lithium niobate / 05 Making / 5.11
5.11 Dicing, facets, packaging, fiber attach
L1 Phenomenon
A finished wafer is cut into chips. Light enters through a polished or etched facet, and a fiber is aligned and fixed in front of a taper that enlarges the sub-micrometre mode to fiber size.
Process viewer stepsopen in the Process viewer
| # | STEP | ROUTE |
|---|---|---|
| 21 | Dice and polish facets | ridge |
| 19 | Chip separation by deep dry etch and backside grinding | strip |
| 22 | Align and attach fibers to edge couplers | ridge |
| 23 | RF probe or wire bond to the electrode pads | ridge |
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21/23Dice and polish facets (ridge route)
L2 Model and data
| Step | Value | Source; status |
|---|---|---|
| Chip separation, wafer-scale | deep dry etch, then backside grinding: clean, vertical facets without a Si pedestal | P |
| Chip release (LiTaO3 analog) | SiO2 boundary etch (F chemistry), Bosch Si etch, backside grind | P |
| Inverse taper to lensed fiber, strip | 250 nm tip; about 3 dB/facet | P |
| Bilayer inverse taper to lensed fiber, rib | < 1.7 dB/facet | P(abs) |
| Typical before couplers | > 10 dB/facet | P(abs) |
| Grating couplers | about 6 dB per facet | P |
| Photonic wire bonding to TFLN | amplifier-TFLN hybrid laser | P(abs) |
L3 Details and open points
- Packaged TFLN modulator outlines, adhesives, and hermeticity were not found in a primary source.
- Coupling losses are not comparable across tapers without stating fiber mode field diameter and polarization.