M Squared Lasers Limited

University of Strathclyde

Solus Technologies Limited

Gareth Thomas Maker

Graeme Peter Alexander Malcolm

Simon Munro

Stephen Webster

Craig James Hamilton

John Nicholls

Graeme Malcolm

Gordon Robertson

Lukasz Kornaszewski

William Miller

A method and system for injection-locking multiple optical amplifiers is disclosed. A master laser is employed to generate a continuous-wave output field. Optical modulators then produce first and second seed optical fields from the continuous-wave output field. The first and second seed optical fields provide an input to injection lock one or more optical amplifiers, optionally at different operating frequencies. Since the first and second seed optical fields are generated from the continuous-wave output field then the output fields of the optical amplifiers exhibit a high phase-coherence with each other and with the continuous-wave output field. Employing the first and second optical fields reduces the requirement to induce large frequency shifts on a single optical field. Techniques for phase-locking the output of the injection-locked laser systems are also provided to further reduce phase noise within the systems.

Injection-locked laser system

A method and apparatus for mounting optical components is described. The apparatus is suitable for mounting multiple optical components and comprises a baseplate having opposing first and second surfaces. Recesses or apertures are formed within the baseplate and are located upon the first or second surfaces so as to define thermally activated optic mounting areas. Pillars are then located within the thermally activated optic mounting areas and these provide a means for attaching the optical component to the baseplate. The employment of the recesses or apertures act to significantly reduce the thermal conduction throughout the baseplate. As a result preferential heating can be provided to the one or more thermally activated optic mounting areas while maintaining the baseplate with a desired mechanical strength. The optical mounting apparatus exhibits a high thermal stability thus making the apparatus ideally suited for use within commercial optical system.

Method and apparatus for mounting optical components

An electro-optic modulator (EOM) for altering an optical path length of an optical field is described. The EOM comprises first and second Brewster-angle cut nonlinear crystals having a first and second optical axis. The optical axes are orientated relative to each other such that when an optical field propagates through the nonlinear crystals it experiences no overall deviation. The nonlinear crystals are also arranged to be opposite handed relative to the optical field. The EOM has the advantage that its optical losses are lower when compared with those EOMs known in the art. In addition, the EOM can be inserted into, or removed from, an optical system without any deviation being imparted onto the optical field. This reduces the levels of skill and effort required on the part of an operator. The described method and apparatus for mounting the nonlinear crystals also suppresses problematic piezo-electric resonances within the nonlinear crystals.

Electro-optic modulator

A method and apparatus for mounting optical components is described. The apparatus () is suitable for mounting multiple optical components () and comprises a baseplate () having opposing first () and second () surfaces. Recesses or apertures () are formed within the baseplate and are located upon the first or second surfaces so as to define thermally activated optic mounting areas. Pillars () are then located within the thermally activated optic mounting areas and these provide a means for attaching the optical component to the baseplate (). The employment of the recesses or apertures act to significantly reduce the thermal conduction throughout the baseplate. As a result preferential heating can be provided to the one or more thermally activated optic mounting areas while maintaining the baseplate with a desired mechanical strength. The optical mounting apparatus exhibits a high thermal stability thus making the apparatus ideally suited for use within commercial optical system.

A laser diode drive system for generating a drive current for a laser diode is described. The laser diode drive system comprises a first laser diode driver connected to the laser diode by a first cable to provide a drive current source for the laser diode. A second laser diode driver is then connected to the laser diode by a second cable to provide a low current sink for the laser diode. A feedback control loop is employed to provide a feedback signal for the second laser diode driver from to sample of an output field of the laser diode. The laser diode drive system exhibits low power consumption while being capable of creating sufficient feedback bandwidth to reduce the excess optical noise by at least an order of magnitude at 1 MHz compared with laser diode drive systems comprising just a first laser diode driver.

Laser diode drive system

A nonlinear crystal comprising a first end face and an opposing second end face is described. The first and second end faces are separated along an optical axis of the nonlinear crystal by a length in the range of 0.25 mm and 2 mm. Although the length of the nonlinear crystal results in a reduction in the nonlinear effects induced on an optical field propagating through the crystal it also provides for reduced deviation experienced by the generated optical field when the nonlinear crystal is rotated. Therefore, when the nonlinear crystals are incorporated within an enhancement cavity their reduced length allows for the deviation of the output field to be minimised by servo control electronics arranged to adjust a single cavity mirror. This significantly reduces the complexity, and thus expensive of the servo control electronics when compared to those employed with the prior art enhancement cavities.

Nonlinear crystal

A laser system comprising two phase-locked solid-state laser sources is described. The laser system can be phase-locked at a predetermined offset between the operating frequencies of the lasers. This is achieved with high precision while exhibiting both low noise and high agility around the predetermined offset frequency. A pulse generator can be employed to generate a series of optical pulses from the laser system, the number, duration and shape of which can all be selected by a user. A phase-lock feedback loop provides a means for predetermined frequency chirps and phase shifts to be introduced throughout a sequence of generated pulses. The laser system can be made highly automated. The above features render the laser system ideally suited for use within coherent control two-state quantum systems, for example atomic interferometry, gyroscopes, precision gravimeters gravity gradiometers and quantum information processing and in particular the generation and control of quantum bits.

