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Is it possible to couple the Casio 445nm laser into optical fiber

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youfellow

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I have a more ambitious project. I wish to couple the lasers into a single mode fiber and then can pass the light through the corners or under the doors or just for all the other fun of it.

I have successfully coupled about 50mW of the 405nm blue laser to the Corning SMF 28 fiber, and am planning to do the same for the Casio 455 nm laser. But I read from the posts that the Casio laser is a rectangular "multimode" laser. What does that exactly mean? Does it has multiple emitter or just have one large-area emitter that the light is not confined as single mode? If that's the case, how big is the emitter? Is it still possible to couple that "multimode" blue light into single-mode fiber?

Thanks a lot!:wave:
 





HIMNL9

HIMNL9

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It emits on different "planes" (sorry, don't know the right word), so the emission is larger than a single mode emitter, and also more "rectangular" shaped ..... no, the emitter is still one ..... and, if the fiber is a big one (large diameter fiber), is still possible to couple it, with few loss, but if you want to couple it in a small transmission fiber, you need a specific optic (beam correction or fast axis correction, followed from a positive for focus it into a single point in the fiber input)

BTW, what fiber you want to use ? ..... if you're using a light transfer fiber like the ones for carry light for microscopes or illumination, maybe you can also just couple it directly .....
 
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youfellow

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Thank you. I have corning SMF 28 single mode fiber. The core size is about 10 um. I found if I use the large core fiber (such as the 62.5um fiber), the output beam is difficult to collimate.

I was confused by the "rectangular" beam. The 405 nm laser emits "elliptical" beams, and I can use a cylindrical lens to somewhat correct for that. What makes the 445nm rectangular rather than elliptical?

HIMNL9 said:
It emits on different "planes" (sorry, don't know the right word), so the emission
BTW, what fiber you want to use ? ..... if you're using a light transfer fiber like the ones for carry light for microscopes or illumination, maybe you can also just couple it directly .....
Click to expand...
 
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heruursciences

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You will need a very short FL cylinder lens as well as a standard launching lens to couple it into a fiber. The fiber you will need to couple about 90% of the light will be 100um or bigger. To couple into a single mode telecom type fiber will be very difficult, but getting power throughput of 15 to 20% isn't unrealistic.
 
oic0

oic0

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Cant tell you why, but it makes a beam like this pic only wider, this is going through a lens, just defocused, the edges are distorted and clipped by the lens. It makes a series of wide faintly eliptical lines stacked on each other with the middle ones being brightest
2krfvq.jpg
 
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youfellow

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Thank for the picture from oic. Usually the oligo-mode (not sure how to say the multimode that only has a few modes in it, rather than the more usual multimode that has thousands of modes) laser have some interference pattern that forming lobes, but this kind of symmetrical lobes are unusual. Maybe it is from the lens aberration effects?

As heruursciences said, it maybe possible to couple 20% of it into a fiber, with 1 watts, 20% is 200 mw, still plenty of power. :yh:
 
pullbangdead

pullbangdead

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It is a single emitter, ~15 microns wide. That width allows the multiple lateral mode behavior.

Definitely possible to fiber couple, and as it seems you've already surmised, how difficult it is depends exactly on what kind of performance you require.
 
millirad

millirad

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^ Yeah, you can see the wave-front addition and cancellation in the beam spot.
 
Bluefan

Bluefan

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Just 15 micron wide? That's tiny for a 1W diode! Are you sure pbd?
 
Toke

Toke

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Have you tried this, it is 3, 6, and 10mm fibre.
It should be possible to fit the beam into the end of it.

There could be some losses, actually I have no idea if it is suitable or not.
 
Cyparagon

Cyparagon

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Those are WAY... WAY too big to properly carry a laser beam. You'd get an LED out the other end.
 
HIMNL9

HIMNL9

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Naah, is just that those are plastic fibers ..... good for carry light sources in stranges or difficult places, but not for carry laser beams ..... these are made with a single mix of plastic, where instead glass fibers are made with a "core" of a specific type of glass (that is the part that phisically guide the light), with an external layer of a different type of glass, with a different diffraction index (that is mainly placed there for give a better "reflection index" to the external layer of the fiber, loosing the less possible light)
 
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