Intensity noise properties of quantum cascade lasers

We present investigations of the relative intensity noise (RIN) of a quantum cascade laser (QC) laser in continuous wave Operation. We analyze the intensity noise properties in terms of the relative intensity noise (RIN). In contrast to conventional interband semiconductor diode lasers we obtain a different scaling behavior of RIN with increasing optical output power for QC lasers. From a semiclassical noise model we find that this result is due to the cascaded active regions each incorporating three laser levels, and is therefore a particular feature of QC lasers

Measurements of the alpha factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique"

We demonstrate measurements of the factor of a distributed-feedback quantum cascade laser (QCL) by using a newly modified self-mixing interferometric technique exploring the laser itself as the detector. We find a strong dependence of the factor on the injection current, ranging from −0.44 at 120 mA to 2.29 at 180 mA, which can be attributed to the inherent physics of QCLs

Measurements of the alpha factor of a distributed-feedback quantum cascade laser by an optical feedback self-mixing technique

We demonstrate measurements of the factor of a distributed-feedback quantum cascade laser (QCL) by using a newly modified self-mixing interferometric technique exploring the laser itself as the detector. We find a strong dependence of the factor on the injection current, ranging from −0.44 at 120 mA to 2.29 at 180 mA, which can be attributed to the inherent physics of QCLs

Quantum Cascade lasers for the Mid-Infrared Spectral Range: Devices and Applications

Quantum cascade lasers emitting at lambda about 5 µm based on different active region designs are investigated. Using lattice-matched GaInAs/ AlInAs on InP substrates the maximum peak optical power as well as the maximum pulsed-mode operating temperature is enhanced by incorporating AlAs blocking barriers together with strain-compensating InAs layers into the active regions. Further improvement is achieved by employing strain-compensated GaInAs/ AlInAs quantum wells for which maximum pulsed-mode operating temperatures in excess of 350 K are observed. High-reflectivity coated devices mounted substrate-side down show a maximum continuous-wave operating temperature of 194 K. Also the normalized relative intensity noise is investigated. Finally, a comparison trace-gas sensing experiment employing one of the present quantum cascade lasers and a lead-chalcogenide laser is presented. Detecting the P (25) absorption line of CO, higher stability is obtained using a quantum cascade laser