Patent ID: 7295748

Claim:
A variable optical attenuator comprising: a first optical waveguide for launching an optical beam having first and second wavelength components, the first wavelength component having a shorter wavelength than the second wavelength component; a second optical waveguide for receiving the optical beam; a lens, having an optical axis, for collimating the optical beam from said first optical waveguide, and for focusing the optical beam onto said second optical waveguide; a tiltable mirror for receiving the optical beam from said lens and to reflect the optical beam back through said lens to the second optical waveguide, whereby different angular positions of the tiltable mirror result in different levels of attenuation, and result in an intrinsic wavelength dependent loss (WDL) in which the first and second wavelength components are not subject to the same levels of attenuation at the different angular positions; and a chromatic dispersion wedge placed between said lens and said tiltable mirror, said wedge having a refractive index of n and a wedge angle α, set to deflect the first wavelength component by a different amount than the second wavelength component for compensating the intrinsic WDL, whereby the first and second wavelength components are subject to substantially the same levels of attenuation at each angular position over a range of attenuations from 0 dB to 20 dB.