Alireza Khorsandi, Maryam Maleki,
Volume 7, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol 7, No 1, Winter-Spring 2013)
Abstract
In this research, tunability of a commercial diode laser has extended to about more than ± 11 nm using a V-shaped external-cavity fabricated around the laser. Although under normal condition it can be tuned up to about ± 4 nm just by changing its temperature and injection current. Such modified diode laser has then used in a difference-frequency generation (DFG) experimental setup as pump source in order to continuous tuning of the generated DFG spectrum up to about ± 100 nm from 4.76 m to 4.85 m in the mid-infrared region. An AgGaS2 crystal is used as nonlinear medium.
Dr. Morteza Janfaza, Dr. Hamed Moradi, Mr. Morteza Maleki,
Volume 15, Issue 2 (Summer-Fall 2021)
Abstract
Graphene and molybdenum disulfide (MoS2), as two of the most attractive two-dimensional (2D) materials, are used to improve the temperature and strain sensing responses of the few-mode fibers (FMFs). The temperature and strain effects are detected based on distributed optical fiber sensors equations, where the Brillouin scattering (BS) is investigated for the FMF tapered region. For this purpose, the 2D materials were assumed as cover layers on the tapered FMF to enhance its sensitivity. Graphene and MoS2 are used as the cover layer on the FMF cladding at a distance of 10 μm from the core, and the impact of the number of material layers is investigated. By increasing the graphene layers, the temperature and strain sensitivities increase (3% and 16%, respectively) due to the rise of the inter-modal interference of the FMF. Moreover, the increasing of the MoS2 layer number improves the temperature sensitivity by 28% but shows a lower impact on strain sensitivity (about 13%). The advantage of MoS2 with respect to graphene originates from the imaginary part of the refractive index of graphene (assumed with chemical potential of 0.4 eV at the working wavelength of 1550 nm), which leads to a lower effective index of the tapered region, hence lower sensitivities. This sensitivity enhancement can improve the performance of the BS-based sensors for local detection of the parameters under-investigation in multi-parameter sensors.
