van den Gn Gerlas Hoven

Net optical gain at 1.53 mu m in Er-doped Al2O3 waveguides on silicon

A 4 cm long Er‐doped Al2O3 spiral waveguide amplifier was fabricated on a Si substrate, and integrated with wavelength division multiplexers within a total area of 15 mm2. When pumped with 9 mW 1.48 μm light from a laser diode, the amplifier shows 2.3 dB net optical gain at 1.53 μm. The gain threshold was 3 mW. The amplifier was doped with Er by ion implantation to a concentration of 2.7×1020 cm−3. The data agree well with calculations based on a model which includes the effects of cooperative upconversion and excited state absorption. For an optimized amplifier, net optical gain of 20 dB is predicted.

Photoluminescence characterization of Er-implanted Al2O3 films

Al2O3 films on oxidized Si substrates were implanted with 800 keV Er ions to peak concentrations ranging from 0.01 to 1 at. %. The samples show relatively broad photoluminescence spectra centered at λ=1.533 μm, corresponding to intra‐4f transitions in Er3+. At an Er peak concentration of 0.23 at. %, post‐implantation thermal annealing up to 950 °C increases the photoluminescence intensity by a factor 40. This is a result of defect annealing, which increases the luminescence lifetime from 1 to 7 ms, as well as an increase in the Er3+ active fraction. High Er concentrations are achieved with only moderate concentration quenching effects.

Upconversion in Er-implanted Al2O3 waveguides

When pumped with a 1.48 μm laser diode, Er‐implanted Al2O3 ridge waveguides emit a broad spectrum consisting of several distinct peaks having wavelengths ranging from the midinfrared (1.53 μm) to the visible (520 nm). In order to explain these observations, three different upconversion mechanisms are considered: cooperative upconversion, excited state absorption, and pair‐induced quenching. It is found that for samples with a high Er concentration (1.4 at. %), cooperative upconversion completely dominates the deexcitation of the Er3+ ions. For a much lower concentration (0.12 at. %), the influence of cooperative upconversion is strongly reduced, and another upconversion effect becomes apparent: excited state absorption. These conclusions are based on measurements of the luminescence emission versus pump intensity, and also on measured luminescence decay curves. The upconversion coefficient is found to be (4±1)×10−18 cm3/s; the excited state absorption cross section is (0.9±0.3)×10−21 cm2. It is shown that...

Absorption and emission cross sections of Er(3+) in Al(2)O(3) waveguides.

Al(2)O(3) slab waveguide films were doped with erbium using ion implantation to a peak concentration of 1.5 at. %. Prism coupling measurements show absorption caused by (4)I (15/2) ?(4)I (13/2) intra-4f transitions in Er(3+) with a maximum at 1.530 mum of 8 dB/cm. The Er(3+) absorption cross section is determined as a function of wavelength. We used the McCumber theory to derive the emission cross section spectrum from the absorption results, which we then compared with the Er(3+) photoluminescence spectrum. The peak absorption and emission cross sections are found to be 6 x 10(-21) cm(-2). The results are used to predict the optical gain performance of an Er-doped Al(2)O(3) optical amplifier that operates around 1.5 mum.

Direct imaging of optical interference in erbium-doped Al2O3 waveguides

Interference of 1.48-microm light in multimode interference waveguides is made visible by imaging green and infrared upconversion luminescence from Er(3+) ions dispersed in the waveguide. A two-dimensional mode density image can be derived from the data and agrees well with mode calculations for this structure. This new technique provides an interesting tool for the study of optical mode distributions in complicated waveguide structures and photonic band-gap materials.

Application specific photonic integrated circuits for FlexPON: Progress of the EuroPIC project

Passive optical network (PON) architectures and systems of today are not efficient in utilizing capacity and spectrum. The daily usage patterns and the ever-growing bandwidth demand in access require a transport technology that is dynamically operated and that is based on wavelength division multiplexing (WDM). FlexPON is designed to meet those requirements: it combines a reconfigurable WDM layer with “on-demand” time division multiple access (TDMA) and wavelength-agnostic optical networking units (ONUs). As such, it enables flexible capacity planning between such stacked TDMA/WDM PONs on single fiber architectures. In this work, progress is reported on multi-wavelength transmitter (TX) and receiver (RX) sub-systems that are used at the optical line termination (OLT) at the central office. The Indium Phosphide (InP)-based application specific photonic integrated circuits (ASPICs) are realized following the generic integration method proposed by the European EuroPIC project. Static and dynamic measurements are shown. The TX8-channel ASPIC is operated at 12.5 Gbps in a back-to-back (BTB) and 20 km standard single-mode fiber (SSMF) configuration. Error-free BTB operation at 10 Gbps is obtained employing a 231 -1 pseudo random bit sequence (PRBS).