Ultracompact Q-switched microlasers and related method

• US 5,488,619 A
• Filed: 10/06/1994
• Issued: 01/30/1996
• Est. Priority Date: 10/06/1994
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Holcomb, Terry L., Injeyan, Hagop
• Primary Examiner(s): Healy, Brian
• Assistant Examiner(s): Wise, Robert E.
• Application Number:
  US08/319,192
• Time in Patent Office: 481 Days
• Field of Search: 372/11, 372/12, 372/17
• US Class Current: 372/12
• CPC Class Codes: H01S 3/025 of solid state lasers, e.g. housings or mountings
• CPC Class Codes: H01S 3/0604 in the form of a plate or disc
• CPC Class Codes: H01S 3/0627 the resonator being monolithic, e.g. microlaser
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/1063 using a solid state device provided with at least one potential jump barrier
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/115 using intracavity electro-optic devices
• CPC Class Codes: H01S 3/2383 Parallel arrangements
• CPC Class Codes: H01S 5/42 Arrays of surface emitting lasers

Abstract

An ultracompact array of microlasers in which Q-switching is performed by intracavity electroabsorptive modulators, to provide an array of relatively high-power beams with good beam quality and other beam characteristics. The microlasers are optically pumped by light beams from an array of semiconductor diode lasers, each of which is individually controlled by a separate electrode. Light from the diode lasers is coupled directly into a slab of solid-state crystal material, such as Nd:YVO₄ (neodymium:yttrium vanadate), in which laser action takes place. The solid state material in part defines an array of laser cavities and an array of individually controllable Q-switching elements is integrated into the cavities, permitting Q-switching of each of the array elements. The Q-switching elements are electroabsorptive modulators that permit extremely rapid switching of the microlaser elements and provide output pulses of relatively high peak powers.

Claims

1. An array of Q-switched microlasers, comprising:

an array of individually addressable diode lasers adapted to produce an array of generally parallel output light beams;

an array of microlenses positioned in the array of generally parallel output light beams to provide collimation of the output beams;

a crystal functioning as a laser gain medium, positioned to receive the generally parallel output light beams from the diode lasers, such that the light beams operate to provide optical pumping of the laser gain material of the crystal;

an array of individually addressable electroabsorptive modulators formed in resonant cavities that are defined in part by the laser gain medium; and

means for selectively electrically biasing the electroabsorptive modulators periodically to provide a Q-switching function in which relatively higher power output peaks are obtained from selected elements of the microlaser laser array.

2. An array of Q-switched microlasers as defined in claim 1, wherein:

the array of individually addressable diode lasers is formed in a composite semiconductor layer that includes an active layer and a pair of integral reflective surfaces for each member of the array, to produce an emitted light beam for each member of the array generally perpendicular to the composite semiconductor layer.

3. An array of Q-switched microlasers as defined in claim 1, wherein:

the array of electroabsorptive modulators includes a single semiconductor quantum well stack and multiple biasing electrodes positioned at positions adjacent to respective light beams output from the laser gain medium, to provide individually addressable Q-switching of the light beams emitted from the microlaser array.

4. An array of Q-switched microlasers as defined in claim 3, wherein:

the crystal functioning as a gain medium and the array of electroabsorptive modulators incorporate reflective surfaces that define a laser cavity encompassing both the laser gain medium and the electroabsorptive modulators.

5. An array of Q-switched microlasers as defined in claim 1, and further comprising:

a frequency doubling crystal formed adjacent to the electroabsorptive modulators.

6. An array of Q-switched microlasers as defined in claim 1, and further comprising:

an optical parametric oscillator for conversion of light emitted from the array to longer wavelengths.

7. A method of generating an array of laser beams of relatively high power and beam quality, comprising the steps of:

generating an array of generally parallel light beams from an array of semiconductor diode lasers;

collimating each of the generally parallel light beams in the array;

optically pumping an array of solid-state lasers by introducing the array of generally parallel light beams into a laser crystal gain medium that in part defines a laser cavity for each of an array of solid state lasers;

emitting an array of amplified laser light beams from the gain medium; and

selectively Q-switching the solid-state lasers to provide pulsed output beams of relatively high peak powers, wherein the Q-switching function is performed by controlling an electroabsorptive modulator element associated with each of the output beams.

8. A method as defined in claim 7, wherein:

the step of selectively Q-switching the solid-state lasers includes selectively biasing the electroabsorptive modulator elements to effect switching between a transparent state in which lasing is permitted to take place and an absorptive state in which lasing is suppressed.

9. A method as defined in claim 8, and further comprising:

doubling the output frequency of light beams emitted in the emitting step, using a frequency multiplier crystal.

10. A method as defined in claim 8, and further comprising:

converting the light beams emitted in the emitting step to longer wavelengths, using an optical parametric oscillator.