A device and optical equipment for generating a supercontinuum light source across octaves

Abstract

The invention relates to the technical field of supercontinuum generation, and specifically provides a device for generating a supercontinuum light source across octaves and an optical device. The device comprises a focusing lens and at least one group of solid structures. Ultrashort pulse fundamental frequency light is incident on the solid structure after being tightly focused. The fundamental frequency light after the incident first undergoes self-phase modulation and cross-phase modulation in a first nonlinear action medium to generate a first supercontinuum with a certain spectrum width at the central wavelength of the fundamental frequency light. The first supercontinuum is transmitted through a frequency doubling crystal except for the central wavelength. The spectrum at the central wavelength passes through the frequency doubling crystal to realize the frequency doubling light of an ultrashort pulse. The frequency doubling light with high peak intensity undergoes self-phase modulation in a second nonlinear action medium to generate a second supercontinuum at the central wavelength of the frequency doubling light. The two supercontinuums constitute a supercontinuum light source across octaves, thereby realizing the generation of a supercontinuum with high pulse energy, further broadening the range of supercontinuum generation, and realizing the generation of supercontinuum with multiple spectrum segments.

Description

Technical Field

[0001] The invention relates to the technical field of supercontinuum generation, and specifically provides a device and an optical device for generating a supercontinuum light source across an octave. Background Art

[0002] Supercontinuum light sources have the characteristics of high brightness, wide spectrum, and simple generation device. They are widely used in optical communications, optical coherence tomography, material analysis, hyperspectral microscopy and other fields.

[0003] At present, supercontinuum light sources are generally generated using highly nonlinear optical fibers such as photonic crystal fibers. However, highly nonlinear optical fibers are limited by damage threshold factors. It is difficult to achieve a supercontinuum light source with high pulse energy using highly nonlinear optical fibers. There is an urgent need to provide a supercontinuum light source that can achieve cross-octave supercontinuum light. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a device and optical equipment for generating supercontinuum light source across octaves, which adopts a solid structure of cross-stacked distribution of frequency doubling crystals and multi-layer nonlinear action media for supercontinuum generation, solves the problem of low pulse energy in supercontinuum light source generation based on highly nonlinear optical fibers such as photonic crystal fibers, and realizes the generation of supercontinuum with high pulse energy through multiple self-phase modulation and frequency doubling and other nonlinear processes. In addition, the self-phase modulation process is first performed on the fundamental frequency light before the frequency doubling process, which further broadens the range of supercontinuum generation and realizes the generation of supercontinuum with multiple spectral bands.

[0005] In a first aspect, an embodiment of the present invention provides a device for generating a cross-octave supercontinuum light source, comprising a focusing lens and at least one group of solid structures, wherein the solid structure comprises a first nonlinear action medium, a frequency doubling crystal, and a second nonlinear action medium;

[0006] An ultrashort pulse fundamental frequency light is incident on the solid structure through the focusing lens, the ultrashort pulse fundamental frequency light undergoes self-phase modulation in the first nonlinear action medium to generate a first supercontinuum spectrum with a first predetermined spectral width at the central wavelength of the ultrashort pulse fundamental frequency light, the first supercontinuum spectrum and the remaining ultrashort pulse fundamental frequency light are incident on the frequency doubling crystal, and frequency doubling light with the narrow spectral bandwidth of the ultrashort pulse is generated in the frequency doubling crystal, the ultrashort pulse fundamental frequency light and the first supercontinuum spectrum are incident on the second nonlinear action medium together, the ultrashort pulse fundamental frequency light undergoes self-phase modulation in the second nonlinear action medium to generate a second supercontinuum spectrum with a second predetermined spectral width at the central wavelength of the frequency doubling light, the first supercontinuum spectrum and the second supercontinuum spectrum are used to form a cross-octave supercontinuum spectrum light source, wherein the frequency doubling crystal has a high frequency doubling conversion efficiency for the central wavelength of the ultrashort pulse fundamental frequency light.

[0007] As a preferred solution, the focal position of the ultrashort pulse fundamental frequency light after focusing is located at the rear side of the light emitting surface of the second nonlinear action medium.

