In lab experiments I was needed to perform surface plasmon excitation. Surface plasmon excitation can be performed only with TM polarization. So it is good experiment to check if a laser has TE or TM polarization. Can you recommend other/ simpler experiments to check if a laser has TE or TM polarization. Thank you in advance.
TM and TE modes are used for waveguide structures like semiconductor lasers. In a free space they become a TEM type. The laser can be polarized linearly, circularly, even randomly. The linear polarization can be orientated vertically, horizontally, or something in between. The polarizer is used to find out it. If the linearly polarized laser can be rotated around it axis, the glass plate tilted to a Brewster angle can be used to orientate a laser polarization to a desired orientation with a good accuracy.
Lets say, the laser electrical field must be horizontal. The glass plate normal is set to ~55 deg angle to the beam, and the laser is rotating around the axis to get a minimal reflection. You might tweak an glass plate orientation and repeat rotation. Then work with your sample (orientate vertical or horizontal) to excite plasmons.
I assume you know a laser safety stuff too - don't shoot up and somewhere; and wear safety glasses.
TEM is the transverse mode of laser, for instance TEM00 shows Gaussian beam profile.
TE or s polarization and TM or p polarization are orthogonal and can be detected by a couple of rotating polarizers. Brewster angle glass plate, Fresnel rhomb and QWP are among other useful optical components for polarizometry.
Thank you for your responses.
I not really know what is the Fresnel rhomb and QWP, but if I had one, how with their help I will understand if I have TE or TM polarization?
Try to use this: Your laser-> polarized cube ->you surface to be excited.
Since only on TM mode you will get the plasmon excitation, rotate the polarized cube like 45 degree each time and make an measurement for your surface until you get the plasmon excitation curve. You should use an power-meter at the end of this montage. Simple use the laser->polarizer cube-> power meter and see if you have changes at the cube or laser rotation.
Is not about if your laser is polarized or not, just use a n polarizor cube and then u can go further with your plasmon excitation measurements. If you need more info I can help with your experiment regarding the montage for your plasmon excitation.
Dear Vladimir,
U may try this:
1. Use the same experimental setup as SPR experiment by using noncoated prism (bare prism without metal layer). Follow the same experimental procedure as well.
2. Record the value of optical reflectance, R obtained by power meter. Collect data by increasing the value of incident angle.
3. If Brewster angle is observed, the light is TM polarized and vice versa. To understand more about Brewster angle, u can refer "Fundamentals of Photonics" book by Saleh.
Good luck
You can use polarizing beam splitter to check the polarization of your beam.
Look for Newport or Throlabs.
I did not understand what do you mean (TE or TM are not laser polarization), but polarizers can ever help to show what type of polarization your laser has.
Yes, but you need special polarizer to situate in front of laser beam!
First of all you need to know the wavelength of the laser then choose the properly devices, put in front of the laser beam a polarization beam splitter or a polarizer and an optical power meter or oscilloscope, with the latter you can recognize the intensity of each polarization which are normally have different levels
Everyone is trying to do this the hard/expensive way. If you want to figure out which way the laser is polarized, stick a pair of polarized sunglasses in the path of the beam in the same orientation as they would sit on your face (as long as the beam is not too powerful, if it is, expand the beam using any lens-concave or convex beyond the focal point) and then see if the output beam through the glasses is mostly transmitted through or is mostly absorbed/reflected. Sunglasses block horizontally polarized light (electric field parallel to the floor) in order to reduce reflections from water and roads, etc. If the laser light is blocked, then your laser light's electric field is parallel to the floor, if it's transmitted then it is perpendicular to the floor. There, this is essentially a free solution to an optics problem...
My source, in case you were curious: https://www.polarization.com/water/water.html
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