Biomedical subjects

Christopher J K Richardson

Publications and source records attributed to Christopher J K Richardson.

2 recordsLinked to original sources

PubMed2006

Implementation of discrete unitary transformations by multimode waveguide holograms.

Integration of holograms into multimode waveguides allows the implementation of arbitrary unitary mode transformations and unitary matrix-vector multiplication. Theoretical analysis is used to justify a design approach to implement specific functions in these devices. Based on this approach, a compact mode-order converter, a Hadamard transformer, and a spatial pattern generator-correlator are proposed and analyzed. Beam propagation simulations are used to verify the theoretical calculations and to address bandwidth, scalability, and fabrication criteria. Optical pattern generators were successfully fabricated using standard photolithographic techniques to demonstrate the feasibility of the devices.

Journal Article↗

PubMed2002

Narrowband generation of ultrafast acoustic and thermal transients in thin films for enhanced detectability.

A technique for the narrowband generation of ultrafast acoustic and thermal transients in thin films is demonstrated; this technique allows for enhanced detectability of these transients. The approach pursued uses a reduced-bandwidth, optical pulse train for excitation that is constructed from a series of time-delayed pulses derived from a single-laser pulse. The underlying physical limitations of this approach are considered in order to assess conditions under which successful bandwidth reduction can be realized. Results in an aluminum thin film on a tungsten-carbide substrate show successful generation and detection of a narrowband acoustic signal centered at 32.34 GHz.

Journal Article↗