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In this work, a straightforward and highly sensitive design of a CO2 gas sensor is numerically investigated using the finite element method. The sensor is based on a plasmonic metal-insulator-metal (MIM) waveguide side coupled to a square ring cavity filled with polyhexamethylene biguanide (PHMB) functional material. The refractive index of the functional material changes when exposed to the CO2 and that change is linearly proportional to the concentration of the gas. The sensors based on surface plasmon polariton (SPP) waves are highly sensitive due to the strong interaction of the electromagnetic wave with the matter. By utilizing PHMB polymer in the MIM waveguide plasmonic sensor provides a platform that offers the highest sensitivity of 135.95 pm/ppm which cannot be obtained via optical sensors based on silicon photonics. The sensitivity reported in this work is ∼7 times higher than reported in the previous works. Therefore, we believe that the results presented in this paper are exceedingly beneficial for the realization of the sensors for the detection of toxic gases by employing different functional materials.

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A multipurpose plasmonic sensor design based on a metal-insulator-metal (MIM) waveguide is numerically investigated in this paper. The proposed design can be instantaneously employed for biosensing and temperature sensing applications. The sensor consists of two simple resonant cavities having a square and circular shape, with the side coupled to an MIM bus waveguide. For biosensing operation, the analytes can be injected into the square cavity while a thermo-optic polymer is deposited in the circular cavity, which provides a shift in resonance wavelength according to the variation in ambient temperature. Both sensing processes work independently. Each cavity provides a resonance dip at a distinct position in the transmission spectrum of the sensor, which does not obscure the analysis process. Such a simple configuration embedded in the single-chip can potentially provide a sensitivity of 700 nm/RIU and −0.35 nm/°C for biosensing and temperature sensing, respectively. Furthermore, the figure of merit (FOM) for the biosensing module and temperature sensing module is around 21.9 and 0.008, respectively. FOM is the ratio between the sensitivity of the device and width of the resonance dip. We suppose that the suggested sensor design can be valuable in twofold ways: (i) in the scenarios where the testing of the biological analytes should be conducted in a controlled temperature environment and (ii) for reducing the influence on ambient temperature fluctuations on refractometric measurements in real-time mode.

We demonstrate one of the first monolithically integrated multiwavelength lasers fabricated in an industrial fab according to generic foundry model. Our devices were realized on an indium phosphide (InP)-based platform and use an arrayed waveguide grating (AWG) as intra-cavity filter. The designed sources generate wavelengths around 1.55 μm with optical output power up to 5 dBm and side-mode suppression ratio (SMSR) better than 40 dB.

The emission properties of the 3 P0 state of praseodymium ions in lithium niobate crystal have been studied. Blue-green emission at 510 nm corresponding to the 3 P0 3 H4 transition in Pr3+ :LiNbO3 crystals was generated after direct and up-conversion excitation with orange and infrared radiation around 920 nm. The up-conversion mechanisms were shown to be energy transfer and excited state absorption for orange and infrared excitation, respectively. The processes responsible for non-radiative relaxation of the 3 P0 state were also determined.

The excited state absorption (ESA) spectra of ZBLAN glass activated by trivalent holmium ions have been measured in a wide spectral range (550–1750 nm) and simulated using such theoretical tools as the Judd–Ofelt formalism and McCumber theory of stimulated emission. We also propose a systematic approach for prediction of various types of up-conversion mechanisms in a given type of material. Experimental results on ESA up-conversion processes in ZBLAN:Ho3+ under red and infrared laser excitation, which confirm theoretical analysis, are presented. The optical linewidths were studied using high resolution laser spectroscopy at low temperatures and the existence of different crystallographic sites for Ho3+ ions was revealed.