Tom Blauwendraat

Reliable Low-Cost Fabrication of Low-Loss Waveguides With 5.4-dB Optical Gain

A reliable and reproducible deposition process for the fabrication of Al₂O₃ waveguides with losses as low as 0.1 dB/cm has been developed. The thin films are grown at ~ 5 nm/min deposition rate and exhibit excellent thickness uniformity within 1% over 50times50 mm² area and no detectable OH^- incorporation. For applications of the Al₂O₃ films in compact, integrated optical devices, a high-quality channel waveguide fabrication process is utilized. Planar and channel propagation losses as low as 0.1 and 0.2 dB/cm, respectively, are demonstrated. For the development of active integrated optical functions, the implementation of rare-earth-ion doping is investigated by cosputtering of erbium during the Al₂O₃ layer growth. Dopant levels between 0.2-5times10²⁰ cm^-3 are studied. At Er³⁺ concentrations of interest for optical amplification, a lifetime of the ⁴I_13/2 level as long as 7 ms is measured. Gain measurements over 6.4-cm propagation length in a 700-nm-thick Al₂O₃:Er³⁺ channel waveguide result in net optical gain over a 41-nm-wide wavelength range between 1526-1567 nm with a maximum of 5.4 dB at 1533 nm.

Reliable low-cost fabrication of low-loss

A reliable and reproducible deposition process for the fabrication of Al₂O₃ waveguides with losses as low as 0.1 dB/cm has been developed. The thin films are grown at ~ 5 nm/min deposition rate and exhibit excellent thickness uniformity within 1% over 50times50 mm² area and no detectable OH^- incorporation. For applications of the Al₂O₃ films in compact, integrated optical devices, a high-quality channel waveguide fabrication process is utilized. Planar and channel propagation losses as low as 0.1 and 0.2 dB/cm, respectively, are demonstrated. For the development of active integrated optical functions, the implementation of rare-earth-ion doping is investigated by cosputtering of erbium during the Al₂O₃ layer growth. Dopant levels between 0.2-5times10²⁰ cm^-3 are studied. At Er³⁺ concentrations of interest for optical amplification, a lifetime of the ⁴I_13/2 level as long as 7 ms is measured. Gain measurements over 6.4-cm propagation length in a 700-nm-thick Al₂O₃:Er³⁺ channel waveguide result in net optical gain over a 41-nm-wide wavelength range between 1526-1567 nm with a maximum of 5.4 dB at 1533 nm.

Al_2O_3:Er^{3+}

A reliable and reproducible deposition process for the fabrication of Al₂O₃ waveguides with losses as low as 0.1 dB/cm has been developed. The thin films are grown at ~ 5 nm/min deposition rate and exhibit excellent thickness uniformity within 1% over 50times50 mm² area and no detectable OH^- incorporation. For applications of the Al₂O₃ films in compact, integrated optical devices, a high-quality channel waveguide fabrication process is utilized. Planar and channel propagation losses as low as 0.1 and 0.2 dB/cm, respectively, are demonstrated. For the development of active integrated optical functions, the implementation of rare-earth-ion doping is investigated by cosputtering of erbium during the Al₂O₃ layer growth. Dopant levels between 0.2-5times10²⁰ cm^-3 are studied. At Er³⁺ concentrations of interest for optical amplification, a lifetime of the ⁴I_13/2 level as long as 7 ms is measured. Gain measurements over 6.4-cm propagation length in a 700-nm-thick Al₂O₃:Er³⁺ channel waveguide result in net optical gain over a 41-nm-wide wavelength range between 1526-1567 nm with a maximum of 5.4 dB at 1533 nm.

waveguides with 5.4-dB optical gain

Reactively co-sputtered aluminum oxide layers with low background loss and varying Er concentrations have been deposited. Net optical gain of 0.76 dB/cm was obtained for an Er concentration of 0.9times1020 cm-3 in a channel waveguide.

Reliable Low-Cost Fabrication of Low-Loss

PCT No. PCT/EP93/02622 Sec. 371 Date May 27, 1994 Sec. 102(e) Date May 27, 1994 PCT Filed Sep. 27, 1993 PCT Pub. No. WO94/08169 PCT Pub. Date Apr. 14, 1994.In a flexible connection arrangement for two pipe portions having a metallic bellows which is connected axially on either side in a gastight manner with connection pieces, the sides of the connection pieces facing the bellows are provided with radially widened end portions. Also provided are a damping insert, which extends coaxially relative to the bellows a along its length and is in a working connection therewith, and heat protection device for the bellows acting in the radially inward direction. The damping insert encloses the bellows radially outwardly such that the turns of the bellows contact the damping insert. The lateral end regions of the damping insert are held in the widened end portions without being fastened thereto and are supported radially outwardly by the latter. The connection pieces are connected with one another via a spring which surrounds the damping insert radially outwardly. The heat protection means are formed by a pipe segment which extends within the bellows coaxially relative to the bellows at a radial distance from the latter and which is fastened to the connection piece located in the front as viewed in the direction of flow.

\hbox{Al}_{2}\hbox{O} _{3}{:}\hbox{Er}^{3+}

Reactively co-sputtered amorphous Al2O3 waveguide layers with low propagation losses have been deposited. In order to define channel waveguides in such Al2O3 films, the etching behaviour of Al2O3 has been investigated using an inductively coupled reactive ion etch system. The etch rate of Al2O3 and possible mask materials was studied by applying various common process gases and combinations of these gases, including CF4/O2, BCl3, BCl3/HBr and Cl2. Based on a comparison of the etch rates and patterning feasibility of the different mask materials, a BCl3/HBr plasma and and standard resist mask were used to fabricate channel waveguide structures. The etched structures exhibit straight sidewalls with minimal roughness and etch depths of up to 530 nm, sufficient for defining waveguides with strong optical confinement and low bending losses. Low additional propagation losses were measured in single-mode Al2O3 ridge waveguides defined using the developed etch process. In initial investigations, Al2O3:Er layers fabricated using the same deposition method applied for the undoped layers show typical emission cross-sections, low green upconversion luminescence and lifetimes up to 7 ms.