Automatic alignment and locking method and apparatus for fiber optic module manufacturing

• US 5,745,624 A
• Filed: 08/23/1996
• Issued: 04/28/1998
• Est. Priority Date: 08/23/1996
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Chan, Eric Yuen-Jun, Beranek, Mark William
• Primary Examiner(s): Ullah, Akm E.
• Application Number:
  US08/701,889
• Time in Patent Office: 613 Days
• Field of Search: 385/50, 385/52, 385/88, 385/89, 385/90, 385/91, 385/92, 385/147, 219/85.14, 219/85.18
• US Class Current: 385/91
• CPC Class Codes: G02B 6/4221 involving a visual detection of the position of the elements, e.g. by using a microscope or a camera
• CPC Class Codes: G02B 6/4226 Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount
• CPC Class Codes: G02B 6/4227 Active alignment methods, e.g. procedures and algorithms
• CPC Class Codes: G02B 6/4238 Soldering

Abstract

A method and apparatus for aligning an optical fiber (120) with an optoelectronic hybrid device (112) and locking the optical fiber in the aligned position are disclosed. A fiber coated with an external layer of gold is threaded through a solder preform (130). The optical fiber (120) rests upon a ceramic substrate (104). The ceramic substrate also supports a device submount (108) that houses the optoelectronic device (112). The ceramic substrate (104) supports a resistor/heater formed of a thin film of nickel-chromium alloy (604). The resistor/heater supports a pad (609) formed of a layer of nickel (610) and a layer of gold (612). Located atop the pad (609) is the solder preform (130). Precise control of heating is provided by applying a predetermined voltage to the resistor/heater (122) for precise time periods, thereby eliminating the necessity of making temperature measurements during heating. As the resistor/heater (122) is energized, the solder preform is liquefied. An open loop search process that utilizes signal strength feedback is used to control the operation of an x-y-z micropositioning stage (328) that precisely positions an arm (306) that supports the optical fiber (120). The alignment system also includes a fixturing setup that includes a probe head (340) having multiple electrical probes (502a, 502b, 504a, 504b) and a vertical rod (506) that applies a downward force to the solder during manufacturing.

Claims

1. An alignment and locking system for aligning an optical fiber with an optoelectronic device secured to a substrate and locking the optical fiber in place, said system comprising:

a computer;

a thin metallic resistor/heater overlying the substrate;

a solder preform overlying said thin metallic resistor/heater, said optical fiber positioned adjacent said solder preform, said solder preform having a known melting temperature and the ability to form a chemical bond with said thin metallic resistor/heater;

a power source for supplying electrical power to said thin metallic resistor/heater suitable for causing said solder preform to melt based on power control signals received by said power source from said computer;

an instrument for determining the amount of light passing between said optical fiber and said optoelectronic device and supplying related received power signals to said computer; and

a manipulator for aligning said optical fiber with said optoelectronic device based on alignment control signals received from said computer, said alignment control signals being based on said received power control signals, said manipulator aligning said optical fiber while said solder preform is melted.

2. The system of claim 1, wherein said thin metallic resistor/heater comprises a thin layer of nickel-chromium alloy.

3. The system of claim 2, wherein said thin metallic resistor/heater further comprises a thin layer of nickel located between said thin layer of nickel-chromium alloy and said solder preform.

4. The system of claim 3, further comprising a thin layer of gold located between said layer of nickel and said solder preform.

5. The system of claim 1, wherein, prior to melting, said solder preform includes a hole sized to receive said optical fiber.

6. The system of claim 5, wherein said solder preform comprises Sn and Ag.

7. The system of claim 5, wherein said solder preform comprises Sn96.5 Ag3.5.

8. The system of claim 1, wherein said optoelectronic device includes terminals, said thin metallic resistor/heater includes terminals, and said manipulator includes a probe head, said probe head including probes positioned to contact the terminals of said optoelectronic device and said thin metallic resistor/heater.

9. The system of claim 8, wherein said probe head also includes a rod positioned to contact said solder preform.

10. The system of claim 9, wherein said probe head lies above said substrate and is lowered such that said probes contact said terminals of said optoelectronic device and said thin metallic resistor/heater, and said rod contacts said solder preform prior to power being applied to said thin metallic resistor/heater and said optical fiber being manipulated.

11. The system of claim 10, wherein said manipulator includes a manually operated mechanism for manipulating said optical fiber prior to said optical fiber being aligned while said solder is melted.

12. The system claimed in claim 11, wherein said manipulator manipulates said optical fiber along three orthogonally oriented axes.

13. The system of claim 1, wherein said computer controls the magnitude and duration of the voltage applied to said thin metallic resistor/heater by said power source.

14. The system of claim 13, wherein, after a predetermined voltage is applied to said thin metallic resistor/heater for a predetermined interval, the voltage is sequentially stepped down to a lower voltage level.

15. A method of aligning an optical fiber with an optoelectronic device so that the optimum amount of light passes between the optical fiber and the optoelectronic device, said method comprising:

positioning an optical fiber adjacent a solder preform located atop a thin metallic resistor/heater positioned on a substrate that also supports an optoelectronic device;

supplying electrical power to said thin metallic resistor/heater for a predetermined time period sufficient for the thin metallic resistor/heater to heat the solder preform to the melting point of the solder;

passing light between said optical fiber and said optoelectronic device while said solder preform is melted;

detecting the amount of light passing between said optical fiber and said optoelectronic device while said solder preform is melted; and

automatically manipulating the position of said optical fiber relative to said optoelectronic device so as to increase the amount of light passing between said optical fiber and said optoelectronic device while said solder preform is melted.

16. The method of claim 15, wherein the level of voltage of the electrical power supplied to said thin metallic resistor/heater changes during said predetermined time period.

17. The method of claim 16, wherein a first level of voltage occurs for a first predetermined period of time, and said first level of voltage is stepped down to a second level of voltage after said first predetermined period of time has elapsed.

18. The method of claim 17, wherein said optical fiber is automatically manipulated along each axis of a plurality of orthogonal axes by:

moving the optical fiber relative to the optoelectronic device in steps in one direction;

detecting the amount of light transmitted between the optical fiber and said optoelectronic device after each step; and

reversing the direction of movement of the optical fiber relative to the optoelectronic device if the amount of light detected after the latest step is less than the amount of light detected after the preceding step.

19. The method of claim 18, wherein the solder preform comprises Sn and Ag.

20. The method of claim 18, wherein the thin metallic resistor/heater is formed of nickel-chromium alloy.

21. The method of claim 20, wherein the solder preform has a hole through said preform, the hole sized to receive the fiber optic member.