Edwin Jan Klein - Universiteit Twente

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Fabrication
Figure 5.3. Realized MR based reflector (left) and a single resonator (right). The inset shows
a close-up of the coupling region of the resonator. The gap between the waveguides is 800
nm.
5.2.2 Mask layout
Figure 5.4 shows the layout of a typical mask used to define laterally coupled
resonators. This layout of this mask, like the masks used to define the vertically
coupled resonators, follows a set of strict layout rules. The mask layout consists of
several columns of which the width is an integer multiple of 5 mm. In each column
there are 6 device groups and in each group are up to 20 individual microringresonators,
depending on the size of these resonators.
Alignment bar
Minor dice line
Major dice line
Gap width:
Figure 5.4. Mask layout used to define laterally coupled resonators.
Within the groups the devices are created in pairs (two of each for redundancy) and
only one parameter is varied. The two racetrack resonators in the right image of
Figure 5.3, for instance, are identical but for the length of their coupling regions: the
upper resonator has a coupler length of 180 µm whereas the lower has a coupler
length of 200 µm.
The groups within a single column are used to implement variation in the gap width
but are otherwise identical. For laterally coupled silicon nitride racetrack resonators
with a waveguide thickness of 140 nm a range in gap widths from 0.8 to 1.3 µm is
used as shown in the Figure 5.4. Best performance of the resonators is usually in the
0.8
0.9
1.0
1.1
1.2
1.3