Terahertz bench: a CO2 laser and a tunable QCL overlapped on a metasurface chip

CO2QCLTHz
Drag a part to move · click a laser’s green button to switch
How it makes terahertz

Subtract two frequencies

The chip mixes both pumps. What comes out is the gap between them, so tuning the QCL tunes the output.

Frequency axis: CO2 at 28.3 THz, QCL tunable from 30 to 43 THz, output at the difference, 2 to 15 THz 0 10 20 30 40 THz Terahertz output, 2 to 15 THzTHz out CO2 pump, 28.3 THzCO2 QCL pump, tunableQCL Δf
Top view of the bench with both beam pathsCO2 laserCO2 laser driverTunable QCLRotation stageQCL output opticsMetasurface chipTerahertz portLow black plateRound headHeat-sunk moduleApertureRed sensor 1Red sensor 2Butterfly packageMicrometer stageRaised plateFocusing opticsBlack kinematic mountChip stageFold mirror 1Fold mirror 2Fold mirror 3Pump-axis mirrorCage cubeQCL mirror 1QCL mirror 2QCL mirror 3Beam combinerCO2 laserQCLchipenclosurelaser bayTHz outM1M2M3M4CM5M6M7D
Top view

Where each beam goes

Positions come from the photo. The pump axis is one straight line: mirror, focusing cage, chip, port.

CO2, 10.6 µm
Tunable QCL, mid-IR
Terahertz output
Gold mirror
Other optic