Method of operating a tunable optical device
An optical wavelength routing device utilizes a free space optical beam propagating therethrough is provided. The device includes at least one optical fiber input, at least one optical fiber output, an optical element having an actuator with at least one tilt axis and a diffraction element having a surface thereon. The device also includes an optical beam-splitting element having spatially varying optical properties. An optical beam transfer arrangement is positioned between the optical element and the diffraction element such that tilt actuation of the optical element elicits a proportional change in an angle of incidence of the optical beam onto the diffraction element, wherein the center of rotation for the angular change is the surface of the diffraction element. Optical routing between the fiber input and the fiber output can be configured by the positioning of the optical element.
1. A method of variably adjusting the center wavelength and drop bandwidth of a 3 port tunable filter comprising:
directing input wavelengths from an optical element having an actuator with at least one tilt axis through an optical beam transfer element and to a dispersive optical element to thereby disperse the input wavelengths laterally across an optical arrangement oriented to reflect input wavelengths into a first output port;
selectively positioning, by tilt actuation of the optical element, the dispersed wavelengths over an optical beamsplitting region of the optical arrangement that splits the portion of the optical beam impinging on the beamsplitting region and directs the split portion of the beam to a second output port;
adjusting the position of the input wavelengths along a first axis to position the center wavelength on the beamsplitting region;
adjusting the position of the input wavelengths along a second axis perpendicular to the first axis to position the input wavelengths on a portion of the beamsplitting region that is wider or narrower depending on whether a wider or narrower bandwidth, respectively, is desired.
2. The method according to claim 1 further comprising a hitless bandwidth tunability on the first output during a change in wavelength configuration by further adjusting a position of the incident wavelengths along the second axis via the narrower beamsplitting region direction to a region of the optical arrangement that has no beamsplitter; adjusting the position of the incident wavelengths along the first axis to align a selected center wavelength adjacent to a narrowest portion of the beamsplitter region.
3. The method of claim 1 wherein the dispersive optical element is a diffractive optical element.