JPH0442979A - Laser diode exciting solid state laser - Google Patents

Abstract

PURPOSE:To obtain an ultrashort pulse and a high peak output as compared with prior art by forming a laser diode in a pulse oscillation type laser diode. CONSTITUTION:A laser resonator is formed of a laser rod end face 8 at an LD exciting light 6 incident side and an output mirror 5, and the reflecting surface of a laser oscillation light of the mirror 5 is coated with a coating having high reflectivity for the oscillation light. As a laser rod 3, a solid state laser material such as a YAG, etc., can be used. As a mode lock element 4 and a Q switch element 5, an acoustic-optical element, etc., can be used. A pulse semiconductor laser having several 10 - several 100W peak output is used to form a higher inverted distribution state, and an effect of short pulse and high peak output in the mode lock oscillation and the Q switch oscillation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a single diode pumped solid state laser.

[Prior Art] Laser diode (LD)-pumped solid-state lasers do not require water cooling because the excitation light source has a longer lifespan and there is almost no thermal effect on the laser medium compared to conventional lamp-pumped solid-state lasers. All-solid-state devices with small size and long life
It is attracting attention as a nose.

In addition, as for all-solid-state lasers, the above-mentioned LD (known as T-I) currently has problems such as the spatial output shape of the laser beam being elliptical and instantaneous end face destruction. In the LD pumped solid-state laser, these problems have been solved, and since the lifetime at the excited level is long, energy can be stored, and high peak output can be obtained by Q-switch operation. Therefore, LD pumped solid-state lasers are expected to be used in various fields.

[Problems to be Solved by the Invention] Incidentally, in order to apply the LD-excited solid-state laser to fields such as processing, communication, and measurement, it is desirable to use pulsed laser light. As shown in FIG. 4, in the conventional LD-pumped solid-state laser, the LD-pumped solid-state laser light is pulsed (gain switch) by current modulating the continuous wave (CW) pumping semiconductor laser 11. A method has been used in which the laser 11 is CW pumped and the LD pumped solid-state laser light is pulsed by inserting a Q-switch element 5 or a mode-locked element into the laser resonator.

Here, 2 is a condenser lens, 3 is a laser rod, 7 is an output mirror, 6 is an excitation light, 8.9 is an end face of the laser rod, 1
0 is the emitted laser beam.

However, in the case of the conventional method using a CW oscillation semiconductor laser as the excitation light, the CW oscillation of the excitation semiconductor laser
Since the peak power obtained by power or current modulation is on the order of several watts, solid-state laser crystals such as YAG cannot be excited to sufficiently high gain, and gain switches, Q-switches, and mode-locks in LD-pumped solid-state lasers cannot be excited. The peak power of the pulse obtained was about IKW, which was not that high.

The object of the invention is to overcome the aforementioned drawbacks of the prior art.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes at least a Q-switch element and a mode-locked element inside a laser resonator using a laser diode as an excitation light source. The present invention provides a laser diode-pumped solid-state laser having one of the above, characterized in that the laser diode is a pulse oscillation type laser diode.

Hereinafter, the present invention will be explained according to embodiments. FIG. 1 is a block diagram showing the basic configuration of the present invention.

1 is a pulsed laser diode, 2 is a condensing lens,
3 is a laser rod, 4 is a mode-locked element, 5 is a Q-switch element, 6 is LD excitation light, 7 is an output mirror, and IO is an output laser beam.

The laser resonator has a laser rod end face 8 on the incident side of the LD excitation light 6 (coated with a coating having high transmittance for the LD excitation light 6 and high reflectance for the oscillation light).

) and an output mirror 5.

The laser oscillation light reflecting surface of the output mirror 5 is coated with a coating having a high reflectance (preferably 90% or more) for the laser oscillation light.

The laser rod 3 is YAG or YLF.

Solid state laser materials such as YAP and GGG can be used. As the mode-locked element 4 and the Q-switch element 5, an acousto-optic element, an electro-optic element, a supersaturated dye, etc. can be used.

[Function] In a semiconductor laser pumped solid-state laser, the higher the power of the semiconductor laser that is the pumping light, the higher the gain state of the laser crystal becomes, and the higher the power oscillation becomes possible, the more mode-locked oscillation and Q-switch oscillation are possible. Beak power also increases. While conventionally used CW semiconductor lasers have an output of several watts at most, in the present invention, by using a pulsed semiconductor laser with a peak output of several lθ to several 100 watts, a higher population inversion state can be achieved. It is possible to produce shorter pulses and higher peak output effects in mode-locked oscillation and Q-switched oscillation.

[Embodiments] Three embodiments of the present invention are shown in FIGS. 1 to 3. In the embodiment shown in FIG. 1, acousto-optic elements are used as the mode-locking element 4 and the Q-switching element 5, and a YAG crystal is used as the laser rod 3. A mode-locked pulse train of 80 psec was observed in a Q-switched pulse with a resonator length of 30+mm and a full width at half maximum of Ions (Q-switched mode-locked pulse).

FIG. 2 shows an embodiment in which only Q-switching is performed in FIG. 1.

At this time, a Q-switch pulse with a pulse width of 10 ns is obtained.

FIG. 3 shows a case where an optical fiber coupling method is used as the excitation light guide method in FIG. 2 (FIGS. 1 and 2 are direct coupling methods). At this time as well, a Q-switch pulse with a pulse width of 10 ns is obtained. Note that the repetition of the Q-switch pulses in FIGS. 2 and 3 is equal to the repetition number of the pulse oscillation type semiconductor laser. In addition, the edge reversal of the mode-locked pulse in Figure 1 is determined by the resonator length, and when the resonator length is 30 mm, it is approximately 5G.
Hz.

[Effect of the invention] The Q of the pulse oscillation type LD excited solid 1/-the according to the present invention
Switch pulses and mode-locked pulses are conventional CW
Compared to the Q-switched pulse and mode-locked pulse of the LD-excited solid 1 nose, the pulse is much shorter (20ns → 1n
ns or less) and high peak power (I KW -10KW)
This also has the excellent effect of enabling more efficient wavelength changes. In addition, due to its high peak output, it can be used as a light source for various nonlinear optics, for example, in optical property evaluation equipment for examining crystal defects, fluorescence, and absorption characteristics of specimens by measuring Raman scattering and Prillouin scattering, and in semiconductor integrated circuits. It also has the excellent effect of being usable as a light source for trimming, photomask repair equipment, etc.

[Brief explanation of the drawing]

FIGS. 1 to 3 show three embodiments of the present invention, and FIG. 1 shows a laser diode-pumped laser diode pumped with a mode-locked element and a Q-switched element in the resonator of a solid-state one laser pumped with a pulsed oscillation type laser diode. FIG. 2 is a block diagram of the basic configuration of a solid-state laser device; FIG. 2 is a block diagram of FIG. 1 with only a Q-switch element; FIG. FIG. 4 is a block diagram of the basic configuration of a conventional CW laser diode pumped solid-state laser device. 1: Pulse laser diode 2: Condensing lens 3: Laser rod 4: Mode locking element 5: Q switch 6 + LD excitation light 7: Output mirror 10: Output laser light 11: CW laser diode 12; Coupling lens 13: Optical fiber 2nd figure

Claims (1)

[Claims] A laser diode-pumped solid-state laser that uses a laser diode as an excitation light source and has at least one of a Q-switch element and a mode-locked element inside a laser resonator, wherein the laser diode is a pulsed laser diode. A laser diode-pumped solid-state laser characterized by: