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: An electro-optic device includes a semiconducting layer in which is formed a waveguide, a modulator formed across the waveguide comprising a p-doped region to one side and an n-doped region to the other side of the waveguide, wherein at least one of the doped regions extends from the base of a recess formed in the semiconducting layer. In this way, the doped regions can extend further into the semiconducting layer and further hinder escape of charge carriers without the need to increase the diffusion distance of the dopant and incur an additional thermal burden on the device. In an SOI device, the doped region can extend to the insulating layer. Ideally, both the p and n-doped regions extend from the base of a recess, but this may be unnecessary in some designs. Insulating layers can be used to ensure that dopant extends from the base of the recess only, giving a more clearly defined doped region.

Abstract: An optic system including an integrated variable optical attenuating device for attenuating an input optical signal, the integrated optical variable attenuating device including a first electrically controllable attenuating element and a second electrically controllable attenuating element cascaded together, the first attenuating element having a first range of optical attenuation smaller than that of the second attenuating element but requiring less input power than the second attenuating element to switch between levels of attenuation within the first range of attenuation, and wherein the optic system further includes electrical circuitry for controlling the first and second attenuating elements in coordination with one another so as to achieve the desired level of total attenuation of the optical signal.

Abstract: An integrated optical arrangement for reducing or preventing the transmission of unwanted or stray light within an optical substrate, the device comprising trenches formed in the substrate for deflecting said light from one area of the substrate to one or more selected regions in another area of the substrate, these region(s) comprising a light trap and/or an absorptive region so as to prevent the majority of the light received thereby from escaping therefrom.