Abstract: The sensor includes an optical waveguide defined in a light-transmitting medium. The waveguide includes a sensing portion and an non-sensing portion. The light-transmitting medium included in the sensing portion has defects that provide the light-transmitting medium with a deep band gap level between a valence band of the light-transmitting medium and a conduction band of the light-transmitting medium. The deep band gap level is configured such that the waveguide guiding light signals through the light-transmitting medium in the sensing portion causes free carriers to be generated in the light-transmitting medium. A detector is configured to detect the free carriers in the sensing region of the waveguide.

Abstract: The sensor includes an optical waveguide defined in a light-transmitting medium. The waveguide includes a sensing portion and an non-sensing portion. The light-transmitting medium included in the sensing portion has defects that provide the light-transmitting medium with a deep band gap level between a valence band of the light-transmitting medium and a conduction band of the light-transmitting medium. The deep band gap level is configured such that the waveguide guiding light signals through the light-transmitting medium in the sensing portion causes free carriers to be generated in the light-transmitting medium. A detector is configured to detect the free carriers in the sensing region of the waveguide.

Abstract: The sensor includes an optical waveguide defined in a light-transmitting medium. The waveguide includes a sensing portion and an non-sensing portion. The light-transmitting medium included in the sensing portion has defects that provide the light-transmitting medium with a deep band gap level between a valence band of the light-transmitting medium and a conduction band of the light-transmitting medium. The deep band gap level is configured such that the waveguide guiding light signals through the light-transmitting medium in the sensing portion causes free carriers to be generated in the light-transmitting medium. A detector is configured to detect the free carriers in the sensing region of the waveguide.

Abstract: An integrated optical waveguide (1) having an in-line light sensor (2) integrally formed therewith for tapping off a small proportion of the signal transmitted along the waveguide (1). A first part (1A) of the waveguide leads to a photodiode portion (2) and a second part (1B) of the waveguide leads away from the photodiode portion (2), the photodiode portion (2) comprising one or more regions (14) of light absorbing material within the waveguide (1) arranged to absorb a minor proportion of light transmitted along the waveguide (1) and thereby to generate free charge carriers within the waveguide (1). Deep band gap levels (21) are introduced into photodiode portion by ion implantation to enable it to absorb selected wavelengths. The free charge carriers are detected by a p-i-n diode formed across the waveguide (1). Wavelength selective reflectors (11, 12) may be provided either side of the photodiode portion (2) so light passes repeatedly through the photodiode portion (2).

Abstract: A method of selectively adjusting the refractive index of the propagating portion of an optic waveguide, the method including the step of implanting into selected portions of the propagating portion of the optic waveguide a dopant material selected so as to minimise the number of additional attenuating, extrinsic charge carriers in the propagating portion of the optic waveguide.

Abstract: An optical coupling between first and second optical components 1, 8 in which an input face 2A through which light is to pass of the first component 1 being directly bonded to an output face 8C through which light is to pass of the second component 8. Such a coupling may be provided, for example, between a rib waveguide 2 and an optical fibre 7.