A direct UV grating writing technique based on phase-controlled interferometry is proposed and demonstrated in a silica-on-silicon platform, with a wider wavelength detuning range than any previously reported UV writing technology. Electro-optic phase modulation of one beam in the interferometer is used to manipulate the fringe pattern and thus control the parameters of the Bragg gratings and waveguides. Various grating structures with refractive index apodization, phase shifts and index contrasts of up to 0.8 × 10 −3 have been demonstrated. The method offers significant time/energy efficiency as well as simplified optical layout and fabrication process. We have shown Bragg gratings can be made from 1200nm to 1900nm exclusively under software control and the maximum peak grating reflectivity only decreases by 3dBover a 250 nm (~32THz) bandwidth.

Currently, various electronic devices make our life more and more safe, healthy, and comfortable, but at the same time, they produce a large amount of nondegradable and nonrecyclable electronic waste that threatens our environment. In this work, we explore an environmentally friendly and flexible mechanical sensor that is biodegradable and recyclable. The sensor consists of a bacterial cellulose (BC) hydrogel as the matrix and imidazolium perchlorate (ImClO 4 ) molecular ferroelectric as the functional element, the hybrid of which possesses a high sensitivity of 4 mV kPa −1 and a wide operational range from 0.2 to 31.25 kPa, outperforming those of most devices based on conventional functional biomaterials. Moreover, the BC hydrogel can be fully degraded into glucose and oligosaccharides, while ImClO 4 can be recyclable and reused for the same devices, leaving no environmentally hazardous electronic waste.

The first monolithically integrated all-optical single-sideband filter based on photonic Hilbert transform and planar Bragg gratings is proposed and experimentally demonstrated. Single-sideband suppression of 12 dB at 6 GHz and sideband switching are achieved via thermal tuning. An X-coupler, photonic Hilbert transformer, flat top reflector and a micro heater are incorporated in a single silicon-on-silica substrate. The device can be thermally tuned by the micro heater on top of the channel waveguide. The device is fabricated using a combination of direct UV grating writing technology and photolithography.Single-sideband (SSB) modulation is a well-known technique in telecommunications for improving performance in terms of required power, enhancing spectral efficiency and reducing fading. In the conventional electronic domain, Hilbert transform techniques have been widely used in SSB modulation applications, and devices have been implemented in both analogue and digital systems and geometries [1]. In the all-optical field, photonic Hilbert transformers (PHTs) offer potential for a wide range of applications as they provide operational bandwidths and speeds far beyond current electronic technologies. In addition they also reduce dispersion related artifacts such as signal power fading [2]. Various methods have been demonstrated to produce PHTs, e.g. in phase-shifted apodized fiber Bragg gratings (FBGs) [2, 3], free space optical components [4], Mach-Zehnder interferometers with optical delay lines [5, 6], sampled FBGs [7] and a programmable wave-shaper [8]. Previous works on all-optical SSB modulation such as that reported in [2, 7] deal with complex fiber-based schemes comprising optical circulators, attenuators and optical delay lines. The complexity and size of physically realizing these schemes results in costly systems that lack the mechanical and thermal stability required for system applications.In this work, we demonstrate a monolithically integrated all-optical SSB filter, for the first time to our knowledge. This initial proof-of-concept device shows 12 dB suppression ratios at 6 GHz microwave frequency. We use a silica-on-silicon planar format [9

Integrated photonics is a proven platform for physical and chemical sensing. It offers miniaturised solutions that are suited for use in extreme environments, including strong EM-fields, EM-pulses and contact with flammable materials, often far exceeding electronic sensors in this regard. This review looks into direct UV-written planar Bragg grating technology and its application to integrated photonic sensors. The platform has been demonstrated widely for measurement of physical properties such as temperature, pressure and strain. In addition, by using an evanescent interaction, refractive index can be measured allowing for chemical and biochemical detection. Further to this, the platform has recently been utilised in quantum information processing, where quantum gate operations and single photon detection has been shown.

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Terahertz bandwidth photonic Hilbert transformers are proposed and experimentally demonstrated. The integrated device is fabricated via a direct UV grating writing technique in a silica-on-silicon platform. The photonic Hilbert transformer operates at bandwidths of up to 2 THz (~16nm), which is at least ten fold greater bandwidth than any previously reported experimental approaches. Achieving this performance requires detailed knowledge of the system transfer function of the direct UV grating writing technique, this allows improved linearity, and yields THz bandwidth Bragg gratings with improved spectral quality. By incorporating a flat-top reflector and Hilbert grating with a waveguide coupler an ultra wideband alloptical single-sideband filter is demonstrated.