Tunable filter

A method for hitless tuning of an optical device having an optical functional element of a controllable adjustable operation for affecting light passing therethrough, the method comprising:

• passing input light through a polarizing assembly thereby producing at least one light component of a predetermined polarization direction;
• passing the light of the predetermined polarization direction through an input variable coupler having an input port for receiving the input light and two output ports associated with first and second spatially separated paths, said functional elements being located in the first optical path
• recombining the second optical path and the fist optical path downstream of the optical functional element with respect to a direction of light propagation through the device, to thereby produce output of the optical device propagating through an output channel,
• thereby allowing for selectively directing substantially the entire energy of the input light through the second optical path, the adjustment of the operation of the functional optical element, and redirecting at least a predetermined portion of the input light to the first optical path to be affected by the functional element, upon completion of the adjustment.

A method for hitless tuning of an optical device having an optical functional element of a controllable adjustable operation for affecting light passing therethrough, the method comprising:

• applying frequency selective variable coupling to multi-frequency input light to thereby produce first and second light components propagating through two spatially separated channels, respectively, the first light component comprising at least a portion of power of a selected frequency band of the input light, and the second light component comprising a remaining portion of the selected frequency band and all other frequency bands of the input light;
• selectively creating a phase delay between the two channels by adjusting the phase of said first light component;
• depending on the phase of said first light component, either directing all the power of the selected frequency band through a first path where the functional element is located while directing all other frequency components of the input light through a second path spatially separated from the first path, or combining the first and second light components to propagate through the second path with substantially no power in the first path;
• and
• combining the first and second paths by an output variable frequency selective coupler structure, which is located downstream of the optical functional element with respect to a direction of light propagation through the device, and has two input ports associated with said first and second paths and an output port associated with an output of the optical device;
• thereby allowing for selectively directing substantially the entire energy of the input light through the second optical path, during the adjustment of the operation of the functional optical element, and selectively redirecting the selected frequency band to the first path while allowing propagation of all other frequencies of the input light through the second path, upon completion of the adjustment.

An optical device comprising:

• an input variable coupler structure having an input port for receiving input light and two output ports associated with first and second spatially separated paths;
• an optical functional elements located in the first optical path and operable in a controllably adjustable manner to affect light passing therethrough;
• an output variable coupler structure located downstream of the optical functional element with respect to a direction of light propagation through the device, the output variable coupler structure having two input ports associated with said first and second paths and output associated with output of the optical device;
• a control unit having means for adjusting the operation of the functional element, and means for operating the input and output variable coupler structures, to thereby enable distibution of the input light energy between the first and second paths to allow for selectively directing substantially the entire energy of the input light through the second path, during adjustment of the operation of the functional optical element, and redirecting at least a predetermined portion of the input light to the first path to pass through the functional element, upon completion of the adjustment.

An optical device comprising:

• a polarizing assembly operable to receive input light and produce at least one light component of a predetermined polarization direction;
• an input variable coupler having an input port for receiving said at least one light component of the input light, and two output ports associated with first and second spatially separated paths;
• an optical functional elements located in the first optical path and operable in a controllable adjustable manner for affecting light passing therethrough;
• a recombination element located in the first and second paths downstream of the optical functional element with respect to a direction of light propagation through the device, to thereby produce output of the optical device propagating through an output channel;
• a control unit operating the input variable coupler structure and the recombination element for selectively directing substantially the entire energy of the input light through the second optical path, during the adjustment of the operation of the functional optical element, and redirecting at least a predetermined portion of the input light to the first optical path to be affected by the functional element, upon completion of the adjustment.

An optical device comprising:

• an input frequency selective variable coupler structure comprising a first coupling element operable to apply a frequency selective coupling mechanism to multi-frequency input light to thereby produce first and second light components propagating through two spatially separated channels, respectively, the first light component comprising at least a portion of power of a selected frequency band of the input light, and the second light component comprising a remaining portion of the selected frequency band and all other frequency bands of the input light;
• a phase adjusting element located in the first optical channel and operable to selectively create a phase delay between the two channels by adjusting the phase of said first light component;
• and a second coupling element operable to, depending on the phase of said first light component, either direct all the power of the selected frequency band through a fist path while directing all other frequency components of the input light through a second path spatially separated from the first path, or combining the first and second light components to propagate through the second path with substantially no power in the first path;
• an optical functional element located in said first path and operable in a controllable adjustable manner for affecting light passing therethrough, and
• an output frequency selective variable coupler structure operable in conjunction with said input variable coupler structure, such that the same percentage of the input light energy redirected by the input coupler structure into each of the first and second paths is recombined by the output coupler structure.