of the bidirectional optical amplifier along the optical path. According to the utility model, the two Faraday rotators and the polarizer are utilized, the oscillation of the linear polarization fundamental frequency laser is realized by using the non-polarization-maintaining gain fiber, the generation of the frequency doubling laser is realized through the frequency doubling crystal in the cavity, and finally the stable frequency doubling laser is output through the endoscope; the utility model has the characteristics of low manufacturing cost, high extinction ratio and high frequency doubling efficiency.

Description

TECHNICAL FIELD

[0001] The utility model relates to laser technology field especially a cavity frequency multiplication laser. BACKGROUND

[0002] Under the current vigorous development of optoelectronic technology, laser has been widely penetrated into material processing, medical cosmetology, communication, scientific research and other key fields. These different application scenarios have put forward extremely diverse and stringent requirements on the wavelength, power and beam quality of the laser output light. In order to meet the specific wavelength requirements, frequency multiplication technology has become a key means to obtain new wavelength laser, and cavity frequency multiplication is favored in practical application due to its high frequency multiplication efficiency. The traditional cavity frequency multiplication fiber laser often uses a polarization maintaining gain fiber as a gain medium. Although the polarization maintaining gain fiber has advantages in maintaining the polarization state of light, its complex manufacturing process and high material cost result in high manufacturing cost of the entire laser, which greatly limits its popularization and application in cost-sensitive large-scale application scenarios. SUMMARY

[0003] Therefore, the utility model aims at providing a cavity frequency multiplication laser with low manufacturing cost, high extinction ratio and high frequency multiplication efficiency.

[0004] The utility model adopts the following scheme: a cavity frequency multiplication laser, comprising a pump source, a light combiner and a bidirectional optical amplifier, a first optical fiber collimator, a first Wollaston prism, a first roof prism, a first Faraday rotator, a polarizer, a frequency doubling crystal, a first reflecting mirror and a second reflecting mirror are sequentially arranged along the light path on one side of the bidirectional optical amplifier; a second optical fiber collimator, a second Wollaston prism, a second roof prism, a second Faraday rotator and a right-angle prism are sequentially arranged along the light path on the other side of the bidirectional optical amplifier.

[0005] The first and second optical fiber collimators are used for collimating the fundamental frequency laser;

[0006] The first and second Wollaston prisms are used for dividing the fundamental frequency laser into S-polarized light and P-polarized light;

[0007] The first and second roof prisms are used for changing the fundamental frequency laser of S-polarized light and P-polarized light into parallel transmission;

[0008] The first and second Faraday rotators are used for rotating the polarization direction of the fundamental frequency laser by 45° in a non-reciprocal manner;

[0009] The frequency doubling crystal is used for changing the fundamental frequency laser with a frequency of ω into frequency doubling laser with a frequency of 2ω after passing through the frequency doubling crystal;

[0010] The first reflecting mirror is coated with a high-reflection film for the fundamental frequency laser and an antireflection film for the frequency doubling laser;

[0011] The second reflective mirror is coated with a high-reflection film for the fundamental laser;

[0012] The right-angle prism reflects the fundamental laser;

[0013] The pump light generated by the pump source is coupled to the bidirectional optical amplifier by the light combiner, and the bidirectional optical amplifier absorbs the pump light and generates, amplifies and outputs the fundamental laser.

