H.A.G.M. van Wolferen

Ultra-narrow-linewidth, single-frequency distributed feedback waveguide laser in Al2O3:Er3+ on silicon.

We report the realization and performance of a distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a standard thermally oxidized silicon substrate. The diode-pumped continuous-wave laser demonstrated a threshold of 2.2 mW absorbed pump power and a maximum output power of more than 3 mW with a slope efficiency of 41.3% versus absorbed pump power. Single-longitudinal-mode and single-polarization operation was achieved with an emission linewidth of 1.70+/-0.58 kHz (corresponding to a Q factor of 1.14 x 10(11)), which was centered at a wavelength of 1545.2 nm.

Photonic generation of stable microwave signals from a dual-wavelength

We report the fabrication and characterization of a dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminum oxide. Operation of the device is based on the optical resonances that are induced by two local phase shifts in the distributed-feedback structure. A stable microwave signal at ~15 GHz with a -3 dB width of 9 kHz was subsequently created via the heterodyne photodetection of the two laser wavelengths. The long-term frequency stability of the microwave signal produced by the free-running laser is better than ±2.5 MHz, while the power of the microwave signal is stable within ±0.35 dB.

Al_2O_3:Yb^{3+}

We report the fabrication and performance of a highly efficient, monolithic distributed-Bragg-reflector channel waveguide laser in ytterbium-doped aluminum oxide. The 1 cm long device was fabricated on a standard thermally oxidized silicon substrate and was optically pumped with a 976 nm laser diode. Single-longitudinal-mode and single-polarization operation was achieved at a wavelength of 1021.2 nm. Continuous-wave output powers of up to 47 mW and a launched pump power threshold of 10 mW resulted in a slope efficiency of 67%.

distributed-feedback waveguide laser

We present results related to the fabrication of a novel and potentially highly sensitive mechano-optical sensor for hydrogen gas, based on microcantilevers, provided with a selectively gas-absorbing palladium layer, suspended above a Si3N4 grated waveguide (GWG). Integrated microcantilever-GWG devices have been fabricated successfully using microelectromechanical systems (MEMS) techniques. Several technical problems encountered during the preparation of such integrated devices (i.e., grating production, surface roughness, facet quality) will be discussed, and solutions to address these issues will be given as well. We also present preliminary experimental results, showing the sensing of cantilever nano-displacements, and so the feasibility of proposed read-out principle.

Highly efficient, low-threshold monolithic distributed-Bragg-reflector channel waveguide laser in Al

We report on the production of large-area 2D photonic crystals from high-index material with laser interference lithography (LIL). A new image reversal photoresist is used in combination with an anti-reflection coating to suppress undesired reflections. The photonic crystals possess a cubic pattern of air holes in a 500 nm silicon layer and cover an area of 1 cm2.

_{2}

The fabrication and gas flow characterization of an ultra-thin inorganic nanosieve structured by interference lithography and a bond-micromachining approach are reported. The nanosieve has been observed to exhibit transition gas flow behaviour around atmospheric pressure and ambient temperature. The small lip thickness (45 nm) of the nanopores with respect to their diameter (120 nm) helps in understanding pure transition flow by minimizing interactions between the molecule and inner pore wall. Due to the absence of these collisions, the transition flux is the superimposition of viscous and molecular fluxes without the need for higher-order slip correction. The nanosieve shows a flow selectivity of 3.1 between helium and argon at 20 mbar.

O

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.

_{3}

The favourable optical properties of aluminium oxide (Al<inf>2</inf>O<inf>3</inf>) waveguides make it an excellent laser gain medium for monolithic laser devices. Recently, low-loss erbium-doped aluminium oxide (Al<inf>2</inf>O<inf>3</inf>:Er³⁺) channel waveguide amplifiers have demonstrated internal net gain over a wavelength range of 80 nm (1500–1580 nm), with a peak gain of 2.0 dB/cm at 1533 nm [1]. Consequently, the first integrated Al<inf>2</inf>O<inf>3</inf>:Er³⁺ laser was demonstrated in a ring resonator geometry soon thereafter [2]. Due to the wide gain bandwidth, the laser was shown to operate on several wavelengths in the range 1530–1557 nm.

:Yb

We demonstrate the versatility of a silicon nitride grated waveguide optical cavity as compact integrated optical sensors for (bulk) concentration detection, label-free protein sensing, and — with an integrated cantilever suspended above it — gas sensing.

^{3+}

transparent in the desired wavelength ranges around 1300 and 1550 nm. It must be easily tunable with respect to the refractive index and not dissolving the substrate microstructures. Two complete new, UV-curable material systems have been developed io work with PMMA as substrate and cover material. The first material system is EGDMA or EGDMAD14 (ethylenglycoledimethacrylate or fully deuterated version) tuned by TFPMA (tetrafluorinepropylmethacrylate), whereby TFPMA lowers the refractive index of EGDMA. The deuterated version shows low losses at 1300 nm (<0.1 dB/cm), however, unacceptable losses at 1550 nm (-1.5 dB/cm). The other material system is PFPMA/TeCEA (pentalfluorophenylmethacrylate / tetrafl~orinepropylmethacrylate)?~ PFPMA lowers the refractive index of TeCEA. This polymer system shows low transmission loss at 1300 nm (-0.1 dB/cm) as well as at 1550 nm (-0.3 dB/cm) (Fig. 3). The best achieved intrinsic waveguide losses for straight waveguides with PMMA as substrate material are 0.2 dB/ cm at 1300 nm (-0.1 dB/cm bulk absorption, -0.1 dB/cm scattering loss) and 0.7 dB/cm at 1550 nm (-0.3 dB/cm bulk absorption, -0.3 dB/cm cladding absorption, -0.1 dB/cm scattering loss). The spectral behaviour of the insertion loss of a straight PFPMA/TeCEA-waveguide is shown in Fig. 3 in comparison to the bulk substrate material PMMA and the bulk waveguide core material PFPMA/ TeCEA. Due to weak waveguiding the optical field penetrates relatively deep into the cladding and, therefore, the influence of the PMMA substrate on the absorption spectrum becomes obvious, in particular at 1550 nm. The waveguides are designed to yield high overlap with standard telecommunication fibres. Coupling efficiencies better than 98% are achieved.