METHOD FOR OPERATING DIODE-PUMPED PULSED LASERS

Abstract

The present invention relates to a method for operating a pulsed diode-pumped solid-state laser comprising: providing a pump light source for pumping a solid-state laser, said pump light source comprising at least one laser diode unit configured for emitting a series of light pulses for pumping the solid-state laser, modulating the series of light emission pulses of the at least one laser diode unit such that only the light pulses with a frequency close to or equal to a requested frequency setting of the solid-state laser are operated with a/the required pulse amplitude and/or a/the required pulse duration to trigger light emission of the solid-state laser, and such that any other light pulses of the at least one laser diode unit are operated to not trigger light emission of the solid-state laser.

Claims

1. A method for operating a pulsed diode-pumped solid-state laser comprising: providing a pump light source for pumping a solid-state laser, said pump light source comprising at least one laser diode unit configured for emitting a series of light pulses for pumping the solid-state laser, modulating the series of light emission pulses of the at least one laser diode unit such that only the light pulses with a frequency close to or equal to a requested frequency setting of the solid-state laser are operated with a required pulse amplitude and/or a required pulse duration to trigger light emission of the solid-state laser, and such that any other light pulses emitted by the at least one laser diode unit are operated to not trigger light emission of the solid-state laser.

2. The method according to claim 1, wherein the requested frequency setting for the solid-state laser lies at a frequency below 300 Hz.

3. The method according to claim 1, wherein the requested frequency setting for the solid-state laser is one of the following frequency settings: 5, 10, 20, 25, 50, 75 or 100 Hz, and wherein the at least one laser diode unit is operated to emit light pulses with a frequency of 100 Hz, and wherein for a requested solid-state laser frequency setting of 5 Hz, only every 20.sup.th light pulse of the laser diode unit is operated with the required pulse amplitude and/or the required pulse duration to trigger light emission of the solid-state laser, and wherein for a requested solid-state laser frequency setting of 10 Hz only every 10.sup.th light pulse of the laser diode unit is operated with the required pulse amplitude and/or the required pulse duration to trigger light emission of the solid-state laser, and wherein for a requested solid-state laser frequency setting of 20 Hz only every 5.sup.th light pulse of the laser diode unit is operated with the required pulse amplitude and/or the required pulse duration to trigger light emission of the solid-state laser, and wherein for a requested solid-state laser frequency setting of 25 Hz only every 4.sup.th light pulse of the laser diode unit is operated with the required pulse amplitude and/or the required pulse duration to trigger light emission of the solid-state laser, and wherein for a requested solid-state laser frequency setting of 50 Hz only every 2.sup.nd light pulse of the laser diode unit is operated with the required pulse amplitude and/or the required pulse duration to trigger light emission of the solid-state laser, and wherein for a requested solid-state laser frequency setting of 75 Hz or 100 Hz all pulses of the laser diode unit are operated with the required pulse amplitude and/or the required pulse duration to trigger light emission of the solid-state laser.

4. The method according to claim 1, wherein during operation of the pulsed diode-pumped solid-state laser, an electrical current provided to drive the at least one laser diode unit is non-zero at all times.

5. A diode-pumped solid-state laser system comprising: a solid-state laser, at least one laser diode unit configured to operate according to claim 1.

6. The diode-pumped solid-state laser system according to claim 5, wherein the solid-state laser is a Tm:YAG laser.

7. The diode-pumped solid-state laser according to claim 5, wherein the at least one laser diode unit is configured to emit light pulses with a wavelength between 778 to 782 nm at 100 Hz and with pulse durations of up to 500 μs and with amplitudes of up to a maximum current of 250 A.

8. The diode-pumped solid-state laser according to claim 5, wherein the at least one laser diode unit comprises a single laser diode or a one-dimensional array of laser diodes or a two-dimensional array of laser diodes or a three-dimensional array of laser diodes.

9. The diode-pumped solid-state laser according to claim 8, wherein the at least one laser diode unit comprises the one-dimensional array of laser diodes, and wherein the one-dimensional array of laser diodes is a diode laser bar.

10. The diode-pumped solid-state laser according to claim 8, wherein the at least one laser diode unit comprises the two-dimensional array of laser diodes, and wherein the two-dimensional array of laser diodes is a stack of diode laser bars.

11. The diode-pumped solid-state laser according to claim 8, wherein the at least one laser diode unit comprises the three-dimensional array of laser diodes, and wherein the three-dimensional array of laser diodes is multiple stacks of diode laser bars.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0057] The following figures illustrate exemplary:

[0058] FIG. 1: Exemplary modulation of a series of light emission pulses of a laser diode unit

[0059] FIG. 2: Exemplary solid-state laser power/energy output at different frequency settings

DETAILED DESCRIPTION

[0060] FIG. 1 illustrates an exemplary modulation 100 of a series 108 of light emission pulses 105, 106, 107 of an exemplary laser diode unit/laser diode(s) (not shown), with the ordinate axis 104 exemplary representing the amplitude or energy of the light pulses 105, 106, 107 or exemplary representing the electrical current(s) provided to the laser diode unit/laser diode that triggers/trigger said light pulses 105, 106, 107, and with the abscissa axis 103 exemplary representing time.

[0061] The exemplary pulses denoted with reference numerals 106 and 107 exemplary represent pulses emitted by the laser diode unit/laser diode(s) with an amplitude/energy that are required or sufficient to trigger light emission of a/the solid-state laser (not shown) that is receiving said pulses from the laser diode unit/laser diode(s), i.e. said pulses 106, 107 are operated at or above the lasing threshold of the solid-state laser and with a frequency 101 corresponding to a/the requested frequency setting of the pulsed solid-state laser.

