# A Are green lasers Left Circularly Polarized Light?

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1. Sep 26, 2016

### Pet Scan

I'm getting ready to do some testing, and need to decide which lasers to use . I need both left and right circularly polarized laser light .
I was told that green diode lasers, the kind readily commercially available (usually around 200 - 500 mW.) , are LEFT CPL.
1. Is that usually true, and why?
2. Are red diode lasers RIGHT CPL??
I know I can convert the LCPL into RCPL with a 1/2 wave retarder plate, but that's too expensive....

2. Sep 26, 2016

### Simon Bridge

Last edited by a moderator: May 8, 2017
3. Sep 26, 2016

### Pet Scan

Thx, SB; however, I am still stuck.
How can I be sure I am obtaining a Left circularly polarized laser?? Will the manufacturer know....? How can I be sure >

4. Sep 26, 2016

### Simon Bridge

Pass it through a $\lambda/4$ wave retarder and see if the output is (almost) linearly polarized. Anyway, why do you need it to be left circular if you do the experiment only with this type of polarization (i.e. not comparing it with right circular)?