Tunable laser generation system

Abstract

The invention provides a tunable laser generation system, and relates to the field of nonlinear optical parametric amplification. The tunable laser generation system comprises a laser generation module and an amplification module. The laser generation module is suitable for generating seed light, first pumping laser and second pumping laser; the amplifying module comprises two reflecting mirror groups which are suitable for reflecting the first pumping laser and the second pumping laser respectively; a first amplification crystal and a second amplification crystal; the first light path switching assembly is suitable for enabling the seed light to alternately enter the first amplification crystal and the second amplification crystal; wherein the first amplification crystal performs optical parametric amplification on any wavelength component of a first sub-band of the seed light by using the reflected first pumping laser to obtain first amplified laser, and the second amplification crystal performs optical parametric amplification on any wavelength component of a second sub-band of the seed light by using the reflected second pumping laser to obtain second amplified laser; and second amplified laser is obtained.

Description

Technical Field

[0001] The invention relates to the field of nonlinear optical parameter amplification, and in particular to a tunable laser generating system. Background Art

[0002] Optical Parametric Amplification (OPA) technology is a laser amplification method based on nonlinear optical effects. It achieves efficient amplification of signal light energy through the interaction between pump laser and signal light in nonlinear crystals. Its core principle is to use the second-order nonlinear polarization effect (such as the χ² effect) to transfer part of the energy of the pump laser to the signal light and idler light. It has the characteristics of flexible wavelength tuning, wide gain bandwidth, and high peak power. It has important applications in ultrafast lasers, high-resolution spectroscopy, and quantum optics. However, the existing OPA technology faces some problems when amplifying wide-band seed light. When the seed light band range is wide (for example, covering an octave or wider range), the phase matching bandwidth of a single nonlinear crystal is usually difficult to cover the entire seed light band. This is because the phase matching conditions of the crystal (such as angle tuning or temperature tuning) are highly sensitive to wavelength, resulting in limited gain bandwidth. To solve this problem, two nonlinear crystals are usually used in existing methods to achieve optical parametric amplification of seed light, but this method causes the amplification efficiency of some wavelength components of the seed light to be significantly reduced or even completely lost. Summary of the invention

[0003] In view of this, the present invention provides a tunable laser generating system.

[0004] As a first aspect of the present invention, the tunable laser generating system comprises:

[0005] A laser generating module, adapted to generate a seed light and a first pump laser and a second pump laser having different wavelengths;

[0006] Amplification module, including:

[0007] Two reflector groups, adapted to respectively reflect the first pump laser and the second pump laser;

[0008] a first amplifying crystal and a second amplifying crystal;

[0009] A first optical path switching component is used to switch the transmission of the seed light between the first path and the second path, so that the seed light is alternately incident on the first amplifying crystal and the second amplifying crystal;

[0010] The first amplifying crystal uses the reflected first pump laser to perform optical parametric amplification on any wavelength component of the first sub-band of the seed light to obtain the first amplified laser, and the second amplifying crystal uses the reflected second pump laser to perform optical parametric amplification on any wavelength component of the second sub-band of the seed light to obtain the second amplified laser; the wavelength of the first sub-band is different from the wavelength of the second sub-band and can cover all bands of the seed light.

[0011] According to an embodiment of the present invention, the tunable laser generating system further comprises:

[0012] The first output module switches the transmission of the first amplified laser between the third path and the fourth path, and doubles the frequency of the first amplified laser transmitted along the fourth path to obtain the first frequency-doubled laser, and outputs the first amplified laser transmitted along the third path; and is adapted to switch the transmission of the second amplified laser between the fifth path and the sixth path, and doubles the frequency of the second amplified laser transmitted along the sixth path to obtain the second frequency-doubled laser, and outputs the second amplified laser transmitted along the fifth path;

[0013] The second output module switches the transmission of the second frequency-doubled laser between the seventh path and the eighth path, and doubles the frequency of the second frequency-doubled laser with a wavelength greater than a preset wavelength transmitted along the eighth path to obtain a third frequency-doubled laser, and outputs the second frequency-doubled laser transmitted along the seventh path.

[0014] According to an embodiment of the present invention, the first output module includes two frequency multiplication components respectively arranged on the fourth path and the fifth path, and the second output module includes one frequency multiplication component arranged on the eighth path;

[0015] Each frequency doubling component includes two concave mirrors and a frequency doubling crystal located between the two concave mirrors. The laser transmitted to the frequency doubling component is focused onto the frequency doubling crystal via one of the concave mirrors, and is output via the other concave mirror after being doubled in frequency on the frequency doubling crystal. The frequency doubling crystal is mounted on a universal adjustment frame, which is used to adjust the direction of the optical axis of the frequency doubling crystal.

[0016] According to an embodiment of the present invention, the tunable laser generating system further comprises:

[0017] The compression module is adapted to compress the pulse width of the first amplified laser and the second amplified laser, and transmit the compressed first amplified laser and the compressed second amplified laser to the first output module.

[0018] According to an embodiment of the present invention, the pulse width of the compressed first amplified laser light and the compressed second amplified laser light is 25 fs.

[0019] According to an embodiment of the present invention, the seed light is chirped light, the reflector group includes at least one reflector, the position of the at least one reflector is adjustable, and when the position of the at least one reflector changes, the wavelength component of the first sub-band or the second sub-band amplified by the first pump laser or the second pump laser reflected by the reflector group changes.

[0020] According to an embodiment of the present invention, the wavelength range of the seed light is λ~2λ.

[0021] According to an embodiment of the present invention, λ is 510 nm.

[0022] According to an embodiment of the present invention, the laser generating module comprises:

[0023] A laser, suitable for generating initially polarized laser light;

[0024] A beam splitting component, adapted to split the initial polarized laser light into a first polarized laser light and a second polarized laser light;

[0025] A seed light generating component, adapted to generate seed light according to a first polarized laser;

[0026] The pump laser generating component is suitable for obtaining a first pump laser and a second pump laser according to a second polarized laser.

