A 532nm naturally polarized light frequency doubler

Abstract

The invention discloses a 532nm naturally polarized light frequency doubler, comprising a beam splitting coupling output mirror, an LBO frequency doubling crystal I, an LBO frequency doubling crystal II, and a first reflecting mirror. A 1064nm laser is input and incident on the beam splitting coupling output mirror at 45 degrees, reflected and entered into orthogonally arranged LBO frequency doubling crystals II and I for a first frequency doubling, incident on the first reflecting mirror at 0 degrees for reflection, and after reflection by the first reflecting mirror, enters into orthogonally arranged LBO frequency doubling crystals I and II for a second frequency doubling. After the double frequency doubling, the 532nm laser is output through the beam splitting coupling output mirror as a 532nm frequency doubling laser. The invention utilizes orthogonally installed LBOs for direct frequency doubling of the natural polarization state, reduces polarization loss and adverse effects on beam quality compared to a polarization method, and can achieve a frequency doubling efficiency of up to 80% and good beam quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of frequency doublers for end-pumped solid lasers in natural polarization states, and in particular is a natural polarization frequency doubler which realizes high frequency doubling efficiency by utilizing dual LBOs in an orthogonal combination of polarization states. Background Art

[0002] End-pumped solid-state lasers can have both linearly polarized and naturally polarized output states, depending on the laser medium. The linearly polarized output state is a well-established frequency-doubling method, achieving a double-frequency efficiency of 80%. However, the naturally polarized output state typically utilizes a linearly polarized frequency-doubling method followed by polarization, typically with a frequency-doubling efficiency of approximately 50%-60%. Furthermore, the beam quality is affected by the polarization effect, making it difficult to achieve a satisfactory horizontal output state. Summary of the Invention

[0003] Therefore, in order to address the above-mentioned shortcomings, the present invention provides a 532nm naturally polarized light frequency doubler and its device; the 532nm naturally polarized light frequency doubler uses orthogonally mounted LBOs to directly double the natural polarization state, which reduces the polarization loss and the adverse effects on the beam quality compared to the polarization method, and can achieve a frequency doubling efficiency of up to 80% and obtain good beam quality.

[0004] In order to achieve the above-mentioned object, the present invention discloses a 532nm natural polarization light frequency doubler, comprising a beam splitting coupling output mirror, an LBO frequency doubling crystal I, an LBO frequency doubling crystal II, a first reflecting mirror, an input 1064nm optical path or an oscillator input optical path, and a 532nm frequency doubling light output optical path;

[0005] A 1064nm laser is input through the 1064nm input optical path or the oscillator input optical path, incident on the spectroscopic coupling output mirror at 45°, reflected into the orthogonal LBO frequency doubling crystal II and LBO frequency doubling crystal I for the first frequency doubling, incident on the first reflector at 0° for reflection, and after reflection by the first reflector, enters the orthogonal LBO frequency doubling crystal I and LBO frequency doubling crystal II again for the second frequency doubling. The 1064nm laser after two frequency doublings is reflected back to the oscillator through the spectroscopic coupling output mirror, and the 532nm laser is output through the spectroscopic coupling output mirror to become a 532nm frequency doubling laser through the 532nm frequency doubling light output optical path.

[0006] Furthermore, the beam splitting coupling output mirror is configured as a plane mirror and has both a 1064nm laser high reflection film and a 532nm laser anti-reflection film on its surface. It has a diameter of 12.7mm and a thickness of 1-6mm. The transmittance of the beam splitting coupling output mirror to 532nm laser is greater than 98%.

[0007] Furthermore, the surface of the first reflector is set to be a plane mirror and is coated with 1064nm and 532nm high reflective coatings at the same time, with a thickness of 6mm and a diameter of 12.7mm.

[0008] Furthermore, the LBO frequency doubling crystal I and LBO frequency doubling crystal II both use LBO crystals with crystal specifications of 3mm x 3mm x 10mm. The surfaces of the LBO frequency doubling crystal I and LBO frequency doubling crystal II are coated with a high-transmittance film for 1064nm laser and 532nm laser. The transmittance of the LBO frequency doubling crystal I and LBO frequency doubling crystal II to 1064nm laser and 532nm laser is 99%.

[0009] Furthermore, the LBO frequency doubling crystal I and the LBO frequency doubling crystal II each include a rectangular crystal frame and an LBO family crystal having a front polished surface and a rear polished surface parallel to each other, and the front polished surface and the rear polished surface of the LBO family crystal are both coated with a front antireflection film and a rear antireflection film;

[0010] The rectangular crystal frame is provided with a light-through hole passing through the rectangular crystal frame; a square card slot is provided in the rectangular crystal frame, and the square card slot is communicated with the light-through hole;

[0011] The LBO crystal is placed in the slot of the matrix crystal frame, and a 1064nm laser is incident on the front anti-reflection film on the front surface of the LBO crystal along the axis of the through hole of the matrix crystal frame. After phase matching is achieved inside the LBO crystal, the frequency-doubled light is emitted from the rear anti-reflection film on the rear surface of the LBO crystal along the axis of the through hole of the matrix crystal frame.

