High-power liquid quantum dot laser amplifier

Abstract

The invention discloses a high-power liquid quantum dot laser amplifier, which is characterized in that a pump light beam is divided into a light path I and a light path II after entering the laser amplifier, and the light path I and the light path II simultaneously reach a second liquid quantum dot laser medium after being separated; the light path I is sequentially provided with a beam splitter, a cylindrical mirror, a first liquid quantum dot laser medium, a reflective blazed grating, a tunable total reflective mirror, an output coupling mirror, a total reflective mirror, a diaphragm, a collimating lens and a second liquid quantum dot laser medium along the incident direction of a pumping light beam; the light path II is sequentially provided with a beam splitter, two right-angle prisms arranged in a mirror image mode, a collimating lens, a focusing lens and a second liquid quantum dot laser medium in the incident direction of the pump light beam. The method provided by the invention is stable and universal, stable, high-power and tunable liquid quantum dot laser output is realized, and the defects that a gain medium of an organic dye molecule laser in the prior art is easy to inactivate and the working stability is low under high power are effectively overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid laser equipment, and in particular relates to a high-power liquid quantum dot laser amplifier. Background Art

[0002] Solution-based optical amplification effectively avoids a series of challenges faced by excited solid-state thin-film gain media, such as heat accumulation during high-power operation, scattering caused by particle agglomeration, non-radiative losses due to Förster resonance energy transfer, environmental effects on the performance of solid-state gain media, and the influence of film morphology on lasing. Since the 1960s, research on solution lasers has largely focused on using organic dye molecules as gain media, employing simple two-mirror systems or ring fibers as resonators. However, when organic dye molecules are in a static solution, they undergo irreversible photobleaching, necessitating complex pumping systems to maintain constant flow. Furthermore, under continuous optical excitation, organic dye molecules gradually photodecompose, hindering stable high-power laser output. Colloidal semiconductor quantum dots, with their high optical absorption coefficient, photoluminescence quantum yield, and compositionally tunable band gap, are theoretically well-suited to replace organic dye molecules as a next-generation liquid-liquid quantum dot laser medium. However, current research on colloidal quantum dot lasers has been largely limited to solid-state lasers, with only a few reports demonstrating initial lasing in liquids. The output power and system stability fall far short of practical requirements. Therefore, developing a liquid quantum dot laser amplifier with high average power and high beam quality is of great significance to the application development of liquid lasers. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-power liquid quantum dot laser amplifier, which can effectively solve the problems existing in the background technology.

[0004] In order to address the defects of the prior art, the present invention provides a high-power liquid quantum dot laser amplifier that adopts a grazing incidence grating working mode to tune the liquid quantum dot laser emission wavelength and a double-sided transverse pumping mode to achieve the amplification effect of the injected laser. After the pump beam enters the laser amplifier, it is divided into optical path I and optical path II. After optical path I and optical path II are separated, they simultaneously reach the second liquid quantum dot laser medium 10; the optical path I is provided with: a beam splitter 1, a cylindrical mirror 2, a first liquid quantum dot laser medium 3, a reflective blazed grating 4, a tunable total reflection mirror 5, an output coupling mirror 6, a total reflection mirror 11, an aperture 7, a collimating lens 8 and a second liquid quantum dot laser medium 10 in sequence along the incident direction of the pump beam; the optical path II is provided with: a beam splitter 1, two mirrored right-angle prisms 9, a collimating lens 12, a focusing lens 13 and a second liquid quantum dot laser medium 10 in sequence along the incident direction of the pump beam.

[0005] The pump beam is always kept at a fixed height and transmitted in the laser. The injected laser is spatially shaped by the focusing lens 13 and focused into a thin line in the transverse direction of the laser amplifier to provide high-energy excitation light. The first liquid quantum dot laser medium 3 is made of quartz (the pulse laser damage threshold is 20 MW / cm 2 The peak intensity of the pump light pulse is controlled at 20 MW / cm 2 under.

