Non-mode-locking ultrafast laser

Abstract

The invention relates to a non-mode-locking ultrafast laser which comprises a pump laser, a resonant cavity and a laser gain medium, and further comprises a phase conjugate mirror and a dispersion element which are sequentially arranged between the laser gain medium and a laser output cavity mirror, and the phase conjugate mirror and the dispersion element are both arranged on a laser light path. The laser output cavity mirror is a laser coupling output cavity mirror; the laser further comprises a light beam shaping system arranged between the pump laser and the resonant cavity, and the light beam shaping system shapes light emitted by the pump laser into a flat-topped laser beam. According to the laser, pulse lasers with different wavelengths are generated at different positions of the gain crystal through cooperation of the dispersion element and the spatial filter, and the Q-switched device on the main optical path can enable synchronous oscillation starting of different wavelengths, incoherent superposition of the pulse lasers with different wavelengths on the main optical path and pulse width compression on a time domain. And therefore, ultra-fast laser with narrow pulse width is generated.

Description

Technical Field

[0001] The invention relates to a non-mode-locked ultrafast laser, belonging to the technical field of ultrafast lasers. Background Art

[0002] Ultrafast lasers are also called ultrashort pulse lasers, which generally refer to lasers with pulse widths of picoseconds or femtoseconds. Ultrafast lasers in the prior art are all mode-locked lasers, and the mode-locking methods include Kerr lens mode-locking, SESAM mode-locking, and active mode-locking by acousto-optic modulators. Lasers with pulse widths in the order of ps or even fs. They have the advantages of ultrashort pulse width, high single pulse energy, and high repetition rate. They are one of the most powerful research tools in scientific research fields such as satellite ranging, laser fine micromachining, nonlinear optics, laser spectroscopy, biomedicine, strong field optics, and condensed matter physics.

[0003] The mode-locked method of producing fast laser systems is complex and easily affected by temperature fluctuations, making stable operation difficult. Summary of the invention

[0004] In order to overcome the above problems, the present invention provides a non-mode-locked ultrafast laser, which has a simple structure, a mature and stable Q-switching process, and a strong environmental adaptability of the system.

[0005] The technical solution of the present invention is as follows:

[0006] A non-mode-locked ultrafast laser comprises a pump laser, a resonant cavity and a laser gain medium, and further comprises a phase conjugate mirror and a dispersion element which are sequentially arranged between the laser gain medium and a laser output cavity mirror, wherein the phase conjugate mirror and the dispersion element are both arranged on a laser optical path; the laser output cavity mirror is a laser coupling output cavity mirror; and further comprises a beam shaping system which is arranged between the pump laser and the resonant cavity, wherein the beam shaping system shapes the light emitted by the pump laser into a flat-top laser beam.

[0007] Furthermore, the dispersion element is a diffraction grating or a prism or a combination of a diffraction grating and a diffraction grating or a combination of a prism and a prism or a combination of a diffraction grating and a prism.

[0008] Furthermore, the diffraction grating is a reflection grating or a transmission grating.

[0009] Furthermore, the diffraction grating is a plane grating.

[0010] Furthermore, the dispersion element includes a first reflection grating and a second reflection grating; the first reflection grating and the second reflection grating are parallel, and the light emitted by the laser gain medium is reflected by the first reflection grating, reaches the second reflection grating, and then reflects by the second reflection grating to reach the laser output cavity mirror.

[0011] Furthermore, a Q-switching device is provided between the dispersion element and the laser output cavity mirror, and the Q-switching device is located on the laser optical path.

[0012] Furthermore, it also includes a spatial filter arranged between the phase conjugate mirror and the dispersion element.

[0013] The present invention has the following beneficial effects:

[0014] The laser uses a dispersion element in conjunction with a spatial filter to generate pulsed lasers of different wavelengths at different positions of the gain crystal. The Q-switched device on the main optical path can synchronize the oscillation of different wavelengths, perform incoherent superposition of pulsed light of different wavelengths on the main optical path, and compress the pulse width in the time domain, thereby generating ultrafast lasers with narrow pulse widths. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 2 is a light path diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] refer to Figure 1 A non-mode-locked ultrafast laser comprises a pump laser, a resonant cavity and a laser gain medium, and also comprises a phase conjugate mirror and a dispersion element sequentially arranged between the laser gain medium and the laser output cavity mirror, wherein the phase conjugate mirror and the dispersion element are both arranged on the laser optical path; the laser output cavity mirror is a laser coupling output cavity mirror; and also comprises a beam shaping system arranged between the pump laser and the resonant cavity, wherein the beam shaping system shapes the light emitted by the pump laser into a flat-top laser beam.