Laser system

A method and apparatus for passively synchronising the repetition rate of two or more mode-locked lasers is described. The method and apparatus involve forming a first synchronising optical field () by separating a portion of an output field of a first mode-locked laser () and thereafter redirecting this synchronising optical field to form a driving signal for a second mode-locked laser (). Employing these techniques results in systems with timing jitter of less than 1 fs. The method is independent of the wavelength and polarisation at which the mode-locked lasers operate and so is not limited to use with any particular type of mode-locked laser. Since the technique is passive it does not require the employment of electronics, variable time delay paths or additional non-linear optical crystals. Therefore, the method and apparatus are significantly less complex than those known in the art and are not power limited by additional non-linear optical processes. Part of the output () of the first mode-locked laser () is redirected via a beam splitter () and beam steering mirrors () and a half-wave plate () to a polariser () in the beam line of the second mode-locked laser (). The seeding and synchronising signal from the first mode-locked laser () may be perpendicularly polarized with respect to the polarization of the second mode-locked laser () and may have a different wavelength.

Method and apparatus for repetition rate synchronisation of mode-locked lasers

An optical frequency mixing module is described that comprises a nonlinear medium for frequency mixing the photons of one or more input optical fields to generate an output optical field; a nonlinear medium tuner for automatically phase matching the nonlinear medium to the one or more input optical fields to select the wavelength of the output optical field generated by the nonlinear medium; and a first direction correcting optic. The position of the first direction correcting optic relative to the nonlinear medium is dependent upon the selected wavelength of the output optical field and therefore ensures that the position and angle of propagation of this field remains constant and independent of its wavelength of. The optical frequency mixing modules therefore provides a means for automatically selecting the wavelength of the output field with no deviation being imparted onto the position or angle of propagation of the output field.

Optical frequency mixing module

A purging system for a laser system is described. The purging system comprising a cartridge that houses a desiccant material and which is configured for removable mounting with an enclosure of the laser system. The cartridge comprising a first mesh layer that provides a means for a fluid to flow to the desiccant material housed within the cartridge. The purging system further comprises a membrane located over the first mesh layer. The purging system therefore provides a mean for passively purging the laser system and so its operation does not require the employment of a pump. The employment of the removable cartridge also has the advantage that the downtimes of the laser system with which it is deployed are reduced during periods when it is required to dry or replace the desiccant material.

Purging system for a laser system

A nonlinear crystal comprising a first curved face and an opposing second curved face is described. The first and second curved faces are arranged to provide the nonlinear crystal with rotational symmetry about at least one axis of the nonlinear crystal. The nonlinear crystal allows for frequency tuning of a generated optical field that is generated by propagating a fundamental optical field through the nonlinear crystal by rotation of the nonlinear crystal about an axis of rotation without any significant, or minimal, deviation being introduced to the generated optical field. These nonlinear crystals can therefore be incorporated into an external cavity frequency doubler or mixer without any need for the employment of optical compensation optics or servo control electronics to automatically realign the cavity mirrors.

An apparatus and a method monitor fluid loss from one or more casks during a maturation process. The apparatus comprises a multi-pass absorption cell arranged in fluid communication with one or more fluid conduits, a pump and a monitoring system. The pump and fluid conduits transport a fluid sample (e.g. vapor sample) from a perimeter of the one or more casks to the multi-pass absorption cell. The monitoring system detects and identifies fluid within the multi-pass absorption cell.

Maturation monitoring apparatus and methods

The present invention describes a method and apparatus for mounting a semiconductor disc laser (SDL). In particular there is described a cooling apparatus assembly () for mounting the semiconductor disc laser () the cooling apparatus assembly comprising a crystalline heat spreader () made of diamond, sapphire or SiC and optically contacted to the SDL (). The apparatus further comprises a heatsink () made of copper and a recess () located on a first surface () of the heatsink. A pliable filler material () which may be In or an In alloy is provided within the recess () such that when a sealing plate () is fastened to the heatsink the SDL () is hermetically sealed within the recess. Hermetically sealing the SDL within the recess is found to significantly increase the lifetime of the device comprising the SDL. The heat sink () may be water cooled with pipes () delivering the water. In case the sealing plate () is made from for example Invar, it has an aperture ().

Method and apparatus for mounting a semiconductor disk laser (SDL)

A tunable reference cavity () with two independently controllable mirrors () is disclosed. The mirrors are mounted on respective piezoelectric crystals () so that thermal expansion of the piezoelectric crystals moves the cavity mirrors in the same direction along a longitudinal axis of the reference cavity thereby reducing a change of the cavity length. Also disclosed is a system for locking and scanning the output of a laser cavity (). An error signal is generated between an output of the laser cavity () and the transmission () of the laser through the external reference cavity (). A dual piezo-actuated mirror () permits processing of the error signal () with separate signal processing circuits () used to provide an electrical feedback signal to the dual piezoelectric crystal ().

Method and apparatus for locking and scanning the output frequency from a laser cavity

The invention provides an apparatus and a method that reduces fluid loss from a cask during a maturation process by sealably enclosing the cask in a vessel that provides an expansion volume to receive fluid vapor from the cask, a monitoring system and a method that monitors fluid loss from a cask during a maturation process using a light source and a detector to determine the presence of fluid vapor in the vicinity of the cask, a corresponding system for controlling a maturation process in which environmental conditions are controlled, and a cask leak testing system and method making use of the above.

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Glasgow, United Kingdom

Gareth Thomas Maker