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Photonic integrated circuits (PICs) represent a promising technology for the muchneeded medical devices of today. Their primary advantage lies in their ability to integrate multiple functions onto a single chip, thereby reducing the complexity, size, maintenance requirements, and costs. When applied to optical coherence tomography (OCT), the leading tool for state-of-the-art ophthalmic diagnosis, PICs have the potential to increase accessibility, especially in scenarios, where size, weight, or costs are limiting factors. In this paper, we present a PIC-based CMOS-compatible spectrometer for spectral domain OCT with an unprecedented level of integration. To achieve this, we co-integrated a 512-channel arrayed waveguide grating with electronics. We successfully addressed the challenge of establishing a connection from the optical waveguides to the photodiodes monolithically co-integrated on the chip with minimal losses achieving a coupling efciency of 70%. With this fully integrated PIC-based spectrometer interfaced to a spectral domain OCT system, we reached a sensitivity of 92dB at an imaging speed of 55kHz, with a 6dB signal roll-of occurring at 2mm. We successfully applied this innovative technology to obtain 3D in vivo tomograms of zebrafsh larvae and human skin. This ground-breaking fully integrated spectrometer represents a signifcant step towards a miniaturised, cost-efective, and maintenance-free OCT system.
Semiconducting metal oxides are widely used for solar cells, photo-catalysis, bio-active materials and gas sensors. Besides the material properties of the semiconductor being used, the specific surface topology of the sensors determines device performance. This study presents different approaches for increasing the sensing area of semiconducting metal oxide gas sensors. Micro- and nanopatterned laser-induced periodic surface structures (LIPSSs) are generated on silicon, Si/SiO2 and glass substrates. The surface morphologies of the fabricated samples are examined by FE SEM. We selected the nanostructuring and characterization of nanostructured source Ni/Au and Ti/Au films prepared on glass using laser ablation as the most suitable of the investigated approaches. Surface structures produced on glass by backside ablation provide 100 nm features with a high surface area; they are also transparent and have high resistivity. The value of the hydrogen sensitivity in the range concentrations from 100 to 500 ppm was recorded using transmittance measurements to be twice as great for the nanostructured target TiO2/Au as compared to the NiO/Au. It was found that such transparent materials present additional possibilities for producing optical gas sensors.
We present design, technological verification, and optimization of a compact 512-channel silicon nitride-based AWG-spectrometer developed for the realization of an on-chip spectral domain optical coherence tomography system. The spectrometer was designed for TM-polarized light with a central wavelength of 850 nm and having a resolution of 0.1 nm. For the design the AWG-Parameters tool was used. Simulations were performed using Optiwave’s PHASAR photonics tool and the designed structure was fabricated in a standard CMOS foundry process. The simulated and measured optical spectra were evaluated and used to further optimize the AWG structure. The AWG-spectrometer was integrated onto the chip and the OCT measurements proved its suitability for OCT on chip applications.
The paper deals with designing and verifying the technological procedure of quasi-planar fiber array assembly to PCB by mechanical optical interface PRIZM® LightTurn®. Mechanical optical interface allows excellent fiber array coupling to the VCSEL or photodiode array up to 12 elements. By image processing from its two CCD cameras, the spatial positions of the centre of the elements array on the PCB and the centre of the mounted mechanical optical interface on the 6D position stage are detected. After this detection, they are then mutually adjusted to the optimal relative position in 3D space by active adjustment to the maximum optical powers of the two outermost optical fibres of the fiber array. Subsequently, the mechanical optical interface is fixed by UV-A curable adhesive to the PCB through its four hollow feet designed for this. The technological process is designed and optimized for the Fiber Line 300 machine from Ficontec, GmbH.
This article aims to compare different types of optical amplifiers implemented in metropolitan xWDM-PON networks. The first part is an analysis of the issue with the focus on the used optical access network based on xWDM-PON. In the next part the deployment of optical amplifiers (SOA, EDFA and Raman) into the network and their analysis is presented. The following part is dedicated to the simulation of WDM-PON networks in the OptiSystem tool from Optiwave, with applied appropriate optical amplifier for chosen channels. In the last part, the simulated results (based on optical power, BER, Q-factor, eye-diagram and spectral analysis) are evaluated and discussed.