[0008] As a preferred solution, the front light-transmitting surface of the first nonlinear medium is coated with a fundamental frequency light anti-reflection film, and the rear light-transmitting surface of the first nonlinear medium is coated with a broadband anti-reflection film centered on the fundamental frequency light.

[0009] As a preferred solution, the front light-transmitting surface of the frequency doubling crystal is coated with a broadband anti-reflection film centered on the fundamental frequency light, and the rear light-transmitting surface of the frequency doubling crystal is coated with an anti-reflection film of the frequency doubling light band.

[0010] As a preferred solution, the front light-transmitting surface of the second nonlinear medium is coated with a film system consistent with the rear light-transmitting surface of the frequency doubling crystal.

[0011] As a preferred solution, the first nonlinear action medium and the second nonlinear action medium are the same medium or different media.

[0012] As a preferred solution, the light transmission wavelength of the second nonlinear action medium includes the supercontinuum band at the central wavelength of the ultrashort pulse fundamental frequency light.

[0013] In a second aspect, an embodiment of the present invention provides an optical device having the above-mentioned cross-octave supercontinuum light source generating device.

[0014] The present invention provides a device and optical equipment for generating a supercontinuum light source across octaves, comprising a focusing lens and at least one group of solid structures, mainly a sandwich structure of a first nonlinear medium-frequency doubling crystal-second nonlinear medium, wherein ultrashort pulse fundamental frequency light is incident on the solid structure after being tightly focused, and the fundamental frequency light after incident first undergoes self-phase modulation and cross-phase modulation in the first nonlinear medium to generate a first supercontinuum with a certain spectrum width at the central wavelength of the fundamental frequency light. The first supercontinuum transmits through the frequency doubling crystal except for the central wavelength, and the spectrum at the central wavelength passes through the frequency doubling crystal to realize the frequency doubling light of the ultrashort pulse, and the frequency doubling light with high peak intensity undergoes self-phase modulation in the second nonlinear medium to generate a supercontinuum light source at the central wavelength of the frequency doubling light, which together with the supercontinuum at the central wavelength of the fundamental frequency light constitutes the generation of a supercontinuum across octaves, and can realize the splicing of two sections of supercontinuum to form a multi-octave supercontinuum light source of ultraviolet-visible light, and realize the generation of a supercontinuum with high pulse energy through multiple nonlinear processes such as self-phase modulation and frequency doubling. In addition, the fundamental frequency light is subjected to a self-phase modulation process before the frequency doubling process to further broaden the range of supercontinuum generation and achieve multi-band supercontinuum generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the optical path of a device for generating a cross-octave supercontinuum light source provided according to an embodiment of the present invention.

[0016] Reference numerals include:

[0017] 1. Ultrashort pulse fundamental frequency light, 2. Focusing lens, 3. First nonlinear action medium, 4. Frequency doubling crystal, 5. Second nonlinear action medium, 6. Cross-octave supercontinuum spectrum light source. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0020] Combination Figure 1 As shown, in an embodiment of the present invention, a device for generating a supercontinuum light source across an octave is provided, comprising a focusing lens 2 and at least one group of solid structures, wherein the solid structure comprises a first nonlinear action medium 3, a frequency doubling crystal 4 and a second nonlinear action medium 5, wherein the focusing lens 2 is used to converge an ultrashort pulse fundamental frequency light 1, the first nonlinear action medium 3 is used to cause the ultrashort pulse fundamental frequency light 1 to undergo a self-phase modulation effect in the first nonlinear action medium 3, thereby generating a first supercontinuum at the central wavelength of the fundamental frequency light, the frequency doubling crystal 4 is used to achieve a frequency doubling effect on the fundamental frequency light in the supercontinuum, thereby generating an ultrashort pulse frequency doubling light, and the second nonlinear action medium 5 is used to cause the ultrashort pulse frequency doubling light to undergo a self-phase modulation effect in the second nonlinear action medium 5, thereby generating a second supercontinuum at the central wavelength of the frequency doubling light.

