Abstract: The optical circulator according to the present invention comprises two birefringent crystal end-plates, non-reciprocal Faraday rotators inserted between birefringent crystal plates, and a pair of matched birefringent crystal plates disposed between the rotators. The first birefringent crystal end-plate functions as a dividing and combining means for dividing a beam into two beams of orthogonal electric field vectors from different paths into one on the same path. The pair of matched birefringent crystal plates serve as beam path determining means shifting a beam to a different direction depending on the direction of the electric field vector and the propagation. The pair of crystal plates are substantially identical but oppositely oriented, such that the pair of means have opposite beam shifted directions.

Abstract: This invention relates to a method of data output. In data collection and analysis, it is often essential that the information be displayed in a two dimensional graphical representation. Each datum is represented by a point (t,u). By displaying each point in the data, a graphical image is created. A method is disclosed for improving data delivery of an image to an output device. The method involves grouping the points into columns and selecting 4 points from each column having the minimum and maximum values along each axis. These selected points are then stored. These stored points can then be output to form a two dimensional graphical representation of the data.

Abstract: A chromatic dispersion compensation device is provided in the form of an etalon having first partially reflecting mirror providing an input and output port for porting a signal into and out of the etalon cavity. A second partially reflective mirror parallel to and spaced apart from the first mirror, being more reflective than the first mirror provides a monitoring port for monitoring energy within the cavity. Means are optionally provided for controlling a parameter related to the cavity in dependence upon a signal ported from the monitoring port. Means may be provided to control a transmitting laser in dependence upon the signal ported from the monitoring port.

Abstract: The prevention of counterfeiting of currencies, passports, cheques, bank cards, credit cards, optical disks and the like is addressed by introducing thin film structures having both optically-variable security properties and encoded optical data decodable by optical means. The thin film structures comprise a substrate and a multilayer interference coating carried by the substrate, producing an inherent color shift with a change of viewing angle. The multilayer interference coating has a dielectric material which is transparent and the recording layer made of a light absorbing material, a crystalline-structural changing material or a magneto-optic material. The encoded data is in the form of bar codes or digital data. The information is encoded by photolithographic means or by optical recording means. The encoded data is retrieved by an optical recording system having a light source and an optical guiding system and a light detector.

Abstract: A method and apparatus is provided for injecting an optical test pulse mid-stream into an optical path to be tested by providing a switch that in normal transmitting and receiving of data includes two lenses separated by a gap. Data is usually transmitted across the gap from one lens to the other. In a test mode where OTDR is to be performed, a prism functioning in a similar manner to a periscope is moved into the gap between the lenses to couple/inject a test pulse into one of the lenses. An arrangement is described wherein either side of transmission line on either side of the gap can be tested.

Abstract: A device for splitting an optical beam into two beams propagating along different optical paths, is provided. The device includes a pair of graded index collimating lenses having their planar collimating ends aligned such that they are both inwardly facing and share a common optical axis. A partially transmitting partially reflective material is disposed between the lenses. At least one of the planar endfaces of the collimating ends are wedge shaped such that a non-zero angle is formed between the two endfaces. This non-zero angle reduces the effect of unwanted optical interference.

Abstract: By using a pumped erbium doped fibre (EDF) cascaded with a non-saturable absorbing fibre (NSAF), an amplifier is provided with a desired flat uniform output response for a input signals with different intensities at a plurality of wavelengths. Furthermore, from a commercial standpoint, the amplifier is relatively inexpensive and simple to fabricate, being compatible with standard telecommunication fibre. With this particular invention, a previously recognized undesired characteristic of NSAF, its poor amplification qualities, are now being used to an advantage.

Abstract: A device is provided for controllably moving an optical element such as an attenuator, into one of a plurality of positions. The device includes a rotatable, cylindrical member having a face cam that is an endless cammed surface for supporting and moving a cam follower. As the cammed surface is rotated, the cam follower resting upon it moves the optical element in a controlled manner. A gearing means in the form of a toothless planetary gear box is coupled to the cylindrical member and provides fine control over the range of movement of the device.