Simulation and analysis of plasmonic sensor in NIR with fluoride glass and graphene layer

•CaF2 substrate based biosensor having graphene as interacting layer in NIR region.•Effect of number of graphene layers is also taken into consideration.•Nearly 287% field enhancement and about 3.5–4 times higher FOM values are achievable in comparison to conventional SPR sensor.•Sensor’s performance is better than previously reported works.•Favorable optical properties of CaF2 and graphene may find applications in bio- and gaseous sensing. A calcium fluoride (CaF2) prism based plasmonic biosensor with graphene layer is proposed in near infrared region (NIR) of operation. The stacking of multilayer graphene is considered with dielectric interlayer sandwiched between two graphene layers. Excellent optical properties of CaF2 glass and enhanced field at the graphene-analyte interface are intended to be exploited for proposed sensor structure in NIR spectral region. Performance parameters in terms of field enhancement at interface and figure of merit (FOM) are analyzed and compared with those of conventional SPR based sensor. It is demonstrated that the same sensor probe can also be used for gas sensing with nearly 3.5–4 times enhancement in FOM, compared with conventional sensor. The results show that CaF2 based SPR sensor provides much better sensitivity than that based on other glasses.