Intensity Noise Properties of Mid-Infrared Injection Locked Quantum Cascade Lasers: I. Modeling

Experimental investigation of intensity noise in injection locked mid-infrared quantum cascade lasers

“…In this paper, we present detailed experimental results on optical injection locking (OIL), and compare them with the previous theoretical predictions of 16 . Apart from the experimental results, a new modeling approach based on travelling wave equations was used here instead of the well-known rate equation model in 16 with respect to the classical rate equation model, and provides the possibility of studying injection locking into secondary longitudinal modes of the laser cavity and is more realistic as it takes into account the gain profile of the laser cavity as a function of the wavenumber.…”

“…A rate equation (RE) model based on the assumption of the laser homogeneity in the spatial coordinate (direction of propagation z) has been used in 16 to theoretically investigate the intensity noise properties of a DFB quantum cascade laser. Here, instead of the RE model, a travelling-wave (TW) model is employed.…”

“…The term E sp (z,t) is the spontaneous emission noise per unit length generated in each subsection of the active region and added to the propagating field. Its expression is derived using the Langevin formulation of 16 and includes the spontaneous emission factor β (e.g. the coupling of the spontaneous emission to the lasing mode.…”

“…Many excellent contributions regarding the phase noise 8 , intensity modulation properties of quantum cascade lasers 9, 10 and their behavior under external light injection have appeared in the literature 11 -15 . Recently we investigated numerically the noise properties of the QCLs under optical injection 16 . Our analysis showed that the optical injection may have beneficial effect on the noise behavior of QCL devices, and the noise reduction becomes more significant as injection strength increases and the slave laser is operated close to threshold.…”

“…Apart from the experimental results, a new modeling approach based on travelling wave equations was used here instead of the well-known rate equation model in 16 with respect to the classical rate equation model, and provides the possibility of studying injection locking into secondary longitudinal modes of the laser cavity and is more realistic as it takes into account the gain profile of the laser cavity as a function of the wavenumber. Theoretical and experimental results are in close agreement and confirm the potential of external light injection towards the realization and implementation of low-noise laser systems in the mid-infrared wavelength region.…”