[0027] According to an embodiment of the present invention, an angle between an incident direction of the second pump laser when incident on the second amplifying crystal and an incident direction of the seed light when incident on the second amplifying crystal is 2° to 9°.

[0028] According to an embodiment of the present invention, when the wavelength range of the seed light is relatively wide, for example, when the seed light is supercontinuum white light (for example, supercontinuum white light with a wavelength range of 510nm~1020nm), it is necessary to use two amplifying crystals to realize optical parametric amplification of the seed light. Under the action of the first optical path switching component, the seed light can be directed into the first amplifying crystal or the second amplifying crystal, and the first amplifying crystal and the second amplifying crystal respectively realize optical parametric amplification of any wavelength components of the two sub-bands in the seed light under the action of the first pumping laser and the second pumping laser. Since the wavelength of the first sub-band is different from the wavelength of the second sub-band, and can cover all the wavelength bands of the seed light, the range of optical parametric amplification that can be realized by the first pumping laser and the second pumping laser can cover all the wavelength bands of the seed light. After adopting the first optical path switching component, there is no need to use a beam splitter to split the seed light and respectively irradiate it into the two amplifying crystals, thereby avoiding the problem of band loss introduced by the beam splitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 shows an optical path diagram of a tunable laser generating system provided according to an embodiment of the present invention;

[0030] Figure 2 The spectrum of supercontinuum white light generated by a 3 mm thick sapphire crystal according to an embodiment of the present invention is shown;

[0031] Figure 3 The spectrum of the first amplified laser light obtained by performing optical parametric amplification on the seed light using the third harmonic light according to the embodiment of the present invention is shown;

[0032] Figure 4 shows the spectrum of the second amplified laser obtained by performing optical parametric amplification of seed light using second harmonic light according to an embodiment of the present invention;

[0033] Figure 5 shows an optical path diagram of a tunable laser generating system provided according to another embodiment of the present invention;

[0034] Figure 6 A spectrum diagram of a first frequency-doubled laser output by a first frequency-doubled component provided in an embodiment of the present invention is shown;

[0035] Figure 7 shows a spectrum diagram of the second frequency-doubled laser output by the second frequency-doubled component provided in an embodiment of the present invention;

[0036] Figure 8 The figure shows a spectrum diagram of the third frequency-doubled laser output by the third frequency-doubled component provided according to an embodiment of the present invention.

[0037] Description of reference numerals:

[0038] 1-laser generation module; 2-amplification module; 3-first output module; 4-second output module; 5-first light block; 6-second light block; 7-third light block; 11-laser; 12-beam splitting assembly; 13-seed light generation assembly; 14-pump laser generation assembly; 121-first half-wave plate; 122-polarization beam splitting cube; 123-second half-wave plate; 131-white light crystal; 132-first lens; 133-first total reflection mirror; 13 4-second lens; 135-filter; 136-second total reflection mirror; 141-third reflection mirror; 142-third lens; 143-second harmonic generation crystal; 144-third harmonic generation crystal; 145-first harmonic beam splitter; 146-second harmonic beam splitter; 21-first optical path switching component; 22-first amplifying crystal; 23-second amplifying crystal; 24-first reflection mirror group; 25-second reflection mirror group; 26-fourth lens; 2 7-fifth lens; 28-sixth lens; 29-seventh lens; 211-first flip-up reflector; 212-third total reflector; 241-first reflector; 251-second reflector; 31-first frequency doubling component; 32-second frequency doubling component; 33-second optical path switching component; 34-third optical path switching component; 35-eighth lens; 36-ninth lens; 311-first concave mirror; 312-second concave mirror; 313-first frequency doubling crystal Body; 321-third concave mirror; 322-fourth concave mirror; 323-second frequency doubling crystal; 331-second flip reflector; 332-fourth total reflector; 341-third flip reflector; 342-fifth total reflector; 41-third frequency doubling component; 42-fourth optical path switching component; 411-fifth concave mirror; 412-sixth concave mirror; 413 third frequency doubling crystal; 421-fourth flip reflector; 422 sixth total reflector. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the invention thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated, and the same reference numerals throughout represent the same elements.

[0040] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0041] Figure 1 An optical path diagram of a tunable laser generating system provided according to an embodiment of the present invention is shown.

[0042] like Figure 1 As shown, the tunable laser generating system includes: a laser generating module 1 and an amplifying module 2 .

[0043] The laser generating module 1 is suitable for generating seed light and for generating a first pump laser and a second pump laser with different wavelengths. The amplifying module 2 includes: a first optical path switching component 21, two reflector groups, a first amplifying crystal 22 and a second amplifying crystal 23. The two reflector groups are suitable for reflecting the first pump laser and the second pump laser respectively. The two reflector groups are a first reflector group 24 and a second reflector group 25. The first reflector group 24 is used to reflect the first pump laser, and the second reflector group 25 is used to reflect the second pump laser. The first optical path switching component 21 is suitable for switching the seed light between the first path and the second path so that the seed light is alternately incident on the first amplifying crystal 22 and the second amplifying crystal 23. Among them, the first amplifying crystal 22 uses the reflected first pump laser to perform optical parametric amplification on any wavelength component of the first sub-band of the seed light to obtain the first amplified laser, and the second amplifying crystal 23 uses the reflected second pump laser to perform optical parametric amplification on any wavelength component of the second sub-band of the seed light to obtain the second amplified laser; the wavelength of the first sub-band is different from the wavelength of the second sub-band and can cover all bands of the seed light.

[0044] According to an embodiment of the present invention, the wavelength range of the seed light is, for example, λ~2λ, for example, λ is 510 nm.

