What is the difference between the QCL OEM and the QCL OEM(+)?


The QCL OEM and QCL LAB were originally released as low noise current sinks to power Quantum Cascade Lasers with significantly reduced electronic noise. This allows spectroscopy systems to operate with narrower linewidth, more stable center wavelength, and repeatable scans.

The QCL OEM(+) was released in 2015 to serve the needs of QCLs that require a current source rather than a current sink. This allows the other terminal of the QCL to be grounded.

fq1124 Diagram

The output stage in the QCL OEM(+) uses a P-channel MOSFET instead of an N-channel. This decreases the bandwidth of the current source.

Additionally, in the QCL OEM(+), the Analog Input signal must be inverted to work with the control electronics. The addition of the inverter increases current noise slightly. To achieve the same current noise as the QCL OEM, the inverter can be removed from the system. The Analog Input signal range is 0 to +5 V with the inverter in and -5 V to 0 V with the inverter out.