Abstract: A sensor includes a light emitter capable of producing stimulated emission. The sensor includes an optical fiber comprising at least one fiber Bragg grating. A first end of the optical fiber is optically coupled to a first emitting end of the light emitter. The fiber Bragg grating is located at a measurement region of the optical fiber away from the first end. A change in wavelength of the laser emission in the optical fiber is induced by a change in peak reflectivity of the fiber Bragg grating. The change in the peak reflectivity occurs in response to an environmental change at the measurement region, e.g., which changes a physical periodicity and/or the refractive index of the grating. The sensor includes an optical detector coupled to the optical fiber or the light emitter that detects the change in the wavelength.

Abstract: A controllable current limiting circuit (30) that, when used with a low precision current limiting circuit (10), will limit the current of the output driver transistor M1 to a relatively flat response over a broad temperature range. The current is limited by setting the voltage across a resistance, R1, to a certain value. To overcome temperature induced variations in this voltage, the compensation circuit (20) generates a current that varies with temperature. This current is injected into a terminal of the resistance, R1. This current is generated in such as a manner to ensure that the current flowing in the output driver transistor M1 is relatively constant over a wide temperature range.