Optical waveguides – Planar optical waveguide – Thin film optical waveguide
Reexamination Certificate
1998-09-21
2001-06-12
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Planar optical waveguide
Thin film optical waveguide
C385S125000
Reexamination Certificate
active
06246825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a planar liquid filled optical waveguide, which has particular but not exclusive application as a fast all optical switching device for time division multiplexing (TDM) network architectures and sub-systems.
2. Related Art
In a TDM network, low bit rate data streams, typically at 64 kbits/sec per telephony channel, derived from digital sources such as modems and digitally sampled analogue sources such as telephones, together with other information such as billing data, are multiplexed for transmission across the network by interleaving the signals in time to create a much higher bit rate signal, at up to 1 Gbit/sec or greater, but typically at 500 Mbits/sec. All-optical switching devices may be used in such systems to provide functions such as optically controlled modulation and all-optical clock signal recovery in high frequency systems.
Liquid filled optical waveguides are known. Reference is directed to our Publication Number WO 96/10282; “Optical fibre with quantum dots”, in which a hollow tubular glass cladding is filled with a colloidal solution of quantum dots through an opening at either end. The principle extends to a planar waveguide where, for example, the waveguide is a channel formed in a substrate.
Although the method of end filling is suitable for short lengths of waveguide, it becomes increasingly difficult to fill longer lengths in this way. This is partly due to the viscous drag at the liquid/waveguide interface and partly the increasing chance that impurities at this interface will cause only partial wetting, which may stop the filling process entirely. Longer waveguide lengths are desirable as they may enable the device to operate with lower powered sources than would otherwise be possible, in turn reducing the risk of optical damage to certain materials which have useful optical properties and which may be used in the construction of such devices. Whilst the application of reduced or increased pressure may be used to assist the process of end filling, this may not be possible with materials such as volatile liquids.
U.S. Pat. No. 5,473,721 discloses a multi-mode optical circuit in which channels for receiving optical fibres are machined into a substrate. The channels can be filled with liquid through transversely arranged filling passages, the liquid in the wave guiding region so formed being confined by the ends of the optical fibres inserted into the machined channels. U.S. Pat. No. 5,394,239 discloses a solid optical waveguide in the form of a coil on a substrate.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a planar optical waveguide comprising an elongate liquid filled wave guiding region on a substrate, the liquid being confined within the waveguide after filling, wherein the ends of the wave guiding region are defined by respective regions of the substrate, further comprising a filling channel for filling the wave guiding region arranged transversely to its length.
An advantage associated with examples of this invention is that the difficulty involved in fabricating long liquid filled waveguides can be reduced. A further advantage is that optical coupling to the liquid waveguide is not hindered by the presence of glue or other sealant necessary to retain the liquid in an end-filled waveguide configuration.
The filling channel can be sealed after filling, although the surface tension of the liquid within the waveguide may be sufficient to confine the liquid within it.
To further enhance optical coupling, the waveguide may include a short section of solid waveguide introduced between the substrate edge and the liquid filled channel.
The invention may be implemented by forming a coiled or otherwise folded liquid filled waveguide on a substrate, with filling channels arranged radially to connect the waveguide to a reservoir fabricated in the substrate. In accordance with the invention there is provided a planar optical waveguide comprising an elongate liquid filled wave guiding region and a filling channel arranged transversely to its length, wherein the wave guiding region is in the form of a coil having a plurality of turns, and the channel connects to the wave guiding region at each of at least two of the turns of the coil. An advantage of these arrangements is that it is possible to construct a device with long overall path lengths while at the same time minimising device size.
The waveguide may include a plurality of filling channels, each of which connects to the wave guiding region at each of at least two of the turns of the coil. One or more filling channels may connect to each of the turns of the coil, advantageously allowing simultaneous filling of each turn or part of a turn.
In accordance with the invention, there is further provided apparatus for producing a planar optical waveguide with a liquid filled wave guiding region, comprising a planar optical waveguide having an elongate hollow wave guiding region and a filling channel arranged transversely to the length of the wave guiding region to enable filling of the wave guiding region by capillary action from an external source, and a reservoir for immersing the waveguide in a liquid contained therein so as to fill the wave guiding region with the liquid.
There is also provided, in accordance with the invention, a method of manufacturing a planar optical waveguide having a liquid filled wave guiding region, comprising the steps of providing a substrate having an elongate channel for forming the wave guiding region wherein the ends of the channel are defined by respective regions of the substrate, forming a filling channel in the substrate transversely to the length of the guiding region, and filling the wave guiding region with a liquid by capillary action through the filling channel, such that the liquid is confined within the waveguide.
REFERENCES:
patent: 5394239 (1995-02-01), Valette
patent: 5473721 (1995-12-01), Myers et al.
patent: 2038285 (1970-07-01), None
patent: 4212392 A1 (1992-04-01), None
patent: 0534590 A1 (1993-03-01), None
patent: 0679881 A1 (1995-11-01), None
patent: 1-97841 (1989-04-01), None
patent: 01097841 (1989-04-01), None
patent: WO 92/06394 (1992-04-01), None
patent: WO 96/10282 (1996-04-01), None
Patent Abstracts of Japan, vol. 13, No. 337, Jul. 28, 1989 & JP 01 097841A (Hitachi Ltd.) Apr. 17, 1989.
Patent Abstracts of Japan, vol. 006, No. 096 (P-120), Jun. 4, 1982 & JP 57 030803 A(Olympus Optical Co Ltd), Feb. 19, 1982.
McCormick et al, “Microengineering Design and Manufacturing Using the LIGA Process”, Engineering Science and Education Journal, Dec. 1994, pp. 255-262.
Kanbara et al, “Optical Kerr Shutter Using Organic Nonlinear Optical Materials in Capillary Waveguides”, IEEE Photonics Technology Letters, vol. 3, No. 9, Sep. 1991, pp. 795-797.
Kashyap et al, “Nonlinear Polarization Coupling and Instabilities in Single-Mode Liquid-Cored Optical Fibers”, Optics Letters, vol. 17, No. 6, Mar. 15, 1992, pp. 405-407.
Manning et al, “Ultrafast Refractive Nonlearity Displayed by Organic Monomode Fibre Waveguides”, Integrated Photonics Research Topical Meeting, Palm Springs, USA, Mar. 1993.
British Telecommunications PLC
Connelly-Cushwa Michelle R.
Nixon & Vanderhye P.C.
Sanghavi Hemang
LandOfFree
Liquid filled optical waveguide does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid filled optical waveguide, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid filled optical waveguide will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2491836