Properly Pipe Laser Light Around With Homebrew Fiber Couplings

It’s a rare person who can pick up a cheap laser pointer and not wield it like a lightsaber or a phaser, complete with sound effects. There’s just something about the “pew-pew” factor that makes projecting a laser beam fun, even if it’s not the safest thing to do, or the most efficient way to the light from one place to another.

We suspect that [Les Wright] has pew-pewed his way through more than a few laser projects in his lab, including his latest experiments with fiber coupling of lasers. The video below is chock full of tips on connecting cheap communications-grade fiber assemblies, which despite their standardized terminations aren’t always easy to use with his collection of lasers. Part of the challenge is that the optical fiber inside the cladding is often very small — as few as 9 microns. That’s a small target to hit without some alignment help, which [Les] uses a range of hacks to accomplish.

The meat of the video demonstrates how to use a cheap fiber fault locator and a simple optical bench setup to precisely align any laser with an optical fiber. A pair of adjustable mirrors allow him to overlap the beams of the fault locator and the target laser precisely. The effects can be interesting; we had no idea comms-grade fiber could leak as much light through the cladding as this, and the bend-radius limits are pretty dramatically illustrated. [Les] teases some practical sensing applications for this in a follow-up video, which we’re looking forward to.

Looking for more laser fun with your remaining eye? Check out [Marco Reps] teardown of a 200-kW fiber laser.

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Sorry, Your Internet Connection Is Slow

How fast is your Internet connection? The days of 56K modems are — thankfully — long gone for most of us. But before you get too smug with your gigabit fiber connection, have a look at what researchers from the Network Research Institute in Japan have accomplished. Using a standard diameter fiber, they’ve moved data at a rate of 1 petabit per second.

The standard fiber has four spatial channels in one cladding. Using wavelength division multiplexing, the researchers deployed a total of 801 channels with a bandwidth over 20 THz. The fiber distance was over 50 km, so this wasn’t just from one side of a lab to another. Well if you look at the pictures perhaps it was, but with big spools of fiber between the two lab benches. The project uses three distinct bands for data transmission with 335 channels in the S-band, 200 channels in the C-band, and 266 channels in the L-band.

To put this into perspective, a petabit — in theory — could carry a million gigabit Ethernet connections if you ignore overhead and other losses. But even if that’s off by a factor of 10 it is still impressive. We can’t imagine this will be in people’s homes anytime soon but it is easy to see the use for major backhaul networks that carry lots of traffic.

We are still amazed that we’ve gone from ALOHA to 2.5-gigabit connections. Although the Raspberry Pi can’t handle even a fraction of the bandwidth, you can fit it with a 10-gigabit network card.

A fusion splicer being used to repair an optical fiber

Using A Fusion Splicer To Repair A Samsung TV’s Cable

Some Samsung TVs come with a system called One Connect, where all external cabling is connected to a separate box so that only one small signal cable goes to the TV. In some versions, the cable linking the TV with its Connect Box is a pure fiber optic cable that’s nearly transparent and therefore easy to hide.

Thin fiber optic cables are fragile however; when [Elecami Wolf] got one of these TVs for a very low price it turned out that this was because its One Connect cable had snapped. Replacement cables are quite expensive, so [Elecami Wolf] went on to investigate the inner workings of the fiber optic cable and figured out how to repair a broken one.

The cable consists of four pairs of plastic-coated glass fibers, which are attached to receivers and transmitters inside the thick connectors on either end. Repairing the cable required two things: figuring out which fibers should connect to each other, and a reliable way of connecting them together.

The first was difficult enough: a simple 1:1 connection didn’t work, so it took a bit of work to figure out the correct connection setup. One clever trick was pointing a camera at a working cable and comparing the flashing lights at each end; this helped to identify the right order for two of the four pairs. For the other two, a combination of reverse-engineering the electronic circuits and some systematic trial-and-error yielded a complete wiring diagram.

For the second part, [Elecami Wolf] called on a fiber optic expert who lent him a fusion splicer. This is a rather neat piece of equipment that semi-automatically brings two pieces of fiber together and welds them with an electric arc. Once this was complete, it was a matter of covering the splices to protect them from sharp bends, and the fancy TV was working again.

