Laser system for ranging applications
View Patent ↗A passively, Q-switched laser operating at an eye safe wavelength of between 1.2 and 1.4 microns is described. The laser may operate at a lasing wavelength of 1.34 microns and use a gain element of Nd:YVO 4 and a saturable absorber element of V:YAG. The systems and methods to produce short pulses having a pulse duration less than 1 ns and high energy pulses having pulse energies greater than 2 μJ are described.
1 . A laser system configured to output a pulsed laser beam having a wavelength
between 1.2 and 1.4 microns comprising:
a first gain element having a first and a second surface, the first surface having a highly reflective coating at the lasing wavelength to form a first end of a resonator;
a second gain element within the resonator;
a second end of the resonator formed by a second surface having a partially transmitting optical coating at the lasing wavelength between 1.2 and 1.4 microns; and
a saturable absorber element located in the resonator, the saturable absorber being configured to output the pulsed laser beam,
wherein the pulsed output laser beam has an average power greater than 1 Watt.
2 . The laser system as recited in claim 1 , wherein the pulsed output laser beam has a pulse energy of at least approximately 2 μJ and a pulse repetition rate of at least approximately 500 kHz.
3 . The laser system as recited in claim 1 , wherein the partially transmitting optical coating at the lasing wavelength between 1.2 and 1.4 microns is on a surface of the saturable absorber.
4 . The laser system as recited in claim 1 , further comprising a multiple emitter pump source having a plurality of emitters, wherein the multiple emitter pump source is composed of multiple discrete emitters.
5 . The laser system as recited in claim 4 , further comprising a pump laser driver, wherein the multiple emitters of the pump source are arranged in series such that a current flowing through each emitter of the multiple emitter pump source is the same.
6 . A laser ranging system comprising:
the laser system as recited in claim 1 ; and a detector, wherein the laser ranging system measures distances to a target located more than 1 km from the laser ranging system.
7 . A laser system configured to output a pulsed laser beam having a wavelength
between 1.2 and 1.4 microns comprising:
a first gain element having a first and a second surface, the first surface having a highly reflective coating at the lasing wavelength between 1.2 and 1.4 microns to form a first end of a resonator;
a second gain element within the resonator;
a second end of the resonator formed by a second surface having a partially transmitting optical coating at the lasing wavelength between 1.2 and 1.4 microns;
a saturable absorber element located in the resonator, the saturable absorber being configured to output the pulsed laser beam; and
a multiple emitter pump source configured to generate a plurality of pump beams that spatially overlap in a common pump spot in the gain elements to form a combined pump beam by bringing the plurality of pump beams together along their fast axes, wherein the combined pump beam occurs only in or adjacent to the gain elements and the multiple emitter pump source is composed of multiple discrete emitters.
8 . A laser system configured to output a pulsed laser beam having a wavelength
between 1.2 and 1.4 microns comprising:
a first gain element having a first and a second surface, the first surface having a highly reflective coating at the lasing wavelength between 1.2 and 1.4 microns to form a first end of a resonator;
a second gain element within the resonator;
a second end of the resonator formed by a second surface having a partially transmitting optical coating at the lasing wavelength between 1.2 and 1.4 microns;
a saturable absorber element located in the resonator, the saturable absorber being configured to output the pulsed laser beam; and
a multiple emitter pump source having a plurality of edge-emitting laser diodes each configured to emit an associated polarized pump beam that is incident in polarized form on a common pump spot in the gain element, wherein at least a selected one of the edge-emitting laser diodes in the multiple emitter pump source operates in a wavelength range between 875 nm to 890 nm and is grating-locked to wavelength-narrow and -stabilize the associated pump beam generated by the selected emitter and wherein the multiple edge-emitting laser diodes of the pump source are arranged in series such that a current flowing through each laser diode of the plurality of laser diodes is the same.
9 . The laser system as recited in claim 1 , wherein the first gain element has a lower doping level than the second gain element.
10 . The laser system as recited in claim 1 , wherein the partially transmitting optical coating at the lasing wavelength between 1.2 and 1.4 microns is on a discrete output coupler.
11 . A laser ranging system as recited in claim 4 , wherein each of the multiple emitters is configured to emit an associated polarized pump beam that is incident in polarized form on a common pump spot in the gain element by bringing the plurality of pump beams together along their fast axes.
12 . The laser system as recited in claim 8 , wherein the first gain element has a lower doping level than the second gain element.
13 . The laser system as recited in claim 7 , further comprising a pump laser driver, wherein the multiple emitters of the pump source are arranged in series such that a current flowing through each emitter of the multiple emitter pump source is the same.
14 . The laser system as recited in claim 7 , wherein the plurality of pump beams are directly delivered to the gain elements without the use of optical fiber.
15 . The laser system as recited in claim 7 , wherein the first gain element has a lower doping level than the second gain element.