Meeting With Pavel 10_7_17 10 am

moved to 17_7_17 as Pavel not available.

Bar Position Tests

Varied the position of the metallic bar from central to aligning with the edge of the substrate in 0.25mm increments: 0, 0.25, 0.5, 0.75, 1.0, 1.25. The resulting graph is below. By varying the position away from off central, the refractive index position is increased in frequency, and the intensity of the resonance is decreased.

This change of the refractive index will have an effect on the part of the spectrum that is totally internally refracted. Therefore, if we design the bulk target at a given angle and misalign the pattern on the reverse of the wafer, we will lose part of the spectrum. This change in the part of the TIR is the main constraint on the alignment error that we can afford.

Silicon Wafer Target

Depose on both sides of a silicon wafer. On one side the resonators and on the other side, the bars. The wafer is:

6in Diameter

400um Thick

Max deposition depth = 100nm

To carry out the deposition, just a metallic mask is required, not a full photomask. I looked into laser cutting a mask as the ring width is on the edge of the machining technology available at the RHUL workshop. The masks are typically made from stainless steel.

With the new specifications, the refractive index response is:

From this graph, 50 percent of the radiation is transmitted while the rest is reflected and absorbed. Given, this refractive index response we need to ensure that none of the radiation is within the region of total internal reflection. The following graph shows that this is the case for a 45deg angle!

To do from meeting

  • Send off drawing to company and RHUL lab to see the feasibility and cost of manufacturing the mask.
  • Look into the Si wafer. Is it doped? We need pure Si. Also, look at the cutting of the wafer. We need a nice edge.
  • Aligning, the bars and the resonators, is important!! We need to find a method.
  • THink of the spacing, and try to see if we can use some wafers and make some test spacing

-- TomVaughan - 10 Jul 2017

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Topic revision: r2 - 17 Jul 2017 - TomVaughan

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