[0018] The laser gain medium is preferably a wide-bandwidth laser gain medium because the lasing bandwidth is related to the bandwidth of the laser gain medium.

[0019] The phase conjugate mirror is used to eliminate the wavefront distortion between different lasers. The source of the distortion is the laser gain medium, so the phase conjugate mirror needs to be placed between the dispersion element and the laser gain medium.

[0020] The function of the dispersion element is to change the optical path of lasers at different positions so that lasers of different wavelengths can resonate.

[0021] To generate lasers of different wavelengths at different positions in the gain crystal, the gain needs to be greater than the loss, and the pump light energy at each position must be sufficient. If the pump light is not shaped into a flat-top beam, the position with low pump power will have insufficient gain, resulting in the output laser spectrum not being wide enough and unable to produce a narrow enough pulse width.

[0022] In one embodiment of the present invention, the dispersive element is a diffraction grating or a prism or a combination of a diffraction grating and a diffraction grating or a combination of a prism and a prism or a combination of a diffraction grating and a prism.

[0023] Specifically, the dispersive element may be a prism pair or a diffraction grating pair.

[0024] In one embodiment of the present invention, the diffraction grating is a reflection grating or a transmission grating.

[0025] In one embodiment of the present invention, the diffraction grating is a plane grating.

[0026] In one embodiment of the present invention, the dispersion element includes a first reflection grating and a second reflection grating; the first reflection grating and the second reflection grating are parallel, and the light emitted by the laser gain medium is reflected by the first reflection grating, reaches the second reflection grating, and then reflects by the second reflection grating to reach the laser output cavity mirror.

[0027] In one embodiment of the present invention, a Q-switching device is provided between the dispersion element and the laser output cavity mirror, and the Q-switching device is located on the laser optical path.

[0028] In one embodiment of the present invention, a spatial filter is further included between the phase conjugate mirror and the dispersion element.

[0029] The spatial filter improves the quality of laser beam by filtering out the high-order modes of the laser. It consists of two lenses + 1 pinhole light bar. The lenses are positive lenses placed on both sides of the pinhole light bar, and the pinhole light bar is placed at the focus of the two lenses. After the lens is focused, the spot size of the high-order mode is larger, and the loss of the high-order mode is increased through the pinhole, which suppresses the oscillation of the high-order mode laser, thereby improving the laser beam quality. It works together with the dispersion element to improve the beam quality of lasers (with different wavelengths) that are oscillated at different positions.

[0030] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure made using the contents of the present invention's specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A non-mode-locked ultrafast laser, comprising a pump laser, a resonant cavity and a laser gain medium, characterized in that: It also includes a phase conjugate mirror and a dispersion element which are sequentially arranged between the laser gain medium and the laser output cavity mirror, and the phase conjugate mirror and the dispersion element are both arranged on the laser optical path; the laser output cavity mirror is a laser coupling output cavity mirror; and it also includes a beam shaping system which is arranged between the pump laser and the resonant cavity, and the beam shaping system shapes the light emitted by the pump laser into a flat-top laser beam.

2. The non-mode-locked ultrafast laser according to claim 1, characterized in that: The dispersive element is a diffraction grating or a prism, a combination of a diffraction grating and a diffraction grating, a combination of a prism and a prism, or a combination of a diffraction grating and a prism.

3. The non-mode-locked ultrafast laser according to claim 2, characterized in that: The diffraction grating is a reflection grating or a transmission grating.

4. The non-mode-locked ultrafast laser according to claim 2, characterized in that: The diffraction grating is a plane grating.

5. The non-mode-locked ultrafast laser according to claim 4, characterized in that: The dispersion element includes a first reflection grating and a second reflection grating; the first reflection grating and the second reflection grating are parallel, and the light emitted by the laser gain medium is reflected by the first reflection grating, reaches the second reflection grating, and then reflects by the second reflection grating to reach the laser output cavity mirror.

6. The non-mode-locked ultrafast laser according to claim 5, characterized in that: A Q-switching device is arranged between the dispersion element and the laser output cavity mirror, and the Q-switching device is located on the laser optical path.

7. The non-mode-locked ultrafast laser according to claim 1, characterized in that: Also included is a spatial filter disposed between the phase conjugate mirror and the dispersive element.

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