=====T13=====
This sample has the identifier G2 on it, but since there is no G set of samples and it is a part of the grating test samples it has been labeled T13 for electronic purposes.

This sample has 3, 500um x 1000um, gratings with a feature size of 1um (2um Period). They were written on the ESEM although future iterations can now come through the Heidelberg. It used a 45nm Al hard mask in the RIE and was processed for about 20 min. Depth is still unknown.

It was polished to an angle of 30° as measured from the top surface of the device on the side of the gratings and 90° on the far edge.

Testing was successful. Green light in the characterization apperatus with the rotation stage set to 338.5° was successfully coupled into the substrate. Only TE light coupled into the waveguide. The top surface of the substrate was 15° off axis of beam and the beam was resting on the edge of the polished face that mates with the bottom of the  substrate.

The following pictures were the result the difference in angle was a fraction of a degree and clear waveguiding is evident although there is a lot of other light bouncing around.

^  Not Waveguiding  ^  Waveguiding  ^
|  {{:samples:t13_grating_waveguiding3.jpg |}}  |  {{:samples:t13_grating_waveguiding1.jpg |}}  |


Here is the prettier view of the waveguiding phenomenon:

 {{:samples:t13_grating_waveguiding2.jpg |}}