[0045] According to an embodiment of the present invention, when the wavelength range of the seed light is relatively wide, for example, when the seed light is supercontinuum white light (for example, supercontinuum white light with a wavelength range of 510nm~1020nm), two amplifying crystals are required to realize optical parametric amplification of the seed light. Under the action of the first optical path switching component 21, the seed light can be incident in a direction into the first amplifying crystal 22 or the second amplifying crystal 23. The first amplifying crystal 22 and the second amplifying crystal 23 respectively realize optical parametric amplification of any wavelength components of the two sub-bands in the seed light under the action of the first pumping laser and the second pumping laser. Since the wavelength of the first sub-band is different from the wavelength of the second sub-band, and can cover the entire wavelength band of the seed light, the range of optical parametric amplification that can be realized by the first pumping laser and the second pumping laser can cover the entire wavelength band of the seed light. After adopting the first optical path switching component 21, there is no need to use a beam splitter to split the seed light and respectively incident on the two amplifying crystals, thereby avoiding the problem of band loss introduced by the beam splitter.

[0046] Exemplarily, the wavelength range of the seed light is 510nm~1020nm, the first amplifying crystal 22 is a BBO crystal with a cutting angle of 37°, and the second amplifying crystal 23 is a BBO crystal with a cutting angle of 26.5°. Under specific phase matching conditions, the first amplifying crystal 22 can use the first pumping light to amplify any wavelength component of the first sub-band of the seed light, that is, the 510~620nm sub-band, to obtain a first amplified laser with a wavelength in the 510~620nm band. The second amplifying crystal 23 can use the second pumping laser to amplify any wavelength component of the second sub-band of the seed light, that is, the 620~1020nm sub-band, to obtain a second amplified laser with a wavelength in the 620~1020nm band.

[0047] According to an embodiment of the present invention, the first optical path switching component 21 includes a first flippable reflector 211 and a third total reflector 212. The first flippable reflector 211 is used to transmit the seed light along the first path or transmit the seed light along the second path, and the third total reflector 212 is located on the second path, and when the seed light is transmitted along the second path, it is used to reflect the seed light to the second amplifying crystal 23.

[0048] According to an embodiment of the present invention, the amplification module 2 further includes a fourth lens 26 and a fifth lens 27. The fourth lens 26 is located on the first path, and when the seed light is transmitted along the first path, it is used to focus the seed light onto the first amplification crystal 22. The fifth lens 27 is used to focus the seed light from the third total reflection mirror 212 onto the second amplification crystal 23.

[0049] According to an embodiment of the present invention, the amplification module 2 further includes a sixth lens 28 and a seventh lens 29. The sixth lens 28 is used to focus the first pump laser output by the laser generation module 1, and transmit the focused first pump laser to the first reflector group 24. The seventh lens 29 is used to focus the second pump laser output by the laser generation module 1, and transmit the focused second pump laser to the second reflector group 25. The focal length of the sixth lens 28 is, for example, 30 cm, and the focal length of the seventh lens 29 is, for example, 35 cm.

[0050] According to an embodiment of the present invention, the seed light is chirped light, each reflector group includes at least one reflector, and the position of at least one reflector is adjustable. When the position of at least one reflector changes, the wavelength component of the first sub-band or the second sub-band amplified by the first pump laser or the second pump laser reflected by the reflector group changes. Specifically, when the seed light is chirped light, there is a difference in the time delay of different wavelength components (frequency components) of the seed light reaching the amplifying crystal. In order to achieve selective amplification of specific wavelength components of the seed light, two conditions need to be met. First, it is necessary to make the pump light (first pump light or second pump light) achieve the best time delay matching with a specific wavelength component in the seed light inside the amplifying crystal (first amplifying crystal 22 or second amplifying crystal 23), and secondly, it is also necessary to ensure that the angle of the pump light relative to the seed light meets the phase matching condition of the specific wavelength component of the seed light. Therefore, when changing the amplified wavelength component in the seed light, it is necessary to change the optical path of the pump light and the angle between the pump light and the seed light, which can be achieved by adjusting the position of the reflector. By flexibly adjusting the position of the reflector, the amplified wavelength can be dynamically adjusted to achieve a continuously tunable output of the wavelength component.

[0051] Specifically, the first reflector group 24 includes a plurality of first reflectors 241. The second reflector group 25 includes a plurality of second reflectors 251. The plurality of first reflectors 241 are used to sequentially reflect the first pump laser so as to reflect the first pump laser onto the first amplifier crystal 22. The plurality of second reflectors 251 are used to sequentially reflect the second pump laser so as to reflect the second pump laser onto the second amplifier crystal 23. By adjusting the position of at least one first reflector 241 in the first reflector group 24, the optical path of the first pump light and the angle between the first pump light and the seed light can be changed, thereby changing the wavelength component amplified in the first sub-band. By adjusting the position of at least one second reflector 251 in the second reflector group 25, the optical path of the second pump light and the angle between the second pump light and the seed light can be changed. Thus, the wavelength component amplified in the second sub-band is changed.

[0052] According to an embodiment of the present invention, at least one first reflector 241 and at least one second reflector 251 may be mounted on a linear translation stage, and the linear translation stage may be used to change the posture of at least one first reflector 241 or at least one second reflector 251. The stroke of the linear translation stage may be, for example, 13 mm.

[0053] According to an embodiment of the present invention, the angle between the incident direction of the second pump laser when incident on the second amplifying crystal and the incident direction of the seed light when incident on the second amplifying crystal is 2°~9°. In particular, under phase matching conditions, when the angle between the incident direction of the second pump laser when incident on the second amplifying crystal and the incident direction of the seed light when incident on the second amplifying crystal is 6°~9°, the second pump laser can be used to achieve effective optical parametric amplification of the seed light in the 920~1020nm band.

