Below you can see a video of me trying to suppress the TEM00 mode (or supermode?) of a blue laser diode by providing feedback with a +/- 20% partially silvered mirror at the focal point of a lens. At low current it's fully suppressed, you only see the two lines of the very elongated TEM10 mode. But at around 0:55 I'm ramping up the current in steps (you can hear the clicks of the dials on my supply) and you will see the TEM00 coming back at its new threshold level. With a lower level of feedback in this setup (4%) it was possible to get some of the higher order modes to lase at low currents, but this level of feedback was not enough to suppress modes.
vrijdag 30 juli 2010
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