[0021] An ultrashort pulse fundamental frequency light 1 is incident on the solid structure through the focusing lens 2, and the ultrashort pulse fundamental frequency light 1 undergoes self-phase modulation in the first nonlinear action medium 3 to generate a first supercontinuum spectrum with a first predetermined spectral width at the central wavelength of the ultrashort pulse fundamental frequency light 1. The first supercontinuum spectrum and the remaining ultrashort pulse fundamental frequency light 1 are incident on the frequency doubling crystal 4, and the frequency doubling light with the narrow spectral bandwidth of the ultrashort pulse is generated in the frequency doubling crystal 4. The ultrashort pulse fundamental frequency light 1 and the first supercontinuum spectrum are incident on the second nonlinear action medium 5 together, and the ultrashort pulse fundamental frequency light 1 undergoes self-phase modulation in the second nonlinear action medium 5 to generate a second supercontinuum spectrum with a second predetermined spectral width at the central wavelength of the frequency doubling light. The first supercontinuum spectrum and the second supercontinuum spectrum constitute a cross-octave supercontinuum spectrum light source 6, wherein the frequency doubling crystal 4 has a high frequency doubling conversion efficiency for the central wavelength of the ultrashort pulse fundamental frequency light 1.

[0022] It should be noted that the solid structure mentioned in the present invention is mainly a sandwich structure of the first nonlinear medium 3-frequency doubling crystal 4-second nonlinear medium 5, and can be expanded to a multi-layer cross-stacked structure of nonlinear medium and frequency doubling crystal 4.

[0023] In some embodiments, based on this solid structure, in some cases, especially when the light band after frequency doubling is in the ultraviolet region, when the shortest wavelength of the supercontinuum at the center wavelength of the ultrashort pulse fundamental light 1 is consistent with or partially overlaps with the longest wavelength of the supercontinuum at the center wavelength of the frequency doubling light, the band splicing of the two supercontinuum spectra can be achieved to form a multi-octave supercontinuum light source of ultraviolet-visible light.

[0024] It should be noted that, since the power density at the center of the spot of the ultrashort pulse fundamental frequency light 1 is greatly weakened after passing through the frequency doubling crystal 4, the supercontinuum spectrum at the center wavelength of the fundamental frequency light realized by the ultrashort pulse fundamental frequency light 1 in the nonlinear action medium is relatively weak.

[0025] The focal position of the ultrashort pulse fundamental frequency light 1 after focusing is generally located behind the light exiting surface of the second nonlinear medium 5, and the focal spot diameter and the phase position between the solid structure and the focal point can be adjusted according to actual conditions to change the power density of the fundamental frequency light at the nonlinear medium and the frequency doubling crystal 4. At the same time, the medium thickness of the first nonlinear medium 3, the frequency doubling crystal 4 and the second nonlinear medium 5 and the spacing between them can also be changed according to actual needs. Usually, the thickness of the nonlinear medium and the frequency doubling crystal 4 is in the order of tens to hundreds of μm, which basically does not broaden the pulse width of the fundamental frequency light and the frequency doubling light.

[0026] It should be noted that, for a clearer description, when it comes to the front and rear light-transmitting surfaces of the first nonlinear action medium 3, the frequency doubling crystal 4 and the second nonlinear action medium 5, the surface along the light propagation direction and facing the ultrashort pulse fundamental frequency light 1 is unified as the front light-transmitting surface, and the other surface is the rear light-transmitting surface, which will not be repeated below.

[0027] In some embodiments, the front light-transmitting surface of the first nonlinear medium 3 is coated with a fundamental frequency anti-reflection film, and the rear light-transmitting surface of the first nonlinear medium 3 is coated with a broadband anti-reflection film centered on the fundamental frequency light.

[0028] In some embodiments, the front light-transmitting surface of the frequency doubling crystal 4 is coated with a broadband anti-reflection film centered on the fundamental frequency light, and the rear light-transmitting surface of the frequency doubling crystal 4 is coated with a frequency doubling light band anti-reflection film.

[0029] In some embodiments, the front light-transmitting surface of the second nonlinear medium 5 is coated with a film system consistent with the rear light-transmitting surface of the frequency doubling crystal 4, and the rear light-transmitting surface is coated with a corresponding film system according to the actually achievable process conditions.

