Optical coherence tomography (OCT) allows the 3D imaging of skin tissue on a depth scale of ~1-2mm with resolution ~10um. It has been described as an optical analog of ultrasound imaging and offers significantly better resolution than MRI and ultrasound. It has already gained clinical acceptance in ophthalmology and is emerging into other fields such as oncology, monitoring wound healing, cardiology, and guided surgery. The advantages of OCT include:- Video rate images of sub-surface morphology at resolutions ~100 better than ultrasound and voxel rates ~1000 higher than microscopy. Label-free imaging of the sample (in vivo or in vitro). Non-ionizing radiation. Non-contact Endoscopic OCT is ideal for imaging 1~2mm below the surface in biological tissue. Our project is concerned with the development of a prototype swept laser source with 200 - 300 nm sweep range providing sub cellular resolution. We will develop the laser system and trial it in an OCT imagining system.

Lasers are a key enabling technology in countless areas of modern society, touching on our lives in terms of ubiquitous connectivity, data storage, healthcare, security, environmental monitoring, etc. Examples include telecommunications, where they are used to generate the information carrying optical signals that are transmitted along thin glass optical fibres, manufacturing, where they are used for welding and cutting materials, and medicine, where they are used for sensing blood oxygen levels, and precisely resecting tissues. For almost all laser applications, it is necessary to use the laser source in combination with another technology that directs or "steers" the laser light in the desired direction. In some cases, this technology can be "passive", as is the case with the glass optical fibres used in telecommunications. In other cases, the steering technology must be "active" to change the direction of the laser beam in time, as is the case with the rapidly moving mirror systems used in some laser cutting and laser imaging systems. Conventional active laser steering technologies are often costly, bulky, and fragile. One or more of these disadvantages makes them sub-optimal for many important applications, including laser imaging systems for automotive applications, space-based laser communications systems, and drone-based remote sensing systems. To address this, there is currently a global drive to develop fully integrated solid-state beam-steering technologies, where the laser light is steered without the use of any physically moving components. Currently, however, even state-of-the-art solid-state laser beam steering systems have limited functionality, and do not meet the requirements of many real-world applications. In this project, we will exploit recent advances in two key integrated optical technologies - coherent Photonic Crystal Surface Emitting Laser (PCSEL) diode arrays and three-dimensional optical waveguide devices known as "integrated photonic lanterns" - to develop fully Integrated Solid-State Steerable Lasers (I-STEER) that can deliver agile beam steering in two dimensions and can, in principle, function at any diode laser wavelength. I-STEER will target the development of 900-mode PCSEL arrays, but will deliver the technological advances necessary to enable future PCSEL arrays (using commercial manufacturing facilities) that generate 10's of thousands of independently phase and ampltiude controllable coherent laser modes. A key aim of I-STEER is to enable denser PCSEL arrays, where the laser mode diameter is reduced to 20 microns (~20 wavelengths) and the centre-to-centre separation is reduced to ~50 microns (~50 wavelengths) - current PCSEL arrays exhibit 50 micron diameter laser modes with centre-to-centre separations of 400 microns. Unfortunately, even the ambitious spatial scales we are targeting mean that the PCSEL array will still be unsuitable for direct use as an optical phased array (OPA), since OPAs require very tightly packed wide angle emitters to achieve large angle/lobe free beam-steering. To address this, I-STEER introduces the fresh idea of using three-dimensional integrated optical waveguide transitions known as "integrated photonic lanterns" to adiabatically combine the PCSEL modes into a single highly multimode pattern of light, the spatial phase and amplitude properties of which can be directly controlled for beam steering via the PCSEL drive electronics. Through the I-STEER project, we aim to redefine the laser diode as an all-electronic integrated steerable light source enabling new functionally in countless applications including free-space optical communications and LiDAR. The generation of intellectual property and capability in this area will place the UK in a leading position with regards this strongly growing academic field, wealth generation through the creation of licensing and/or spin-outs, and in early adoption of UK based OEMs of this new technology.

The sensing, processing and transport of information is at the heart of modern life, as can be seen from the ubiquity of smart-phone usage on any street. From our interactions with the people who design, build and use the systems that make this possible, we have created a programme to make possible the first data interconnects, switches and sensors that use lasers monolithically integrated on silicon, offering the potential to transform Information and Communication Technology (ICT) by changing fundamentally the way in which data is sensed, transferred between and processed on silicon chips. The work builds on our demonstration of the first successful telecommunications wavelength lasers directly integrated on silicon substrates. The QUDOS Programme will enable the monolithic integration of all required optical functions on silicon and will have a similar transformative effect on ICT to that which the creation of silicon integrated electronic circuits had on electronics. This will come about through removing the need to assemble individual components, enabling vastly increased scale and functionality at greatly reduced cost.