Passive Q-switched microminiature laser based on Nd: YAG crystal

Abstract

The utility model discloses a passive Q-switched microminiature laser based on an Nd: YAG crystal. The passive Q-switched microminiature laser comprises a semiconductor laser chip, a fast axis collimating lens, the Nd: YAG crystal, a Cr < 4 + >: YAG passive Q-switched switch and a resonant cavity output mirror. The semiconductor laser chip is sintered on the laser optical mounting seat; the fast axis collimating lens is fixed on the semiconductor laser chip; a crystal mounting seat is fixed on the laser optical mounting seat, and the Nd: YAG crystal is mounted in the crystal mounting seat; a passive Q-switch mounting seat is also fixed on the laser optical mounting seat; a Cr < 4 + >: YAG passive Q-switch is mounted in the passive Q-switch mounting seat; and the resonant cavity output mirror is fixed on the laser optical mounting seat. The laser is a pulse laser which is small in size, high in repetition frequency and high in stability, and pulse laser output with the repetition frequency not lower than 15 kHz at the 1064nm waveband can be achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of laser, especially a passive Q-switching micro laser based on Nd:YAG crystal. BACKGROUND

[0002] The compact 1.06 mu m Nd:YAG crystal laser is widely used in the fields of environment monitoring, space communication, laser radar and the like, and meanwhile, through the passive Q-switching technology, the 1.06 mu m pulse laser output with high repetition frequency and kW level peak power can be realized. 4+ Among the many saturable absorbers for passive Q-switching, the Cr 4+ :YAG crystal is an ideal saturable absorber material because of its advantages of high light damage threshold, good light-heat stability, large absorption cross section, high doping concentration tolerance and long-term reliability.

[0003] The commercial passive Q-switching 1064nm pulse laser can realize mJ level energy and MW level peak power operation, and has been widely applied in the fields of laser ranging, laser radar, LIBS (laser-induced breakdown spectroscopy), optical parametric oscillator and the like, but such lasers have the following problems: (1) poor beam quality and output stability: the increasing output energy means that the pump power also increases, which makes the thermal lens effect in the gain medium stronger, seriously limiting the output beam quality; meanwhile, under high peak power, the optical system is extremely sensitive to the device state and external environment changes, and the long-term working reliability is affected to a certain extent; (2) large overall size: in order to ensure long-term reliable operation, an external active cooling system is needed to control the laser operating temperature, which not only greatly increases the equipment power consumption, but also limits its application in the field of small-size portable devices; (3) low working frequency: such lasers basically work at low repetition frequency, which is difficult to meet the requirement of extremely fast light source scanning speed in radar and imaging systems.

[0004] At present, relevant personnel have only realized stable pulse laser output with a repetition frequency of 3-5kHz on an optical platform, and no mature product has been put into market application. In order to meet the actual demand for high repetition frequency and high peak power, the utility model provides a 1064nm micro chip laser based on Nd:YAG crystal high repetition frequency passive Q-switching. CONTENT OF THE UTILITY MODEL

[0005] The utility model discloses a passive Q switching miniature laser based on Nd:YAG crystal aims at providing a kind of passive Q switching miniature laser based on Nd:YAG crystal. 4+ The Nd:YAG crystal laser of passive Q switching based on Cr

[0006] To achieve the above technical purpose, reach the above technical effect, the utility model discloses the following technical scheme:

[0007] A kind of passive Q switching miniature laser based on Nd:YAG crystal, including semiconductor laser chip, fast axis collimating lens, Nd:YAG crystal, Cr 4+ :YAG passive Q switching and resonant cavity output mirror that are sequentially arranged;Semiconductor laser chip is sintered on laser optical mounting seat;Fast axis collimating lens is fixed on the output end of semiconductor laser chip;Crystal mounting seat is fixed on the laser optical mounting seat, and Nd:YAG crystal is installed in the crystal mounting seat;Passive Q switching mounting seat is also fixed on the laser optical mounting seat, and Cr 4+ :YAG passive Q switching is installed in the passive Q switching base;Resonant cavity output mirror is fixed on the laser optical mounting seat;TEC temperature control sheet is installed on the bottom of the laser optical mounting seat.

[0008] Further, gold-plated PCB board that is close to the position of semiconductor laser chip is also bonded on the laser optical mounting seat;Semiconductor laser chip is connected by gold wire with gold-plated PCB board.

