Bell Telephone Laboratories

Richland Glass Company, Inc.

Theodore C Rich

Irfan Camlibel

Michael A Karr, Iii

Mauro Di Domenico, Jr

Walter W Benson

Donald R Mackenzie

An optical system transmits and reflects a laser beam along a common optical path between a laser generator and the target area on a workpiece. Illuminating light is transmitted along a portion of the optical path to the workpiece and is reflected therefrom to form an image of the target area projected onto a display screen. The reflected laser beam is focused at a detection point to monitor etch rate while the illuminating light is reflected adjacent thereto from the optical path to provide a visual indication of the laser beam locations on the workpiece corresponding to the image being simultaneously displayed.

Laser etch monitoring system

A process for hermetically sealing an optical fiber to a metal housing is described. An optical fiber 12 is threaded through a thick-walled metal tube 10 which has a bore 11 of slightly larger diameter than the fiber. The tube and fiber are inserted in a pneumatically operated collet and uniform radial pressure is applied to the tube to form a unitary hermetic assembly. Metal tube 10 is characterized in that it has or, prior to forming the assembly, is annealed to have a Rockwell hardness of less that 15 T 15. At this value the metal is soft and the pressure required to cause the metal to cold flow around the fiber is less than that required to break the fiber. The tube is then soldered or otherwise secured in a hole in the housing, thus completing the hermetic seal. Such a seal is useful in hermetic packaging of optical devices. It is advantageous over the prior art for its simplicity and inexpensiveness. The technique is suited to high yield mass production of reliable seals.

Optical fiber-to-metal hermetic seal

An optical fiber tap is described which comprises a beamsplitter formed by positioning bevelled, parallel endfaces of two segments of optical fiber in coaxial alignment and in close proximity to each other. A suitable dielectric film, such as air, fills the gap between the endfaces. Light propagating into the tap from the first fiber segment is partially reflected and partially refracted at the bevelled endfaces. The refracted portion enters the second fiber segment and the reflected portion leaves the tap and is detected by a photodetector. By choice of the proper angle for the bevelled endfaces, the tap can be made substantially mode independent. A greater degree of mode independence can be obtained by interposing a steady-state mode exciter between the light source and the beamsplitter. The tap is particularly useful for semiconductor junction laser stabilization by the feedback arrangement described herein since the ratio of the intensity of the reflected portion to that of the refracted portion is substantially constant. A package assembly for use in the feedback arrangement is also described.

Optical fiber light tap

An optical fiber is hermetically sealed to a metal housing containing an optical device (e.g, a semiconductor junction laser or photodiode) by threading and centering the fiber through a thin walled metal tube, filling the tube with solder (e.g., a cylindrical preform) and allowing it to cool. The solder, upon solidifying and cooling, squeezes against the fiber and forms a hermetic seal. The tube-fiber assembly is inserted through an aperture in the housing wall, the fiber is aligned with the optical device and then the tube is soldered to the wall. The housing is out-gassed and then back-filled with a noncorrosive ambient such as nitrogen. Other aspects of the hermetic package, including a laser mount, are also described.

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Berkeley Heights, NJ, United States of America

Theodore C Rich