[0054] Continue to refer Figure 1 According to an embodiment of the present invention, the laser generating module 1 includes: a laser 11, a beam splitting component 12, a seed light generating component 13, and a pump laser generating component 14. The laser 11 is suitable for generating an initial polarized laser. The beam splitting component 12 is suitable for splitting the initial polarized laser into a first polarized laser and a second polarized laser. The seed light generating component 13 is suitable for generating a seed light according to the first polarized laser. The pump laser generating component 14 is suitable for obtaining a first pump laser and a second pump laser according to the second polarized laser. When the wavelength of the first sub-band is smaller than the wavelength of the second sub-band (the first sub-band can be, for example, 510nm~610nm, and the second sub-band can be, for example, 610nm~1020nm, or the first sub-band can be, for example, 510nm~620nm, and the second sub-band can be, for example, 620nm~1020nm), the first pump laser is the third harmonic light of the second polarized laser, and the second pump laser is the second harmonic light of the second polarized laser.

[0055] According to an embodiment of the present invention, a laser 11 is used to generate seed light and two pump lasers. Compared with the case of using multiple lasers, the number of lasers can be reduced, thereby simplifying the optical path design and system structure. This not only reduces the hardware cost, but also reduces the volume and complexity of the system, making it easier to integrate. Since the seed light and the two pump lasers come from the same laser source, the optical properties of the white light seed light and the two pump lasers (such as time delay, bandwidth, etc.) are highly consistent. This consistency helps to optimize the phase matching conditions in the optical parametric amplification process, improve the wavelength conversion efficiency, and ensure the wavelength stability of the output laser. The initial polarized laser generated by the laser 11 of the embodiment of the present invention can efficiently distribute the initial polarized laser energy to the seed light generating component 13 and the pump laser generating component 14 through the beam splitting component 12, avoiding the problem of uneven energy distribution in a system including multiple lasers. The embodiment of the present invention uses a laser 11 to maximize the utilization rate of the initial laser energy, so that the overall efficiency of the system is higher.

[0056] Exemplarily, the initial polarized laser output by the laser 11 has the following parameters: a pulse width of about 290 fs, an average power of 0.4 W to 4 W, a repetition frequency of 50 kHz to 500 kHz, a pulse energy of 8 μJ, and a wavelength of 1030 nm.

[0057] According to an embodiment of the present invention, the second harmonic light and the third harmonic light obtained by the pump laser generating component 14 are both polarized lasers. When the two amplifying crystals are type I phase-matched crystals, the polarization directions of the first polarized laser and the second polarized laser generated by the beam splitting component are the same. When the amplifying crystal is a type II phase-matched crystal, the polarization directions of the first polarized laser and the second polarized laser generated by the beam splitting component 12 are opposite. This is because, when the two amplifying crystals are type I phase-matched crystals, it is necessary to ensure that the polarization directions of the pump laser and the seed light are the same to achieve efficient energy transfer. When the two amplifying crystals are type II phase-matched crystals, it is necessary to ensure that the pump laser and the seed light meet the orthogonal polarization condition (that is, the polarization directions are vertical). However, the second harmonic light and the third harmonic light generated by nonlinear frequency conversion are opposite to the polarization direction of the second polarized laser. Therefore, when the amplifying crystals use different types of phase matching, the polarization directions of the first polarized laser and the second polarized laser need to meet different conditions respectively.

[0058] According to an embodiment of the present invention, Figure 1 FIG. 1 shows only the composition of the beam splitter assembly 12 when the optical parametric amplifier crystal is a type II phase-matched crystal, and Figure 1 In the description, an example is given in which the first polarized laser is a vertically polarized laser and the second polarized laser is also a vertically polarized laser.

[0059] refer to Figure 1 The beam splitting component 12 may include, for example, a first half-wave plate 121 , a polarization beam splitting cube 122 , and a second half-wave plate 123 .

[0060] The first half-wave plate 121 is used to change the polarization direction of the initial polarized laser to obtain a first intermediate polarized laser, which has both a horizontal component and a vertical component. The polarization beam splitter cube 122 is used to split the first intermediate polarized laser into a first sub-laser and a second sub-laser with perpendicular polarization directions, the polarization direction of the first sub-laser is horizontal, and the polarization direction of the second sub-laser is vertical. Among them, the second sub-laser serves as the second polarized laser. The second half-wave plate 123 is used to change the polarization direction of the first sub-laser to a vertical direction to obtain a first polarized laser. Schematically, when the angle between the fast axis of the first half-wave plate 121 and the vertical direction is 9°, the intensity ratio of the horizontal component to the vertical component can be made approximately 1:4, so that the intensity ratio of the first polarized laser used to generate seed light and the second polarized laser used to generate harmonic light is 1:4.

[0061] Continue to refer Figure 1 The seed light generating assembly 13 includes: a white light crystal 131 , a first lens 132 , two first total reflection mirrors 133 , a second lens 134 , a filter 135 , and a second total reflection mirror 136 .

[0062] After the first polarized laser is totally reflected by the two first total reflection mirrors 133, it enters the white light crystal 131 under the focus of the first lens 132 to generate initial white light, which is supercontinuum white light. The initial white light is re-collimated into parallel white light under the action of the second lens 134, and then under the action of the filter 135, the initial polarized laser included in the parallel white light can be effectively filtered out to obtain seed light. The second total reflection mirror 136 is used to reflect the seed light to change the optical path of the seed light. The second total reflection mirror 136 can be, for example, a 450-1100nm total reflection mirror.

[0063] Exemplarily, in order to obtain the seed light of 510nm~1020nm, the spectrum range of the initial white light covers the wavelength band of 510nm~1020nm, the first total reflection mirror 133 can be, for example, a total reflection mirror of 1030nm, the focal length of the first lens 132 can be, for example, 5cm, and the focal length of the second lens 134 can be, for example, 5cm. The initial white light is re-collimated into parallel white light under the action of the second lens 134. When the wavelength of the initial polarized laser is 1030nm, under the action of the filter 135, the wavelength component of 1030nm in the parallel white light can be effectively filtered out to obtain the seed light.

[0064] According to an embodiment of the present invention, when the wavelength range of the seed light is 510nm-1020nm, the white light crystal 131 can be, for example, a sapphire crystal with a thickness of 3mm. The principle of generating initial white light with a spectrum range of 510nm-1020nm by incidenting the first polarized laser on the white light crystal 131 is described in detail below.

