A tunable laser generation system

Abstract

The present invention provides a tunable laser generation system, which relates to the field of nonlinear optical parametric amplification. The tunable laser generation system includes: a laser generation module and an amplification module. The laser generation module is suitable for generating seed light and a first pump laser and a second pump laser; the amplification module includes: two reflector groups, suitable for reflecting 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, suitable for allowing the seed light to alternately enter the first amplifying crystal and the second amplifying crystal; wherein 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.

Description

Technical Field

[0001] The present invention relates to the field of nonlinear optical parametric 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 a nonlinear crystal. Its core principle is to transfer part of the pump laser's energy to the signal and idler light using second-order nonlinear polarization effects (such as the χ² effect). OPA technology offers flexible wavelength tuning, a wide gain bandwidth, and high peak power, making it an important application in ultrafast lasers, high-resolution spectroscopy, and quantum optics. However, existing OPA technology faces challenges when amplifying broadband seed light. When the seed light wavelength range is wide (e.g., covering an octave or wider), the phase matching bandwidth of a single nonlinear crystal is often insufficient to cover the entire seed light band. This is because the crystal's phase matching conditions (such as angle tuning or temperature tuning) are highly wavelength-sensitive, resulting in a limited gain bandwidth. To address this issue, existing methods typically use two nonlinear crystals to achieve optical parametric amplification of the seed light. However, this approach significantly reduces or even completely eliminates the amplification efficiency of certain wavelength components of the seed light. 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 of different wavelengths;

[0006] Amplification module, including:

[0007] two reflecting mirror 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 adapted 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 that of the second sub-band and can cover all wavelength bands of the seed light.

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

[0012] The first output module is configured to switch the transmission of the first amplified laser light between the third path and the fourth path, and to double the frequency of the first amplified laser light transmitted along the fourth path to obtain first frequency-doubled laser light, and output the first amplified laser light transmitted along the third path; and is configured to switch the transmission of the second amplified laser light between the fifth path and the sixth path, and to double the frequency of the second amplified laser light transmitted along the sixth path to obtain second frequency-doubled laser light, and output the second amplified laser light 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 causes the second frequency-doubled laser with a wavelength greater than the preset wavelength transmitted along the eighth path to undergo double frequency 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 assembly includes two concave mirrors and a frequency doubling crystal located between the two concave mirrors. The laser transmitted to the frequency doubling assembly is focused onto the frequency doubling crystal through one of the concave mirrors. After double frequency generation on the frequency doubling crystal, the laser is output through the other concave mirror. The frequency doubling crystal is mounted on a universal adjustment mount, 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 includes:

[0017] The compression module is 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.

[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, and the position of the at least one reflector is adjustable. 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 includes:

[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 beam;

[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 seed light has a wide wavelength range, such as when the seed light is supercontinuum white light (e.g., supercontinuum white light with a wavelength range of 510nm to 1020nm), two amplifying crystals are required to achieve 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. Under the action of the first pump laser and the second pump laser, respectively, the first amplifying crystal and the second amplifying crystal achieve optical parametric amplification of any wavelength components in the two sub-bands of the seed light. Because the wavelengths of the first and second sub-bands are different and cover the entire wavelength range of the seed light, the range of optical parametric amplification achieved by the first and second pump lasers can cover the entire wavelength range of the seed light. With the first optical path switching component, there is no need to use a beam splitter to split the seed light and separately inject it into the two amplifying crystals, thus 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 one embodiment of the present invention;

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

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

[0032] Figure 4 shows the spectrum of the second amplified laser light 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 shows a spectrum diagram of the first frequency-doubled laser output by the first frequency-doubled component provided in an embodiment of the present invention;

[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 reflection mirror; 341-third flip reflector; 342-fifth total reflection mirror; 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 reflection mirror. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. However, the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present invention thorough and complete and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity, and like reference numerals denote like elements throughout.

[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 presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0041] Figure 1 FIG2 shows an optical path diagram of a tunable laser generating system according to an embodiment of the present invention.

