Tailoring the Optical Parameters of Optical Fiber Interferometer With Dedicated Boron‐Doped Nanocrystalline Diamond Thin Film

Abstract

An optical fiber interferometer using nanocrystalline boron‐doped diamond film is investigated. The diamond films are deposited on glass plates using a Microwave Plasma‐Enhanced Chemical Vapor Deposition (µPE CVD) system. The growth time is 3 h, with boron doping level of 10 000 ppm producing films (B‐NCD‐10) of thickness ≈200 nm. The presence of boron atoms in the diamond film is evident in Raman spectrum as peaks at 1212 and 1306 cm−1. The scanning electron microscopy (SEM) images show homogenous and continuous surface morphology, thus enabling the use of the diamond film as a reflective layer in fiber optic devices. The optical fiber interferometric sensor in Fabry‐Pérot configuration with a diamond reflective layer as a mirror was designed and built. Measurements are performed using two superluminescent diodes with central wavelengths of 1290 and 1550 nm. The detection of the measured signal is achieved using an optical spectrum analyzer. All devices are connected with commercially available, single‐mode telecommunications fibers and coupler. Using B‐NCD‐10 films in fiber optic interferometer a very high value of the measured signal contrast is obtained, equal to 0.99. The use of B‐NCD‐10 film as a reflective surface allows the Fabry‐Pérot cavity length to be reduced while achieving very good signal visibility. Consequently, the volume of the sample in the cavity can be reduced, compared with that of the traditional mirrors.

Doped Nanocrystalline Diamond Films as Reflective Layers for Fiber-Optic Sensors of Refractive Index of Liquids

“…The diamond films used in this experiment were previously applied in fiber-optic sensors for determining their potential in measurements of biological samples and for distance measurements [14,22], hence, their detailed characterizations can be found there. The investigation has shown that the thickness of the doped NCD films is around 300 nm, and the root mean square roughness is equal to 22 nm and 49 nm for BD-NCD-Si and ND-NCD-Si, respectively [22].…”

“…The use of dopants in the working gas mixture has an impact on the resulting film, including the optical properties. Hence it is possible to tune the process to achieve a suitable structure for the reflective layer in the interferometer [14,15,16].…”

Nitrogen-Doped Diamond Film for Optical Investigation of Hemoglobin Concentration

“…A set of micromechanical elements for positioning the optical fiber was used in the measurement system ( Figure 1 ). The measurement system was described in detail elsewhere [ 24 ].…”

Low-coherence photonic method of electrochemical processes monitoring

“…Our previous research on fiber-optic sensors presented a measurement module employing boron-doped diamond (BDD) film as a mirror 27 , 28 . The results demonstrate that optical spectra are modulated by changes in the refractive index of the investigated liquid inside the cavity bounded by the BDD film, and by the change in the cavity length comprised of the investigated liquid.…”