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Optical coherence tomography (OCT) is a widely used optical imaging technology [1]. Current OCT systems contain a variety of fiber and free-space optical components, which add to the instrument size and cost. By utilizing a suitable mass-fabrication technology and a monolithic design, integrated optics can provide miniaturized OCT systems that offer dramatic cost and size reduction as well as more...
Integrated spectrometers are usually of the Rowland mounting type [1]. For applications in which a continuous output spectrum needs to be imaged directly onto a linear detector array, the curved image plane of the Rowland mounting would result in additional losses and aberrations at the outer detector channels. Therefore, a flat-focal-field spectrometer would be highly desirable for such applications...
There is a strong need for arrayed waveguide gratings (AWGs) with low-loss and box-like pass band over a broad spectral range. Most of the approaches proposed to implement flat-top AWGs suffer from increased insertion loss and large device size [1,2]. A Mach-Zehnder-interferometer (MZI) synchronized AWG [3] can provide a flattened pass band without introducing intrinsic loss. However, due the wavelength...
In many applications, such as on-chip optical coherence tomography (OCT) or Raman spectroscopy, it is necessary to produce a collimated light beam from an optical waveguide, and collimation in one dimension has been demonstrated, see e.g. [1,2,3]. However, in order to increase the efficiency of chip-sample coupling, collimation in two dimensions is required [4,5]. In this work, we demonstrate an on-chip...
Photonic generation of microwave carriers by using a dual-frequency distributed feedback waveguide laser in ytterbium-doped aluminum oxide is demonstrated. A highperformance optical frequency locked loop is implemented to stabilize the microwave carrier. This approach results in a microwave frequency at ∼14 GHz with a phase noise of −75 dBc/Hz at 1 MHz offset from the center frequency. The frequency...
We demonstrate an integrated optical particle sensor based on a dual-wavelength distributed-feedback waveguide laser. Micro-particles were detected down to a size of 1 μm, which represents the typical size of many fungal and bacterial pathogens.
We demonstrate the optical generation of stable microwave signals from a dual-wavelength distributed-feedback waveguide laser in ytterbium-doped alumina. The microwave beat signal was produced at ∼15 GHz with a frequency stability of ±2.5 MHz.
The effect of discrete output channels and polarization dependency of an arrayed-waveguide-grating (AWG) spectrometer on spectral-domain optical low-coherence reflectometry performance is investigated.
The influence of migration-accelerated energy-transfer upconversion and fast luminescence quenching on the performance of Al2O3:Er3+ waveguide amplifiers is investigated. Results indicate that the latter has the stronger impact on the amplifier small-signal gain.
We show that the expression for the relaxation frequency in rare-earth-ion doped solidstate lasers needs to be modified when dealing with materials that suffer from lifetime quenching.
We measured Raman spectra of extracted human teeth using an integrated arrayed-waveguide-grating spectrometer fabricated in silicon-oxynitride technology. The results represent a step towards the realization of compact, hand-held, integrated spectrometers for the detection of early dental caries.
We report a number of recently demonstrated integrated Al2O3:Er3+ devices and present spectroscopic investigations revealing the presence of a fast quenching mechanism — undetected in typical luminescence decay measurements — which limits the Al2O3:Er3+ amplifier performance.
Monolithic distributed Bragg reflector (DBR) cavities with quality factors exceeding one million have been realized in aluminum oxide channel waveguides. This technology enabled the successful demonstration of the first DBR laser in this waveguide platform.
KY1−x−yGdxLuy(WO4)2 channel waveguide lasers demonstrated 650 mW output power and 72% slope efficiency at 981 nm for Yb3+ doping. For Tm3+ doping, 149 mW output power and 31.5% slope efficiency at 1846 nm were obtained.
Amplifier performance of Nd3+-doped polymer and Al2O3 channel waveguides at 880 nm is investigated. Tapered amplifiers are embedded between optical backplane waveguides, and a maximum 0.21 dB net gain is demonstrated.
We present experimental results of a spectral-domain optical coherence tomography system that includes an integrated spectrometer. A depth range of 1 mm and axial resolution of 19 μm was measured. A layered phantom was imaged.
The fabrication and characterization of rare-earth-ion-doped monolithic distributed feedback channel waveguide lasers in aluminum oxide are presented. Erbium-doped lasers with linewidths of 1.7 kHz and ytterbium-doped lasers with slope efficiencies of 67% are demonstrated.
The design, fabrication, and characterization of surface relief Bragg gratings integrated with aluminum oxide ridge waveguides are reported. After patterning a photoresist layer by laser interference lithography, uniform gratings with a depth of ∼120nm and a period of 507nm were etched into the SiO 2 top cladding. The grating length varied between 1.25mm and 4.75mm. The grating-induced loss...
The variety of integrated optical devices which have recently been demonstrated in the aluminum oxide (Al2O3) waveguide platform is evidence of the favourable optical properties of this material [1–3]. The wafer-scale fabrication process and its compatibility with existing silicon waveguide technology further emphasize the significance of this material [4]. The ability to integrate Bragg grating structures...
Al2O3:Er3+ is an established material for integrated amplifier applications, offering several advantages such as low background losses, a broad emission spectrum, and a relatively high refractive index of 1.65, which enables the fabrication of small optical waveguide structures [1]. Our growth method allows for straightforward deposition on silicon wafers [2] and direct integration with silicon photonic...
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