Anyone working in Photonics? - Page 1
Forum section: electronics / general

author: hvna
author_rank: Contributor
timestamp: March 19, 2021, 09:32:41 am
content: I'm almost finished with my second year of university which is "pre-engineering" and at the start of the next semester I declare my engineering major. I've been set on Electrical for years but my school is offering a degree in Optical and Photonics engineering. The courses are almost exactly the same as electrical engineering but with a few more courses in optics and laser engineering. I really like the idea of it, but since it is such a new and small program, I haven't found many personal accounts of professionals working in the field.Just wondering if anyone here is working in photonics or optics?

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 19, 2021, 10:51:49 am
content: I’d say go for it, it is a very interesting field with new applications yet to be uncovered. Remote sensors and measurements being one example. That few people are doing this is actually good, more new things to discover. What you have to do is connect the dots, find niche markets and applications that would benefit a certain technology

author: hvna
author_rank: Contributor
timestamp: March 19, 2021, 11:54:50 am
content: Quote from: MasterTech on March 19, 2021, 10:51:49 amIt is something that interests me. I also like the idea of how small the program is and in itself a niche topic. Glad to hear someone else thinks the same. Thanks!

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 19, 2021, 12:20:38 pm
content: I use lasers the measure the motion of nanoparticles in liquids in order to estimate their size and electrostatic charge. It involves measuring frequency shifts of the laser of less than one part in 10^15.

author: hvna
author_rank: Contributor
timestamp: March 19, 2021, 02:18:30 pm
content: Quote from: JohnnyMalaria on March 19, 2021, 12:20:38 pmThat's really interesting. For what reason would you need to know particles size and electrostatic charge in water? It seems inefficient if you are testing the water for something.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 19, 2021, 02:53:47 pm
content: Quote from: hvna on March 19, 2021, 02:18:30 pmGosh. Where do I beginThis is the realm of colloid science or, as it's becoming more commonly known, nanosuspensions/nanofluids. Just about every manufactured product you buy involves the use of something that can be considered colloidal. Whether it's the final product, an intermediate, or a processing aid. For example, cosmetics, pharmaceuticals, inks and paints, water purification, just about any processed food...What they have in common are small particles (typically 10 - 1000 nanometers) in a liquid. Without the necessary control, the particles will inherently want to aggregate with each other. That can be prevented by inducing electrical charge. Measuring and controlling that charge is important, as is measuring and controlling the size of the particles.In nanomedicine, for example, quantum dots (very small particles of inorganic materials such as CdS) can have their surfaces modified by attaching a protein that helps the particles reach a target location in the body. With the right chemistry, the particles can be designed to adhere to certain types of cells, such as liver cancer cells. This means that the particles can be administered with the intent of accumulating only where there are liver cancer cells. Such particles can be detected by MRI, for example, and help detect/monitor the progress of disease. Such particles are imaging agents. Other types of particles could contain drug molecules or other agents. For example, the mRNA-based COVID-19 vaccines have small fragments of genetic material within liposomes. These are fatty-like particles about 100 - 200 nm in diameter.In the semiconductor industry, fabrication of the product requires polishing silicon wafers. The polishing agent is typically 20 - 80 nm diameter silica particles in water at a specific pH. The polishing efficiency is greatly affected by the amount of charge the particles possess and their size.In the wastewater treatment industry, one of the first steps is to add something to coagulate/flocculate suspended matter. In nature, the same process occurs when fresh water containing suspended clay particles meets the sea. The salt in the seawater causes the particles to aggregate and sediment, leading to deposits such as deltas. If you've ever cut yourself shaving and used a "styptic pencil" to stop the bleed, you've used the same process - the salt causes the blood cells to aggregate.This only scratches the surface of a hidden microscopic world that is essential to control in many industries.

author: hvna
author_rank: Contributor
timestamp: March 19, 2021, 07:11:55 pm
content: Quote from: JohnnyMalaria on March 19, 2021, 02:53:47 pmThat's amazing. Thank you for the write-up. It's always great to find out about these all-encompassing processes that rule my daily life yet I've never even given it a thought. I remember reading an article a few years ago about why white paint is more expensive than other types and it had to do with the expense of creating titanium dioxide nanoparticles.