[0009] Further, laser power supply anode and laser power supply cathode are welded on the gold-plated PCB board.

[0010] Further, the non-light passing surface of Nd:YAG crystal and Cr 4+ :YAG passive Q switching is wrapped by indium film.

[0011] Further, the crystal mounting seat includes crystal groove base and crystal groove upper cover, and V-shaped crystal groove is arranged on the crystal groove base and the crystal groove upper cover, and Nd:YAG crystal is installed in the space formed by two V-shaped crystal grooves.

[0012] Further, the passive Q switching mounting seat includes L-shaped base and L-shaped upper cover, and Cr 4+ :YAG passive Q switching is fixed on the L-shaped base by the L-shaped upper cover.

[0013] Further, a film layer capable of transmitting light of 1064nm wavelength is coated on the front light passing surface of the resonant cavity output mirror, and an antireflection film is coated on the rear light passing surface of the resonant cavity output mirror.

[0014] Further, a thermistor is further mounted on one side of the laser optical mounting base; the TEC power supply positive pole, the TEC power supply negative pole and the thermistor are connected with the temperature controller.

[0015] Further, the laser optical mounting base is fixed on a laser outer base, and a laser outer upper cover is fixed on the laser outer base.

[0016] Further, the laser outer upper cover is provided with a window piece near the resonant cavity output mirror.

[0017] The laser device has the advantages that:

[0018] The laser device emits a pump beam with a center wavelength of 808nm from a semiconductor laser chip, and the pump beam is shaped by a fast-axis collimation lens; after absorbing the shaped pump beam with a wavelength of 808nm, the Nd:YAG crystal emits a 1064nm laser beam through Nd 3+ ions 4 F 3 / 2 and 4 I 11 / 2 radiative transition between energy levels, and then a high-repetition-frequency 1064nm pulse laser beam is output through a Cr 4+ :YAG passive Q-switch.

[0019] The semiconductor laser chip, the fast-axis collimation lens, the Nd:YAG crystal, the Cr 4+ :YAG passive Q-switch and the resonant cavity output mirror are integrated and mounted through cooperation of the laser optical mounting base, the crystal mounting base and the passive Q-switch mounting base, so that the volume is small.

[0020] The Nd:YAG crystal is used as a gain medium, and TEC temperature control and conduction heat dissipation are used to improve heat dissipation in the working process of the laser device, so that the thermal effect of the crystal is reduced; the semiconductor laser chip is directly sintered on the laser optical mounting base, the laser optical mounting base shell is used to improve heat dissipation of the chip, and no additional heat dissipation device is needed, so that the volume is reduced and the weight is lightened. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a whole structure schematic view of the passive Q-switch micro laser device.

[0022] Figure 2The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing.

[0023] Figure 3 The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing.

[0024] Figure 4 The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing.

[0025] Figure 5 The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing.

[0026] Figure 6 The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing. 4+ :YAG passive Q-switching's installation structure schematic drawing.

[0027] Figure 7 The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing.

[0028] In the drawing, 1 - laser power negative pole, 2 - laser power positive pole, 3 - gold -plated PCB board, 4 - semiconductor laser chip, 5 - fast -axis collimating lens, 6 - crystal groove base, 7 - crystal groove upper cover, 8 - Nd:YAG crystal, 9 - L type base, 10 - L type upper cover, 11 - Cr 4+ :YAG passive Q-switching, 12 - resonant cavity output mirror, 13 - laser optical mounting seat, 14 - laser outer upper cover, 15 - window piece, 16 - fan, 17 - thermistor, 18 - TEC temperature control piece, 19 - laser outer base, 20 - TEC power positive pole, 21 - TEC power negative pole, 22 - thermistor lead, 23 - the front light -transmitting surface of Nd:YAG crystal, 24 - the rear light -transmitting surface of Nd:YAG crystal, 25 - the front light -transmitting surface of Cr 4+ :YAG passive Q-switching, 26 - the rear light -transmitting surface of Cr 4+ :YAG passive Q-switching, 27 - the front light -transmitting surface of resonant cavity output mirror, 28 - the rear light -transmitting surface of resonant cavity output mirror. DETAILED DESCRIPTION

[0029] The utility model discloses a passive Q-switching micro laser's partial structure schematic drawing.

