Jean-Marc Delavaux

Design and fabrication of efficient diffraction transmission gratings on step-index optical waveguides

High-efficiency and low loss constant periodicity gratings have been fabricated and evaluated on single-mode planar optical wave guides. The most important parameters that will affect the lens performance are the coupling coefficient and the Q (or ρ) factor. The coupling coefficient has been found to be given by Kc = Δneff/(λ0/2). Investigation of the Δneff value has shown that for small groove heights larger Δneff can be obtained for CeO2 deposited grooves than for etched grooves. In grating structures where Q and ρ factors are high, the effect of the higher orders of diffraction is negligible, and there is a good agreement between the experimentally measured characteristics and the prediction from the coupled mode theory. However, minor variations in the fabrication processes (e.g., Δn ≃ 0.02) may cause the diffraction efficiency to vary as much as 15%, while the angular field of view does not seem to be affected by process variations.

Comparison of the experimental and theoretical diffraction characteristics of transmission gratings on planar dielectric waveguides

Experimental diffraction characteristics of dielectric transmission gratings on planar optical waveguides are compared to theoretical results from the rigorous coupled-wave analysis. The deep-grooved square gratings are shown to have high diffraction efficiency (>90%). In particular, the effects of higher orders of diffraction on the diffraction efficiency, at fixed wavelength, are presented in this paper for both TE and TM polarizations. The rigorous coupled-wave analysis is shown to produce excellent general agreement with the measured diffraction characteristics.

A Generalized Two-Dimensional Coupled-Mode Analysis of Curved and Chirped Periodic Structures in Open Dielectric Waveguides

A generalized two-dimensional coupled-mode analysis of curved and chirped quasi-periodic structures in planar dielectric waveguides has been formulated. This analysis can be used to design curved and chirped quasi-periodic structures for obtaining phase matched interaction between two specific guided-wave beams. Alternatively, it can be used to calculate the amplitude and the phase of the diffracted guided-wave beam for a given quasi-periodic structure and for a specific incident beam, including the effect of the phase mismatch.

Electrooptic linear chirped grating lenses on planar optical Ti:LiNbO 3 waveguides

We report the experimental investigation of the first electrooptic chirped grating lenses (F/28 and F/56) on single-mode planar Ti-indiffused LiNbO 3 waveguides for TE and TM modes at 633 nm. These lenses perform simultaneously the basic functions of focusing, switching, and modulation of guided wave beams.

Fabrication And Performance Of Diffraction Lenses

We present here the theoretical design and the experimental fabrication and evaluation of diffraction lenses in LiNbO3 waveguides.

5W 1950nm Brillouin-free efficient single clad TDFA

We report the performance of a two stage single clad (SC) Thulium-doped fiber amplifier (TDFA), delivering an output power of 5 W at 1952 nm without stimulated Brillouin scattering (SBS) for a single-frequency input signal. A slope efficiency greater than 60 %, a signal gain greater than 60 dB and an input dynamic range > 30 dB are achieved. The amplifier topology was optimized with a modelization tool of the SC TDFA performance: experimental results and simulations are in good agreement.

Multistage single clad 2 micron TDFA with a shared L-band pump source

We report the experimental performance and simulation of a multiwatt two-stage TDFA using an L-band (1567 nm) shared pump source. We focus on the behavior of the amplifier for the parameters of output power Pout, gain G, noise figure NF, signal wavelength λs, and dynamic range. We measure the spectral performance of the TDFA for three specific wavelengths (λs= 1909, 1952, and 2004 nm) chosen to cover the low-, mid-, and upper-wavelength operating regions of the wideband amplifier. We also compare the performance of the two-stage shared pump TDFA with a one stage shared pump amplifier. Experimental results are in good agreement with simulation.

20-W 1952-nm tandem hybrid single and double clad TDFA

A simple engineering design is important for achieving high Thulium-doped amplifier (TDFA) performance such as good power conversion, low noise figure (NF), scalable output power, high gain, and stable operation over a large dynamic range. In this paper we report the design, performance, and simulation of two stage high-power 1952 nm hybrid single and double clad TDFAs. The first stage of our hybrid amplifier is a single clad design, and the second stage is a double clad design. We demonstrate TDFAs with an output power greater than 20 W with single-frequency narrow linewidth (i.e. MHz) input signals at both 1952 and 2004 nm. An optical 10 dB bandwidth of 80 nm is derived from the ASE spectrum. The power stage is constructed with 10 μm core active fibers showing a maximum optical slope efficiency greater than 50 %. The experimental results lead to a 1 dB agreement with our simulation tool developed for single clad and double clad TDFAs. Overall this hybrid amplifier offers versatile features with the potential of much higher output power.