[0062] Furthermore, the reference numeral 102 exemplary denotes an/the operating frequency of the exemplary laser diode unit/laser diode(s) with which the laser diode unit/laser diode(s) emits light pulses 105, 106, 107 to pump the solid-state laser and wherein the light pulses 105 with a frequency different from a/the requested frequency setting 101 are operated to not trigger light emission of the solid-state laser, i.e. are operated with an amplitude/energy below the lasing threshold of the solid-state laser.

[0063] FIG. 2 exemplary illustrates test results 200 comparing the solid-state laser power/energy output at different requested frequency settings 200a, 200b, 200c comprising the requested frequency settings of 5 Hz, 10 Hz and 25 Hz when using standard pumping methods 203a, 203b, 203c as compared to pumping methods of a solid-state laser with a laser diode unit/laser diode(s) according to the herein described means and methods.

[0064] For example, the panel 200a shows the solid-state laser power/energy output 202 at a requested solid-state laser frequency setting of 5 Hz in dependence of the electrical current 201 supplied to a/the laser diode unit/laser diode(s) for a standard pumping 203a (line connecting the diamond-shaped measurement points) and for a modulated pumping 204a according to the method exemplary described herein (line connecting the square-shaped measurement points).

[0065] The panel 200b exemplary shows the solid-state laser power/energy output 202 at a requested solid-state laser frequency setting of 10 Hz in dependence of the electrical current 201 supplied to a/the laser diode unit/laser diode(s) for a standard pumping 203b (line connecting the diamond-shaped measurement points) and for a modulated pumping 204b according to the method exemplary described herein (line connecting the square-shaped measurement points).

[0066] The panel 200c exemplary shows the solid-state laser power/energy output 202 at a requested solid-state laser frequency setting of 25 Hz in dependence of the electrical current 201 supplied to a/the laser diode unit/laser diode(s) for a standard pumping 203c (line connecting the diamond-shaped measurement points) and for a modulated pumping 204c according to the method exemplary described herein (line connecting the square-shaped measurement points).

[0067] As can be seen when comparing the three different panels 200a, 200b, 200c which have the same scales, the gains/improvements in solid-state laser power/energy output efficiencies are significant for all requested frequency settings but highest for lower requested frequency settings.

[0068] For completeness, it is noted that for the shown results the laser diode unit/laser diode(s) for exemplary pumping the solid-state laser according to the method exemplary described herein, the exemplary operating frequency of the laser diode unit/laser diode(s) was 100 Hz.

[0069] However, the significant gains in laser power/energy output of a/the solid-state laser can be achieved also with other operating frequencies of the laser diode unit/laser diode(s).

[0070] Followed by two sheets comprising FIG. 1 and FIG. 2, wherein the reference numerals identify the following components. [0071] 100 exemplary modulation of light pulses for pumping a solid-state laser [0072] 101 exemplary (requested) frequency/frequency setting of a/the solid-state laser [0073] 102 exemplary operating frequency of exemplary laser diode unit/exemplary laser diode(s) [0074] 103 exemplary abscissa axis, exemplary time axis, t [0075] 104 exemplary ordinate axis, exemplary representing amplitude/energy of light pulses emitted by exemplary laser diode unit/exemplary laser diode(s) or exemplary electrical current, I, supplied to the laser diode unit/laser diode(s) [0076] 105 exemplary light pulse(s) emitted by exemplary laser diode unit/exemplary laser diode(s) [0077] that are operated with amplitudes/energies that do not trigger light emission by the solid- [0078] state laser, i.e. exemplary laser diode unit/exemplary laser diode pulses for pumping [0079] the solid-state laser that are operated below the lasing threshold of the solid-state laser [0080] 106, 107 exemplary light pulse(s) emitted by exemplary laser diode unit/exemplary laser diode(s) that are operated with sufficient high amplitudes/energies that trigger light emission by the solid-state laser, i.e. exemplary laser diode unit/exemplary laser diode pulses for pumping the solid-state laser that are operated at or above the lasing threshold of the solid-state laser [0081] 108 exemplary series of light pulses emitted by exemplary laser diode unit/laser diode(s) for pumping a/the solid-state laser [0082] 200 exemplary test results for achieved gains in laser power output of a/the solid-state laser in pulsed mode when pumped according to the herein described method as compared to standard pumping methods [0083] 200a, 200b, 200c exemplary test results for requested frequency settings 5 Hz, 10 Hz and 25 Hz of solid-state laser [0084] 201 exemplary abscissa axis, exemplary electrical current supplied to exemplary laser diode unit/exemplary laser diode(s), for example in units of Ampere [0085] 202 exemplary ordinate axis, exemplary laser power/energy output of exemplary solid-state laser in pulsed mode, for example specified in millijoule (mJ) [0086] 203a exemplary laser power/energy output of solid-state laser for standard pumping and a requested frequency setting of 5 Hz for the solid-state laser [0087] 204a exemplary laser power/energy output of solid-state laser for pumping according to the herein described method and a requested frequency setting of 5 Hz for the solid-state laser [0088] 203b exemplary laser power/energy output of solid-state laser for standard pumping and a requested frequency setting of 10 Hz for the solid-state laser [0089] 204b exemplary laser power/energy output of solid-state laser for pumping according to the herein described method and a requested frequency setting of 10 Hz for the solid-state laser [0090] 203c exemplary laser power/energy output of solid-state laser for standard pumping and a requested frequency setting of 25 Hz for the solid-state laser [0091] 204c exemplary laser power/energy output of solid-state laser for pumping according to the herein described method and a requested frequency setting of 25 Hz for the solid-state laser