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445 diode polarization

Fieras

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Since these diodes are some type of multimode, can anyone test if the polarization of the light from these diodes is random or uniform? It might impact the plans of anyone planing to use these for a white laser, since if its random they'd have to use a dichro and not a PBS cube at that stage of color mixing.
 



Pontiacg5

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Seeing as how many have used 660nm and 635nm diodes in projectors before I would say it is possible. I'm pretty sure they are polarized. Are all lasers not somewhat polarized?
 

FireMyLaser

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I just confirmed with my diode which just arrived, that the light IS polarized. No problems there.
 

JonWienke

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Coherent light, by definition, is polarized. For light to be coherent, the wavelength has to be the same, the phase relationship of the photons must be the same, and the orientation of the electromagnetic fields of the photons must be the same. If any of these conditions are not met, one photon can cancel out another photon, and the light is no longer coherent.
 

Meatball

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I've seen on PL, that someone has already combined two 445s with a PBS... makes for a nice amount of blue.


Here's a knife edging combination for the heck of it..


-Tyler
 

ElektroFreak

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Laser diodes are always polarized in the direction of the fast axis. In other words, if you look at the spot, whichever axis of the spot is longer is the fast axis. The polarization is parallel to this axis.
 

JonWienke

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So how can newport sell a randomly polarized HeNe laser? Does that mean when two beams are combined with a PBS, the resulting beam is no longer coherent?
If it's randomly polarized, the beam isn't coherent in the first place. Combining two such beams won't make the combined result less coherent, because the component beams weren't coherent in the first place. They might be monochromatic and have low divergence, but that alone does not make them coherent.
 

IntraWinding

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So how can newport sell a randomly polarized HeNe laser? Does that mean when two beams are combined with a PBS, the resulting beam is no longer coherent?

Helium-Neon (HeNe) Lasers - Red 633 nm
HeNe lasers are unpolarised unless there is a polariser in the cavity (or some other trick, like magnets) - normally just a glass plate at the Brewster angle.
In fact, if I remember correctly, 'Unpolarised' is slightly wrong. The beam is polarised, but the angle of polarisation rotates randomly at very high speed.
 

Event_Horizon

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HeNe lasers are unpolarised unless there is a polariser in the cavity (or some other trick, like magnets) - normally just a glass plate at the Brewster angle.
In fact, if I remember correctly, 'Unpolarised' is slightly wrong. The beam is polarised, but the angle of polarisation rotates randomly at very high speed.
This is correct.
 

drlava

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Just to add to the info, yes the 445nm is polarized, yes it is polarized along the fast axis, and the fast axis lies along the plane defined by the 2 power pins.
 

pullbangdead

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Just to add to the info, yes the 445nm is polarized, yes it is polarized along the fast axis, and the fast axis lies along the plane defined by the 2 power pins.
I think your diode is sideways from mine...because the plane of the laser is parallel to the 2 power pins on the back, the fast axis is definitely perpendicular to that plane.
 




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