[0065] When a polarized laser with a sufficiently strong peak power enters a transparent medium, under the combined effect of nonlinear mechanisms such as self-focusing and self-phase modulation, the spectrum of the polarized laser will be greatly broadened to produce supercontinuum white light. In the embodiment of the present invention, the initial polarized laser is a pulse light with a pulse width of about 290fs, a pulse energy of 1.6μJ, and a wavelength of 1030nm. Therefore, the peak power of the initial polarized laser is relatively strong, and the peak power of the first polarized laser obtained from the initial polarized laser is also strong enough. By using the first lens 132, the first polarized laser is focused into the white light crystal 131, which can produce supercontinuum white light covering the 510~1020nm band. The minimum spot diameter of the supercontinuum white light can reach 10μm when focused by a lens with a focal length of 5cm, and the peak power density can reach 10μm. . In addition to the peak power density, the thickness of the white light crystal is also an important parameter. On the one hand, the longer the distance that the first polarized laser is transmitted in the white light crystal, the stronger the cumulative nonlinear effect and the more significant the spectral broadening. On the other hand, the thicker the white light crystal, the more obvious chirp will be produced between the frequency components of the generated seed light, and the excessive time delay between the different spectral components of the seed light will result in only a very small part of the spectral components of the seed light being able to overlap in time with the corresponding pump laser and obtain optical parametric amplification, thereby limiting the gain bandwidth of the amplified laser. Taking these two factors into consideration, in an embodiment of the present invention, for example, a 3mm thick sapphire crystal can be selected as the white light crystal.

[0066] Figure 2 The spectrum of supercontinuum white light generated by a 3 mm thick sapphire crystal according to an embodiment of the present invention is shown.

[0067] like Figure 2 As shown, the first polarized laser generated by the initial laser with a pulse width of 290fs and a central wavelength of 1030nm is focused into a 3mm thick sapphire crystal through the first lens 132, and can generate supercontinuum white light with a wavelength covering 510nm~1020nm.

[0068] According to an embodiment of the present invention, the pump laser generating assembly 14 includes: a plurality of third reflectors 141, a third lens 142, a second harmonic generating crystal 143, a third harmonic generating crystal 144, a first harmonic beam splitter 145 and a second harmonic beam splitter 146. The second polarized laser light emitted from the polarization beam splitting cube 122 is incident on the first third reflector 141, and after being deflected by the third reflector 141, it is focused by the third lens 142. After being deflected by the second third reflector 142, the focused light beam falls between the second harmonic generating crystal 143 and the third harmonic generating crystal 144, and the second harmonic light and the third harmonic light of the second polarized laser light are respectively produced. The wavelength of the second harmonic light is, for example, 515nm, and the wavelength of the third harmonic light is, for example, 343nm. The first harmonic beam splitter 145 can reflect the third harmonic light, and transmit the second harmonic light and the remaining second polarized laser light. The second harmonic beam splitter 146 can reflect the second harmonic light and transmit the remaining second polarized laser light. Under the action of two harmonic beam splitters, the separation of the second harmonic light, the third harmonic light and the second polarized laser is achieved.

[0069] Exemplarily, the focal length of the third lens 142 is, for example, 30 cm, the second harmonic generating crystal 143 may be, for example, a BBO crystal with a cutting angle of 23.5°, and the third harmonic generating crystal 144 may be, for example, a BBO crystal with a cutting angle of 62.8°.

[0070] Figure 3The spectrum of the first amplified laser obtained by performing optical parametric amplification on seed light using third harmonic light according to an embodiment of the present invention is shown.

[0071] Part (a) shows the linear shape of the first amplified laser obtained by optically parametrically amplifying the seed light using the third harmonic light, that is, the variation of the light intensity of the first amplified laser with the wavelength. Part (b) shows the relationship between the wavelength and power of the first amplified laser obtained by optically parametrically amplifying the seed light using the third harmonic light.

[0072] exist Figure 3 In the figure, the wavelength of the third harmonic light is 343nm, the wavelength range of the seed light is 510nm~1020nm, and the first amplifying crystal 22 is a BBO crystal with a cutting angle of 37°. As can be seen from part (a), the first amplified laser obtained by optical parametric amplification of the white light seed light using the third harmonic light is a tunable laser with a wavelength in the 510~620nm band. As can be seen from part (b), the power of the first amplified laser in the 510~620nm band is maintained above 10mW, and the local peak power can reach 30mW.

[0073] Figure 4 The spectrum of the second amplified laser obtained by performing optical parametric amplification on the seed light using the second harmonic light provided by the embodiment of the present invention is shown.

[0074] Part (a) shows the linear shape of the second amplified laser obtained by optically parametrically amplifying the seed light using the second harmonic light, that is, the variation of the intensity of the second amplified laser with the wavelength. Part (b) shows the relationship between the wavelength and power of the second amplified laser obtained by optically parametrically amplifying the seed light using the second harmonic light.

[0075] exist Figure 4 In the figure, the wavelength of the second harmonic light is 515nm, the wavelength range of the seed light is 510nm~1020nm, and the second amplifying crystal 23 used is a BBO crystal with a cutting angle of 26.5°. From part (a), it can be seen that the second amplified laser obtained by optical parametric amplification of the white light seed light using the second harmonic light is a tunable laser with a wavelength in the 620~1020nm band. From part (b), it can be seen that the power of the second amplified laser in the 620~1020nm band is maintained above 30mW, and the local peak power can reach 130mW.

[0076] According to an embodiment of the present invention, the tunable laser generation system further includes a first light block 5, a second light block 6 and a third light block 7. The first light block 5 is used to block the remaining second polarized light that passes through the second harmonic beam splitter 146. The second light block 6 is used to block the remaining first pump laser that passes through the first amplifying crystal 22. The third light block 7 is used to block the remaining second pump laser that passes through the second amplifying crystal 23.

