A digitally controlled voltage controlled oscillator comprising an Nbit digital to analogue convertor arranged to receive a frequency change demand signal as a digital Nbit word, and having an output provided via an integrator to a voltage controlled oscillator configured to provide a frequency output.

An iterative method for determining scattering coefficients of the cavity of a laser gyro in operation supporting two counter-propagating modes, comprises steps of: determining a set of variables dependent on characteristic physical quantities of the laser gyro, one reference variable per dependency relationship being selected from the variables; measuring values of the characteristic physical quantities of the laser gyro in operation; determining measured values of the variables; estimating, via an iterative method, estimated values of the coefficients minimising a discrepancy between the measured values of the reference variables and estimated values of the reference variables, which are estimated from the values of the coefficients and the measured values of the variables other than the reference variables; and determining estimated values of the scattering coefficients from the estimated values of the coefficients.

A ring laser gyroscope comprises a block defining a hermetically sealed cavity for a ring laser formed when a lasing medium disposed within the cavity is excited. A cathode and an anode are attached to the block at two fill positions comprised within the cavity, and exposed to the lasing medium such that the lasing medium is ionized when a high voltage pulse is supplied across cathode and anode. At least two RF electrodes are attached to the block, positioned on opposing sides to generate a capacitive discharge for the purpose of keeping the lasing medium excited. The gyro comprises a matching circuit to tune the frequency of a radio frequency (RF) signal generated by a RF power source before the RF signal is sent to the electrodes. The matching circuit is coupled to the RF electrodes via respective lead wires, and comprises an element matching network.

A ring laser gyroscope comprises a block defining a hermetically sealed cavity for a ring laser formed when a lasing medium disposed within the cavity is excited. A cathode and an anode are attached to the block at two fill positions comprised within the cavity, and exposed to the lasing medium such that the lasing medium is ionized when a high voltage pulse is supplied across cathode and anode. At least two RF electrodes are attached to the block, positioned on opposing sides to generate a capacitive discharge for the purpose of keeping the lasing medium excited. The gyro comprises a matching circuit to tune the frequency of a radio frequency (RF) signal generated by a RF power source before the RF signal is sent to the electrodes. The matching circuit is coupled to the RF electrodes via respective lead wires, and comprises an element matching network.

A matter-wave gyro with counter-propagating traps uses three-dimensional lattices formed of interference fringes from three pairs of interfering laser beams. Particles, such as neutral atoms, ion, or molecules are cooled to a ground state near absolute zero. The resulting ultra-cold particles are loaded into the lattices. The laser beams used to form the lattices are driven according to functions that cause the lattices to counter-propagate about a closed path (Sagnac loop) N times, where a desired tradeoff between spatial resolution and temporal resolution can be achieved by choosing an appropriate integer value of N. The lattices can be extinguished so that the particles can be imaged to identify an interference pattern. A shift in the interference pattern relative to an interference pattern that would occur with zero angular momentum can be used to measure angular momentum.

An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first silicon nitride (SiN) waveguide layer that constitute a rotation sensing element; and, a second SiN waveguide layer with additional silicon nitride (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element. The two SiN waveguide layers can be stacked together to have a multi-layer configuration vertically coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated to the SiN waveguide platform. The phase shifters can be made of lithium niobate or other electro optic material.

The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.

The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.

A disk resonator is pumped by counterpropagating pump signals to produce corresponding counterpropagating Brillouin laser signals. The pump laser optical frequencies are separated by a frequency offset Δν.sub.P but excite the same nominal resonator optical mode; the Brillouin laser optical frequencies are separated by a beat frequency Δν.sub.L with 0<Δν.sub.L<Δν.sub.P. A photodetector receives the Brillouin laser signals and produces an electrical signal at the beat frequency Δν.sub.L. The frequency offset Δν.sub.P can be large so enough to prevent locking of the Brillouin laser signals onto a common Brillouin laser frequency. A signal processing system derives from the beat frequency Δν.sub.L an estimated angular velocity component of the disk optical resonator about an axis substantially perpendicular to the disk optical resonator.

An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first silicon nitride (SiN) waveguide layer that constitute a rotation sensing element; and, a second SiN waveguide layer with additional silicon nitride (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element. The two SiN waveguide layers can be stacked together to have a multi-layer configuration vertically coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated to the SiN waveguide platform. The phase shifters can be made of aluminum nitride (AlN) or strontium bismuth titanate (SBT).