[0030] As Figures 1 to 7A preferred embodiment of a passively Q-switched microlaser based on an Nd:YAG crystal is shown, comprising a semiconductor laser chip 4, a fast-axis collimating lens 5, and a neodymium-doped yttrium aluminum garnet crystal (Nd:Y3Al5O4) arranged sequentially. 12 8. Chromium-doped yttrium aluminum garnet crystal (Cr) 4+ :Y3Al5O 12 Cr 4+ :YAG) Passive Q-switching switch 11 and resonant cavity output mirror 12.

[0031] The semiconductor laser chip 4 serves as a pump source, emitting pump light that can be absorbed by the Nd:YAG crystal gain medium. The center wavelength of the semiconductor laser chip 4 is 808 nm, and its spectral width is 5 nm (measured at 95% power). The semiconductor laser chip 4 is sintered onto the laser optical mounting base 13 using tin-silver-copper solder. A gold-plated PCB board 3, positioned close to the semiconductor laser chip 4, is also bonded to the laser optical mounting base 13; the gold-plated PCB board 3 is connected to the semiconductor laser chip 4 via gold wires. A positive laser power supply terminal 1 and a negative laser power supply terminal 2 are soldered onto the gold-plated PCB board 3. The positive and negative laser power supply terminals 1 and 2 are used to electrically connect the semiconductor laser chip 4 to an external power supply.

[0032] The fast-axis collimating lens 5 is used to shape the beam. The fast-axis collimating lens 5 compresses the divergence angle of the beam along the fast axis and is fixed to the aluminum nitride heat sinks on both sides of the output end of the semiconductor laser chip 4 by UV-curing adhesive.

[0033] The gain medium used in this laser is Nd:YAG crystal 8, with an end face size of 2*2mm. 2 Nd in crystal 3+ The doping concentration is 0.8–1.2 at.%. A crystal mounting base is fixed on the laser optical mounting base 13, and the Nd:YAG crystal 8 is installed in the crystal mounting base. Specifically, the crystal mounting base includes a crystal slot base 6 and a crystal slot cover 7. Both the crystal slot base 6 and the crystal slot cover 7 are provided with V-shaped crystal slots. During installation, an indium film with a thickness of 0.5 mm is used to wrap the four non-light-transmitting sides of the Nd:YAG crystal 8 and place it on the V-shaped crystal slot of the crystal slot base 6. The Nd:YAG crystal 8 is then fixed by the crystal slot cover 7. The front light-transmitting surface 23 of the Nd:YAG crystal is coated with a high-reflection film (HR@1064nm, R>99.8%) and an anti-reflection film (AR@808nm, R<0.2%) to increase the transmittance of pump light and improve pump efficiency. The rear light-transmitting surface 24 of the Nd:YAG crystal is coated with an anti-reflection film (AR@1064nm, R<0.2%) to reduce Fresnel reflection loss on this surface.

[0034] The laser optical mounting base 13 is also fixed with a passive Q-switch mounting base, Cr 4+ :YAG passive Q-switch 11 is installed in the passive Q-switch base; specifically, the passive Q-switch mounting base comprises an L-shaped base 9 and an L-shaped upper cover 10; during installation, Cr 4+ :YAG passive Q-switch 11 is fixed by wrapping the Cr 4+ :YAG passive Q-switch 11 with an indium film with a thickness of 0.5 mm in an L-shaped groove of the L-shaped base 9, and then fixing the Cr 4+ :YAG passive Q-switch 11 is used to adjust the cavity loss, and realize 1064 nm pulse laser output. 4+ :YAG passive Q-switch's front light-transmitting surface 25 and rear light-transmitting surface 26 are both coated with an anti-reflection film (AR@1064nm, R<0.2%), to reduce the cavity reflection loss.

[0035] The resonant cavity output mirror 12 is fixed on the rear end of the laser optical mounting base 13 by ultraviolet curing glue; the resonant cavity output mirror's front light-transmitting surface 27 is coated with a film layer that transmits light of 1064 nm wavelength, with a transmittance of 20%-50%, and the resonant cavity output mirror's rear light-transmitting surface 28 is coated with an anti-reflection film (AR@1064nm, R<0.2%).

[0036] The bottom of the laser optical mounting base 13 is installed with a TEC temperature control sheet 18, which is used to control the laser operating temperature. One side of the laser optical mounting base 13 is also installed with a thermistor 17; the TEC positive electrode 20, TEC negative electrode 21 of the TEC temperature control sheet 13 and the thermistor 17 are all connected with a temperature controller. The thermistor 17 is one of a positive temperature coefficient thermistor, a negative temperature coefficient thermistor and a critical temperature coefficient thermistor, which is connected with the temperature controller through a thermistor lead 22, and is used to feedback the temperature of the laser optical mounting base 13.

