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An apparatus and process using a high-power, short-pulsed thulium laser to output infrared laser pulses delivered through an optical fiber, for cutting and ablating biological tissue. In some embodiments, the pulse length is shortened sufficiently to keep inside the stress-confined ablation region o

An apparatus and process using a high-power, short-pulsed thulium laser to output infrared laser pulses delivered through an optical fiber, for cutting and ablating biological tissue. In some embodiments, the pulse length is shortened sufficiently to keep inside the stress-confined ablation region of operation. In some embodiments, the pulse is shortened to near the stress-confined ablation region of operation, while being slightly in the thermal-constrained region of operation. In some embodiments, the laser is coupled to a small low —OH optical fiber (˜100 μm diameter). In some embodiments, the device has a pulse duration of about 100 ns for efficient ablation; however in some embodiments, this parameter is adjustable.

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1. A method comprising: providing a dual-mode laser system in a self-contained user-carriable unit having a battery, wherein the providing of the dual-mode laser system includes providing a rare-earth doped large-mode-area (LMA) first fiber gain-medium section and one or more passive polarization-ma

1. A method comprising: providing a dual-mode laser system in a self-contained user-carriable unit having a battery, wherein the providing of the dual-mode laser system includes providing a rare-earth doped large-mode-area (LMA) first fiber gain-medium section and one or more passive polarization-maintaining (PM) fiber sections configured in series to have a ring optical signal path that extends through the first fiber gain medium, and providing a rare-earth-doped second fiber gain medium;in a first mode, generating CW or quasi-CW laser light from the dual-mode laser system;in a second mode, generating pulsed laser light from the dual-mode laser system;supplying power from the battery to the laser system for the generating of the CW or quasi-CW laser light and for the generating of the pulsed laser light from the dual-mode laser system;in the first mode, using the CW or quasi-CW laser light from the dual-mode laser system to coagulate fluids in human tissue;in the second mode, using the pulsed laser light from the dual-mode laser system to cause precise laser ablation of human tissues in an irradiated tissue zone within a medical procedure by localized tissue heating that induces stress tissue damage with minimal collateral heat damage outside the irradiated tissue zone;generating a ring signal laser beam in the ring optical signal path by optically pumping the first fiber gain medium and propagating the ring signal laser beam across free-space parts of the ring optical signal path, wherein the ring signal laser beam has a first wavelength;Q-switching the ring signal laser beam between free-space parts in the ring optical signal path but outside of the first fiber gain medium in order to generate the pulsed laser light of the second mode;extracting an intermediate optical signal beam from the ring signal laser beam in the ring optical signal path outside of the first fiber gain medium;optically pumping the second fiber gain medium; andamplifying the intermediate signal beam in the second fiber gain medium to form the pulsed laser light; andcarrying, by the user, the entirety of the laser system during the using of the CW or quasi-CW laser light in the first mode and during the using of the pulsed laser light in the second mode. 2. The method of claim 1, further comprising tuning a wavelength of the laser light in a spectral range from about 1.9 to about 2.0 μm. 3. The method of claim 1, further comprising generating the laser light using a thulium fiber laser. 4. The method of claim 1, further comprising generating the laser light using a Q-switched solid-state thulium laser. 5. The method of claim 1, wherein the second mode's ablation includes using the laser light for removing human tissue. 6. The method of claim 1, wherein, in the second mode, the pulsed laser light has a pulse-repetition rate of about 20 kHz. 7. The method of claim 1, wherein, in the second mode, the pulsed laser light has a pulse-repetition rate that is adjustable between about 0.001 Hz and about 100 kHz. 8. The method of claim 1, wherein, in the second mode, the pulsed laser light has a pulse energy of about 5 mJ. 9. The method of claim 1, wherein, in the second mode, the pulsed laser light has a pulse energy that is adjustable to non-zero values up to about 50 mJ. 10. The method of claim 1, wherein, in the second mode, the pulsed laser light has a pulse duration tunable between 10-1000 nsec. 11. The method of claim 1, further comprising using an optical delivery fiber of about 100 μm diameter. 12. The method of claim 1, further comprising using an optical delivery fiber that is interchangeable with other delivery fibers having diameters from 50-1000 μm. 13. The method of claim 1, wherein the dual-mode laser system is configured to use a Q-switch in the second pulse mode to obtain the pulsed laser light and in the first continuously on mode to obtain the CW or quasi-CW laser light. 