[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 generation module 1 is suitable for generating seed light and for generating a first pump laser and a second pump laser of different wavelengths. The amplification 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 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 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 seed light has a wide wavelength range, such as when the seed light is supercontinuum white light (e.g., supercontinuum white light with a wavelength range of 510nm to 1020nm), two amplifying crystals are required to achieve optical parametric amplification of the seed light. Under the action of the first optical path switching component 21, the seed light can be directed into the first amplifying crystal 22 or the second amplifying crystal 23. Under the action of the first pump laser and the second pump laser, respectively, the first amplifying crystal 22 and the second amplifying crystal 23 achieve optical parametric amplification of any wavelength components in the two sub-bands of the seed light. Because the wavelengths of the first and second sub-bands are different and cover the entire wavelength range of the seed light, the range of optical parametric amplification achieved by the first and second pump lasers can cover the entire wavelength range of the seed light. With the first optical path switching component 21, there is no need to use a beam splitter to split the seed light and separately inject it into the two amplifying crystals, thus avoiding the problem of wavelength loss introduced by the beam splitter.

[0046] For example, the seed light has a wavelength range of 510 nm to 1020 nm. The first amplifying crystal 22 is a BBO crystal with a 37° cut angle, and the second amplifying crystal 23 is a BBO crystal with a 26.5° cut angle. Under specific phase matching conditions, the first amplifying crystal 22 can use the first pump light to amplify any wavelength component in the first sub-band of the seed light, i.e., the 510-620 nm sub-band, to produce a first amplified laser with a wavelength in the 510-620 nm band. The second amplifying crystal 23 can use the second pump light to amplify any wavelength component in the second sub-band of the seed light, i.e., the 620-1020 nm sub-band, to produce a second amplified laser with a wavelength in the 620-1020 nm band.

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

[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 is used to focus the seed light onto the first amplification crystal 22 when the seed light is transmitted along the first path. 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 the at least one reflector is adjustable. When the position of the at least one reflector changes, the wavelength components 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 change. Specifically, when the seed light is chirped light, the different wavelength components (frequency components) of the seed light have different time delays when reaching the amplifying crystal. To achieve selective amplification of specific wavelength components of the seed light, two conditions must be met. First, the pump light (first pump light or second pump light) must achieve optimal time delay matching with a specific wavelength component of the seed light within the amplifying crystal (first amplifying crystal 22 or second amplifying crystal 23). Second, the angle between the pump light and the seed light must ensure that the phase matching condition for the specific wavelength component of the seed light is met. Therefore, changing the amplified wavelength component of the seed light requires changing the optical path of the pump light and the angle between the pump light and the seed light. Both of these changes can be achieved by adjusting the position of the reflector. By flexibly adjusting the reflector's position, the amplified wavelength can be dynamically adjusted, achieving 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 amplifying 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 amplifying 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 reflective mirror 241 and at least one second reflective mirror 251 can be mounted on a linear translation stage, and the linear translation stage can be used to change the posture of at least one first reflective mirror 241 or at least one second reflective mirror 251. The stroke of the linear translation stage can 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° to 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° to 9°, the second pump laser can be used to achieve effective optical parametric amplification of the seed light in the 920-1020 nm band.

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

[0055] According to an embodiment of the present invention, a single laser 11 is used to generate the seed light and two pump lasers. This reduces the number of lasers required compared to using multiple lasers, thereby simplifying the optical path design and system structure. This not only reduces hardware costs but also reduces the size and complexity of the system, facilitating integration. Because the seed light and the two pump lasers originate from the same laser source, the optical properties (such as time delay, bandwidth, etc.) of the white light seed light and the two pump lasers are highly consistent. This consistency helps optimize phase matching conditions during optical parametric amplification, improves wavelength conversion efficiency, and ensures wavelength stability of the output laser. The initial polarized laser light generated by the laser 11 in this embodiment of the present invention is efficiently distributed to the seed light generating assembly 13 and the pump laser generating assembly 14 through the beam splitting assembly 12, avoiding the problem of uneven energy distribution in a system including multiple lasers. The use of a single laser 11 in this embodiment of the present invention maximizes the utilization of the initial laser energy, resulting in higher overall system efficiency.

[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 third harmonic light generated by the pump laser generating assembly 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 assembly are the same. When the amplifying crystals are type II phase-matched crystals, the polarization directions of the first polarized laser and the second polarized laser generated by the beam splitting assembly 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 (i.e., the polarization directions are perpendicular). However, the second harmonic light and the third harmonic light generated by nonlinear frequency conversion have opposite polarization directions to 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 Only the composition of the beam splitter assembly 12 when the optical parametric amplification crystal is a type II phase-matched crystal is shown in FIG. 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 assembly 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. 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 being totally reflected by two first total reflection mirrors 133, the first polarized laser light enters the white light crystal 131 under the focus of the first lens 132, generating initial white light. This initial white light is then re-collimated into parallel white light by the second lens 134. Subsequently, the initial polarized laser light included in the parallel white light is effectively filtered out by the filter 135, resulting in seed light. The second total reflection mirror 136 is used to reflect the seed light to change its optical path. For example, this second total reflection mirror 136 can have a wavelength of 450 to 1100 nm.