[0012] The phase matching angle θ of the LBO frequency doubling crystal I and the LBO frequency doubling crystal II is both set to 42.7°, and the LBO frequency doubling crystal I and the LBO frequency doubling crystal II are installed orthogonally at 90 degrees along the optical axis.

[0013] Furthermore, the front polished surface and the back polished surface of the LBO family crystal are both crystallographic c-planes of the LBO family crystal; the surface roughness Ra is 0.3 nanometers, and the surface accuracy is 1 / 8λ.

[0014] The present invention has the following advantages:

[0015] The 532nm naturally polarized light frequency doubler of the present invention utilizes orthogonally mounted LBOs to directly double the natural polarization state, which reduces polarization loss and adverse effects on beam quality compared to polarization methods, and can achieve a frequency doubling efficiency of up to 80% and good beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural schematic diagram of a 532nm naturally polarized light frequency doubler according to the present invention.

[0017] Description of the accompanying drawings: 1-first reflecting mirror; 2-LBO frequency doubling crystal I; 3-LBO frequency doubling crystal II; 4-splitting coupling output mirror; 5-input 1064 optical path; 6-532 frequency doubling light output optical path. DETAILED DESCRIPTION

[0018] The following will be combined with the Figure 1 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The present invention discloses a 532nm naturally polarized light frequency doubler, comprising a beam splitting coupling output mirror 4, an LBO frequency doubling crystal I2, an LBO frequency doubling crystal II3, a first reflector 1, an input 1064nm optical path or an oscillator input optical path 5, and a 532nm frequency doubling light output optical path 6;

[0020] A 1064nm laser is input through the 1064nm input optical path or the oscillator input optical path, incident on the spectroscopic coupling output mirror at 45°, reflected into the orthogonal LBO frequency doubling crystal II and LBO frequency doubling crystal I for the first frequency doubling, incident on the first reflector at 0° for reflection, and after reflection by the first reflector, enters the orthogonal LBO frequency doubling crystal I and LBO frequency doubling crystal II again for the second frequency doubling. The 1064nm laser after two frequency doublings is reflected back to the oscillator through the spectroscopic coupling output mirror, and the 532nm laser is output through the spectroscopic coupling output mirror to become a 532nm frequency doubling laser through the 532nm frequency doubling light output optical path.

[0021] This embodiment uses polarization state coupling to directly double the frequency of the natural polarization state using orthogonally installed LBOs, which can achieve a frequency doubling efficiency of up to 80% and good beam quality, while reducing polarization loss compared to the polarization method.

[0022] The following table shows the comparison data of the frequency doubling efficiency of this embodiment and the existing natural polarization light frequency doubler:

[0023] Compared with the polarization method, the polarization loss is reduced and the frequency doubling efficiency is increased by 20%.

[0024] In a preferred embodiment, the spectroscopic coupling output mirror 4 is configured as a plane mirror and its surface has both a 1064nm laser high-reflection film and a 532nm laser anti-reflection film, a diameter of 12.7mm, a thickness of 1-6mm, and a transmittance of the spectroscopic coupling output mirror 4 to 532nm laser greater than 98%.

[0025] In a preferred embodiment, the surface of the first reflector 1 is configured as a plane mirror and is coated with both 1064nm laser and 532nm laser high-reflection coatings, with a thickness of 6mm and a diameter of 12.7mm.

[0026] In a preferred embodiment, the LBO frequency doubling crystal I2 and the LBO frequency doubling crystal II3 are both LBO crystals with a crystal length of 3mm x 3mm x 10mm. The surfaces of the LBO frequency doubling crystal I and the LBO frequency doubling crystal II are coated with a high-transmittance film for 1064nm laser and 532nm laser. The transmittance of the LBO frequency doubling crystal I and the LBO frequency doubling crystal II to 1064nm laser and 532nm laser is 99%.

[0027] In a preferred embodiment, the LBO frequency doubling crystal I and the LBO frequency doubling crystal II each comprise a rectangular crystal frame and an LBO family crystal having a front polished surface and a rear polished surface parallel to each other, and the front polished surface and the rear polished surface of the LBO family crystal are both coated with a front antireflection film and a rear antireflection film;

[0028] The rectangular crystal frame is provided with a light-through hole passing through the rectangular crystal frame; a square card slot is provided in the rectangular crystal frame, and the square card slot is communicated with the light-through hole;

[0029] The LBO crystal is placed in the slot of the matrix crystal frame, and a 1064nm laser is incident on the front anti-reflection film on the front surface of the LBO crystal along the axis of the through hole of the matrix crystal frame. After phase matching is achieved inside the LBO crystal, the frequency-doubled light is emitted from the rear anti-reflection film on the rear surface of the LBO crystal along the axis of the through hole of the matrix crystal frame.

