Analytical expression for large signal transfer function of an optically filtered analog link.

We present an analytical expression for the transfer function of an optically-filtered radio frequency photonic link using phase modulation and coherent detection. This solution is applicable to quadrature passband signals and is significant for evaluating the distortion and consequently improving the linearity of such electrical-optical-electrical links. We show that the nonlinearity appears as an envelope distortion and discuss linearization techniques along with experimental validation.

[Renunciation of routine coagulation diagnostics before ENT operations in children. Results of a survey into the implementation of this recommendation in Dresden]. / Verzicht auf eine Routinegerinnungsdiagnostik vor HNO-Eingriffen bei Kindern. Ergebnisse einer Umfrage zur Umsetzung dieser Empfehlung in Dresden.

UNLABELLED: In Germany a recommendation was introduced by experts from several medical associations concerning the renunciation of preoperative coagulation diagnostics in ENT interventions in children with inconspicuous bleeding history and published in July 2006. In August 2007 a survey concerning the implementation of this recommendation was sent to all pediatricians and ENT doctors working in medical offices in Dresden. RESULT: The survey was answered by 23 (49%) paediatricians out of 47 who were contacted and 8 (33%) out of 24 ENT doctors. Fifteen pediatricians (65%) and 3 ENT doctors (38%) have implemented the recommendation consequently and 6 respectively 3 occasionally. Only 2 pediatricians and 2 ENT doctors did not accept the recommendation. Four paediatricians and 4 ENT doctors expressed their concerns with the implementation of recommendation. Since the implementation of this recommendation 3 children suffered from bleeding complications in ambulant ENT operations but in no case a coagulation disorder was present. CONCLUSION: The implementation of the recommendation at the regional level is practicable. Its acceptance is obviously higher in paediatricians than in ENT doctors.

Enhanced confidentiality using OCDM-based code scrambling and self-obscuration.

Code scrambling combined with self obscuration in a spectral phase encoded OCDM system shows promise for enhanced confidentiality in high data rate networks. We demonstrate code scrambling using reconfigurable ring-resonator-based integrated coders for obscuring a 20 Gb/s OCDM signal comprising four polarization multiplexed coded tributaries.

Guided blue and green upconversion fluorescence in an erbium-ytterbium-containing silicate glass.

We observe guided blue and green upconversion fluorescence in an ion-exchanged waveguide that is fabricated in an erbium-ytterbium-codoped silicate laser glass. The guides are optically pumped at room temperature by using a Ti:sapphire laser with lambda = 880-980 nm; the observed fluorescence is in two bands, 480-490 and 520-560 nm, and results from multiphoton excitation.

Experimental observation of spatial soliton interactions.

We report the experimental observation of interaction forces between two fundamental spatial optical solitons in a nonlinear glass waveguide. Both attraction and repulsion were observed, depending on the relative phase between the solitons.

Observation of spatial optical solitons in a nonlinear glass waveguide.

We report the observation of spatial optical solitons due to the Kerr nonlinearity in a planar glass waveguide and present measurements of the nonlinear response obtained by placing a pinhole at the output of the waveguide. For input intensities greater than that required for the fundamental soliton, we observe breakup of the output owing to the effect of two-photon absorption.

Bistable optical switching using electrochemically generated bubbles.

We demonstrate a novel bistable optical waveguide switch, which may be suitable for incorporation in large-dimension optical cross connects. The switching is based on the electrolytic creation and catalytic destruction of bubbles and is both wavelength and polarization independent. Calculations indicate that low losses and cross talk, which are crucial for large switching arrays, can be achieved with the combination of materials used in the prototype. The intrinsic bistability of the switch eliminates the need for a holding voltage and permits matrix addressing.

Ion-exchanged optical waveguides for all-optical switching.

Current interest in all-optical waveguide devices has created a need for suitable nonlinear materials and fabrication techniques. To meet this need, we have made optical waveguides using ion exchange in two glasses, which were designed both to have large optical nonlinearities and to be compatible with the ion-exchange processing. We find that the choice of alkali metal ion in the glass has a major effect on the exchange process and on the optical quality of the ensuing guides. Guides made in one of these glasses have been used for demonstrations of spatial soliton propagation, which can be used as the basis of an all-optical switch.

Adiabatic invariance in GRIN channel waveguides and its use in 3-dB cross couplers.

We have extended the local normal mode approach of Burns and Milton to derive the condition for adiabatic invariance in graded-index channel waveguides. The results show that in spite of the index-grading and 2-D confinement, the inequality describing the adiabatic condition is basically the same as that for step-index slab waveguides. To verify the predictions of the theory, we have fabricated, using ion exchange in glass, a cross coupler with two asymmetric input channel waveguides and two symmetric output guides. The experimental results show equal output power (3.0 +/- 0.1 dB) from the two symmetric guides when either of the two unequal guides is excited, demonstrating excellent agreement with the theory.

Voltage tunable LiNbO(3) wavelength filters.

We describe here the design and operation of voltage tunable wavelength filters fabricated in titanium diffused LiNbO(3). The devices, based on the nonsymmetric interferometer, have channel separations of 11-31 nm at lambda= 1300 nm, and tuning rates of 3-10 nm/V. The periodic wavelength response of these filters allows them to be cascaded to combine or separate 2(N) channels in N stages.

Glass waveguides made using low melting point nitrate mixtures.

Silver-sodium ion exchange is a commonly used method for making waveguides in glass. This paper discusses two exchange media, KNO(3):AgNO(3) and AgNO(3) in NaNO(3):KNO(3) which increase the flexibility of the process and decrease its cost. Exchange in the KNO(3):AgNO(3) can be performed at temperatures as low as 150 degrees C, which is particularly useful for field assisted exchange. When exchange is performed in a NaNO(3):KNO(3) eutectic with small (

Optical waveguides in LiTaO(3): silver lithium ion exchange.

Silver lithium ion exchange has been found to produce optical waveguides in x-cut LiTaO(3)at temperatures well below the Curie temperature, producing waveguides that require no repoling. This process is attractive for integrated optics because LiTaO(3) is less susceptible to optical damage and has much lower birefringence than the more commonly used LiNbO(3) substrate. The exchange process has been studied as a function of temperature. Diffusion coefficients, activation energy, losses, and temperature dependence of the extraordinary index change are given. Index increases of Deltan(e) ~ 0.03-0.05 at lambda = 632.8 nm and losses of 0.8-1.3 dB/cm for the TE(O) mode are comparable with values for Ti-diffused guides in LiNbO(3), making this technique potentially useful for integrated optics applications.