True time delay circuit based on an optical waveguide switching array for RF phased array antenna beam steering

An electro-optic cascade device comprising:

• a plurality of time delay devices connected in series by one-by-two optical splitters, each of the plurality of time delay devices being capable of producing a time delay of a time delay increment in an optical signal, each of the plurality of time delay devices comprising:
• a plurality of four-port switches arranged along a distance in an array of four-port switches, each four-port switch of the plurality of four-port switches comprising a first port, a second port, a third port and a fourth port, there being at least a first four-port switch and a last four-port switch in the array of four-port switches, the first port of each four-port switch in the array of four-port switches being in optical communication with the second port of a closest preceding four-port switch in the array of four-port switches except for the first four-port switch in the array of four-port switches, the fourth port of each four-port switch in the array of four-port switches being in optical communication with the third port of the closest preceding four-port switch in the array of four-port switches except for the first four-port switch in the array of four-port switches, each of the plurality of four-port switches having an OFF state and an ON state, each of the plurality of four-port switches being configured to place the first port thereof in optical communication with the fourth port thereof at least when it is in the ON state,
• wherein the time delay device has an input for receiving the optical signal and an output for the optical signal to be communicated onward;
• and
• a plurality of electro-optic or heating elements, for each of the plurality of four-port switches there being at least one respective electro-optic or heating element among the plurality of electro-optic or heating elements, each of the plurality of electro-optic or heating elements being configured to operably interact with a respective one of the plurality of four-port switches at least when the electro-optic or heating element is energized by applying an electrical control signal to the electro-optic or heating element, wherein the time delay increment between the optical signal at the input of the time delay device and the optical signal at the output of the time delay device is capable of being selectively varied at least by placing a selected one of the plurality of four-port switches in the ON state while other remaining four-port switches of the plurality of four-port switches are in the OFF state,
• wherein each of the plurality of four-port switches is adapted to be in the ON state when the electrical control signal is applied to its respective electro-optic or heating element,
• wherein the optical signal can cross each one of the plurality of four-port switches when it is in the ON state from its first port to its fourth port,
• wherein the optical signal cannot cross each one of the plurality of four-port switches from its first port to its fourth port when it is in the OFF state but continues on from its first port to its second port, and then, except for the last switch in the array of four-port switches, on to the first port of a closest succeeding four-port switch in the array of four-port switches,
• wherein each of the plurality of time delay devices is tunable such that it can provide a time delay selected from a respective plurality of time delay increments, wherein the plurality of time delay devices includes a first time delay device and a last time delay device, wherein the plurality of time delay devices are connected in series with the output of each of the plurality of time delay devices, except for the last time delay device, being connected to the input of a closest succeeding one of the plurality of time delay devices to form a cascade.