The E-Beam can do Tin Oxide

It is transparent, colorless, and hard. Some sources suggest the ability to make films with as high as n=2.3.

Spatial Filter

I added the larger of the two pinholes labeled 25um to the interference photo-lithography system. I believe it may have a hole around 100um. It was just big enough to not clip the edges. The exposure light is now more uniform.

Output Coupling Gratings

I have successfully create output coupling gratings in SiN.

During the process I tried two samples at each of three exposure times: 2.5, 3, 3.5min. Each created gratings on one sample and failed to create then on the other. 3min was the most uniform covering all of the device. 2.5min covered 2/3 of the device. 3.5min covered only 1/5 of the device along an edge. The resist thickness seemed nonuniform, but that may have not been the case. It might be worth it for uniformity sake to use a pure resist rather than dilute. I want to try 2.75min, 165sec, exposure times to see if that will be any better.

A 4 min RIE ecth completely cleared the pattern from the SiN. A 2min etch left the pattern. A 3min run and 1min run could be instructive to how much time needs to be spent in the RIE. Both samples tried at 2min came out but the quality of the grating in the 3min sample decreased. I am guessing this is due to over-etching the SiN.

The large circular patterns continue to cover the exposed area. A spatial filter may remove some of these imperfections.

I finally formatted the FPGA correctly to get the Line Drivers working. What follows are images of the internal clocks and two independent lines with offset phase.

I found the sub micron gratings created by the lithography setup. They cover a region about 1 inch tall by 2 inches wide. They can be seen in all areas and have a great uniformity however the overall exposure across that area is poor with large defects caused in part by the lens. I should have a new lens and the ability to spatially filter the light soon.

8/30/2016 First Sub Micron Gratings

The software, in verilog, is completed for the FPGA implementation of AM delay line drivers for the tactile field. Proof of its functionality is shown below. The first picture shows the PWM encoding of the Carrier frequency on two line with different phases. The second picture show the same two lines when the amplitude of the modulating signal is -1. Note that the PWM is constant. The final picture shows the entire timeline. The yellow line is the sample line and you can see that the Pulse Duration does note change while the modulation amplitude is at its lowest point, -1.

Hardware is yet to be implemented, but should be just assignment of pins, dealing with frequency inputs, and routing the clock.

Simplified Lithography Setup Testing has begun. 4 minute exposures are producion lines at about 40-25um spacing that appear in a radial pattern with the center of the circle appearing to orriginate at the optical center of the beam.

8/25/2016 SPLT

Michelson Interferometer Test results are in the laser is coherent for a distance of about 30cm.

Michelson Interferometer Test

Three samples two samples have been processed with very limited results. Follow the link to see the progress.

First Photolithography Tests

The new boards have been created and tested.

This is the shortest electrical pulse sent to the current driving n-mosfet at the base of the laser. The pulse width appears to be in the ballpark of 35ns.

By changing the delay line the pulse width can be modified.

By changing the gain the threshold voltage, and thereby the allowable current through the n-mosfet in saturation, can be adjusted.

The previous design was modified as it failed to provide proper control of the driving current. I was silly enough to place the voltage regulator on the high side of the P-FET that drives the laser. I thereby limited the off state not the on state. Changing the NAND Gate to be PMOS and switching the power should have solved this problem. A new board has been designed and will be tested soon.

One more note, the old design got really hot on the N FET of the first and second inverters. I am still unclear why.

This is the modified Schematic:

A working design for the pulsed laser driver has been created. On the breadboard the pulses reached a minimum pulse length of ~50ns. A prototype on a copper board is now being produced to see if the capacitance of the breadboard slowed down the circuit. The signal generator could also be the limit as its rise time edge is 50ns.

This is the working Schematic:

Created and tested a device with 1mm by .1mm transducers chirped from 400-600MHz. Two of the transducers then had waveguides written by the microfab. All were tested. All showed deflection at 515MHz with high precision required on the vertical alignment but no sensitivity to horizontal position within the substrate. The pictures that follow are characteristic of the results of every IDT. There is no doubt, we have created bulk-wave, polarization-rotating, acousto-optic modulators. Still no conclusive evidence of leaky mode interaction in uFab waveguides.

Without Signal	With Signal

Finished the new translational module for the Holo-monitor. We will see how it compares.

With Erich's help we held our first particle with the LCoS.

With Jacob's help we got it working.

4/29/2016 - 40x Laser Written Waveguide Depth Test

4/28/2016 - Laser Written, S Waveguide Tests

4/20/2016 - More tests of Laser Written Waveguides - 10x Objective

4/5/2016 - First tests of Laser Written Waveguides - 10x Objective

3/29/2016 - Summary of Grating Input Coupling Tests

2nd Grating Etch Depth Tests

Grating Etch Depth Tests

Characterizing Dr Smalleys Mixer board

Color Traces for Leia

Input Before	Input After

Output After

Colosseum Analysis

Original Particle	Cleaned Particle

LED Response	Particle Response

Gerber File Library

There is no auto centering so the origin placement is important!

I have tested the files made on the heidelberg and they worked wonderfully.

Static Holographic BMP Image

Input Coupling Testing

1um Feature Input Grating	0.5um Feature Input Grating

Grating Image EO Device Fabrication

BYU	TIPD	MIT

s1805 Hiedelberg Debug 21/1/2015

Grating Image EO Device

Before	After

1-2um Grating Test 1 Nov-03-2015

Heidelberg Debug Oct-28-2015

Before	After

Y_Device_Code

There is now fully parameterized code to create Y Devices in the matlab file in the groups folder. Look under Scott's DXF also under the same folder is a cleaned and stand alone version of the transducer code called DXF_transducer. The images are combined from two files to show alignment.

Build Tri Color Optics

Test VPL EO Device

Static Hologram

Result: Uneven development, odd surface variation, and disjoint components. As of yet no detectable hologram

Before

After

Assist in Create Al Waveguide Device.

Result: Fully Parameterized Transducer Code. It creates two files as displayed below: