Poplar plywood is the lightest and cheapest plywood: perfect for models, prototypes and large cuts. In exchange it is far less consistent than birch.
Settings: what really matters
Poplar is soft: it cuts faster and with less power than birch at the same thickness. Reuse a birch setting as-is and the edge will be over-burnt.
The flip side of its lightness is glue pockets and internal voids. A pass that goes right through on one board can leave two centimetres attached on the next: always keep a power margin, or add a very fast extra pass.
When engraving, contrast is lighter and softer than on birch, with visible grain. Attractive on a model, less crisp for fine text.
Risks and finishing
Soft and light, it ignites more easily than birch, especially on a slow cut or a second pass along the same line. Keep extraction on and watch it constantly.
Poplar soaks up finish: two coats of primer are needed before painting. For a piece left raw, a light 180-grit sanding then wax evens out the look.
Every figure on LaserSettings comes with the machine, the laser source, the material and the thickness it was tested on. A setting published for a 10 W diode says nothing about a 40 W CO2, and a setting for 3 mm says nothing about 6 mm: check those four things before you copy any number.
Settings are confirmed or disputed by the members who reproduce them, so reliability comes from cross-checking rather than popularity. Photos of the result — cut edges, engraving shades, scorching — tell you more than a single number found on a forum.
Whatever the material, treat a published setting as a starting point: run a small power/speed test grid on an offcut, clean the lens, redo the focus, work with fume extraction and air assist, wear glasses rated for your wavelength and never leave the machine unattended.