[0037] The laser optical mounting base 13 is fixed on a laser outer base 19, and the laser outer base 19 is fixed with a laser outer upper cover 14, which covers the semiconductor laser chip 4, fast-axis collimating lens 5, Nd:YAG crystal 8, Cr 4+ :YAG passive Q-switch 11 and resonant cavity output mirror 12 are covered inside.

[0038] The laser outer upper cover 14 is provided with a window sheet 15 near the resonant cavity output mirror 12. The window sheet 15 is fixed on the opening of the front end face of the laser outer upper cover 14 by ultraviolet curing glue, which plays a filtering role while separating the internal and external environment of the laser, protecting the internal devices from the environment and improving the stability of the long-term work of the laser.

[0039] The whole laser is also provided with a fan 16 for heat dissipation of the whole laser.

[0040] The working principle of the utility model is as follows: external power supply drives the semiconductor laser chip to emit light, the pump beam with the center wavelength of 808nm emitted by the semiconductor laser chip is shaped through the fast axis collimation lens, the Nd:YAG crystal absorbs the shaped 808nm pump beam, and then the Nd 3+ ion 4 F 3 / 2 and 4 I 11 / 2 level radiation transition output 1064nm laser, and then the Cr 4+ :YAG passive Q-switched output high repetition frequency 1064nm pulsed laser.

[0041] It is apparent for those skilled in the art that the utility model is not limited to the details of the above exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or essential characteristics of the utility model. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the utility model is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the utility model. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0042] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments which can be understood by those skilled in the art.

Claims

1. A passively Q-switched microlaser based on Nd:YAG crystal, characterized in that, This includes a semiconductor laser chip, a fast-axis collimating lens, an Nd:YAG crystal, and a Cr laser arranged sequentially. 4+ The laser consists of a passive Q-switched YAG laser and a resonant cavity output mirror; the semiconductor laser chip is sintered on a laser optical mounting base; the fast-axis collimating lens is fixed to the output end of the semiconductor laser chip; a crystal mounting base is fixed on the laser optical mounting base, and the Nd:YAG crystal is mounted in the crystal mounting base; a passive Q-switched switch mounting base is also fixed on the laser optical mounting base, and Cr... 4+ The YAG passive Q-switching switch is installed in the passive Q-switching switch base; the resonant cavity output mirror is fixed on the laser optical mounting base; a TEC temperature control plate is installed on the bottom of the laser optical mounting base.

2. The passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, A gold-plated PCB board, positioned close to the semiconductor laser chip, is also attached to the laser optical mounting base; the gold-plated PCB board and the semiconductor laser chip are connected by gold wires.

3. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 2, characterized in that, The gold-plated PCB board has a positive power supply terminal and a negative power supply terminal for the laser soldered on.

4. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, The Nd:YAG crystal and Cr 4+ The non-light-transmitting surfaces of the YAG passive Q-switched switch are all wrapped with an indium film.

5. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, The crystal mounting base includes a crystal slot base and a crystal slot cover. Both the crystal slot base and the crystal slot cover are provided with V-shaped crystal slots. The Nd:YAG crystal is installed in the space formed by the two V-shaped crystal slots.

6. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, The passive Q-adjustment switch mounting base includes an L-shaped base and an L-shaped top cover, the Cr 4+ The YAG passive Q-adjustment switch is fixed to the L-shaped base via the L-shaped top cover.

7. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, The front light-transmitting surface of the resonant cavity output mirror is coated with a film layer that allows light in the 1064nm wavelength range to pass through, and the rear light-transmitting surface of the resonant cavity output mirror is coated with an anti-reflection film.

8. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, A thermistor is also installed on one side of the laser optical mounting base; the TEC power supply positive terminal and TEC power supply negative terminal of the TEC temperature control plate, as well as the thermistor, are all connected to the temperature controller.

9. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 1, characterized in that, The laser optical mounting base is fixed to the laser outer base, and the laser outer top cover is fixed to the laser outer base.

10. A passively Q-switched microlaser based on Nd:YAG crystal according to claim 9, characterized in that, The outer cover of the laser has a window near the output mirror of the resonant cavity.

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