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

[0064] According to an embodiment of the present invention, when the wavelength of the seed light is in the range of 510 nm to 1020 nm, white light crystal 131 can be, for example, a sapphire crystal with a thickness of 3 mm. The following describes in detail the principle by which the first polarized laser beam incident on white light crystal 131 generates initial white light with a spectral range of 510 nm to 1020 nm.

[0065] When a polarized laser with a sufficiently strong peak power enters a transparent medium, under the combined action 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 various 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 coincide 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 the embodiment of the present invention, for example, a sapphire crystal with a thickness of 3 mm can be selected as the white light crystal.

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

[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, which can generate supercontinuum white light with a wavelength covering 510nm~1020nm.

[0068] According to an embodiment of the present invention, the pump laser generation assembly 14 includes: a plurality of third reflectors 141, a third lens 142, a second harmonic generation crystal 143, a third harmonic generation 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, deflected by the third reflector 141, and focused by the third lens 142. The focused beam is deflected by the second third reflector 142, with the focal point falling between the second harmonic generation crystal 143 and the third harmonic generation crystal 144, respectively, producing the second harmonic light and the third harmonic light of the second polarized laser light. The wavelength of the second harmonic light is, for example, 515 nm, and the wavelength of the third harmonic light is, for example, 343 nm. The first harmonic beam splitter 145 reflects the third harmonic light and transmits it and the remaining second polarized laser light. The second harmonic beam splitter 146 reflects the second harmonic light and transmits the remaining second polarized laser light. Under the action of two harmonic beam splitters, the separation of second harmonic light, third harmonic light and second polarization laser light is achieved.

[0069] Illustratively, 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 light 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 line shape of the first amplified laser light obtained by optically parametrically amplifying the seed light using third-harmonic light, that is, the variation of the light intensity of the first amplified laser light with wavelength. Part (b) shows the relationship between the wavelength and power of the first amplified laser light obtained by optically parametrically amplifying the seed light using third-harmonic light.

[0072] exist Figure 3 In this example, the third harmonic wavelength is 343 nm, the seed light wavelength range is 510 nm to 1020 nm, and the first amplifying crystal 22 is a BBO crystal with a 37° cut angle. As shown in part (a), the first amplified laser light generated by optical parametric amplification of the white seed light using the third harmonic light is a tunable laser with a wavelength in the 510–620 nm band. Part (b) shows that the power of the first amplified laser light in the 510–620 nm band is maintained above 10 mW, with a local peak power reaching 30 mW.

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

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

[0075] exist Figure 4 In this example, the wavelength of the second harmonic light is 515 nm, the wavelength of the seed light ranges from 510 nm to 1020 nm, and the second amplifying crystal 23 employed is a BBO crystal with a 26.5° cut angle. As shown in part (a), the second amplified laser light generated by optical parametric amplification of the white seed light using the second harmonic light is a tunable laser with a wavelength in the 620–1020 nm band. Part (b) shows that the power of the second amplified laser light in the 620–1020 nm band is maintained above 30 mW, with a local peak power reaching 130 mW.

[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 light that passes through the first amplifying crystal 22. The third light block 7 is used to block the remaining second pump laser light that passes through the second amplifying crystal 23.

[0077] Figure 5 FIG. 2 shows an optical path diagram of a tunable laser generating system according to another embodiment of the present invention.

