Abstract: The invention relates to an optical pressure detector for instance in the form of an optical alarm with a multimode light guide (1) imbedded in a contact pad (2) subject to pressure, said light guide being curved by the compression of the contact pad (2). The light guide (1) is mounted between a light source and a light detector, an analyzer being present to analyze the output signals from the light detector changing through mode coupling as a function of the applied pressure, and to process them for instance into an alarm signal. The light detector covers an angle of aperture at the exit of the light guide (1), said angle only enclosing the radiation field in the range of lower-order modes of the light guide (1).