[0014] The S-polarized fundamental laser output from one side of the bidirectional optical amplifier is collimated by the first optical fiber collimator and then enters the first Wollaston prism, and the S-polarized fundamental laser is emitted from above the first Wollaston prism and then is obliquely incident into the first roof prism to become horizontal transmission, and then enters the first Faraday rotator, and is rotated by 45° by the non-reciprocal rotation and then enters the polarizer, and the polarization direction is consistent with the transmission axis direction of the polarizer, and then the S-polarized fundamental laser is transmitted through the polarizer and enters the frequency-doubling crystal, and a part of the S-polarized fundamental laser is converted into the frequency-doubled laser and is output through the first reflective mirror; the S-polarized fundamental laser which is not converted into the frequency-doubled laser is reflected by the first reflective mirror and the second reflective mirror in turn, and then is rotated by 45° by the non-reciprocal rotation of the first Faraday rotator to become the P-polarized fundamental laser, and then enters the bidirectional optical amplifier through the first roof prism, the first Wollaston prism and the first collimator in turn, and then the P-polarized fundamental laser is amplified by the bidirectional optical amplifier and is output from the other side of the bidirectional optical amplifier, and then is collimated by the second optical fiber collimator and then enters the second Wollaston prism, and the P-polarized fundamental laser is emitted from below the second Wollaston prism and then is obliquely incident into the second roof prism to become horizontal transmission, and then enters the second Faraday rotator, and is rotated by 45° by the non-reciprocal rotation and then enters the right-angle prism, and is reflected by the right-angle prism to return to the second Faraday rotator, and is rotated by 45° by the non-reciprocal rotation to become the S-polarized fundamental laser, and then enters the bidirectional optical amplifier through the second roof prism, the second Wollaston prism and the second collimator in turn.

[0015] Further, the pump source, the light combiner and the bidirectional optical amplifier form forward pumping or backward pumping or bidirectional pumping.

[0016] Further, the polarizer is a polarization beam splitter prism or a Glan prism or a polarizer.

[0017] Further, the frequency-doubling crystal includes a KTP crystal, an LBO crystal, a BBO crystal, a PPLN or a KDP.

[0018] Further, the bidirectional optical amplifier includes a non-polarization-maintaining gain optical fiber provided with gain ions.

[0019] Compared with the prior art, the utility model has the following beneficial effects: the utility model discloses two faraday rotators and polarizer, realize the oscillation of linear polarization base frequency laser with non polarization maintaining gain optical fiber, realize the generation of frequency multiplication laser through the frequency multiplication crystal in the cavity, and finally output stable frequency multiplication laser through the cavity mirror.

[0020] In order to make the purpose, technical scheme and advantage of the utility model more clearly, the following will be through concrete embodiment and relevant drawing, make further detailed description to the utility model. DRAWINGS

[0021] Figure 1 It is the structure schematic diagram of a cavity frequency multiplication laser of backward pumping of the application;

[0022] Figure 2 It is the P polarization base frequency laser transmission schematic diagram of a cavity frequency multiplication laser of backward pumping of the application;

[0023] Mark explanation in drawing: 1, right angle prism;2, second faraday rotator;3, second ridge prism;4, second wrothston prism;5, second optical fiber collimator;6, two-way optical amplifier;7, light beam combiner;8, pump source;9, first optical fiber collimator;10, first wrothston prism;11, first ridge prism;12, first faraday rotator;13, polarizer;14, frequency multiplication crystal;15, first reflection cavity mirror;16, second reflection cavity mirror. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0025] It should be noted that the terms used herein are only for the purpose of describing the specific embodiments, and are not intended to limit the exemplary embodiments according to the application. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0026] As Figures 1-2As shown, an intracavity frequency-doubled laser comprises a pump source 8, a light combiner 7 and a bidirectional optical amplifier 6, on one side of the bidirectional optical amplifier 6 along the light path are sequentially arranged a first optical fiber collimator 9, a first Wolaston prism 10, a first roof prism 11, a first Faraday rotator 12, a polarizer 13, a frequency-doubling crystal 14, a first reflecting mirror 15 and a second reflecting mirror 16; on the other side of the bidirectional optical amplifier along the light path are sequentially arranged a second optical fiber collimator 5, a second Wolaston prism 4, a second roof prism 3, a second Faraday rotator 2 and a right-angle prism 1.

