Lucia Sansone

Photoluminescence enhancement of graphene oxide emission by infiltration in an aperiodic porous silicon multilayer

Graphene oxide (GO) is a photoluminescent material whose application in integrated optoelectronics has been strongly limited due to poor emission intensity and handling procedures not compatible with standard microelectronic ones. In this work, a hybrid GO-porous silicon (GO-PSi) structure is realized in order to investigate the emission properties of GO infiltrated into an aperiodic porous multilayered matrix. A photoluminescence enhancement by a factor 32, compared to the same amount of GO deposited on a flat silicon surface, is demonstrated. Photoluminescence measurements also show wavelength modulation of the emitted signal.

Self-Assembled Colloidal Photonic Crystal on the Fiber Optic Tip as a Sensing Probe

This paper presents an effective and efficient method to fabricate novel fiber optic sensing probes. The new, simple, and low cost approach is based on a 3-D photonic crystal dielectric structure directly deposited on the tip of a multimode optical fiber through the self-assembly of colloidal crystals (CCs) via a vertical deposition technique. Here, the CC is made of polystyrene nanospheres with 200 nm diameter, and the optical fiber is a UV–vis fiber with a core diameter of 200 μm. The obtained fiber probes exhibit a resonant peak at 480 nm and an amplitude enhancement of 3.7 with respect to the bare fiber; these results are highly repeatable. A numerical tool based on a finite element method analysis has been developed to study and analyze the 3-D subwavelength structures. Numerical results are in good agreement with the observed experimental spectra. Moreover, refractive index measurements have been carried out, revealing a sensitivity of up to 445 nm/RIU in the 1.33–1.36 values range. The achieved performances, which have been obtained by using very small active areas and an easy and reliable fabrication procedure, demonstrate the future perspectives of these fiber-optic probes for chemical and biological sensing applications.

Photoluminescence of graphene oxide integrated with silicon substrates

In this work we have investigated the photoluminescence signal emitted by graphene oxide (GO) nanosheets infiltrated in silanized porous silicon (PSi) matrix. We have demonstrated that a strong enhancement of the PL emitted from GO by a factor of almost 2.5 with respect to GO on crystalline silicon can be experimentally measured. This enhancement has been attributed to the high PSi specific area. In addition, we have observed a weak wavelength modulation of GO photoluminescence emission, this characteristic is very attractive and opens new perspectives for GO exploitation in innovative optoelectronic devices and high sensible fluorescent sensors.

Graphene oxide-based nanohybrid for label-free optical sensing

In this study we report on optical sensor, based on the sorption properties of graphene film reduced on the tip of a standard single mode optical fiber. Reflectance measurements will be carried out to investigate the changes in the graphene refractive index due to sorption when the sensor probe was exposed to gas molecules.