External cavity type annular human eye safety optical parametric oscillator

Abstract

The invention discloses an external cavity type annular human eye safety optical parametric oscillator, and relates to the technical field of laser. The oscillator sequentially comprises a first cavity mirror, a first nonlinear crystal, a second cavity mirror, a second nonlinear crystal, a third cavity mirror and a third nonlinear crystal, the pump light is converted into human eye safety laser through optical parameters to be output, and the remaining pump light is transmitted and output from the first cavity mirror. An external cavity type OPO technology and a three-mirror annular cavity structure are adopted, a plurality of nonlinear crystals are placed in an annular cavity to fully absorb pump light, high conversion efficiency can be obtained under low pump power density, the problem that optical devices are damaged due to the fact that the power density in an internal cavity type OPO cavity is too high is solved, pump light pumping is an annular route, and the pumping efficiency is greatly improved. And the residual pump light cannot return to the pump light resonant cavity, so that the reliability of the laser is improved.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to an external cavity type annular human eye-safe optical parametric oscillator. Background Art

[0002] Eye-safe lasers are widely used in military fields such as laser ranging, laser imaging, and lidar. Currently, the most commonly used method is to use 1064nm pulsed laser to pump KTP optical parametric oscillator to achieve 1570nm eye-safe laser output.

[0003] Eye-safe optical parametric oscillators are divided into internal cavity and external cavity optical parametric oscillator (OPO) structures. In the internal cavity OPO signal light resonant cavity is placed inside the pump light resonant cavity. The OPO has a short settling time and high parametric conversion efficiency, but it also has the problem of too high optical power density in the cavity, which can easily cause damage to the film layer of the optical element. The pump light and signal light are highly dependent on the resonant cavity, and stable parametric conversion requires the device to have high mechanical stability. In the external cavity OPO optical parametric resonant cavity, the two are independent of each other, and the commonly used is a straight cavity structure.

[0004] However, the external cavity straight cavity OPO has many problems, such as high OPO threshold, low signal light conversion efficiency, large dependence on pump light power density, and the remaining pump light is returned and injected into the pump light resonant cavity, causing unstable pump light operation. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned inner cavity OPO and outer cavity straight cavity OPO, the present invention provides an outer cavity ring cavity OPO structure, and the so-called ring cavity refers to a resonant cavity that can provide a polygonal oscillation loop. Multiple nonlinear crystals are placed in the outer cavity ring cavity to fully absorb the pump light, and high conversion efficiency can be obtained at a lower pump power density, solving the problem of damage to optical devices caused by excessive power density in the inner cavity OPO cavity. The pump light is pumped in a ring route, and the remaining pump light will not return to the pump light resonant cavity, thereby improving the reliability of the laser.

[0006] The present invention provides an external cavity type annular human eye safe optical parametric oscillator, comprising: a first cavity mirror, a first nonlinear crystal, a second cavity mirror, a second nonlinear crystal, a third cavity mirror and a third nonlinear crystal;

[0007] The first cavity mirror, the first nonlinear crystal, the second cavity mirror, the second nonlinear crystal, the third cavity mirror and the third nonlinear crystal arranged in sequence constitute an external cavity type annular cavity;

[0008] The pump light is input through the first cavity mirror, converted into eye-safe laser through the optical parameter of the external cavity ring cavity, and output from the second cavity mirror, and the remaining pump light is transmitted and output from the first cavity mirror.

[0009] In some examples, the pump light is a 1064 nm linearly polarized pulsed laser.

[0010] In some examples, the polarization direction of the pump light is consistent with the Y-axis direction of the first nonlinear crystal, the second nonlinear crystal, and the third nonlinear crystal.

[0011] In some examples, the first laparoscope is placed at a first preset angle with respect to the horizontal direction, the second laparoscope is placed at a second preset angle with respect to the horizontal direction, and the third laparoscope is placed in the horizontal direction.

[0012] In some examples, the first cavity mirror is placed at 30° with respect to the horizontal direction, and the light-transmitting surface of the first cavity mirror is coated with a 1064nm anti-reflection film and a 1570nm high-reflection film.

[0013] In some examples, the first nonlinear crystal, the second nonlinear crystal, and the third nonlinear crystal are all KTP crystals.

[0014] In some examples, the first nonlinear crystal, the second nonlinear crystal and the third nonlinear crystal are all 8mm*8mm*20mm in size, and are coated with 1064nm anti-reflection film and 1570nm anti-reflection film on both ends.

[0015] In some examples, the second cavity mirror is placed at 150° to the horizontal direction, and the light-transmitting surface of the second cavity mirror is coated with a 1064nm high-reflection film and a 1570nm anti-reflection film, and the transmittance is 50%.

[0016] In some examples, the third cavity mirror is a fully reflective mirror.

[0017] In some examples, the third cavity mirror is placed in a horizontal direction, and the light-transmitting surface of the third cavity mirror is coated with a 1064nm high-reflection film and a 1570nm high-reflection film.

