Improved tunable fiber lasers for communications and scientific purposes

New improved tunable fiber lasers consist of the waveguides and filter components, a spot-size converter, and the on-chip tunable laser gain module that is installed at the semiconductor optical amplifier. The development of such a laser system is considered to reduce the cost of the tunable fiber lasers by decreasing the number of laser system’s components and making their assembly less complex.

Additionally, the developed tunable laser system may become a possible solution for next-generation low-cost coherent transceivers. Herewith, these fiber lasers are compact and can expand opportunities in emerging fields of laser application such as lidar for autonomous vehicles and on-chip optical coherence tomography for biomedical sensing process, in addition to optical fiber area.

Although, tunable fiber lasers offer such benefits as cost- and space-efficiency for various applications, they face several challenges. Firstly, the laser systems‘ light emission produced by a laser beam remains still not straightforward because of silicon’s indirect bandgap. 

Secondly, it is possible to produce more ‘pure’ laser beam light by increasing the silicon cavity length but the propagation loss of a silicon waveguide is much higher than that of free-space optics and other material waveguides. Thus, the making of long silica cavity in the tunable laser systems is considered to be impractical.

Thirdly, it should be noted that the cavities of the fiber laser system are very sensitive to any thermal disturbance because silicon material has a relatively large thermo-optic coefficient. Therefore, it becomes very difficult to design a tunable fiber laser that offers a high-frequency precision of <1 GHz.

Finally, several improvements in the laser system’s components have been made to overcome the current limitations. Nowadays, the tunable fiber laser includes a laser gain chip directly butt-coupled to a ring-resonator-based filter chip, as well as two cascaded ring filters to provide lasing mode selection over a large spectral range through the Vernier effect.

Moreover, more powerful semiconductor optical amplifier has been designed to increase the output power in the fiber laser system. Currently, all the construction is packaged in a compact golf box to meet the requirements for laser applications in optical fiber communications.

The manufacturers also confirm that now it is possible to install this laser module into compact coherent transceivers. The new design of the tunable lasers allows not only solving the problems but creating additional benefits such as the compensation of the large coupling and propagation loss of the integrated silicon waveguides by the amplifier, the production of relatively “pure” laser beam light, the reduction of optical power on the silicon chip and the opportunity to control the laser system output power through the amplification of the semiconductor optical amplifier.

Optromix is a fast-growing fiber laser manufacturer and a vendor of optical fiber sensors and optical monitoring systems. The company offers fast turnkey solutions and creates sophisticated fiber laser systems for special purposes. Optromix uses only its own technologies and develops a broad variety of fiber lasers. If you have any questions or would like to buy a tunable laser system, please contact us at info@optromix.com

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