What is it about?

This work describes the development and implementation of an automatic diameter control system (ADC) for the Laser-Heated Pedestal Growth (LHPG) technique. The ADC system is designed to reduce diameter fluctuations in oxide fibers grown from unreacted and non-sinterized pedestals. The system utilizes an artificial vision apparatus to control the pulling speed and the height of the molten zone with high precision. The study shows that the ADC system can significantly reduce diameter fluctuations in single crystal fibers, making them suitable for applications in nonlinear optics and solid-state laser devices. Additionally, the system can be used for periodic in situ axial doping of fibers. The research used pure and Cr3+ doped LaAlO3 and pure LiNbO3 as model materials for experimentation.

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Why is it important?

This work is important because it addresses a critical issue in the production of single crystal fibers (SCFs) for applications in nonlinear optics and solid-state laser devices. Diameter fluctuations in SCFs can lead to light scattering and reduce the optical quality of the fibers. The development of the automatic diameter control system (ADC) for the LHPG technique offers a solution to minimize diameter fluctuations during the growth process. By reducing diameter fluctuations to less than 2% of the average fiber diameter and diminishing average diameter fluctuations over the entire length of the fiber to less than 1%, the ADC system enables the production of high-quality SCFs with improved optical properties. Additionally, the ability to perform in situ axial doping of the fibers using the ADC system opens up possibilities for further customization and enhancement of SCF properties for specific applications. Overall, this work contributes to advancing the technology of SCF production and facilitates the use of SCFs in a wide range of optical and laser-related applications.

Perspectives

This work presents the development of an automatic diameter control system (ADC) for the laser heated pedestal growth (LHPG) technique. The ADC system aims to reduce diameter fluctuations in oxide fibers grown from unreacted and non-sinterized pedestals. It utilizes an artificial vision apparatus to control the pulling speed and the height of the molten zone with high precision. By implementing the ADC system, the study achieved a significant reduction in diameter fluctuations in single crystal fibers, making them suitable for applications in nonlinear optics and solid-state laser devices. Diameter variations were reduced to less than 2% of the average fiber diameter, and average fluctuations along the fiber length were decreased to less than 1%. Additionally, the system allows for periodic in situ axial doping of fibers during the growth process. The research conducted experiments using pure and Cr3+ doped LaAlO3 and pure LiNbO3 as model materials. The results demonstrate the effectiveness of the ADC system in improving the quality and consistency of single crystal fibers. The ability to control fiber diameter and introduce periodic doping opens up possibilities for customized fiber properties and enhanced optical performance in a variety of applications. Overall, this work contributes to advancing the technology of single crystal fiber production, offering perspectives for improved fiber quality, customization through in situ doping, applications in optical devices, automation of production processes, and further research and development in the field of optical materials processing and photonics.

Professor Marcello R. B. Andreeta
Universidade Federal de Sao Carlos

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This page is a summary of: Automatic diameter control system applied to the laser heated pedestal growth technique, Materials Research, January 2003, FapUNIFESP (SciELO),
DOI: 10.1590/s1516-14392003000100019.
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