[0006] The resonant cavity consists of a first liquid quantum dot laser medium 3, a reflective blazed grating 4, a tunable total reflection mirror 5 and an output coupling mirror 6, with a cavity length of 15 cm. The reflective blazed grating 4 has a specification of 1200 lines / mm, a blazed wavelength of 500nm, and a width of 50 mm. The tunable total reflection mirror 5 is a gold-film broadband reflector. The output coupling mirror 6 has high reflectivity to the output wavelength of the liquid quantum dot laser (reflectivity R > 95%) and enhances the transmittance of the pump beam (transmittance T > 95%).

[0007] The output wavelength range of the liquid quantum dot laser is tuned by using a grazing-incidence reflective blazed grating 4. The laser is diffracted twice in the grazing-incidence grating to improve the resolution. The wavelength is tuned by fixing the grazing-incidence angle of the grating and rotating the total reflection mirror 5.

[0008] A high-power liquid quantum dot laser amplifier is realized by adopting the main resonance-power amplification method, which mainly includes a resonant cavity and an amplifier. Considering the trigger delay of the output laser pulse and the change of the laser pulse width, the time matching of the liquid quantum dot laser pulse and the pump laser pulse is achieved by adjusting the optical path; the laser pulse waveform is digitized by collecting signals, and the peak point of the laser pulse is used as the measurement point for delay measurement. Only the wave packet near the peak is selected for binomial fitting to estimate the delay time; the strong first-order diffraction light is fed back into the resonant cavity after being fed back by a total reflection mirror to continue oscillating, and the quantum dot laser transmitted along the axial direction is finally output along the zero-order direction of the grating diffraction; the second liquid quantum dot laser medium 10 is injected and propagates in a direction perpendicular to the pump beam; the pump beam provides energy for the quantum dot to transition from the ground state to the excited state, and the first excited state produces stimulated radiation transition under the stimulation of the injected laser, thereby realizing the amplification effect of the injected laser.

[0009] As a further optimization solution: the first liquid quantum dot laser medium 3 and the second liquid quantum dot laser medium 10 are colloidal quantum dot suspensions with high dispersibility and high stability, and the quantum dot concentration is not less than 100 μmol / L.

[0010] As a further optimization solution: taking the pump laser pulse energy of 25 mJ as an example, the width of the liquid quantum dot gain medium pool is set at about 3.6 mm.

[0011] As a further optimization solution: the liquid quantum dot gain medium pool is placed non-horizontally at positions 3 and 10.

[0012] As a further optimization solution: the distance between the liquid quantum dot liquid quantum dot laser medium and the grating center d ≈ (say 2 ) / min ,in oh is the beam waist radius of the pump light in the liquid quantum dot laser medium.

[0013] Beneficial effects: The method provided by the present invention is stable and universal, achieving stable high-power tunable liquid quantum dot laser output, effectively making up for the shortcomings of the prior art organic dye molecular laser, such as easy deactivation of the gain medium and low working stability at high power. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0016] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] See Figure 1 This specific embodiment is implemented by adopting the following technical solutions. After the pump beam enters the laser, it is divided into two optical paths and reaches the second liquid quantum dot laser medium 10 at the same time. For optical path I, along the incident direction of the pump beam, there are arranged in sequence: a beam splitter 1, a cylindrical mirror 2, a first liquid quantum dot laser medium 3, a reflective blazed grating 4, a tunable total reflection mirror 5, an output coupling mirror 6, a total reflection mirror, an aperture 7, a collimating lens 8 and a second liquid quantum dot laser medium 10. For optical path II, along the incident direction of the pump beam, there are arranged in sequence: a beam splitter 1, two mirror-set right-angle prisms 9, a collimating lens 12, a focusing lens 13 and a second liquid quantum dot laser medium 10.

