Shapes and placement · 6 of 6
Arcs and tapers
Two more primitives have start and end anchors:
| Primitive | Parameters | Shape |
|---|---|---|
arc | radius, width, angle[, segments] | a curved waveguide that starts at the origin heading along +x; a positive angle turns left, a negative one right |
taper | length, width1, width2 | a trapezoid from x = 0, width1 wide, to x = length, width2 wide, symmetric about the x axis |
As with paths, both anchors point the way the waveguide runs: start into the shape, end out of it. Pieces therefore chain naturally: place each one's start at the previous one's end, and laylight turns it to follow on. Moving the first piece moves the whole chain.
Exercise
Complete the mode converter. The taper narrow (3 µm → 500 nm) starts at the origin; attach the 90° bend to its end, and after the bend a new taper wide, 10 µm long, that widens from 500 nm back to 3 µm.