Although not everyone will have access to a multi-mode fusion splicer machine, [Elecami Wolf]’s videos provide fascinating insights into the workings of modern fiber-optic based consumer electronics. This might be the first fiber-optic splicing attempt we’ve seen; but if you’re trying to hook up an optical fiber to your circuit, this ball lens setup is a neat trick.

Continue reading “Using A Fusion Splicer To Repair A Samsung TV’s Cable”

A Ball Lens For Optical Fiber Coupling On The Cheap

It’s fair to say that for most of us, using a fiber optic cable for digital audio or maybe networking will involve the use of an off-the-shelf termination. We snap the cable into the receptacle, and off we go. We know that inside there will be an LED and some lenses, but that’s it. [TedYapo] though has gone a little further into the realm of fibers, by building his own termination. Faced with the relatively high cost of the ball lenses used to focus light from an LED into the end of the fiber he started looking outside the box. He discovered that spherical glass anti-bumping balls used when boiling fluids in laboratories make an acceptable and much cheaper alternative.

A ball lens has an extremely short focal length, meaning that this same property which allowed Antonie van Leeuwenhoek to use them in his microscopes is ideal for LED focusing in a small space at the end of a fiber. Chromatic aberrations are of no consequence for light of a single wavelength. It seems that the glass balls are uniformly spherical enough to do the job. Fitted with the LED and fiber termination in a 3D-printed block, the relative position of the ball can be controlled for optimum light transfer. It’s a relatively simple hack mentioned in passing in a Twitter thread, but we like it because of its cheapness and also for an insight into the world of optical fiber termination.

Curious to know more about optical fibers? We covered just the video for you back in 2011.

German Experiment Shows Horses Beating Local Internet Connections

These days, we’re blessed with wired and wireless networks that can carry huge amounts of data in the blink of an eye. However, some areas are underprovisioned with bandwidth, such as Schmallenberg-Oberkirchen in Germany. There, reporters ran a test last December to see which would be faster: the Internet, or a horse?

The long and the short of it is that Germany faces issues with disparate Internet speeds across the country. Some areas are well-served by high-speed fiber services. However, others deemed less important by the free market struggle on with ancient copper phone lines and subsequently, experience lower speeds.

Thus, the experiment kicked off from the house of photographer [Klaus-Peter Kappest], who started an Internet transfer of 4.5GB of photos over the Internet. At the same time, a DVD was handed to messengers riding on horseback to the destination 10 kilometers away. The horses won the day, making the journey in about an hour, while the transfer over [Kappest’s] copper connection was still crawling along, only 61% complete.

Obviously, it’s a test that can be gamed quite easily. The Internet connection would have easily won over a greater distance, of course. Similarly, we’ve all heard the quote from [Andrew Tanenbaum]: “Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.”

Notably, [Kappest’s] home actually had a fiber line sitting in the basement, but bureaucracy had stymied any attempts of his to get it connected. The stunt thus also served as a great way to draw attention to his plight, and that of others in Germany suffering with similar issues in this digital age.

Top speeds for data transfer continue to rise; an Australian research team set a record last year of 44.2 terabits per second. Naturally, the hard part is getting that technology rolled out across a country. Sound off below with the problems you’ve faced getting a solid connection to your home or office.

Lightwave Multimeter Teardown

You tend to think of test equipment in fairly basic terms: a multimeter, a power supply, a signal generator, and an oscilloscope. However, there are tons of highly-specialized test equipment for very specific purposes. One of these is the 8163A “lightwave multimeter” and [Signal Path] tears one part for repair in a recent video that you can see below.

If you’ve never heard of a lightwave multimeter, don’t feel bad. The instrument is a measuring system for fiber optics and, depending on the plugins installed, can manage a few tests that you’d usually use an optical power meter, a laser or light source, and some dedicated test jigs to perform. Continue reading “Lightwave Multimeter Teardown”

A Brief History Of Optical Communication

We live in the information age where access to the internet is considered a fundamental human right. Exercising this right does largely rely on the technological advances made in optical communication. Using light to send information has a long history: from ancient Greece, through Claude Chappe’s semaphore towers and Alexander Graham Bell’s photophone, to fiber optic networks and future satellite internet constellations currently developed by tech giants.

Let’s dive a little bit deeper into the technologies that were used to spread information with the help of light throughout history. Continue reading “A Brief History Of Optical Communication”