High-gain diode-pumped laser amplifier

A laser amplifier suitable for use in amplifying an incoming laser beam, said laser amplifier comprising:

• a laser active slab having a first lateral face defining a wedge lateral dihedral angle with a second lateral face, wherein said wedge lateral dihedral angle is anproximately 0.1 to 2.0 degrees, said first lateral face having an optical coating highly reflecting at a wavelength of the laser beam,
• a diode bar disposed proximate said first lateral face, said diode bar having a plurality of semiconductor diode lasers for producing a gain sheet in said laser active slab, said optical coating further highly transmitting at a wavelength of said semiconductor diode lasers in a region proximate said gain sheet;
• and
• a microlens disposed between said diode bar and said first lateral face.

A three-pass laser amplifier comprising:

• a diode bar providing pump power;
• a block of laser active material disposed adjacent said diode bar for receiving said pump power and generating a gain sheet in said block of laser active material, said block of laser active material having first and second lateral faces forming a lateral dihedral angle, a first optical coating disposed on said first lateral face highly transmitting at a wavelength of the pump power and highly reflecting to a lasing wavelength, a second optical coating disposed on said second lateral face highly reflecting at said lasing wavelength, said first lateral face having first and second windows highly transmitting at said lasing wavelength, said first window for receiving an input laser beam for making a first zig-zag pass through said gain sheet to said second window, said second lateral face having third and fourth windows highly transmitting at said lasing wavelength;
• a first external mirror disposed proximate said second window for reflecting a one-pass-amplified laser beam back into said second window so as to make a second zig-zag pass through said gain sheet to said third window;
• and
• a second external mirror disposed proximate said third window for reflecting a two-pass-amplified laser beam back into said third window so as to make a third zig-zag pass through said gain sheet and emerge at said fourth window as a three-pass-amplified laser beam.

A four-pass laser amplifier comprising:

• a diode bar providing pump power;
• a block of laser active material disposed adjacent said diode bar for receiving pump power and generating a gain sheet in said block of laser active material, said block of laser active material having a first lateral face with an optical coating highly transmitting at a wavelength of the pump power and highly reflecting to a lasing wavelength, and a second lateral face with an optical coating highly reflecting at said lasing wavelength, said first lateral face further having first and second windows highly transmitting at said lasing wavelength, said first window for receiving an input laser beam for making a first zig-zag pass through said gain sheet to said second window, said second lateral face having third and fourth windows highly transmitting at said lasing wavelength, said first and second lateral faces forming a lateral dihedral angle;
• a first external mirror disposed proximate said second window for reflecting a one-pass-amplified laser beam to a second external mirror disposed proximate said third window, said second external mirror for reflecting said one-pass-amplified laser beam into said third window so as to make a second zig-zag pass through said gain sheet to said fourth window;
• and
• a third external mirror disposed proximate said fourth window for reflecting a two-pass-amplified laser beam back into said fourth window so as to make a third zig-zag pass through said gain sheet to said third window,
• said second external mirror further functioning to reflect a three-pass-amplified laser beam to said first external mirror, said first external mirror further functioning to reflect said three-pass-amplified laser beam into said second window so as to make a fourth zig-zag pass through said gain sheet to emerge at said first window as a four-pass-amplified laser beam.

A laser oscillator system comprising:

• a laser active slab having a first lateral face defining a wedge lateral dihedral angle with a second lateral face, wherein said wedge lateral dihedral angle is anproximately 0.1 to 2.0 degrees, said first lateral face and said second lateral face each having an optical coating highly reflecting to a lasing wavelength, said laser active slab further including a first window highly transmitting to said lasing wavelength on one of said first and second lateral faces, and a second window highly transmitting to said lasing wavelength on one of said first and second lateral faces;
• a diode bar disposed proximate said first lateral face;
• a microlens disposed between said diode bar and said first lateral face;
• a first mirror partially transmitting at said lasing wavelength, said first mirror positioned and oriented to partially reflect laser radiation into said first window;
• and
• a second mirror highly reflecting at said lasing wavelength, said second mirror positioned and oriented to reflect laser radiation into said second window such that said first and second mirrors form a laser cavity with said laser active slab.

A ring laser oscillator system comprising:

• a laser active slab having a first lateral face defining a wedge lateral dihedral angle with a second lateral face, wherein said wedge lateral dihedral angle is approximately 0.1 to 2.0 degrees, said first lateral face and said second lateral face each having an optical coating highly reflecting to a lasing wavelength, said first lateral face further including a first window and a second window;
• a diode bar disposed proximate said first lateral face;
• a microlens disposed between said diode bar and said first lateral face;
• an output coupler mirror partially transmitting at said lasing wavelength;
• and
• first and second mirrors highly reflecting at said lasing wavelength, said first mirror positioned and oriented to reflect laser radiation between said first window and said output coupler mirror, said second mirror positioned and oriented to reflect laser radiation between said second window and said output coupler mirror.

An oscillator-amplifier chain comprising:

• a laser oscillator;
• a first amplifier including a first laser active slab with a first lateral face defining a first wedge lateral dihedral angle with a second lateral face, said first lateral face having a first optical coating highly reflecting at a lasing wavelength;
• a second amplifier including a second laser active slab having a third lateral face defining a second wedge lateral dihedral angle with a fourth lateral face, said third lateral face having a second optical coating highly reflecting at said lasing wavelength;
• a first mode-matching component disposed in an optical path between said laser oscillator and said first amplifier;
• and
• a second mode-matching component disposed in an optical path between said first amplifier and said second amplifier.

A laser amplifier suitable for use in amplifying an incoming laser beam or resonator mode, said laser amplifier comprising:

• a slab of laser active material having a specified width and length, said laser active slab further having a first lateral face defining a wedge lateral dihedral angle with a second lateral face, wherein said wedge lateral dihedral angle is approximately 0.1 to 2.0 degrees;
• a diode bar disposed proximate said first lateral face, said diode bar having a plurality of semiconductor diode lasers emitting pump power for producing a gain sheet in said laser active slab;
• a microlens disposed between said diode bar and said first lateral face,
• a first optical coating disposed on a portion of said first lateral face, said first optical coating highly reflecting at a wavelength of the laser beam and highly transmissive at a wavelength of said pump power;
• a second optical coating disposed on at least a portion of said second lateral face, said second optical coating highly reflecting at said wavelength of the laser beam;
• an entrance window disposed on said first lateral face, said entrance window highly transmitting at said wavelength of the laser beam;
• and
• an output window disposed on at least one of said first lateral face and said second lateral face, said output window highly transmitting at said wavelength of the laser beam;
• whereby, when the input laser beam or resonator mode is injected into said slab of laser active material through said input window, the input laser beam or resonator mode follows a zig-zag path through said gain sheet and exits through said output window, the input laser beam thereby undergoing multiple reflections alternating between said first and second lateral faces along path legs forming respective fold angles at points of said reflections, said fold angles defining a series of path vertices, said path vertices being non-uniformly spaced along said first and second lateral faces, said fold angles further varying as a function of corresponding path vertex spacings or path vertex position along said first and second lateral faces.

An oscillator-amplifier chain comprising:

• a laser oscillator;
• an amplifier including a first laser active slab with a first lateral face defining a first wedge lateral dihedral angle with a second lateral face, wherein said wedge lateral dihedral angle is approximately 0.1 to 2.0 degrees, said first lateral face having a first optical coating highly reflecting at a lasing wavelength;
• and
• a mode-matching component disposed in an optical path between said laser oscillator and said first amplifier.