# TE, TM and TEM Modes in Lasers

1. Oct 15, 2013

### Septim

Greetings everyone,

I am confusing the definitions in the title of the post all the time. I have books about lasers, yet none of them explain these concepts lucidly and clearly in my opinion. For example, what is our reference plane when we are dealing with semiconductor laser diodes and mention TE and TM modes? How can a mode be TEM; are there two reference planes? These sort of questions always confuse my mind and the books I found usually aim too high or too low with regard to my level in my opinion. Where can I learn these definitions by heart? Please do not hesitate to post your suggestions and ideas.

2. Oct 15, 2013

### UltrafastPED

Last edited by a moderator: May 6, 2017
3. Oct 16, 2013

### Septim

Thanks, I will have a through look on this text, by the way I think TE and TM definitions for waveguides and lasers are similar. That is for example in a semiconductor laser in TE mode electric field of the wave is perpendicular to the p and n type planes at the end of semiconductor materials.

Last edited by a moderator: May 6, 2017
4. Oct 19, 2013

### Claude Bile

A TE mode is one where the B-field component in a given direction (typically z; whatever the longituinal direction is) is 0.
A TM mode is one where the E-field component in a given direction is 0.

A TEM mode is one where neither the Magnetic or Electric fields are 0 in said direction.

Remember modes = solutions to the PDE that governs the device. TE and TM definitions are usually the same for waveguides and lasers, but it is not compulsary...it always pays to double-check these things.

Claude.

Last edited: Oct 19, 2013

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