[0027] The first and second optical fiber collimators are used for collimating the fundamental frequency laser;

[0028] The first and second Wolaston prisms are used for dividing the fundamental frequency laser into S-polarized light and P-polarized light;

[0029] The first and second roof prisms are used for changing the S-polarized light and P-polarized light of the fundamental frequency laser into parallel transmission;

[0030] The first and second Faraday rotators are used for rotating the polarization direction of the fundamental frequency laser by 45° in a non-reciprocal manner;

[0031] The frequency-doubling crystal is used for changing the fundamental frequency laser with a frequency of ω into frequency-doubled laser with a frequency of 2ω;

[0032] The first reflecting mirror is coated with high-reflection film for the fundamental frequency laser and anti-reflection film for the frequency-doubled laser;

[0033] The second reflecting mirror is coated with high-reflection film for the fundamental frequency laser;

[0034] The right-angle prism reflects the fundamental frequency laser;

[0035] The pump light generated by the pump source is coupled to the bidirectional optical amplifier by the light combiner, the bidirectional optical amplifier absorbs the pump light and generates, amplifies and outputs the fundamental frequency laser.

[0036] The pump source 8, the light combiner 7 and the bidirectional optical amplifier 6 constitute backward pumping (reverse pumping). The bidirectional optical amplifier 6 adopts a ytterbium-doped optical fiber. The pump source 8 emits pump light, the pump light is incident to the light combiner 7, the light combiner 7 couples the pump light to the bidirectional optical amplifier 6, the ytterbium-doped optical fiber absorbs the pump light to form population inversion, which is used for generating and amplifying the fundamental frequency laser, the fundamental frequency laser can be decomposed into P-polarized fundamental frequency laser and S-polarized fundamental frequency laser. The frequency-doubling crystal is selected as PPLN, and the polarizer is selected as a polarization beam splitter prism.

[0037] As shown in FIG. 1, the frequency-doubled laser is a backward pumping type, which comprises a pump source 8, a light combiner 7 and a bidirectional optical amplifier 6. Figure 1As shown, the S-polarized fundamental frequency laser output from the right side of the bidirectional optical amplifier is collimated by the first fiber collimator 9 and then enters the first Wollaston prism 10. The S-polarized fundamental frequency laser exits from above it, then enters the first roof prism 11 at an oblique angle and becomes horizontally transmitted. It then enters the first Faraday rotator 12, is non-reciprocally rotated counterclockwise by 45°, and enters the polarizer 13. The polarization direction of the fundamental frequency light is consistent with the transmission axis of the polarizer 13. After passing through the polarizer 13, it enters the frequency doubling crystal. A portion of the polarized fundamental frequency laser is converted into a frequency-doubled laser and output through the first reflecting cavity mirror 15. The polarized fundamental frequency laser that is not converted into a frequency-doubled laser is reflected sequentially by the first reflecting cavity mirror 15 and the second reflecting cavity mirror 16, and then enters the first Faraday rotator 12 again. After being non-reciprocally rotated counterclockwise by 45° again, it becomes a P-polarized fundamental frequency laser, and then sequentially enters the first Faraday rotator 12. After passing through the first roof prism 11, the first Wollaston prism 10, and the first collimator 9, the P-polarized fundamental frequency laser enters the bidirectional optical amplifier 6. After being amplified by the bidirectional optical amplifier 6, it is output from the left side of the bidirectional optical amplifier 6. After being collimated by the second fiber collimator 5, it enters the second Wollaston prism 4, from below. Then, it enters the second roof prism 3 at an oblique angle and becomes horizontally transmitted. It then enters the second Faraday rotator 2, is rotated 45° counterclockwise by non-reciprocity, and enters the right-angle prism 1. After being reflected by the right-angle prism 1, it returns to the second Faraday rotator 2. After being rotated 45° counterclockwise by non-reciprocity again, it becomes the S-polarized fundamental frequency laser. It then passes through the second roof prism 3, the second Wollaston prism 4, and the second collimator 5 in sequence before entering the bidirectional optical amplifier 6. After being amplified by the bidirectional optical amplifier 6, the S-polarized fundamental frequency laser is output from the right side of the bidirectional optical amplifier.