[0030] In some embodiments, the first nonlinear medium 3 and the second nonlinear medium 5 are the same medium or different media, and the materials of the first nonlinear medium 3 and the second nonlinear medium 5 are selected based on the standard of achieving optimal supercontinuum generation of ultrashort pulse fundamental frequency light 1 and ultrashort pulse doubled frequency light, respectively. At the same time, the light transmission wavelength of the nonlinear medium should include the supercontinuum band at the center wavelength of the fundamental frequency light.

[0031] In some embodiments, the light transmission wavelength of the second nonlinear medium 5 includes a supercontinuum band at the center wavelength of the ultrashort pulse fundamental frequency light 1 .

[0032] The main structure of the present invention is based on a sandwich structure of nonlinear medium-frequency doubling crystal 4-nonlinear medium, which can be expanded to a structure of multi-layer cross stacking of nonlinear medium and frequency doubling crystal 4. Taking nonlinear medium-frequency doubling crystal 4-nonlinear medium as an example, ultrashort pulse fundamental frequency light 1 is incident on the solid structure after being tightly focused, wherein the focus is generally located at the tail end of the solid structure, that is, the solid structure is located between the fundamental frequency light source and the focusing point and close to the focus position. The fundamental frequency light after the incident first undergoes self-phase modulation and cross-phase modulation in the first nonlinear medium 3 to produce a first supercontinuum spectrum with a certain spectral width at the center wavelength of the fundamental frequency light. The first supercontinuum spectrum is transmitted through the frequency doubling crystal 4 except for the center wavelength, and the spectrum at the center wavelength passes through the frequency doubling crystal 4 to realize the ultrashort pulse frequency doubling light, and the high peak intensity frequency doubling light undergoes self-phase modulation in the second nonlinear medium 5 to produce a supercontinuum spectrum light source at the center wavelength of the frequency doubling light, which constitutes a supercontinuum spectrum generation across octaves with the supercontinuum spectrum at the center wavelength of the fundamental frequency light. In special cases, especially in the ultraviolet band, when the shortest wavelength of the supercontinuum at the central wavelength of the fundamental light is consistent with or partially overlaps with the longest wavelength of the supercontinuum at the central wavelength of the doubled frequency light, the two supercontinuums can be spliced ​​together to form a multi-octave supercontinuum light source of ultraviolet-visible light, solving the problem of low pulse energy in the generation of supercontinuum light sources based on highly nonlinear optical fibers such as photonic crystal fibers, and achieving high pulse energy supercontinuum generation through multiple self-phase modulation and frequency doubling and other nonlinear processes. In addition, the fundamental light is first subjected to self-phase modulation before the frequency doubling process, further broadening the range of supercontinuum generation and achieving multi-band supercontinuum generation.

[0033] The present invention provides a cross-octave supercontinuum light source generation device, which solves the problem of low pulse energy of highly nonlinear optical fiber in supercontinuum light source generation based on a compact solid medium structure. A solid structure in which a frequency doubling crystal 4 and a multi-layer nonlinear action medium are cross-stacked and distributed is used for supercontinuum generation, and the generation of a supercontinuum with high pulse energy is achieved through nonlinear processes such as multiple self-phase modulation and frequency doubling. Based on this structure, when the central wavelength of the incident ultrashort pulse fundamental frequency light 1 is in the range of 410-800nm, the band splicing of two sections of supercontinuum at the central wavelength of the fundamental frequency light and the central wavelength of the frequency doubling light can be achieved to form a multi-octave supercontinuum light source of ultraviolet-visible light, which is a new way to realize a multi-octave supercontinuum light source, and the generation of a supercontinuum with high pulse energy is achieved through nonlinear processes such as multiple self-phase modulation and frequency doubling. In addition, the fundamental frequency light is subjected to a self-phase modulation process before the frequency doubling process, which further broadens the range of supercontinuum generation and realizes the generation of supercontinuum in multiple spectral bands.

[0034] Correspondingly, an embodiment of the present invention further provides an optical device having the above-mentioned cross-octave supercontinuum light source generating device.

