Abstract: A splice tray for use in splicing fiber optic cables has an outer periphery and a cable splicing area inwardly of the outer periphery. A main cable guideway for receiving a pair of side-by-side cables to be spliced extends along a portion of the outer periphery adjacent thereto. The main cable guideway splits into first and second continuation guideways, the first of which curves inwardly from the outer periphery to intersection with the splicing area from one direction. The second continuation guideway continues along another portion of the outer periphery to intersection with the splicing area from another direction. The two fiber optic cables that extend along the main guideway are separated to extend through the first and second continuation guideways to the splicing area for being joined together in a splice. A cable looping device is provided in the splicing area for receiving cable loops to take up slack, and a splice receiving recess is provided in the splice area for holding a splice.

Abstract: An echo cancelling circuit for use with a laser whose generated light is connected to an optical fiber by a connector. The connector reflects part of the laser light to a detector associated with the laser. The echo cancelling circuit attenuates the laser generated light by a predetermined factor. The cancelling circuit then detects the attenuated laser light and develops a signal whose amplitude and phase is such as to substantially cancel the signal representative of the light reflected from the connector.

Abstract: A closed loop control system for a laser which is used in an instrument which may be an optical time domain reflectometer. The system uses the output light of the laser and the light from a fiber to which the laser light is connected to initially set the bias and pulse current amplitudes to the laser and adjust the gain of the receiver which is part of the control system. The control system also responds to light from the fiber to continuously control the pulse current amplitude and receiver gain so that the amplitude of the electrical signal representative of that light is kept within the operating range of the receiver electronics.