Photonically controlled ultrasonic probes

A multiple channel polarization control module comprising:

• a wavelength demultiplexer physically separates the different wavelength light beams;
• two pixelated and orthogonally oriented polarization mode converters receiving and converting the polarization of said different wavelength light beams;
• a Mach-Zehnder interferometer including a cube beamsplitter;
• a cube broadband polarizing beam splitter (PBS) receiving near equal amplitude p and s states of polarization (SOPs) from said polarization mode converters and individually directing the p and s SOPs to separate first and second paths, which are designed to be equal, respectively, in said Mach-Zehnder interferometer;
• first and second phase shifters in said first and second paths providing the required optical phase shift of the s and p SOP beams;
• first and second 90.degree. polarization rotators operating 180.degree. out-of-phase to determine whether p or s linear SOP is output from said polarization control module,
• wherein by controlling said first and second mode converters, said first and second phase shifters, and said first and second rotators, the two beams interfering at said cube beamsplitter can be made to be equal in amplitude, in-phase or 180 degree out-of-phase, and hence of the desired p or s linear SOP;
• and
• multiplexers which recombine the different wavelengths to create the desired s or p SOP collinear multi-wavelength output beams.

An multi-wavelength photonic signal control module comprising:

• a first acousto-optic tunable filter (AOTF) to spatially separate at least one selected wavelength of light from others in a multiwavelength beam;
• an external signal processing port which diverts and re-aligns a beam of one or more of the wavelengths into an optical processing element, said external signal processing port re-aligning said selected light in an optical path of said photonic signal control module;
• and
• a second AOTF and a spatial block for Fourier plane filtering to reduce noise.