author: jonpaul
author_rank: Super Contributor
timestamp: March 19, 2021, 07:17:35 pm
content: Many jobs are in military, defense, cinema pro equipment, lighting.Check the fine tech magazines, in this field like Photonics Spectra.Big trade show is Photonics West, hosted by SPIE.https://spie.org/conferences-and-exhibitions/ar-vr-mrspie.orgBon chance,Jon

author: ajb
author_rank: Super Contributor
timestamp: March 19, 2021, 08:54:59 pm
content: SPIE as jonpaul mentioned would be worth looking into if you'd like to get a better view of the overall industry. They have some career information and a lot of literature you might find helpful/interesting.In general, the advances in LED and laser technologies over the last decade or two have created a lot of new opportunities for products and secondary technologies involving photonics. The growing use of LED and laser sources for illumination involves a whole lot of work in developing optical systems around those sources as well as improvements to the sources themselves, which tend to have annoying optical characteristics that need to be managed by external optics, for all sorts of applications, including architectural lighting, stage lighting, car headlights, agriculture (yes, includingthatkind of agriculture), even cinema projectors. Other nascent industries are investing a lot of money in photonic components, such as LIDAR for self-driving cars, UAV remote sensing systems, 3D printing, etc, anticipating that those technologies will enable huge growth in their respective markets as the system technology develops. Laser manufacturing (both additive and subtractive processes) is steadily growing in terms of market size and the power and capability of systems. There's always a range of niche cutting-edge work going on to develop new capabilities in lasers with weird cavity arrangements and things to support scientific and analytical projects in microscopy, spectroscopy, chemistry, physics, astronomy, etc. Also random interesting things like optical fiber-based sensors, where an optical structure at one end of the fiber exhibits optical characteristics that change in response to an external condition like temperature or strain, which can be read by a light source+detector at the other end of the fiber. There's probably some interesting work going into cell phone camera optics to get good imaging out of tiny sensors in an extremely restrictive mechanical situation.So there's a whole lot of interesting work going on under the photonics umbrella, and tons of options for various kinds of specialization depending on what you find interesting.

author: hvna
author_rank: Contributor
timestamp: March 20, 2021, 11:39:23 am
content: Quote from: jonpaul on March 19, 2021, 07:17:35 pmThanks for the links, checking out some of the free publications and webinars from Photonics Spectra now!

author: Terry Bites
author_rank: Super Contributor
timestamp: March 21, 2021, 04:09:50 pm
content: Loads of photonics applications in medical imaging and diagnostics. Cutting Edge Giga buck industry!

author: jpanhalt
author_rank: Super Contributor
timestamp: March 21, 2021, 05:00:23 pm
content: More than 50 years ago, I chose photochemistry for an advanced degree. Never regretted it; although, that is not what I ended up doing. I know photonics is different, but if your uni offers it and you have the time, I recommend at least one advanced course in chemistry.

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 21, 2021, 09:07:52 pm
content: Quote from: jpanhalt on March 21, 2021, 05:00:23 pmChemistry in this field is quite important for things like waveguides, resonators or interferometers... right now I'm reading about the opto-electrical uses of LiNbO3...

author: mawyatt
author_rank: Super Contributor
timestamp: March 21, 2021, 09:56:17 pm
content: Quote from: MasterTech on March 21, 2021, 09:07:52 pmUsed LiNbO3 in an optical Serrodyne Phase Modulator in early precision Fiber Optic Gyros (Patent 5339055). The optical phase modulator is driven with a waveform that ideally produces a true optical frequency shift of the laser diode without introducing harmonics or spurs. This optical frequency shift was used to "Close the Loop" of the precision Fiber Gyro to get away from the interference pattern offset sinusoidal effects and force the operation at the sine mid-point crossing where the waveform is perfectly linear (see Sagnac effect). Reading (counting) the forcing function (variable frequency for VCO) produced a linear relationship between VCO frequency and rotation rate. LiNbO3 is a very useful Electro-Optical material with beneficial voltage controlled properties.Best,

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 21, 2021, 10:02:30 pm
content: Quote from: mawyatt on March 21, 2021, 09:56:17 pmIndeed. I've used acousto-optic modulators made with it (as well as other that use flint glass or lead molybdate). In my application, I use two to derive a precise, stable and known frequency difference of the order of a few kHz between two laser beams. They combine to create a kind of interferometer to detect nanoparticle motion.

