Optical imaging of multimode interference patterns with a resolution below the diffraction limit

For the first time the optical interference pattern in multimode interference couplers operating at 1485 nm is made visible using an optical microscope. This is done by imaging the green light (519 and 545 nm) which is generated by upconversion at high pumping power levels in waveguides with a high erbium concentration. As the intensity of the green light is roughly proportional to the fourth power of the pump signal intensity it thus becomes possible to image the 1485 nm intensity distribution with a resolution limited by the diffraction limit for 519 and 545 nm ligh

Performance analysis of linear optical amplifiers in dynamic WDM systems

We demonstrate the performance of linear optical amplifiers (LOAs) in a dynamic and reconfigurable wavelength-division-multiplexing (WDM) system. Eight WDM channels, each channel running at 10 Gb/s, are transmitted through two cascaded LOAs. Power transient immune add-drop capability is demonstrated by switching four of the eight channels at rates of 10-100 kHz without affecting the bit-error-rate (BER) or eye pattern. The same WDM system trial using erbium-doped fiber amplifiers instead of LOAs shows identical BER performance for the eight-channel case, but deteriorated eye patterns and bit error penalties for the channel ADD-DROP configuration

Upconversion in Er-implanted Al2O3 waveguides

When pumped with a 1.48 mu m laser diode, Er-implanted Al/sub 2/O/sub 3/ ridge waveguides emit a broad spectrum consisting of several distinct peaks having wavelengths ranging from the midinfrared (1.53 mu m) 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 Er/sup 3+/ 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+or-1)*10/sup -18/ cm/sup 3//s; the excited state absorption cross section is (0.9+or-0.3)*10/sup -21/ cm/sup 2/. It is shown that in spite of these upconversion effects, a high fraction of the Er/sup 3+/ can be excited at low pump powers. For pump powers between 2 and 10 mW, the optimum Er concentration is calculated. The results show that for an Er concentration of 0.5 at.%, more than 2 dB/cm net optical gain is achievable at a pump power less than 10 m

Optical gain in erbium-implanted Al2O3 waveguides

Al/sub 2/O/sub 3/ ridge waveguides implanted with 1.3 at.% Er, pumped with 2.5 mW 1.47 mu m light show 4.5 dB/cm enhancement of a 1.53 mu m signal beam. The maximum gain is limited by cooperative upconversion effects. Calculations for lower Er concentrations show that 1 dB/cm net optical gain is possible at 10 mW pump powe

Erbium ion implantation doping of opto-electronic materials operating at 1.5 mu m

Soda-lime silicate and Al/sub 2/O/sub 3/ waveguide films, LiNbO/sub 3/ single crystal, as well as crystal Si are doped with erbium by ion implantation. All materials show luminescence at 1.5 mu m, characteristic for Er, with lifetimes up to 12 m

1.5 pm room-temperature luminescence from Err-implanted oxygen-doped silicon epitaxial films grown by molecular beam epitaxy

4 pags.; 4 figs.Oxygen-doped Si epitaxial films (OXSEF) grown by molecular beam epitaxy and subsequently implanted with Er show room-temperature luminescence around il = 1.54 ,um. The 45-nm-thick films have an oxygen concentration of 10 at. % and were implanted with 7.8 X lOI4 25 keV Er ions/cm’. The luminescence was optically excited with the 514 nm line of an Ar ion laser and is attributed to intra-4f transitions in Er3+. Thermal annealing at 700-800 “C is necessary to optimize the luminescence after implantation. Pure Si implanted and annealed under the same conditions does not show Er-related luminescence at room temperature. The emission from Er in OXSEF is attributed to the high concentration of oxygen in the films, which forms complexes with Er. The excitation of Er3+ is due to a photocarrier mediated mechanism.This work is part of the research program of the Foundation for Fundamental research on Matter (FOM) and was made possible by financial support from the Dutch Organization for the Advancement of Pure Research (NWO) , the Netherlands Technology Foundation (STW), and the IC Technology Program (IOP ElectroOptics) of the Ministry of Economic Affairs. R. S. acknowledges financial support from CSIC, Spain.Peer Reviewe