[0018] The working process of the device of the present invention is as follows: the pump light enters the system horizontally and is first split into two optical paths (optical path I and optical path II) by a beam splitter 1; for optical path I: the pump light is converted into horizontal stripes by a cylindrical mirror 2 to excite the first liquid quantum dot laser medium 3 of the liquid quantum dot; the spontaneous radiation light is amplified due to the waveguide effect and emitted from one end of the liquid quantum dot pool and enters the reflective blazed grating 4 at a fixed angle; the first-order diffraction light oscillates after passing through a tunable total reflection mirror 5 and returns to the resonant cavity to continue oscillating, and then is axially output to the output coupling mirror 6 along the 0th-order diffraction direction of the grating; then it is reflected by a total reflection mirror to an aperture 7, and the injected liquid quantum dot laser light after spatial shaping is formed into a collimated beam by a collimating lens 8 and reaches the second liquid quantum dot laser medium 10; for optical path II: the pump light transmitted through two right-angle prisms is formed into a collimated beam by a collimating lens and then spatially shaped into a stripe shape by a cylindrical mirror, and reaches the second liquid quantum dot laser medium 10 at the same time as the injected liquid quantum dot laser. Here, the laser beam injected into the liquid quantum dots and the pump beam propagate in perpendicular intersecting directions. The pump light intensity provides the energy for the quantum dots to transition from the ground state to the excited state. The first excited state produces stimulated radiation transition under the excitation of the laser injected into the liquid quantum dots, realizing the amplification effect of the injected laser.

[0019] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-power liquid quantum dot laser amplifier, characterized in that: After the pump light beam enters the laser amplifier, it is divided into an optical path I and an optical path II. After the optical path I and the optical path II are separated, they simultaneously reach the second liquid quantum dot laser medium (10). The optical path I is provided with: a beam splitter (1), a cylindrical mirror (2), a first liquid quantum dot laser medium (3), a reflective blazed grating (4), a tunable total reflection mirror (5), an output coupling mirror (6), a total reflection mirror (11), an aperture (7), a collimating lens (8), and a second liquid quantum dot laser medium (10) in sequence along the incident direction of the pump light beam. The optical path II is provided with: a beam splitter (1), two mirror-arranged right-angle prisms (9), a collimating lens (12), a focusing lens (13), and a second liquid quantum dot laser medium (10) in sequence along the incident direction of the pump light beam.

2. A high-power liquid quantum dot laser amplifier according to claim 1, characterized in that: The first liquid quantum dot laser medium (3) and the second liquid quantum dot laser medium (10) are colloidal quantum dot suspensions with high dispersibility and high stability.

3. A high-power liquid quantum dot laser amplifier according to claim 1 or 2, characterized in that: The first liquid quantum dot laser medium (3) and the second liquid quantum dot laser medium (10) are contained in a non-horizontally placed quartz cuvette.

4. A high power liquid quantum dot laser amplifier according to claim 1, characterized in that: The resonant cavity is composed of a first liquid quantum dot laser medium (3), a reflective blazed grating (4), a tunable total reflection mirror (5) and an output coupling mirror (6), and the cavity length is about 15 cm.

5. A high power liquid quantum dot laser amplifier according to claim 1 or 4, characterized in that: The reflective blazed grating (4) has a specification of 1200 lines / mm, a blazing wavelength of 500 nm, and a width of 50 mm.

6. A high-power liquid quantum dot laser amplifier according to claim 4, characterized in that: The tunable total reflection mirror (5) is a gold film broadband reflection mirror.

7. A high power liquid quantum dot laser amplifier according to claim 4, characterized in that: The output coupling mirror (6) has high reflectivity (reflectivity R>95%) for the output wavelength of the liquid quantum dot laser and increases transmittance (transmittance T>95%) for the pump light.

8. A high-power liquid quantum dot laser amplifier according to claim 4, characterized in that: The grating working mode adopts grazing incidence to tune the liquid quantum dot laser, fixes the grating grazing incidence angle, and adjusts the total reflection mirror angle to achieve tunable output of the liquid quantum dot laser.

9. A high power liquid quantum dot laser amplifier according to claim 4, characterized in that: The distance between the first liquid quantum dot laser medium (3) and the center of the grating d ≈ (πω 2 ) / λ ,in ω is the beam waist radius of the pump light in the liquid quantum dot laser medium.

10. The high-power liquid quantum dot laser amplifier according to claim 1, characterized in that: After the pump light enters the laser, it is divided into two light paths. By adjusting the optical path, the two light beams arrive at the second liquid quantum dot laser medium (10) at the same time. Here, the injected laser light beam propagates through the amplifier in a direction perpendicular to the pump light beam, thereby achieving an amplification effect of the injected laser.

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