[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 configured to switch the transmission of the first amplified laser between the third and fourth paths, and to cause the first amplified laser transmitted along the fourth path to undergo frequency doubling to obtain first frequency-doubled laser light, while the first amplified laser transmitted along the third path is output. The first output module 3 is also configured to switch the second amplified laser between the fifth and sixth paths, and to cause the second amplified laser transmitted along the sixth path to undergo frequency doubling to obtain second frequency-doubled laser light, while the second amplified laser transmitted along the fifth path is output. The second output module 4 is configured to switch the second frequency-doubled laser between the seventh and eighth paths, and to cause the second frequency-doubled laser transmitted along the eighth path, which has a wavelength greater than a preset wavelength, to undergo frequency doubling to obtain third frequency-doubled laser light, while 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 includes 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 primary amplified laser can significantly increase its peak power, concentrating its energy temporally. This is particularly important for nonlinear optical processes such as frequency doubling, as frequency doubling efficiency is generally proportional to the laser's peak power. Higher peak power significantly improves the conversion efficiency of the frequency doubling module, resulting in stronger frequency doubling light output. In multiphoton photoelectron spectroscopy or ultrafast spectroscopy, laser pulses with pulse widths less than 25 fs offer extremely high temporal resolution. This is crucial for studying ultrafast dynamics such as molecular vibrations and electronic transitions, as only sufficiently short pulses can capture these rapidly changing transient phenomena. In optical parametric amplification and frequency doubling, phase matching conditions significantly influence wavelength conversion efficiency. Ultrashort pulse lasers, with their wider spectral bandwidth, better meet phase matching requirements, thereby improving wavelength conversion efficiency and stability. Ultrashort pulse lasers have a wide range of applications in quantum computing, ultrafast spectroscopy, and nonlinear optics. By compressing the pulse width to less than 25fs, the requirements for high temporal resolution and high peak power in these fields can be met, thereby expanding the application scope of optical parametric amplification systems.

[0083] For example, when the wavelength of the first amplified laser is in the 510nm to 620nm range, a frequency doubling process can generate a first frequency-doubled laser in the 255nm to 310nm range. When the wavelength of the second amplified laser is in the 620nm to 1020nm range, a frequency doubling process can generate a second frequency-doubled laser in the 310nm to 510nm range. Specifically, the second output module 4 can, for example, perform a frequency doubling process on the second frequency-doubled laser with a wavelength greater than 410nm, thereby obtaining a third frequency-doubled laser in the 205nm to 255nm range. It should be noted that since 205nm is the frequency doubling limit of a BBO crystal, components less than 205nm cannot be present when using a BBO crystal. Therefore, when a wavelength of 410nm is frequency-doubled, the resulting 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 continuously tunable output in a wide spectrum band 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 located on the fourth and sixth paths, respectively, and the 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. Laser light transmitted to the frequency doubling component is focused onto the frequency doubling crystal via one of the concave mirrors. After undergoing frequency doubling on the frequency doubling crystal, the laser light is output via the other concave mirror. The frequency doubling crystal is mounted on a universal adjustment mount, which 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 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 positioned between the first and second concave mirrors 311, 312. The first frequency doubling crystal 313 is mounted on a first gimbal mount. The second frequency doubling component 32 includes a third concave mirror 321, a fourth concave mirror 322, and a second frequency doubling crystal 323 positioned between the third and fourth concave mirrors 321, 322. The second frequency doubling crystal 323 is mounted on a second gimbal mount. The second optical path switching component 33 includes a second flip-up reflector 331 and a fourth total reflection mirror 332. The third optical path switching component 34 includes a third flip-up reflector 341 and a fifth total reflection mirror 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 then doubled in frequency to obtain a first frequency doubling laser, which is collimated by the second concave mirror 312 and then output. Since the first frequency doubling crystal 313 is installed in the first universal adjustment frame, the angle between the transmission direction of the first amplified laser and the optical axis of the first frequency doubling crystal 313 can be Under the action of the first universal adjustment frame, the frequency doubling of the first amplified laser light of different wavelengths can be achieved. The eighth lens 35 is used to focus the first amplified laser light onto the second flip-up reflector 331.

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

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

[0091] exist Figure 6 In the figure, the wavelength of the first amplified laser input to the first frequency-doubling component lies in the 510-620 nm range. As shown in part (a), the first frequency-doubling component outputs a deeply tunable laser in the ultraviolet to deep ultraviolet wavelength range of 255-310 nm. Part (b) shows that the power of the first frequency-doubling component's output reaches 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 reflection mirror 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 then doubled in frequency to obtain a second frequency doubling laser. The second frequency doubling laser 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 angle between the transmission direction of the second amplified laser and the optical axis of the second frequency doubling crystal 323 can be The ninth lens 36 is used to focus the second amplified laser light onto the third flip-up reflector 341.

