Optical waveguides – Planar optical waveguide
Reexamination Certificate
2002-05-31
2004-11-02
Palmer, Phan T.H. (Department: 2874)
Optical waveguides
Planar optical waveguide
C385S043000, C385S050000, C372S045013
Reexamination Certificate
active
06813432
ABSTRACT:
FIELD OF THE INVENTION
The field of invention relates to optical communication devices in general; and, more specifically but not limited to waveguide tapers in optical devices.
BACKGROUND
Some optical devices may include a waveguide that is intended to be coupled to another waveguide having a significantly larger cross-sectional size. For example, a planar lightwave circuit (PLC) can have a waveguide on the order of four microns in height to be coupled to an optical fiber with a diameter of about ten microns. One way to couple a port of a relatively large waveguide to a port of a significantly smaller waveguide is by forming a tapered waveguide structure to couple the two waveguides. In one type of taper, the taper at one end has a height or diameter of about the same size as the larger waveguide. At the other end, the taper typically comes to a point. The sides of the taper are typically straight so that the taper has a wedge-like shape, with the wider part of the taper being at the end of the waveguide. This end of the taper is used to couple the taper to the larger waveguide. The interior end of the taper serves as a termination, which along with the narrowing shape of the taper helps force light to propagate from the wide end of the taper to the smaller waveguide (or from the smaller waveguide to the wide end of the taper).
One conventional technique to form the above-described taper when the smaller waveguide is a semiconductor waveguide is to form the smaller waveguide with an end portion from which the taper is formed by etching. That is, at this end portion, the smaller waveguide has: (a) a length about equal to the desired length of the taper; and (b) a thickness that is about equal to the sum of the desired thickness of the smaller waveguide and the desired thickness of the taper. This thickness is typically the size of the fiber core (e.g., 8-10 &mgr;m).
This end portion of the smaller waveguide is then etched using standard etching techniques to form the taper with a shape as described above. However, some etching processes cause the taper's edge end to appear eroded and rough, instead of achieving the desired smooth sharp edge. A rough eroded edge can degrade performance of the taper. In addition, typical etching processes cause the etched surfaces to be significantly less smooth than the surfaces that are not etched. This roughness can increase the waveguide's loss (e.g., in some tests the etched surfaces increased loss by about an additional five dB/cm.
REFERENCES:
patent: 4911516 (1990-03-01), Palfrey et al.
patent: 6200502 (2001-03-01), Paatzsch et al.
patent: 6380092 (2002-04-01), Annapragada et al.
patent: 6411764 (2002-06-01), Lee
patent: 09297235 (1997-11-01), None
patent: 11284061 (1999-10-01), None
patent: WO 00/36442 (2000-06-01), None
patent: PCT/US 03/11833 (2003-10-01), None
Brenner T. et al., “Vertically Tapered InGaAsP/InP Waveguides for Highly Efficient Coupling to Flat-end Single-mode Fibers”, American Institute of Physics, Aug. 15, 1994, pp. 798-800, vol. 65, Woodbury, NY, US.
Intel Corporation
Palmer Phan T.H.
LandOfFree
Method for producing vertical tapers in optical waveguides... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing vertical tapers in optical waveguides..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing vertical tapers in optical waveguides... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305161