14. The method of claim 1, wherein the dual-mode laser system is a fiber optic MOPA laser having a ring laser master oscillator that outputs a signal wavelength of approximately 1.94 microns. 15. The method of claim 1, wherein the dual-mode laser system is a fiber optic MOPA laser that utilizes polarization maintaining Thulium-doped double-clad having a core diameter of approximately 25 microns or larger. 16. The method of claim 15, wherein the dual-mode laser system includes a semiconductor pump laser diode system that outputs pump light having a wavelength of approximately 794 nm. 17. The method of claim 1, wherein the one or more passive polarization-maintaining (PM) fiber sections includes a plurality of passive polarization-maintaining (PM) fiber sections configured in series with the rare-earth doped large-mode-area (LMA) first fiber gain-medium section to have a ring optical signal path that extends through the first fiber gain medium. 18. The method of claim 1, wherein the propagating of the ring signal laser beam is controlled to lase in only a single direction around the ring optical signal path, wherein the optically pumping of the first fiber gain medium includes launching pump light into the first fiber gain medium in a direction counter-propagating to the ring signal laser beam;and wherein the optically pumping of the second fiber gain medium includes launching pump light into the second fiber gain medium in a direction counter-propagating to the pulsed laser light. 19. The method of claim 1, wherein the extracting of the intermediate optical signal beam includes beam splitting light of a first polarization into the intermediate optical signal beam while passing light of another polarization into a ring-feedback signal beam. The following is an examiner's statement of reasons for allowance: Applicant's invention pertains to a method of generating two laser modes (e.g. quasi-CW or CW and pulsed, which also corresponds to coagulation and ablation modes, respectively, as well as thermal-confinement mode and stress-confinement modes, respectively) from a user-carriable unit, battery operated device using a rare-earth doped large mode area fiber first gain medium, at least one passive polarization-maintaining fiber section and a rare-earth doped second fiber second gain medium by arranged the gain media in a ring optical signal path and using a Q-switch to extract an optical signal from the ring to generate the pulsed light mode. The most pertinent prior art is Marchitto (20010050083) who teaches generating two optical modes (e.g. CW and pulsed) in a handheld, battery operated device. Marchitto does NOT teach the remaining configuration. Attention is directed to Leonardo (20070248136) who teaches a laser system that uses a Q-switch to generate a pulses and a CW mode used for ablation. Leonardo does teach using LMA fibers and PM fiber couplers, but does NOT teach an optical ring, or a Q-switch that extracts pulses from a ring, and that the PM fiber is in series with the LMA fiber. Applicant's optical configuration is novel. 20. The method of claim 1, wherein the dual-mode laser system includes a manually-operable handpiece, the method further comprising: outputting the laser light of the first and second modes from the handpiece toward a location; andindicating the location to the user, wherein the indicating includes magnifying a view of the location. 21. A method comprising: providing a laser device in a self-contained user-carriable unit having a battery, wherein the providing of the laser device includes providing a rare-earth doped large-mode-area (LMA) first fiber gain-medium section and one or more passive polarization-maintaining (PM) fiber sections configured in series to have a ring optical signal path that extends through the first fiber gain medium, and providing a rare-earth-doped second fiber gain medium;activating a thermal-confinement mode of the laser device;in the thermal-confinement mode, coagulating bodily human fluids of a live human with the laser device;activating a stress-confinement mode of the laser device;in the stress-confinement mode, ablating human tissues of the live human within a medical procedure by stress-confined localized tissue heating that induces thermal tissue damage with minimal collateral damage outside the irradiated tissue zone;supplying power from the battery to the laser device for the activating of the thermal-confinement mode and for the activating of the stress-confinement mode;generating a ring signal laser beam in the ring optical signal path by optically pumping the first fiber gain medium and propagating the ring signal laser beam across free-space parts of the ring optical signal path, wherein the ring signal laser beam has a first wavelength;Q-switching the ring signal laser beam between free-space parts in the ring optical signal path but outside of the first fiber gain medium in order to generate pulsed laser light for the stress-confinement mode;extracting an intermediate optical signal beam from the ring signal laser beam in the ring optical signal path outside of the first fiber gain medium;optically pumping the second fiber gain medium;amplifying the intermediate signal beam in the second fiber gain medium to form the pulsed laser light; andcarrying, by the user, the entirety of the laser device during the ablating of the human tissues in the stress-confinement mode. 22. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes outputting pulsed laser light having a tissue-penetration depth between about 50 microns and about 500 microns. 23. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes outputting pulsed laser light having pulse durations of between about 10 nanoseconds and about 400 nanoseconds. 24. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes outputting pulsed laser light having a tissue-penetration depth between about 0.5 millimeters and about 1 millimeters, and a pulse duration of between about 5 nanoseconds and 10 nanoseconds. 25. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes pulsing a Q-switched master oscillator and amplifying Q-switched pulses from the master oscillator with a power optical amplifier. 26. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes: pulsing a Q-switched optical element in a master ring oscillator,outputting Q-switched pulses from the master ring oscillator, andamplifying the outputted Q-switched pulses with a power optical amplifier, andwherein the activating of the thermal-confinement mode of the laser device includes activating the Q-switched optical element to pass light continuously in the master ring oscillator,outputting CW or quasi-CW laser light from the master ring oscillator, andamplifying the outputted CW or quasi-CW laser light with the power optical amplifier. 27. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes outputting pulsed laser light having a pulse energy of about 5 mJ. 28. The method of claim 21, wherein the activating of the stress-confinement mode of the laser device includes outputting pulsed laser light having a pulse energy that is adjustable to non-zero values up to about 50 mJ. 29. A method comprising: providing a dual-mode laser device in a self-contained user-carriable unit having a battery, wherein the providing of the dual-mode laser system includes providing a rare-earth doped large-mode-area (LMA) first fiber gain-medium section and one or more passive polarization-maintaining (PM) fiber sections configured in series to have a ring optical signal path that extends through the first fiber gain medium, and providing a rare-earth-doped second fiber gain medium;activating a coagulation mode of the laser device using a first manually activatable switch;in the coagulation mode, coagulating bodily human fluids of a live human with the dual-mode laser device;activating an ablation mode of the laser device using a second manually activatable switch;in the ablation mode, ablating human tissues of the live human within a medical procedure by localized tissue heating that induces thermal tissue damage with minimal collateral damage outside the irradiated tissue zone;supplying power from the battery to the laser device for the activating of the coagulation mode and for the activating of the ablation mode;generating a ring signal laser beam in the ring optical signal path by optically pumping the first fiber gain medium and propagating the ring signal laser beam across free-space parts of the ring optical signal path, wherein the ring signal laser beam has a first wavelength;Q-switching the ring signal laser beam between free-space parts in the ring optical signal path but outside of the first fiber gain medium in order to generate pulsed laser light for the ablation mode;extracting an intermediate optical signal beam from the ring signal laser beam in the ring optical signal path outside of the first fiber gain medium;optically pumping the second fiber gain medium; andamplifying the intermediate signal beam in the second fiber gain medium to form the pulsed laser light; andcarrying, by the user, the entirety of the laser device during the coagulating of the bodily human fluids in the coagulation mode, and during the ablating of the human tissues in the ablation mode. 30. The method of claim 29, further comprising outputting different colors of visible-pointer laser light to indicate which mode of the laser device is activated. 31. The method of claim 29, further comprising outputting different temporal intensity patterns of visible-pointer laser light to indicate which mode of the laser device is activated. 32. The method of claim 29, further comprising outputting focussed visible-pointer laser light to indicate a location on the human at which energy from the laser device is delivered. 33. The method of claim 29, wherein the activating of the ablation mode of the laser device includes outputting pulsed laser light having a pulse-repetition rate of about 20 kHz. 34. The method of claim 29, wherein the activating of the ablation mode of the laser device includes outputting pulsed laser light having a pulse energy of about 5 mJ. 35. The method of claim 29, wherein the activating of the ablation mode of the laser device includes outputting pulsed laser light having a pulse energy that is adjustable to non-zero values up to about 50 mJ. 36. The method of claim 29, wherein the ablating of the ablation mode of the laser device includes outputting pulsed laser light having a tissue-penetration depth between about 0.5 millimeters and about 1 millimeters, and a pulse duration of between about 5 nanoseconds and 10 nanoseconds.