[0077] Figure 5 An optical path diagram of a tunable laser generating system provided according to another embodiment of the present invention is shown.

[0078] like Figure 5 As shown, the tunable laser generating system further includes a first output module 3 and a second output module 4 .

[0079] The first output module 3 is used to switch the transmission of the first amplified laser between the third path and the fourth path, and to double the frequency of the first amplified laser transmitted along the fourth path to obtain the first frequency-doubled laser, and the first amplified laser transmitted along the third path is output. The first output module 3 is also suitable for switching the second amplified laser between the fifth path and the sixth path, and to double the frequency of the second amplified laser transmitted along the sixth path to obtain the second frequency-doubled laser, and the second amplified laser transmitted along the fifth path is output. The second output module 4 is used to switch the second frequency-doubled laser between the seventh path and the eighth path, and to double the frequency of the second frequency-doubled laser transmitted along the eighth path with a wavelength greater than the preset wavelength to obtain the third frequency-doubled laser, and the second frequency-doubled laser transmitted along the seventh path is output.

[0080] According to an embodiment of the present invention, since the wavelength range of the seed light is λ~2λ, continuous wavelength band coverage can be formed between the first amplified laser and the second amplified laser before frequency doubling and the first frequency-doubled laser, the second frequency-doubled laser and the third frequency-doubled laser obtained after frequency doubling.

[0081] Optionally, the tunable laser generating system further comprises a compression module, adapted to compress the pulse widths of the first amplified laser and the second amplified laser and transmit the compressed first amplified laser and the compressed second amplified laser to the first output module. Preferably, the compressed first amplified laser and the compressed second amplified laser are compressed to less than 25 fs.

[0082] Compressing the pulse width of the first amplified laser can significantly increase the peak power of the first amplified laser, making the energy of the first amplified laser more concentrated in time. This is particularly important for nonlinear optical processes (such as frequency doubling), because the frequency doubling efficiency is usually proportional to the peak power of the laser. Higher peak power can significantly improve the conversion efficiency of the frequency doubling module, thereby obtaining a stronger frequency doubling light output. In multiphoton photoelectron spectroscopy or ultrafast spectroscopy, laser pulses with a pulse width of less than 25 fs can provide extremely high temporal resolution. This is crucial for studying ultrafast dynamic processes (such as molecular vibrations, electronic transitions, etc.), because only sufficiently short pulses can capture these rapidly changing transient phenomena. In the process of optical parametric amplification and frequency doubling, phase matching conditions have an important influence on the wavelength conversion efficiency. Ultrashort pulse lasers have a wider spectral bandwidth and can better meet the phase matching conditions, thereby improving the efficiency and stability of wavelength conversion. Ultrashort pulse lasers have a wide range of applications in quantum computing, ultrafast spectroscopy, nonlinear optics and other fields. By compressing the pulse width to less than 25fs, the needs of these fields for high temporal resolution and high peak power can be met, thereby expanding the application scope of optical parametric amplification systems.

[0083] Exemplarily, when the wavelength of the first amplified laser is in the band of 510nm to 620nm, a first frequency-doubled laser in the band of 255nm to 310nm can be generated through the double frequency process; when the wavelength of the second amplified laser is in the band of 620nm to 1020nm, a second frequency-doubled laser in the band of 310nm to 510nm can be generated through double frequency conversion. In particular, the second output module 4 can, for example, perform double frequency processing on the second frequency-doubled laser with a wavelength greater than 410nm, thereby obtaining a third frequency-doubled laser in the band of 205nm to 255nm. It should be noted that since 205nm is the frequency-doubled limit of the BBO crystal, it is impossible to have a component less than 205nm when using the BBO crystal, so when the wavelength of 410nm is doubled, the obtained frequency-doubled light will be slightly larger than 205nm.

[0084] Through the coordinated work of the first output module and the second output module, the system can not only directly output amplified laser, but also expand the output band through frequency doubling technology, ultimately achieving continuous tunable output in a wide spectrum of 205nm~1020nm, completely covering multiple important spectral regions such as deep ultraviolet (205nm~300nm), near ultraviolet (300nm~400nm), visible light (400nm~700nm) and near infrared (700nm~1020nm).

[0085] According to an embodiment of the present invention, the first output module 3 includes two frequency doubling components, and the second output module 4 includes one frequency doubling component. The two frequency doubling components of the first output module 3 are respectively located on the fourth path and the sixth path, and one frequency doubling component of the second output module 4 is located on the eighth path. Each frequency doubling component includes two concave mirrors and a frequency doubling crystal located between the two concave mirrors. The laser transmitted to the frequency doubling component is focused onto the frequency doubling crystal via one of the concave mirrors, and is output via the other concave mirror after double frequency occurs on the frequency doubling crystal. The frequency doubling crystal is mounted on a universal adjustment frame, and the universal adjustment frame is used to adjust the direction of the optical axis of the frequency doubling crystal.

[0086] The first output module 3 and the second output module 4 are respectively introduced in detail below.

[0087] Specifically, the two frequency doubling components of the first output module 3 are respectively a first frequency doubling component 31 and a second frequency doubling component 32. In addition, the first output module 3 also includes a second optical path switching component 33, a third optical path switching component 34, an eighth lens 35 and a ninth lens 36. The first frequency doubling component 31 includes a first concave mirror 311, a second concave mirror 312 and a first frequency doubling crystal 313 located between the first concave mirror 311 and the second concave mirror 312. The first frequency doubling crystal 313 is mounted on a first universal adjustment frame. The second frequency doubling component 32 includes a third concave mirror 321, a fourth concave mirror 322 and a second frequency doubling crystal 323 located between the third concave mirror 321 and the fourth concave mirror 322. The second frequency doubling crystal 323 is mounted on a second universal adjustment frame. The second optical path switching component 33 includes a second flippable reflector 331 and a fourth total reflector 332. The third optical path switching component 34 includes a third flippable reflector 341 and a fifth total reflector 342.

