Variable optical attenuators

• Main Authors: ANTHONY J. TICKNOR, KEN G. PURCHASE, JOHN T. KENNEY
• Format: Patent
• Language: English
• Published: 17.09.2001
• Edition: 7
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

A controllable variable optical attenuator for attenuating an optical signal is described herein. The attenuator has an optical waveguide made from similar waveguide core and cladding materials and a coupling layer in close proximity to the waveguide which is configured to provide a difference between the refractive index of the coupling layer in proximity to the waveguide and the effective index of the waveguide. The index of the waveguide can be modified such that if the refractive index of the coupling layer is substantially lower than the effective index of the waveguide, minimal attenuation occurs to the light in the waveguide. Furthermore, if the refractive index of the coupling layer is substantially greater than the effective index of the waveguide, light is coupled into the coupling layer out of the waveguide to attenuate the optical signal. The amount of attenuation varies smoothly between these maximum and minimum values.