MICROWAVE-TO-OPTICAL PHOTON TRANSDUCER

A microwave-to-optical photon transducer (1) is provided for generating coupling between a microwave signal (Sin2) and an optical signal (Spi_in1, Spi_out1). The transducer (1) comprises: a first input port (3); a second input port (5); a first output port (9) for outputting the optical signal (Spi_out1) and one or more optical sideband signals (Sout1, Sout11, Sout12); a first waveguide (13) disposed between the first input port (3) and the first output port (9) to allow the optical signal (Spi_in1) and the one or more optical sideband signals (Sout1, Sout11, Sout12) to propagate in the first waveguide (13); a second waveguide (15) connected to the second input port (5), and extending in the transducer (1) adjacent to the first waveguide (13) to allow the microwave signal (Sin2) to propagate in the second waveguide (15); a phase-matching arrangement to cause at least the optical signal (Spi_in1) and the microwave signal (Sin2) to be phase-matched or quasi-phase-matched. The first waveguide (13) is made of or comprising non-linear material such that a first electromagnetic field generated by the optical signal (Spi_in1) in the first waveguide (13) and a second electromagnetic field generated by the microwave signal (Sin2) in the second waveguide (15) are arranged to interact in the non-linear material so that the number of optical photons in the one or more optical sideband signals (Sout1, Sout11, Sout12) at the first output port (9) equals the number of microwave photons in the microwave signal (Sin2) at the second input port (5) multiplied by a transducer gain.