Illumination – Light fiber – rod – or pipe – With optical fiber bundle
Reexamination Certificate
1999-11-12
2001-09-25
O'Shea, Sandra (Department: 2875)
Illumination
Light fiber, rod, or pipe
With optical fiber bundle
C362S551000, C362S553000, C385S043000, C385S031000, C385S050000
Reexamination Certificate
active
06293688
ABSTRACT:
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
(none)
BACKGROUND OF THE INVENTION
Tapered waveguides are useful for efficiently interconnecting waveguides that support modes of different dimensions. Semiconductor laser chips typically contain waveguides that tightly guide the optical mode, while the optical fiber that transmits the laser light guides weakly so that the modes match poorly if the laser is connected directly to the fiber. Many approaches have been used to improve the efficiency of such interconnections. Vertical, lateral, and refractive index tapers were demonstrated by * R. Logan, U.S. Pat. No. 3,978,426, Aug. 31, 1976, and * R. K. Winn et al., IEEE Trans. Microwave Theory and Techniques MTT23 92 (1975), and * P. G. Suchoski Jr., et al., J. Light. Technology, LT5 1246 (1987). Both waveguide claddings and fibers have been tapered; see * J. Hammer, U.S. Pat. No. 4773720, Sep. 27, 1988, and * H. Schneider, U.S. Pat. No. 4,795,228, Jan 3, 1989. Multiple stage tapers in the vertical and longitudinal directions were shown by * T. Koch, U.S. Pat. No. 4,932,032, Jun. 5, 1990 and * P. Melman, U.S. Pat. No. 5,261,017, Nov. 9, 1993. Pairs of coupled waveguides have been shown with single and multiple horizontal and vertical tapers by * Y. Shani et al., Appl. Phys. Lett. 55 2389 (1989), * E. Kapon, U.S. Pat. No. 5,078,516, Jan 7, 1992, * Zengerle et al., Elect. Lett. 28 631 (1992), * B. Stegmueller, U.S. Pat. No. 5,199,092, Mar. 30, 1993 and * R. Smith et al., IEEE Photon. Technology Lett. 8 1052 (1996). Segmented tapers are shown by Z. Weissman et al., J. Light. Technology, 11 1831 (1993), and R. Adar, U.S. Pat. No. 5,577,141, Nov. 19, 1996. A good deal of effort has also been expended recently on optimizing integrated tapers in semiconductor lasers. However, the practical constraints that apply to any specific implementation tend to require different coupling approaches depending on both materials and geometry: the processes used to manufacture and package a product must be compatible with each other, with the materials used, and with the component layout. A unique geometry of taper and waveguides is required to optimize the coupling between a laser chip that is to be butt coupled in a hybrid configuration to a planar waveguide chip.
SUMMARY OF THE INVENTION
According to the invention, a first waveguide fabricated a first distance above a first substrate may be efficiently coupled to a second waveguide fabricated on a second substrate by means of a third waveguide fabricated a second distance above the second substrate and parallel coupled to the second waveguide. The two substrates are attached to couple energy across the gap between the two respective coupling surfaces. In an embodiment, the first waveguide substrate is flipped upside down relative to the second waveguide substrate, and the two substrates are separated by the sum of the first and second distances. In another, upright, embodiment, the two substrates are separated by a difference of the first and second distances. In a further embodiment, the first substrate is bonded to a carrier substrate that is in turn attached to the second waveguide substrate. In a specific embodiment, the first waveguide is a single mode semiconductor laser waveguide that is flip-chip bonded to the second substrate, the second waveguide is a silica waveguide structure parallel coupled to the third waveguide which is a single mode tantala structure end-fire coupled to the semiconductor laser. The waveguide coupling may be optimized with a high index material in the gap between the two chips, and the waveguide thermal characteristics may be improved by using polymer in the waveguide structure, which imposes process temperature constraints on subsequent steps including bonding and deposition.
The invention will be better understood upon reference to the following detailed description in connection with the accompanying drawings.
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Negron Ismael
O'Shea Sandra
Sparkolor Corporation
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