[0035] The optical device provided by the present invention solves the problem of low pulse energy of highly nonlinear optical fiber in generating supercontinuum light source based on a compact solid medium structure. A solid structure in which a frequency doubling crystal 4 and a multi-layer nonlinear action medium are cross-stacked and distributed is used for supercontinuum generation, and the generation of a supercontinuum with high pulse energy is achieved through nonlinear processes such as multiple self-phase modulation and frequency doubling. Based on this structure, when the central wavelength of the incident ultrashort pulse fundamental frequency light 1 is in the range of 410-800nm, the band splicing of two sections of supercontinuum at the central wavelength of the fundamental frequency light and the central wavelength of the frequency doubling light can be achieved to form a multi-octave supercontinuum light source of ultraviolet-visible light, which is a new way to realize a multi-octave supercontinuum light source, and the generation of a supercontinuum with high pulse energy is achieved through nonlinear processes such as multiple self-phase modulation and frequency doubling. In addition, the fundamental frequency light is subjected to a self-phase modulation process before the frequency doubling process, so as to further broaden the range of supercontinuum generation and realize the generation of supercontinuum with multiple spectral bands.

[0036] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0037] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A device for generating a supercontinuum light source across an octave, characterized in that: It includes a focusing lens and at least one group of solid structures, wherein the solid structure includes a first nonlinear action medium, a frequency doubling crystal and a second nonlinear action medium; An ultrashort pulse fundamental frequency light is incident on the solid structure through the focusing lens, the ultrashort pulse fundamental frequency light undergoes self-phase modulation in the first nonlinear action medium to generate a first supercontinuum spectrum with a first predetermined spectral width at the central wavelength of the ultrashort pulse fundamental frequency light, the first supercontinuum spectrum and the remaining ultrashort pulse fundamental frequency light are incident on the frequency doubling crystal, and frequency doubling light with an ultrashort pulse narrow spectral bandwidth is generated in the frequency doubling crystal, the ultrashort pulse frequency doubling light and the first supercontinuum spectrum are incident on the second nonlinear action medium together, the ultrashort pulse frequency doubling light undergoes self-phase modulation in the second nonlinear action medium to generate a second supercontinuum spectrum with a second predetermined spectral width at the central wavelength of the frequency doubling light, the first supercontinuum spectrum and the second supercontinuum spectrum are used to form a cross-octave supercontinuum spectrum light source, wherein the frequency doubling crystal has a high frequency doubling conversion efficiency for the central wavelength of the ultrashort pulse fundamental frequency light.

2. The device for generating a supercontinuum light source across an octave as claimed in claim 1, characterized in that: The focal position of the ultrashort pulse fundamental frequency light after focusing is located at the rear side of the light emitting surface of the second nonlinear action medium.

3. The device for generating a supercontinuum light source across an octave as claimed in claim 1, characterized in that: The front light-transmitting surface of the first nonlinear medium is coated with a fundamental frequency light anti-reflection film, and the rear light-transmitting surface of the first nonlinear medium is coated with a broadband anti-reflection film centered on the fundamental frequency light.

4. The device for generating a supercontinuum light source across an octave as claimed in claim 1 or 3, characterized in that: The front light-transmitting surface of the frequency doubling crystal is coated with a broadband anti-reflection film centered on the fundamental frequency light, and the rear light-transmitting surface of the frequency doubling crystal is coated with an anti-reflection film in the frequency doubling light band.

5. The device for generating a supercontinuum light source across an octave as claimed in claim 4, characterized in that: The front light-transmitting surface of the second nonlinear action medium is plated with a film system consistent with the rear light-transmitting surface of the frequency doubling crystal.

6. The device for generating a supercontinuum light source across an octave as claimed in claim 1, characterized in that: The first nonlinear medium and the second nonlinear medium are the same medium or different media.

7. The device for generating a supercontinuum light source across an octave as claimed in claim 1 or 6, characterized in that: The light transmission wavelength of the second nonlinear medium includes a supercontinuum band at the central wavelength of the ultrashort pulse fundamental frequency light.

8. An optical device, characterized in that: A device for generating a cross-octave supercontinuum light source as claimed in any one of claims 1 to 7.

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