[0038] like Figure 2 As shown, the P-polarized fundamental frequency laser output from the right side of the bidirectional optical amplifier is collimated by the first fiber collimator 9 and then enters the first Wollaston prism 10. The P-polarized fundamental frequency laser exits from below it, then enters the first roof prism 11 at an oblique angle and becomes horizontally transmitted. It then enters the first Faraday rotator 12, is rotated 45 degrees counterclockwise by non-reciprocity, and then passes through the second reflector 16, the first reflector 15 and the frequency doubling crystal 14 in sequence before entering the polarizer 13. Since the polarization direction of the rotated P-polarized fundamental frequency laser is exactly 90 degrees from the transmission direction of the polarizer 13, it is reflected by the polarizer 13 and cannot continue to propagate in the laser cavity, thus not forming oscillations.

[0039] If the above-mentioned utility model discloses any one of the technical solutions and does not declare otherwise, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range, and any person skilled in the art should understand that the preferred numerical range is only one of the many implementable values with more obvious technical effects or representative values.

[0040] If the above-mentioned utility model discloses or involves mutually fixed connecting parts or structural parts, then, except for another declaration, the fixed connection can be understood as: detachable fixed connection (for example, using bolt or screw connection), and can also be understood as: non-detachable fixed connection (for example, riveting, welding), of course, the mutually fixed connection can also be replaced by an integral structure (for example, integrally formed by using casting process) (except for obviously unable to use integral forming process).

[0041] In addition, the terms used to represent the positional relationship or shape in any one of the above-mentioned utility model disclosed technical solutions include the state or shape similar, similar or close to the meaning thereof, except for another declaration.

[0042] Any component provided by the utility model can be assembled from a plurality of individual components, or can be an individual component manufactured by an integral forming process.

[0043] The above is only a preferred embodiment of the utility model, and does not limit the utility model in other forms, and any person skilled in the art can change or modify the above disclosed technical content to equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification of the above-mentioned embodiments without departing from the technical solution content of the utility model, according to the technical essence of the utility model, still belongs to the protection scope of the technical solution of the utility model.

Claims

1. An intracavity frequency-doubled laser, characterized by: The application relates to a pump source, a light combiner and a bidirectional light amplifier, wherein a first optical fiber collimator, a first Wollaston prism, a first roof prism, a first Faraday rotator, a polarizer, a frequency doubling crystal, a first reflecting mirror and a second reflecting mirror are sequentially arranged along an optical path on one side of the bidirectional light amplifier; a second optical fiber collimator, a second Wollaston prism, a second roof prism, a second Faraday rotator and a right-angle prism are sequentially arranged along the optical path on the other side of the bidirectional light amplifier. The first and second optical fiber collimators are used for collimating the fundamental frequency laser; The first and second Wollaston prisms are used for dividing the fundamental frequency laser into S polarized light and P polarized light; The first and second roof prisms are used for changing the S polarized light and the P polarized light into parallel transmission; The first and second Faraday rotators are used for rotating the polarization direction of the fundamental frequency laser by 45 degrees in a non-reciprocal manner; The frequency doubling crystal is used for changing the fundamental frequency laser with a frequency of omega into frequency doubling laser with a frequency of 2omega; The first reflecting mirror is coated with high-reflection film of the fundamental frequency laser and antireflection film of the frequency doubling laser; The second reflecting mirror is coated with high-reflection film of the fundamental frequency laser; The right-angle prism reflects the fundamental frequency laser; The pump light generated by the pump source is coupled to the bidirectional light amplifier by the light combiner, the bidirectional light amplifier absorbs the pump light and generates, amplifies and outputs the fundamental frequency laser.

2. The intracavity frequency-doubled laser of claim 1, wherein: The pump source, the light combiner and the bidirectional light amplifier form forward pumping, backward pumping or bidirectional pumping.

3. The intracavity frequency-doubled laser of claim 1, wherein: The polarizer is a polarization beam splitter prism, a Glan prism or a polaroid.

4. The intracavity frequency-doubled laser of claim 1, wherein: The frequency doubling crystal includes KTP crystal, LBO crystal, BBO crystal, PPLN and KDP.

5. The intracavity frequency-doubled laser of claim 1, wherein: The bidirectional light amplifier includes a non-polarization maintaining gain optical fiber provided with gain ions.

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