System for the connection of photodetectors to optical fibers

• US 4,709,979 A
• Filed: 10/22/1984
• Issued: 12/01/1987
• Est. Priority Date: 11/04/1983
• Status: Expired due to Fees

• Current Assignee: Alcatel Italia SpA
• Original Assignee: Telettra Telefonia Elettronica E Radio SPA
• Inventors: Tamburello, Mario, Spodati, Fabrizio
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Wise, Robert E.
• Application Number:
  US06/663,240
• Time in Patent Office: 1,135 Days
• Field of Search: 350/96.20, 350/96.21, 350/96.17
• US Class Current: 385/91
• CPC Class Codes: G02B 6/3833 Details of mounting fibres in ferrules; Assembly methods; Manufacture
• CPC Class Codes: G02B 6/3855 characterised by the method of anchoring or fixing the fibre within the ferrule G02B6/3854 takes precedence
• CPC Class Codes: G02B 6/4202 for coupling an active element with fibres without intermediate optical elements, e.g. fibres with plane ends, fibres with shaped ends, bundles
• CPC Class Codes: G02B 6/4212 the intermediate optical element being a coupling medium interposed therebetween, e.g. epoxy resin, refractive index matching material, index grease, matching liquid or gel
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A system for the alignment and assembly of optical fibers to photodetectors in a hermetic package with a glass window and without fiber tail. One end of an optical fiber is terminated with an optical fiber support member. A support plate is provided with two concentric seats on opposite faces of the plate. A photodetector is inserted into one of the seats, and the connector part is inserted into the other seat. Synthetic resins are used to secure the photodetector and connector part to their respective plate seats.

Claims

1. A process for the alignment and assembly of optical fibers to photodetectors of any commerically available structure, and in particular for connecting the glass face of a photodetector to a continuous optical fiber protected substantially along its length by an insulation covering, except for a free end of said continuous optical fiber having a section without insulation covering, said insulation covering terminating abruptly at said section to form an annular shoulder of insulation, comprising the steps of:

(a) inserting the free end of said continuous optical fiber into an optical fiber support member having top and bottom ends with respective top and bottom surfaces, comprising from top to bottom;

(1) a first hollow cylindrical section having an inner diameter slightly larger than the external diameter of said insulation covering;

(2) a hollow truncated conical section having an inner surface with a diameter decreasing from said inner diameter of said first hollow cylindrical section to a diameter slightly larger than the diameter of said optical fiber without said insulation covering, said annular shoulder of insulation abutting said optical fiber support member at said hollow truncated section;

(3) a second hollow cylindrical section having a diameter slightly larger than the diameter of said optical fiber without said insulation covering; and

(4) a recess;

whereby said free end of said optical fiber projects through said optical fiber support member and the section of said free end of said optical fiber without insulation terminates in said recess at said bottom surface;

(b) inserting said photodetector into a cylindrical support plate, said plate having an upper seat and a lower seat, said photodetector being inserted into said lower seat; and

(c) inserting the bottom surface of said optical fiber support member into the upper seat of said cylindrical support plate;

whereby the termination of said free end of said optical fiber is centrally aligned with said glass face of said photodetector and separated from said glass face by a thin layer of air.

2. A process for the alignment and assembly of optical fibers to photodetectors as recited in claim 1, wherein the free end of said optical fiber is properly located and secured in said optical fiber support member by the steps of:

(a) inserting the free end of the optical fiber into said optical fiber support member until the termination end of said insulation covering rests said inner surface of said truncated conical section, and the section of said free end without insulation covering projects down to the bottom surface of said optical fiber support member;

(b) filling the hollow sections of said with epoxy and hardening resin;

(c) applying a resin drop to said recess; and

(d) polymerizing the resin.

3. A process for the alignment and assembly of optical fibers to photodetectors as recited in claim 1 wherein said photodetector is properly located and secured in said cylindrical support plate by the steps of:

(a) coating said photodetector within a thin layer of resin;

(b) inserting the photodetector into the lower seat of said cylindrical support plate;

(c) polymerizing the resin.

4. A process for the alignment and assembly of optical fibers to photodetectors as recited in claim 3, wherein said photodetector is additionally secured in said cylindrical support plate by the steps of:

(a) applying a light layer of resin to the bottom of said photodetector positioned in said lower seat; and

(b) polymerizing said resin.

5. A process for the alignment and assembly of optical fibers to photodetectors as recited in claim 1, wherein said optical fiber support member and said cylindrical support plate containing said photodetector are properly secured together by the steps of:

(a) inserting the bottom surface of said optical fiber support member into the upper seat of said cylindrical support plate;

(b) filling the portion of the upper seat of said cylindrical support unoccupied by said optical fiber support member with resin;

(c) polymerizing the resin.

6. A connection assembly for connecting the glass face of a photodetector of any commercially available structure to continuous optical fiber protected substantially along its length by an insulation covering, except for a free end of said continuous optical fiber having a section without insulation covering, said insulation covering terminating abruptly at said section to form an annular shoulder of insulation comprising:

an optical fiber support member applied onto one end of said continuous optical fiber, said optical fiber support member having a first cylindrical zone with a diameter slightly greater than the insulated optical fiber;

a truncated connection zone, said annular shoulder of insulation abutting said optical fiber support member at said truncated cone;

a second cylindrical zone having a diameter slightly larger than the optical fiber without said insulation covering; and

a terminal flange with a central recess;

a support plate with first and second seats on opposite faces of said plate, said first seat cooperating with said terminal flange of said optical fiber support member and said second seat cooperating with said photodetector, said first and second seats having a cylindrical and coaxial shape and communicating with each other by a hole;

first means for fastening said optical fiber support member to said end of said optical fiber;

second means for fastening said flange of said optical fiber support member into said first plate seat; and

third means for fastening said photodetector into said second seat of the said plate.

7. A connection assembly as recited in claim 6, wherein each of said first, second and third fastening means comprise polymerized resins.