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Nonlinear interactions such as second harmonic generation and sum and difference frequency generation are routinely used for the generation of laser wavelengths. With high power lasers it is necessary to use bulk crystals and tight beam focusing to achieve the maximum conversion efficiency. The use of Quasi- phase-matched (QPM) materials such as PPLN and PPKTP are now routinely reported; however,...
We present the direct measurement and modeling of the sensitivity limit of an integrated refractive index sensor for the detection of molecular monolayers. Direct UV writing can be used to fabricate a wide range of integrated optical devices particularly Bragg gratings. These Bragg gratings are inherently sensitive to temperature and strain. By etching a portion of the cladding, the mode within the...
In this work, the fabrication of direct UV writing (DUVW) structures, compact couplers appropriate for quantum optical circuits is reported, and the use of X-couplers for a more compact device layout with improved fibre compatibility, v-groove launch, and polarisation control is discussed. These devices are well suited to quantum interference applications.
In this letter, we demonstrate for the first time to our knowledge ICFD of an edge emitting laser diode using a periodically poled lithium niobate (PPLN) bulk crystal, which has the potential to be scalable to high production volumes and low costs with immense implication for industrial applications. Our new cavity design uses an external dichroic mirror coated for high reflectivity in the near-infrared...
Diaphragms are one of the most widely used and suitable mechanical structures for use as a pressure sensing element. Pressure applied to one (or both) side(s) of the diaphragm will cause it to deflect until the elastic force balances the pressure; this induces stress along the diaphragm's length. Our presented device monitors this stress using planar Bragg gratings. Similar pressure diaphragm sensors...
Current optical telecommunication systems employ dense wavelength division multiplexing (WDM) techniques to increase the data carrying capacity of fiber networks. Dynamic add/drop and filtering processes are crucial for the precise control of individual channels on these networks. Reconfigurable integrated optical devices, such as planar Bragg gratings, can tune the reflection wavelength over several...
An integrated direct UV written apodised planar Bragg grating reflector with 154 GHz (1.23 nm) of thermo-optic tuning in the C-band and a response speed 31 GHz/ms is demonstrated. The degree and speed of tuning of the fabricated device indicates potential application in dynamic optical networks, as an optical add-drop multiplexer.
A direct UV-written multimode interference device is constructed with a pair of Bragg mirrors that have adaptively manipulated period to minimise excess loss. Excess loss achieved is comparable to that of a regular MMI device.
An integrated pressure/flow sensor using a direct UV written planar Bragg grating situated inside a flexible diaphragm of thickness 200 mum has been fabricated. The diaphragm is created by etching away the underlying silicon support.
Recently developed novel ’flat fiber’ substrate promises flexible, long-haul integrated optical devices. Here, we present the first demonstration of one such device; an evanescent field sensor, based upon direct UV written Bragg gratings.
Recently developed novel psilaflat fiberpsila substrate promises flexible, long-haul integrated optical devices. Here, we present the first demonstration of one such device; an evanescent field sensor, based upon direct UV written Bragg gratings.
Using an appropriately designed quasi-phase matched structure it is theoretically possible to compensate for the deleterious effects of Gouy phase shift allowing a symmetric frequency response and tighter focussing for higher conversion efficiencies.
Direct-UV-written liquid crystal tunable planar Bragg gratings exhibit complex wavelength tuning with threshold points and hysteresis. We discuss the role of disclinations in the liquid crystal and whether they may allow faster wavelength tuning.
We report our recent developments in micro-structured evanescent devices. Micro-machining prior to direct UV writing of channel waveguides provides additional flexibility to fabricate evanescent interacting devices such as modulators and sensors, which allow adiabatic operation.
This study demonstrates Bragg wavelength tuning, with maximum tunability of 114 GHz at 1561.8 nm using patterned ITO glass electrodes with 170 Vpp voltage at 1 kHz. The development of a cascaded architecture of such integrated liquid crystal devices operating at different Bragg wavelengths could pave the way towards true colorless add/drop modules for dynamic dense optical networks.
Price competition and the need for miniaturisation provide powerful incentives for engineers to seek higher device densities in integrated optics. One of the more recently developed techniques known to be capable of fabricating high density integrated optical devices is direct UV writing. This technique has in the past demonstrated successful fabrication of directional power splitters, Bragg gratings...
In this work, we present an alternative approach in which a groove is cut using a polishing saw blade to give a vertical, high optical quality trench. Optical waveguides are then UV written to allow evanescent lateral access of the mode to a fluid placed in the trench. This seemingly subtle change in geometry provides greatly increased flexibility to tailor the interaction between the optical mode...
In this work we are developing bulk devices for higher power operation in which focussing causes an intrinsic spread of k-vectors. Incorporating physical limits such as constant domain size and minimum separation to our grating designs ensures a high fabrication yield. Second harmonic generation via periodically-poled nonlinear materials offers an efficient means of generating high-quality visible...
First demonstration of planar Bragg gratings UV written into collapsed fibre planar samples with ≫200??m cladding thickness is presented. Multiple gratings were written across the sample profile to accurately determine core layer flatness and uniformity.
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