[0093] Exemplarily, the second frequency-doubling crystal 323 is a BBO crystal with a 30° cut angle. The third concave mirror 321 and the fourth concave mirror 322 are total reflection concave mirrors with a focal length of 5 cm. The total reflection wavelengths of the third concave mirror 321 and the fourth concave mirror 322 are 450-1100 nm and 250-520 nm, respectively. When the wavelength of the second amplified laser is in the 620-1020 nm range, the second frequency-doubling assembly 32 can frequency-double the second amplified laser in the 620-1020 nm range, producing a tunable second frequency-doubled laser in the 310-510 nm wavelength range.

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

[0095] exist Figure 7 In the figure, the wavelength of the second amplified laser input to the second frequency-doubler assembly lies in the 620-1020 nm range. As shown in part (a), the second frequency-doubler laser output from the second frequency-doubler assembly is a tunable laser in the ultraviolet to visible range of 310-510 nm. Part (b) shows that the power of the second frequency-doubler 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 reflection mirror 422. 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 adjusted at Flexible internal adjustment.

[0097] The fourth reversible reflector 421 is used to switch the second frequency-doubled laser light between the seventh and eighth paths. The sixth total reflection mirror 422 is used to reflect the second frequency-doubled laser light transmitted along the seventh path, thereby outputting the seventh amplified laser light transmitted along the seventh path. The second frequency-doubled laser light transmitted along the eighth path is transmitted to the fifth concave mirror 411. The second frequency-doubled laser light is converged by the fifth concave mirror 411 to the third frequency-doubled laser light crystal 413. Under the action of the third frequency-doubled laser light crystal 413, the second frequency-doubled laser light, which has a wavelength greater than the preset wavelength, is doubled in frequency to produce the third frequency-doubled laser light.

[0098] Exemplarily, the third-harmonic frequency-doubled crystal 413 is a BBO crystal with a 60° cut angle. The fifth concave mirror 411 is a 250-520 nm total reflection concave mirror with a focal length of 5 cm. The sixth concave mirror 412 is a 205-260 nm total reflection concave mirror with a focal length of 5 cm. The preset wavelength is, for example, 410 nm. Since the third-harmonic frequency-doubled crystal 413 is mounted in a third gimbal mount, the third-harmonic frequency-doubled assembly 41 can output a tunable third-harmonic frequency laser with a wavelength in the 205-255 nm band.

[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 As shown in the figure, it is the result of doubling the second frequency-harmonic laser with a wavelength of 410nm~510nm by using a third frequency-harmonic component. Part (a) is the linear shape of the third frequency-harmonic laser, that is, the relationship between the wavelength and intensity of the third frequency-harmonic laser, and part (b) is the relationship between the wavelength and intensity power of the third frequency-harmonic laser. It can be seen from part (a) that the third frequency-harmonic laser is a deep ultraviolet tunable laser in the 205nm~255nm band. It can be seen from part (b) that the power of the third frequency-harmonic 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 ~ 1020 nm, 310 ~ 510 nm, 205 ~ 255 nm and 255 nm ~ 310 nm.

[0102] The above specific embodiments further illustrate the objectives, 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 scope of protection of the present invention.

Claims

1. A tunable laser generating system, characterized in that: include: A laser generating module is adapted to generate a seed light and a first pump laser and a second pump laser of different wavelengths; 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 light into a first polarized laser light and a second polarized laser light; a seed light generating component, adapted to generate the seed light according to the first polarized laser light; a pump laser generating assembly adapted to generate the first pump laser and the second pump laser according to the second polarized laser; 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, adapted 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; 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 a 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 a second amplified laser. 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 first pump laser is the third harmonic light of the second polarized laser, the second pump laser is the second harmonic light of the second polarized laser, the wavelength of the second harmonic light is 515 nm, the wavelength of the third harmonic light is 343 nm, the wavelength range of the seed light is λ~2λ, λ is 510 nm, the first sub-band is 510 nm~620 nm, and the second sub-band is 620 nm~1020 nm.

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 a third path and a 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 a fifth path and a 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 causes the second frequency-doubled laser with a wavelength greater than the preset wavelength transmitted along the eighth path to undergo double frequency 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 one 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. After the laser is doubled in frequency on the frequency doubling crystal, it is output via the other concave mirror. The frequency doubling crystal is mounted on a universal adjustment mount, which 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, wherein: The tunable laser generating system further comprises: The compression module is 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.

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, wherein: The seed light is chirped light, the reflector group includes at least one reflector, and the position of the at least one reflector is adjustable. 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, wherein: 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°.

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