[0088] The second flip-up reflector 331 is used to switch the first amplified laser between the third path and the fourth path. The fourth total reflection mirror 332 is used to reflect the first amplified laser transmitted along the third path, so that the first amplified laser transmitted along the third path is output. The first amplified laser transmitted along the fourth path is transmitted to the first concave mirror 311. The first amplified laser is converged to the first frequency doubling crystal 313 by the first concave mirror 311 and doubled in frequency to obtain the first frequency doubling laser, which is collimated by the second concave mirror 312 and output. Since the first frequency doubling crystal 313 is installed in the first universal adjustment frame, the transmission direction of the first amplified laser and the optical axis angle of the first frequency doubling crystal 313 can be adjusted at a certain angle. Under the action of the first universal adjustment frame, the frequency doubling of the first amplified laser with different wavelengths can be achieved. The eighth lens 35 is used to focus the first amplified laser onto the second flippable reflector 331.

[0089] Exemplarily, the first frequency doubling crystal 313 is a β-phase barium borate crystal (BBO crystal) with a cutting angle of 41°. The first concave mirror 311 is a 450-1100nm total reflection concave mirror with a focal length of 5 cm, and the second concave mirror 312 is a 250-520nm total reflection concave mirror with a focal length of 5 cm. When the wavelength of the first amplified laser is in the 510-620nm band, the first frequency doubling component 31 can double the wavelength of the first amplified laser in the 510-620nm band to obtain a first frequency doubling laser with a wavelength in the 255-310nm band and tunable.

[0090] Figure 6 The figure shows a spectrum diagram of the first frequency doubling laser output by the first frequency doubling component provided according to an embodiment of the present invention, wherein part (a) is the linear shape of the first frequency doubling laser, that is, the relationship between the intensity and wavelength of the first frequency doubling laser, and part (b) is the relationship between the wavelength and power of the first frequency doubling laser output by the first frequency doubling component.

[0091] exist Figure 6 In the figure, the wavelength of the first amplified laser input to the first frequency doubling component is in the 510-620nm band. From part (a), it can be seen that the first frequency doubling laser output by the first frequency doubling component is a tunable laser in the ultraviolet to deep ultraviolet band of 255nm-310nm. From part (b), it can be seen that the power of the first frequency doubling laser output by the first frequency doubling component can reach three milliwatts.

[0092] The third flip-up reflector 341 is used to switch the second amplified laser between the fifth path and the sixth path, and the fifth total reflector 342 is used to reflect the second amplified laser transmitted along the fifth path so that the second amplified laser transmitted along the fifth path is output. The second amplified laser transmitted along the sixth path is transmitted to the third concave mirror 321. The second amplified laser is converged to the second frequency doubling crystal 323 by the third concave mirror 321 and doubled in frequency to obtain a second frequency doubling laser, which is collimated by the fourth concave mirror 322 and then output. Since the second frequency doubling crystal 323 is installed in the second universal adjustment frame, the transmission direction of the second amplified laser and the optical axis angle of the second frequency doubling crystal 323 can be adjusted at 90°. Under the action of the second universal adjustment frame, the frequency doubling of the second amplified laser with different wavelengths can be achieved. The ninth lens 36 is used to focus the second amplified laser onto the third flippable reflector 341.

[0093] Exemplarily, the second frequency doubling crystal 323 is a BBO crystal with a cutting angle of 30°. The third concave mirror 321 and the fourth concave mirror 322 are total reflection concave mirrors with a focal length of 5 cm, and the total reflection bands of the third concave mirror 321 and the fourth concave mirror 322 are 450~1100nm and 250~520nm respectively. When the wavelength of the second amplified laser is in the 620~1020nm band, the second frequency doubling component 32 can double the wavelength of the second amplified laser in the 620~1020nm band to obtain a second frequency doubling laser with a wavelength in the 310~510nm band and tunable.

[0094] Figure 7 The figure shows a spectrum diagram of the second frequency doubling laser output by the second frequency doubling component provided according to an embodiment of the present invention, wherein part (a) is the linear shape of the second frequency doubling laser, that is, the relationship between the intensity and wavelength of the second frequency doubling laser, and part (b) is the relationship between the wavelength and power of the second frequency doubling laser output by the second frequency doubling unit.

[0095] exist Figure 7 In the figure, the wavelength of the second amplified laser input to the second frequency doubling component is in the 620-1020nm band. From part (a), it can be seen that the second frequency doubling laser output by the second frequency doubling component is a tunable laser in the ultraviolet to visible light band of 310nm-510nm. From part (b), it can be seen that the power of the second frequency doubling laser can reach 20 milliwatts.

[0096] Continue to refer Figure 5 , the frequency doubling component located in the eighth path in the second output module is the third frequency doubling component 41. In addition to the third frequency doubling component 41, the second output module also includes a fourth optical path switching component 42. The fourth optical path switching component 42 includes a fourth flip-up reflector 421 and a sixth total reflector 422, and the third frequency doubling component 41 includes a fifth concave mirror 411, a sixth concave mirror 412, and a third frequency doubling crystal 413 located between the fifth concave mirror 411 and the sixth concave mirror 412. The third frequency doubling crystal 413 is installed in a third universal adjustment mount so that the angle between the incident direction of the second frequency doubling laser and the optical axis of the third frequency doubling crystal 413 can be Flexible internal adjustment.

[0097] The fourth flippable reflector 421 is used to switch the second frequency-doubled laser between the seventh path and the eighth path, and the sixth total reflector 422 is used to reflect the second frequency-doubled laser transmitted along the seventh path, so that the seventh amplified laser transmitted along the seventh path is output. The second frequency-doubled laser transmitted along the eighth path is transmitted to the fifth concave mirror 411. The second frequency-doubled laser is converged to the third frequency-doubled crystal 413 through the fifth concave mirror 411. Under the action of the third frequency-doubled crystal 413, the second frequency-doubled laser with a wavelength greater than the preset wavelength is doubled to obtain the third frequency-doubled laser.

