Low-cost, High-performance Lasers: Novel Applications of Disk Laser Approaches

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The cutting edge laser systems that have been developed in laboratories around the world in recent years do not want for performance. For example, lasers based on crystals of sapphire doped with titanium now routinely produce pulses of a few millionths of a billionth of a second: the shortest of man-made events. For that tiny fraction of a second, the power of the laser light is the equivalent the output of a power-station. These and other extreme specifications of today's high performance laser make them potentially revolutionary tools. Indeed, across science and engineering that revolution has started, allowing the very small, the very fast and the very complex to be studied in detail. The potential, however, is greater still. Today's high performance laser is not yet the penknife in the scientist's pocket; unwieldy and expensive, the titan is chained to the laser lab. The laser engineering challenge is to harness this performance and power in a practical package, such that the laser can go to the user rather than the user having to come to the laser. This will trigger a second - and arguably bigger - applications revolution. We believe that the use of a disk of laser material, rather than the conventional rod, can make a large contribution to civilising high-performance lasers. There are essentially two reasons for this. First, a number of important - but detrimental - properties of laser materials scale with length; these problems can be minimised by using thin disks. Second, finesse lasers, such as those based on titanium sapphire, are typically pumped by other lasers; these pump lasers can cost tens of thousands of pounds due to the performance levels required. The use of disks reduces the quality of the pump beam that is needed; thus, we believe lower cost devices such a laser diodes and even LEDs can be used with laser systems that have traditionally required high cost pump lasers.Serendipitously, the development of blue laser diodes for next generation DVD and high power light emitting diodes (LEDs) for solid-state lighting has led to a considerable improvement in performance of these light sources. As these devices are aimed at mass markets, the unit costs will be small, making them ideal low-cost pump sources. Even with these improvements, such light sources lack the power and the beam quality to pump conventional finesse lasers. However, disk geometries remove these hurdles enabling, we believe, the first demonstration of diode-laser pumping of Ti:sapphire and a new generation of LED pumped lasers. These are potentially disruptive technologies. Lower-cost, more compact Ti:sapphire lasers will take the benefits of this thoroughbred laser system directly to the application and low-cost LED pumped lasers will enable applications - like high-risk undersea or toxic substance sensing - that required finesse lasers but where loss or damage is inevitable.