Recent content by ace1719

Hi Lay1, Your redraw is correct. To answer your second question, Vout is the node that is common to R7 and R8. Some of the other commenters have noted that voltage doesn't really "pass through". I'll try and clarify things for you a bit. Voltage is always measured between two points. For...

I don't know whether this is relevant, but the lumen is made out of nylon-12, which has a refractive index of 1.525. Glass has a refractive index of 1.52. I don't know what the refractive index of the cladding and sheathing is, but they could be low enough to allow for evanescence.

I will say that the laser and the optical hardware are not connected electrically. I don't know much about optics, but I do know a lot about grounding, and we certainly aren't injecting noise from a ground loop or the like. The grounding is solid, and the power supplies are low noise.

No, the emitter is buried 11 mm into the lumen, the tips of the detector fibers poke out of it by about 0.1 mm.

The emitter and the detector fibers are certainly very, very close together. So evanescence is possible (not that I really know what that is).

What do you mean by blocking the beam? If I turn the beam off, the signal goes to 0 (as it should). I can't exactly block the beam from inside the lumen.

Unfortunately our laser can only run CW.

It isn't experimental error. I didn't run this experiment out of interest. I ran it because it was the logical reduction of a real world problem we were seeing. I went back, and looked at data from our earliest prototypes, and even re-tested some of them. The phenomenon is extremely consistent...

We're running the laser CW.

Our fibers are 50 um, glass core, multi-mode fibers They are 2.88 m long. The photodetectors are exquisitely sensitive, although the system itself is extremely lossy. An irradiance of 11.1 mW/cm^2 will yield a voltage to 2.33 (buffered, but unamplified) at the photodetector. The proximal end of...

Our laser is a Class IV that can go up to 5 W, so 500 mW is it's minimum setting. The light could certainly penetrate the cladding, but it shouldn't be able to be coupled into the fiber. I'm certainly not a photonics expert either, but my understanding is that it SHOULD either reflect off the...

Hi Everyone! I have a photonics problem that I was wondering if anyone may be able to shed some light on (no pun intended). I work for a company that is designing a fiber optic emitter/detector as a part of one of our products and we've noticed something that would appear to defy physics...

What can we infer about the bandwidth of that?

k is the index for the summation. I guess I should have explained that. |x(t)|, I presume is absolute.

Homework Statement Consider the PM (phase modulated) signal, s(t) = Acos(wt+x(t)) where x(t) is the information bearing signal. Assume that |x(t)|< y, which is not necessarily small. Using Taylor's series expansion, derive an estimate for the bandwidth of the PM signal s(t). Homework...