Optoelectronic oscillator with tunable filter

• Main Author: Nicholls, Charles William Tremlett
• Format: Patent
• Language: English
• Published: 22.10.2019
• Subjects: ANALOGOUS ARRANGEMENTS USING OTHER WAVES; BASIC ELECTRIC ELEMENTS; BASIC ELECTRONIC CIRCUITRY; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; ELECTRICITY; FREQUENCY-CHANGING; GENERATION OF NOISE BY SUCH CIRCUITS; GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING,BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN ANON-SWITCHING MANNER; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION ORRERADIATION OF RADIO WAVES; MEASURING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; RADIO DIRECTION-FINDING; RADIO NAVIGATION; RESONATORS; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE; SELECTING RESONANT CIRCUITS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; TESTING; TUNING RESONANT CIRCUITS; WAVEGUIDES

An optoelectronic oscillator (OEO) is disclosed comprising an electronically tunable filter for transposing narrow pass band characteristics of a surface acoustic wave (SAW) filter to a microwave frequency to provide mode selection in the OEO. An OEO is disclosed comprising a set of optical domain components, a downconverter in communication with an output of the optical domain components, and a set of radio frequency (RF) domain components in communication with an output of the downconverter. The set of RF domain components comprises a tunable filter operating at a filter center frequency and having an output coupled to the set of optical domain components for communicating a mode selection result. The tunable filter including a tuner; and a sub-filter. The sub-filter operating at a fixed center frequency to provide mode selection and adjacent mode suppression with respect to the tunable filter center frequency. The sub-filter center frequency being lower than the tunable filter center frequency, and a ratio of the tunable filter center frequency to a bandwidth of the sub-filter being at least 1000:1.