Stephen G. Lynch

External cavity diode laser based upon an FBG in an integrated optical fiber platform

An external cavity diode laser is demonstrated using a Bragg grating written into a novel integrated optical fiber platform as the external cavity. The cavity is fabricated using flame-hydrolysis deposition to bond a photosensitive fiber to a silica-on-silicon wafer, and a grating written using direct UV-writing. The laser operates on a single mode at the acetylene P13 line (1532.83 nm) with 9 mW output power. The noise properties of the laser are characterized demonstrating low linewidth operation (< 14 kHz) and superior relative intensity noise characteristics when compared to a commercial tunable external cavity diode laser.

Bragg-grating-stabilized external cavity lasers for gas sensing using tunable diode laser spectroscopy

Conventional singlemode semiconductor DFB and VCSEL lasers used in high resolution spectroscopy are often required to operate at specific, custom wavelengths, such as those associated with gas absorption lines. We present the results of work to develop alternative sources in the 1550nm and 1650nm regions, the latter coinciding with an absorption line of methane. Custom wavelength Bragg gratings have been used to stabilize the output of external cavity lasers implemented in both optical fiber and planar silica-on-silicon integrated circuits, using commercially available semiconductor gain chips, to give laser output at 1648 and 1649 nm, respectively. Thermal expansion or mechanical strain of the Bragg grating offers a suitable wavelength tuning mechanism. Results are presented including the wavelength tuning range, output power, relative intensity noise (RIN), side-mode suppression and linewidth of devices for application in high resolution gas spectroscopy. The different methods of writing Bragg gratings in optical fiber and planar silica-on-silicon allow a high degree of flexibility in the choice of emission wavelength.

UV Written Planar Bragg Grating Sensors - An Overview of Fabrication, Geometries and Applications

The presentation will give an overview of the fabrication process of direct UV written planar Bragg grating sensors and the various geometries and applications investigated over the last several years.

Frequency doubling a compact stable external cavity diode laser using a novel PPLN waveguide

There is increasing demand for low noise, narrow linewidth lasers for applications including spectroscopy, ion traps for optical clocks and gravitational waves measurements. External cavity diode lasers (ECDL) can provide a compact, low cost solution; however these are typically available at a limited range of optical frequencies. The increase in applications requiring robust laser systems (e.g. space borne gravitational wave measurements) has led to a need for alternatives at frequencies where free space lasers have previously been utilised.

Integrated optical fibre coupler

Integrated Optical Fibre (lOF) is a low-loss photonic platform that directly integrates optical fibre to a planar substrate. The platform possess advantages associated with optical fibre including low propagation loss, whilst at the same time enabling planar functionality associated with integrated optics. IOF fabrication is achieved through a modified Flame Hydrolysis Deposition (FHD) technique that forms a robust glass alloy between the fibre and substrate. The binding medium is of optical quality and mechanically robust, illustrated in fig 1 (a). Although non-trivial seamless on/off-chip coupling has also been demonstrated, which could further act to minimise coupling losses typically associated with integrated optics.

Extreme environment refractometers designed in integrated optical fibre

Integrated Optical Fibre (IOF) is a passive optical platform that directly integrates optical fibre to a planar substrate, illustrated in Fig 1(a). It possess advantages associated with optical fibre such a low propagation loss, whilst enabling planar functionality commonplace with integrated optics. Planarization is uniquely achieved through a modified Flame Hydrolysis Deposition (FHD) technique that forms a robust glass alloy between the fibre and substrate. The binding medium is of optical quality and resistant against common solvents, chemicals and elevated temperatures of up to 1000oC. Furthermore as fibre can be brought seamlessly on-off chip there is no need for glues or cumbersome coupling arrangements, which are typically a point of mechanical weakness when monitoring harsh environments.

Integrated Optical Fiber-Tip Cantilevers

A microcantilever at the end face of an integrated optical fiber is reported, fabrication is uniquely achieved using a precision dicing saw. The methodology is a single-step rapid process, capable of achieving trenches with high aspect ratio (>10:1). The platform on which fabrication is made is a monolithic, integrated optical fiber. This integrally fuses optical fiber to a planar substrate using flame hydrolysis deposition and high temperature consolidation (>1000 °C). This paper is the first report of a fiber-tip cantilever using the technique and this integrated platform. As an approach to quantify the optical response of such a multicavity arrangement, a method using Mason’s rule is presented. This is used to infer the spectral responses of individual cavities formed and through physical actuation, an estimation of the cantilever’s spring constant is made.

Planar integrated optics for quantum technologies

Optical quantum Information Processing makes use of the quantum mechanical properties of single photons to achieve useful information processing functions. This talk will present work carried out at the University of Southampton on the fabrication of optical waveguide device to realize essential functions for all optical quantum information handling. Utilizing silica-on-silicon as a platform and direct UV writing of waveguides, the talk will present results on key elements including single photon sources, waveguide circuits and waveguide sensors. The developing field of quantum information processing offers many highly desirable technical advantages over classical information technology. By exploiting the inherent quantum nature of fundamental particles, there is potential to develop disruptive new devices, for example offering unprecedented computing power (in Quantum Computing), approaches to guaranteed secure communications (based on quantum key distribution), as well as a host of new opportunities in precise measurement of time, gravity, magnetic field etc.. Many of these interesting quantum operations require the use of light, either to carry information between nodes, or for the operation of the device itself (e.g., an atom trap), or for carrying out the quantum processing itself. In this talk results on devices fabricated at the University of Southampton will be presented. Much of this work has been carried out collaboratively with colleagues from the University of Oxford and with NIST, Boulder, Co. In this talk the fabrication and device issues will be presented, together with examples of how these devices can be used to achieve such functions as quantum teleportation, quantum enhanced resolution enhancement, and Boson sampling.

Narrow linewidth external cavity diode laser using UV-written gratings in an integrated optical fiber platform

An ECDL is demonstrated using a Bragg grating written into an integrated optical fiber (IOF) platform to form the cavity. The use of IOF enhances thermal stability whilst retaining advantages of fiber and the system is compact with <;14 kHz linewidth and low relative intensity noise (150 dB).

Integrated Optical Fiber: A novel optical platform

Integrated optical fiber is made through adapting a commercial flame hydrolysis deposition technique. Through it optical fiber can be planarised upon a mechanically robust format. Direct optical interaction is demonstrated through tapered structuring.