26 December 2010

Fir and fairy lights

Here milder than recent days; the wind has changed; a new energy is in the air.

Something of a hiatus since last posting. In part being away from here; in part technological disagreement with this device; in part Christmas and preparations for it at home and in the other job; but largely due to a mute lack of inspiration as to what to say. Some thoughts and reading and explorations into the world of electronic engineering and its affiliates have been happening during this time, but nothing has formed that is nugget sized and deemed worthy of presentation here. And to that end I am going to embed in Silicon Photonics, an introduction (Reed and Knights), and Mathematical Techniques (Jordan and Smith) for some time, amidst the fir and fairy lights with a cup of coffee, and see what comes. Happy Christmas.

5 December 2010

Intermittent scrubber

Sunny and chilly Sunday. Stove lit, cats dozing.

Today’s is a tale of time spent in a clean room. I am a part time cleaner (although the house that I inhabit isn’t famously reflective of my skills in this field). It is a job that I find rewarding – the work, which is gratifyingly physical, has the satisfaction of being a defined occupation, completed (and well done, I hope), at the end of the day. Both science and art seem, to me, to be rather open-ended. The word ‘rather’ in this comment is a gross understatement; actually both art and science are infinite. On occasion it can be helpful to imagine them as finite (comprehensible, controllable, constrainable), since thinking of infinite things can be mentally wearing, but nonetheless their enormity is somehow ever evident. In both fields each accomplishment is merely another small step along an eternal path that leads nowhere (and everywhere?). These days, being an intermittent scrubber somehow grounds me in an otherwise limitless world.

But the cleanliness of the clean room that I encounter on this occasion is not my responsibility, thank goodness, for here they try to keep out any particles bigger than 10 micrometers; that is, any speck or fleck bigger than a hundredth of a millimetre in its longest dimension is banished. This room is kept clean in order for work on wafers to be undertaken, among other things; here the wafers are cleaned and coated, acid and acetone baths remove residues, photoresist is applied, lithographic images transferred and patterns etched; the carving of waveguides.

In order to enter the space we must suit up, in a little room between the outside world and the spotless sanctum; I, being a visitor, am given a white papery boiler suit to wear (with matching shoe covers and bathing cap). I am relieved of my sketchbook and pencil, for shards of paper and graphite fragments circulating in the air are vetoed; inside I will be given special sky-blue, shed-free pieces of paper, and allowed use of a biro. Walking across a sticky floor mat (to retain any last minute hitchhikers from the soles of our feet) we enter through the inner door.

My first impression on walking into the room is of several machines with outstretched arms – mutely crying out for interaction. These are sealed boxes, clean within, with arm-length rubber gloves attached in order for manipulations inside them to be possible. But the air pressure in the boxes is such that the arms are inflated outwards, at their ends squishy sausagey fingers, air-filled and bloated. One machine that we repeatedly brush past has a pair of arms at hip height, hip width apart; a static dance partner awaiting animation. It is strangely intimate to stand between the outstretched hands, their airy touch on my boiler-suited hips.

I shadow Renzo, from the bright white light of the main room into the subdued red and yellow lights of small, light-sensitive, filtered rooms off to the side. He has recently completed his PhD, riding high in the light of his recent viva, and is continuing in the group as a post-doc. Today he is experimenting with transferring a pattern of waveguides onto a new wafer that he has been sent from a collaborator. A silicon germanium wafer. The wafer is mirror shiny on one side and matt grey on the other, one edge of its circular circumference cut off, indicating the plane of the integral crystal structure. He carefully breaks it into smaller pieces, and then these are rather laboriously processed via a number of machines and procedures to clean and dry them, prior to being coated with a UV-sensitive resist. Finally the wafer is exposed to UV light, and the image transferred (the next stage will be the etching, but there is no time for that today). Through the course of these repetitions I have been wandering in and out, and exploring the main room, intermittently returning to the ‘yellow room’ to touch base. I meet a woman who is keeping digital readouts under control on one of the armed boxes; she is working on photovoltaics, one of the other big and groundbreaking research areas going on in this building. I see a sputter machine, whose name conjures images of custard pies, or similar, being discharged at unexpected moments. And I stumble upon an aspect of the cleaning capability of this room, a rather fetching turquoise and violet Dyson; a moment of the mundane amidst the state of the art.

1 December 2010

Vehicular uncertainty

If I drive from home to the University of Surrey and you want to know where I am at a given time on my journey then if you know my speed and what time I left home you should be able to calculate roughly where I have got to. (Bear in mind that the queue at the Costa coffee at Exeter Services can be desperately slow, so perhaps factor in a random variable for that). However, if you want to know where I am exactly at any given time, you will not be able to know how fast I am going at that point because in effect you have to stop time at the moment you want to know where I am, in order to accurately calculate my position. And similarly if you want to know how fast I am travelling (relative to the road, I believe) you will have to accept that my position at that time will remain approximate, since calculation of my speed requires that I am moving past any given point as you catch me on your speed camera.

If you want to subvert these complications of quantic information gathering, you could just call me on my mobile, and I can let you know both my position and speed at any time. Maybe understanding the subtleties of quantum theory is merely about being correctly selective about who, or what, you ask the questions of.

Yesterday and today


Man, it’s quiet here this morning. A hard frost has made the surface of the world white, and even the birds are audibly subdued because of the cold. The sky is that very pale mauvey grey type of luminous white that looks as if it is heavy with snow, but may just pass by without releasing its load. There is something about the colour that seems as if all the light is trapped up there in the cloud and is bouncing around in dancing forms, prismatic separations meeting to reform in new shades. Multiplexing and demultiplexing. Almost imperceptible hues of pink, yellow and green shimmer and retreat, embedded amongst the more obvious greys and blues. All that mobility and energy silently rolling around in the heavens.

My friend Sara will testify to my inability to accept the world in terms of polarities (I take great pleasure in regularly exuberantly discussing it with her!); to me everything could never be so flat. Black and white; hot and cold; male and female; wave and particle; how restrictive. So it is with that view that I am trying to make sense of the nature of light. I imagine that since many greater intellects than mine have long pondered the understanding of this intrangible character, with meticulous and rigorous scientific analysis as well as deep thought, that I am not going to find an easy answer any time soon. However, a little undaunted, I again set out on the voyage (which was what formerly led me to try to make head or tail of Feynman) – explorations into light.

And today.

December. A beautiful still and clear morning here, blue sky and sun. Much of the rest of the country white today, but here the edges of the world just shimmer with the pale grey of a hard frost. Quiet.

I spent a frustrating day yesterday trying to learn about quantum physics, trying to understand the models of waves, rays and photons, but found that each piece of writing that I read was built on foundations of words and concepts that I did not fully understand. Each book or article requiring study of another, more fundamental, one in order for it to be fully illuminating. I begin to wonder if there is actually a bottom to this search, or whether I shall find myself back at the most recent of papers on silicon photonics at the end of a circuit of attempted learning. A ring of resonating words and ideas that starts and ends within itself.

I think that for the moment I shall raise my head from the words and go to let my mind wander out in the world, go to look at some watery waves, and feel sunny photons on my face.