Cavity pumped, solid state lasers

• US 5,307,365 A
• Filed: 11/13/1992
• Issued: 04/26/1994
• Est. Priority Date: 08/08/1991
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Inventors: Long, William H. Jr., Stappaerts, Eddy A.
• Primary Examiner(s): Bovernick, Rodney B.
• Assistant Examiner(s): Wise, Robert E.
• Application Number:
  US07/975,748
• Time in Patent Office: 529 Days
• Field of Search: 372/70, 372/72
• US Class Current: 372/72
• CPC Class Codes: H01S 3/0407 Liquid cooling, e.g. by water
• CPC Class Codes: H01S 3/042 for solid state lasers H01S3/0401 takes precedence
• CPC Class Codes: H01S 3/0602 Crystal lasers or glass lasers H01S3/063 takes precedence
• CPC Class Codes: H01S 3/094084 with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators
• CPC Class Codes: H01S 3/0941 of a laser diode

Abstract

A highly efficient pumping configuration for a solid state laser uses a diode bar pumping source producing optical energy coherent along an axis normal to the plane of the diode junctions. Pump energy is nearly collimated by a cylindrical optical fiber and applied through a minimum width injection port to a low absorption solid state laser rod in a highly reflective optical cavity including a cylindrical sleeve forming a coolant chamber around the laser rod. The nearly collimated energy is focussed to a minimum width in the plane of the injection port in order to minimize the loss of energy from the optical chamber by leakage out through the port. The laser rod is substantially evenly illuminated by the entire energy entering the cavity on the first pass. Optical energy not absorbed during illumination through is reflected within the cavity until substantially absorbed by the solid state laser rod.

Claims

1. A solid state laser system comprising,

an elongate, solid state laser rod,

means forming a resonant cavity for supporting lasing in said rod,

means forming an elongate chamber surrounding said rod and including an inwardly facing wall having a highly specularly reflective surface of high reflectivity, said wall and surface being shaped to surround and to focus on said rod so that radiant energy emanating from the region of said rod is redirected by the surface back toward said rod by essentially specular reflection,

means associated with said reflective surface for forming an elongate narrow opening through said surface,

said opening having a tangential extent along the surface and lying in a plane cutting across the elongate dimension of said chamber which is limited so that the area of said opening is, smaller than an amount derived from the condition,

that the ratio of the opening area to the total area of the reflective surface less the area of the opening shall be at least an order of magnitude less than the absorption, per pass, of the rod,

pump means of providing radiant energy capable of pumping said rod by absorption of said energy as it passes through said rod, and

means of causing said pump means to illuminate said rod through said opening,

said rod having diameter which is an order of magnitude smaller than the absorption depth it represents,

the energy not absorbed by said rod being directed from the rod to the reflective surface of said wall from which it is redirected to the rod for absorption or redirection and reflection until substantially absorbed in the rod.

2. The solid state laser system claimed in claim 1, wherein said solid state laser rod further includes:

a roughened outer surface for further diffusing said energy.