[0098] Exemplarily, the third frequency doubling crystal 413 is a BBO crystal with a cutting angle of 60°. The fifth concave mirror 411 is a total reflection concave mirror of 250-520nm with a focal length of 5cm. The sixth concave mirror 412 is a total reflection concave mirror of 205-260nm with a focal length of 5cm. The preset wavelength is, for example, 410nm, because the third frequency doubling crystal 413 is installed in the third universal adjustment frame. Therefore, the third frequency doubling component 41 can output a third frequency doubling laser with a wavelength in the 205nm-255nm band and is tunable.

[0099] Figure 8 The figure shows a spectrum diagram of the third frequency-doubled laser output by the third frequency-doubled component provided according to an embodiment of the present invention.

[0100] like Figure 8 The figure shows the result of doubling the second frequency-doubled laser with a wavelength between 410nm and 510nm using a third frequency-doubled component. Part (a) is the linear shape of the third frequency-doubled laser, that is, the relationship between the wavelength and intensity of the third frequency-doubled laser, and part (b) is the relationship between the wavelength and intensity power of the third frequency-doubled laser. It can be seen from part (a) that the third frequency-doubled laser is a deep ultraviolet tunable laser in the 205nm to 255nm band. It can be seen from part (b) that the power of the third frequency-doubled laser can reach more than 650 microwatts. It should be noted that

[0101] In multi-photon photoelectron spectroscopy technology, single-photon, two-photon, three-photon, four-photon and even higher-order multi-photon excitation processes usually require a laser light source covering the 205 nm~1020 nm band. The first optical path switching component, the second optical path switching component, and the third optical path switching component used in the embodiment of the present invention cooperate with each other to achieve rapid switching of the wavelength of the output laser of the optical parametric amplification system between 620~1020nm, 310~510nm, 205~255nm and 255nm~310nm.

[0102] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A tunable laser generating system, characterized in that: include: A laser generating module, adapted to generate a seed light and a first pump laser and a second pump laser having different wavelengths; Amplification module, including: Two reflector groups, adapted to reflect the first pump laser and the second pump laser respectively; a first amplifying crystal and a second amplifying crystal; A first optical path switching component is used to switch the seed light between the first path and the second path so that the seed light is alternately incident on the first amplifying crystal and the second amplifying crystal; The first amplifying crystal uses the reflected first pump laser to perform optical parametric amplification on any wavelength component of the first sub-band of the seed light to obtain the first amplified laser, and the second amplifying crystal uses the reflected second pump laser to perform optical parametric amplification on any wavelength component of the second sub-band of the seed light to obtain the second amplified laser; the wavelength of the first sub-band is different from the wavelength of the second sub-band and can cover all bands of the seed light.

2. The tunable laser generating system according to claim 1, characterized in that: The tunable laser generating system further comprises: A first output module, adapted to switch the transmission of the first amplified laser between the third path and the fourth path, and to double the frequency of the first amplified laser transmitted along the fourth path to obtain a first frequency-doubled laser, and output the first amplified laser transmitted along the third path; and adapted to switch the transmission of the second amplified laser between the fifth path and the sixth path, and to double the frequency of the second amplified laser transmitted along the sixth path to obtain a second frequency-doubled laser, and output the second amplified laser transmitted along the fifth path; The second output module switches the transmission of the second frequency-doubled laser between the seventh path and the eighth path, and doubles the frequency of the second frequency-doubled laser with a wavelength greater than a preset wavelength transmitted along the eighth path to obtain a third frequency-doubled laser, and outputs the second frequency-doubled laser transmitted along the seventh path.

3. The tunable laser generating system according to claim 2, characterized in that: The first output module includes two frequency multiplication components respectively arranged on the fourth path and the fifth path, and the second output module includes a frequency multiplication component arranged on the eighth path; Each of the frequency doubling components includes two concave mirrors and a frequency doubling crystal located between the two concave mirrors. The laser transmitted to the frequency doubling component is focused onto the frequency doubling crystal via one of the concave mirrors, and is output via the other concave mirror after frequency doubling occurs on the frequency doubling crystal. The frequency doubling crystal is mounted on a universal adjustment frame, and the universal adjustment frame is used to adjust the direction of the optical axis of the frequency doubling crystal.

4. The tunable laser generating system according to claim 2, characterized in that: The tunable laser generating system further comprises: The compression module is adapted to compress the pulse width of the first amplified laser and the second amplified laser, and transmit the compressed first amplified laser and the compressed second amplified laser to the first output module.

5. The tunable laser generating system according to claim 4, characterized in that: The pulse width of the compressed first amplified laser light and the compressed second amplified laser light is 25 fs.

6. The tunable laser generating system according to claim 1, characterized in that: The seed light is chirped light, the reflector group includes at least one reflector, the position of the at least one reflector is adjustable, and when the position of the at least one reflector changes, the wavelength component of the first sub-band or the second sub-band amplified by the first pump laser or the second pump laser reflected by the reflector group changes.

7. The tunable laser generating system according to claim 1, characterized in that: The wavelength range of the seed light is λ~2λ.

8. The tunable laser generating system according to claim 7, characterized in that: λ is 510nm.

9. The tunable laser generating system according to claim 1, characterized in that: The laser generating module comprises: A laser, suitable for generating initially polarized laser light; A beam splitting component, adapted to split the initial polarized laser into a first polarized laser and a second polarized laser; A seed light generating component, adapted to generate the seed light according to the first polarized laser light; The pump laser generating component is adapted to obtain the first pump laser and the second pump laser according to the second polarized laser.

10. The tunable laser generating system according to claim 1, characterized in that: An angle between an incident direction of the second pump laser when incident on the second amplifying crystal and an incident direction of the seed light when incident on the second amplifying crystal is 2° to 9°.

Images