[0018] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0019] In view of the problems existing in the current intracavity OPO and external cavity straight cavity OPO, the external cavity OPO technology and three-mirror ring cavity structure are adopted. Multiple nonlinear crystals are placed in the ring cavity to fully absorb the pump light, which can obtain high conversion efficiency at a lower pump power density and solve the problem of optical device damage caused by excessive power density in the intracavity OPO. The pump light is pumped in a ring route, and the remaining pump light will not return to the pump light resonant cavity, thereby improving the reliability of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of the structure of an external cavity ring-shaped eye-safe optical parametric oscillator provided in an embodiment of the present invention;

[0022] In the figure: 1. first cavity mirror; 2. first nonlinear crystal; 3. second cavity mirror; 4. second nonlinear crystal; 5. third cavity mirror; 6. third nonlinear crystal; 7. pump light; 8. output light. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present invention provides an external cavity ring-shaped human eye-safe optical parametric oscillator, such as Figure 1 As shown, it comprises: a first cavity mirror (1), a first nonlinear crystal (2), a second cavity mirror (3), a second nonlinear crystal (4), a third cavity mirror (5) and a third nonlinear crystal (6); pump light (7) is converted into eye-safe laser light (8) for output through optical parameter conversion, and the remaining pump light is transmitted and output from the first cavity mirror (1);

[0025] The first cavity mirror (1), the first nonlinear crystal (2), the second cavity mirror (3), the second nonlinear crystal (4), the third cavity mirror (5) and the third nonlinear crystal (6) constitute an external cavity type ring-shaped human eye-safe optical parametric oscillator.

[0026] In some examples, the pump light is a 1064nm linearly polarized pulse laser, and the polarization direction is consistent with the Y-axis direction of the first nonlinear crystal (2), the second nonlinear crystal (4) and the third nonlinear crystal (6).

[0027] In some examples, the first cavity mirror (1) is placed at an angle of 30° to the horizontal direction, and the light-transmitting surface of the first cavity mirror (1) is coated with a 1064nm anti-reflection film and a 1570nm high-reflection film.

[0028] In some examples, the nonlinear crystal is a KTP crystal, which generates eye-safe laser through nonlinear frequency conversion. The first nonlinear crystal (2), the second nonlinear crystal (4) and the third nonlinear crystal (6) are all 8mm*8mm*20mm in size, and are coated with 1064nm anti-reflection film and 1570nm anti-reflection film on both ends.

[0029] In some examples, the second cavity mirror (3) is placed at 150° to the horizontal direction, and the light-transmitting surface of the second cavity mirror (3) is coated with a 1064nm high-reflection film and a 1570nm anti-reflection film, with a transmittance of 50%.

[0030] In some examples, the third cavity mirror (5) is placed in a horizontal direction, and the light-transmitting surface of the third cavity mirror (5) is coated with a 1064nm high-reflection film and a 1570nm high-reflection film.

[0031] An external cavity annular eye-safe optical parametric oscillator of the present embodiment adopts external cavity OPO technology and a three-mirror annular cavity structure. Multiple nonlinear crystals are placed in the annular cavity to fully absorb pump light, so that high conversion efficiency can be obtained at a lower pump power density, solving the problem of damage to optical devices caused by excessive power density in the internal cavity OPO cavity. The pump light is pumped in a circular route, and the remaining pump light will not return to the pump light resonant cavity, thereby improving the reliability of the laser.

[0032] The above is a detailed introduction to an external cavity ring-shaped human eye-safe optical parametric oscillator provided in an embodiment of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. An external cavity ring eye-safe optical parametric oscillator, characterized in that: include: A first cavity mirror, a first nonlinear crystal, a second cavity mirror, a second nonlinear crystal, a third cavity mirror and a third nonlinear crystal; The first cavity mirror, the first nonlinear crystal, the second cavity mirror, the second nonlinear crystal, the third cavity mirror and the third nonlinear crystal arranged in sequence constitute an external cavity type annular cavity; The pump light is input through the first cavity mirror, converted into eye-safe laser through the optical parameter of the external cavity ring cavity, and output from the second cavity mirror, and the remaining pump light is transmitted and output from the first cavity mirror.

2. The external cavity ring eye-safe optical parametric oscillator according to claim 1, characterized in that: The pump light is 1064nm linearly polarized pulse laser.

3. The external cavity ring eye-safe optical parametric oscillator according to claim 2, characterized in that: The polarization direction of the pump light is consistent with the Y-axis direction of the first nonlinear crystal, the second nonlinear crystal and the third nonlinear crystal.

4. The external cavity ring eye-safe optical parametric oscillator according to claim 3, characterized in that: The first laparoscope is placed at a first preset angle with respect to the horizontal direction, the second laparoscope is placed at a second preset angle with respect to the horizontal direction, and the third laparoscope is placed in the horizontal direction.

5. The external cavity ring eye-safe optical parametric oscillator according to claim 4, characterized in that: The first cavity mirror is placed at 30° to the horizontal direction, and the light-transmitting surface of the first cavity mirror is coated with a 1064nm anti-reflection film and a 1570nm high-reflection film.

6. The external cavity ring eye-safe optical parametric oscillator according to claim 5, characterized in that: The first nonlinear crystal, the second nonlinear crystal and the third nonlinear crystal are all KTP crystals.

7. The external cavity ring eye-safe optical parametric oscillator according to claim 6, characterized in that: The sizes of the first nonlinear crystal, the second nonlinear crystal and the third nonlinear crystal are all 8mm*8mm*20mm, and the double end faces are coated with 1064nm anti-reflection film and 1570nm anti-reflection film.

8. The external cavity ring eye-safe optical parametric oscillator according to claim 7, characterized in that: The second cavity mirror is placed at 150 degrees to the horizontal direction, and the light-transmitting surface of the second cavity mirror is coated with a 1064nm high-reflection film and a 1570nm anti-reflection film, and the transmittance is 50%.

9. The external cavity ring eye-safe optical parametric oscillator according to claim 8, characterized in that: The third cavity mirror is a total reflection mirror.

10. The external cavity ring eye-safe optical parametric oscillator according to claim 9, characterized in that: The third cavity mirror is placed in a horizontal direction, and the light-transmitting surface of the third cavity mirror is coated with a 1064nm high-reflection film and a 1570nm high-reflection film.

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