[0030] The phase matching angle θ of the LBO frequency doubling crystal I and the LBO frequency doubling crystal II is set to 42.7°. The LBO frequency doubling crystal I and the LBO frequency doubling crystal II are installed orthogonally at 90 degrees along the optical axis. In this embodiment, the phase matching angle θ of the LBO frequency doubling crystal I and the LBO frequency doubling crystal II is set to 42.7°.

[0031] In a preferred embodiment, the front polished surface and the back polished surface of the LBO crystal are both crystallographic c-planes of the LBO crystal; the surface roughness Ra is 0.3 nanometers, and the surface accuracy is 1 / 8λ.

[0032] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A 532nm naturally polarized light frequency doubler, characterized by: It includes a beam splitting coupling output mirror, an LBO frequency doubling crystal I, an LBO frequency doubling crystal II, a first reflecting mirror, an input 1064nm optical path or an oscillator input optical path, and a 532nm frequency doubling light output optical path; A 1064nm laser is input through the 1064nm input optical path or the oscillator input optical path, incident on the spectroscopic coupling output mirror at 45°, reflected into the orthogonal LBO frequency doubling crystal II and LBO frequency doubling crystal I for the first frequency doubling, incident on the first reflector at 0° for reflection, and after reflection by the first reflector, enters the orthogonal LBO frequency doubling crystal I and LBO frequency doubling crystal II again for the second frequency doubling. The 1064nm laser after two frequency doublings is reflected back to the oscillator through the spectroscopic coupling output mirror, and the 532nm laser is output through the spectroscopic coupling output mirror to become a 532nm frequency doubling laser through the 532nm frequency doubling light output optical path.

2. The 532nm naturally polarized light frequency doubler according to claim 1, characterized in that: The spectroscopic coupling output mirror is set as a plane mirror and its surface has both a 1064nm laser high reflection film and a 532nm laser anti-reflection film. It has a diameter of 12.7mm and a thickness of 1-6mm. The transmittance of the spectroscopic coupling output mirror to 532nm laser is greater than 98%.

3. The 532nm naturally polarized light frequency doubler according to claim 2, characterized in that: The surface of the first reflector is set as a plane mirror and is coated with 1064nm laser and 532nm laser high reflection coatings at the same time, with a thickness of 6mm and a diameter of 12.7mm.

4. A 532nm naturally polarized light frequency doubler according to any one of claims 1 to 3, characterized in that: The LBO frequency doubling crystal I and LBO frequency doubling crystal II are both LBO crystals with crystal specifications of 3mm x 3mm x 10mm. The surfaces of the LBO frequency doubling crystal I and LBO frequency doubling crystal II are coated with a high-transmittance film for 1064nm and 532nm. The transmittance of the LBO frequency doubling crystal I and LBO frequency doubling crystal II to 1064nm laser and 532nm laser is 99%.

5. The 532nm naturally polarized light frequency doubler according to any one of claims 1 to 3, characterized in that: The LBO frequency doubling crystal I and LBO frequency doubling crystal II each include a rectangular crystal frame and an LBO family crystal having a front polished surface and a rear polished surface parallel to each other, and the front polished surface and the rear polished surface of the LBO family crystal are both coated with a front antireflection film and a rear antireflection film; The rectangular crystal frame is provided with a light-through hole passing through the rectangular crystal frame; a square card slot is provided in the rectangular crystal frame, and the square card slot is communicated with the light-through hole; The LBO crystal is placed in the slot of the matrix crystal frame, and a 1064nm laser is incident on the front anti-reflection film on the front surface of the LBO crystal along the axis of the through hole of the matrix crystal frame. After phase matching is achieved inside the LBO crystal, the frequency-doubled light is emitted from the rear anti-reflection film on the rear surface of the LBO crystal along the axis of the through hole of the matrix crystal frame. The phase matching angle θ of the LBO frequency doubling crystal I and the LBO frequency doubling crystal II is both set to 42.7°, and the LBO frequency doubling crystal I and the LBO frequency doubling crystal II are installed orthogonally at 90 degrees along the optical axis.

6. The 532nm naturally polarized light frequency doubler according to claim 5, characterized in that: The front polished surface and the rear polished surface of the LBO crystal are both crystallographic c-planes of the LBO crystal; the surface roughness Ra is 0.3 nanometers, and the surface accuracy is 1 / 8λ.

Images