author: nfmax
author_rank: Super Contributor
timestamp: March 21, 2021, 10:07:56 pm
content: Quote from: ajb on March 19, 2021, 08:54:59 pmYou can also use the optical fibre itself as a sensor. Over the years, I've worked developing systems using laser light pulses, launched into one end of a fibre, which are backscattered as they interact with the molecular scale structure of the glass, returning to the launch site as a delayed 'echo', much like a radar or lidar system. Except that the backscatter signal is continuous, being generated at each point in the fibre as the laser pulse reaches it. Simple Rayleigh scattering returns light at the same wavelength as the input pulse, and forms the basis of the OTDR (Optical Time-Domain Reflectometry) method of measuring attenuation in fibres. However, if you use an extremely narrow linewidth laser (~kHz) and coherently detect the backscatter, using a frequency-shifted copy of the laser output as a local oscillator, you can measure microscopicdisplacementsof each point along the fibre. This lets you use the fibre as a distributed vibration sensor or microphone.Raman scattering is a non-linear interaction which causes the wavelength of the backscattered light to be different from that of the incident laser pulse. The Raman scattering process is temperature-sensitive, so you can make a distributed thermometer or temperature sensor based on the intensity of Raman backscatter. It isn't easy, as the amount of Raman-scattered light is very much less than the incident pulse, and there are all sorts of complications arising from the variations in fibre attenuation and group velocity at the different wavelengths involved. However, the wavelength shift is large enough to enable the Raman backscatter to be easily separated from the Rayleigh signal using optical filters.Brillouin scattering is another non-linear process, also sensitive to temperature but sensitive to strain as well. The level of Brillouin scattering is intrinsically much larger than that of Raman scattering (unless the fibre has been specifically designed to suppress it - as some high-performance communication fibres now are) but the wavelength shift is much smaller. Optical filtering is no longer possible, so coherent detection using an optical local oscillator, followed by standard microwave IF technique, is required to recover useful measurements.These sensors have many applications, mostly measuring long, thin things. Like oil wells, gas pipelines, security fences, railways, and even optical communication cables themselves (using either a spare fibre or 'spare' wavelengths in a traffic-carrying fibre). To extend the range, it is possible in some cases to use intermediate optical amplifiers (EDFAs) which are themselves 'pumped' (i.e. powered) by light sent from the measuring instrument.It's an involved and fascinating field. The technical problems are non-trivial, and as well as photonics 'proper', can require expertise in analogue electronics, digital signal processing, measurement physics, and materials science & chemistry.For more information, I recommend finding a copy ofAn Introduction to Distributed Optical Fibre Sensorsby my former colleague Arthur H. Hartog, published by CRC Press Taylor & Francis Group, ISBN 978-1-4822-5957-5

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 21, 2021, 10:17:01 pm
content: Quote from: JohnnyMalaria on March 21, 2021, 10:02:30 pmWhat I wonder is where are devices bought from, are they all custom made or is there a well known supplier for the easiest configurations?

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 21, 2021, 10:33:15 pm
content: Quote from: MasterTech on March 21, 2021, 10:17:01 pmPlenty of off-the-shelf solutions. The ones I've used:https://www.brimrose.com/http://www.isomet.com/https://intraaction.com/

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: March 21, 2021, 11:44:34 pm
content: Quote from: jpanhalt on March 21, 2021, 05:00:23 pmI've worked on non-contact temperature sensing using fluorescence. I knew nothing about it at first, but picked up what I needed. The application was calibrating thermal cyclers for DNA quantitation (via Polymerase Chain Reaction). Using luminescence for non-contact sensing is a fascinating area, with important bio-tech applications.Just now I saw an ad from ThermoFisher for "microvolume UV-Vis spectrophotometers" for protein and nucleic acid research. This kind of instrumentation needs a cross-disciplinary design team: optics, electronics, mechanics, biochemistry, photochemistry, software. If you like that kind of development, an optics+electronics background will give you an edge. Extra advantage if your course teaches you MEMs.

author: mawyatt
author_rank: Super Contributor
timestamp: March 22, 2021, 01:17:38 am
content: Another very interesting application of photonics was started in 1979 called remote sensing spectral radiometry which involved remote sensing the chemical makeup of the atmosphere at up to 5 miles away, and doing so completely passively (no signal source). The technique relied on the small temperature variations in the atmosphere to create an effective absorption and reradiating spectrum in the 8 to 12 micron region which could be detected remotely with an extremely sensitive interferometer. This instrument involved a tiny HeNe laser controlled moving mirror interferometer with cryogenically cooled (Split-Cycle Sterling Cooler) HgTe sensor producing an interferogram which was capture with an 18 bit ADC synched with the moving mirror position.After some math the result was the spectrum at a distance which contained the various complex molecular signatures of molecules in the 8-12 micron region. The unique signatures of known chemical agents used in warfare were stored and compared to the captured spectral signatures. The science advisor to US President Regan claimed this passive technique to be impossible without illuminating the atmosphere with a high power CO2 laser, and the program should be terminated. Lighting up a high power laser in the battlefield in not a good idea for obvious reasons, and the concerns were valid!!A live demo was setup in front of Congressional Selected Scientific Staffers with a non-toxic stimulant agent sprayed from a moving jeep at ~5miles in a battlefield type environment. The result was an outstanding success, the program survived resulting in the continued development of the XM21 Remote Sensing Chemical Agent Detector. Later the XM21 went in full production and protected by early warning the Allied Forces during Desert Storm and made the front page of Newsweek magazineBest,