Tunable fiber Bragg grating applications


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Applications: 1. Optical Telecommunication 2. Tunable Lasers 3. Fiber Optic Sensors

Tunable fiber gratings offer a versatile 'all-fiber' tunable optical filter platform with the benefits of low-insertion loss and high-power handling capabilities. They find applications in a wide range of fields, including tunable lasers, nonlinear optics, quantum optics, fiber optic sensors, and optical fiber telecommunications.

Applications examples:

1. Optical telecommunication, Nonlinear optics

A tunable FBG can be paired with a circulator, enabling the blocking of specific laser lines and the transmission of other light signals, making it valuable for nonlinear optics. A similar configuration is employed as a tunable add-drop filter in optical telecommunication systems. Chirped FBGs find essential roles in managing dispersion within high-speed wavelength-division-multiplexed (WDM) lightwave systems and ultra-fast laser systems.

Fig.1. TFBG used as a tunable band-pass and band-reject filter.

Fig.2. TFBG used as a tunable add-drop multiplexer and demultiplexer.

Tunable Lasers

2. Tunable Lasers

Fiber lasers can emit laser light with high-beam quality across a wide range of wavelengths efficiently. Leveraging the broad gain bandwidth of active fibers, they offer an attractive option for developing wavelength-tunable lasers. Traditional methods for achieving wavelength tuning in fiber lasers often involve bulk optical filters or diffraction gratings. However, these devices typically incorporate free-space optical paths, resulting in high insertion losses and challenges in handling high power.

Wavelength-tunable fiber lasers, configured through direct tuning of the Fiber Bragg Grating, maintain all-fiber connections internally, resulting in minimal cavity loss. This configuration yields a simpler, compact, robust laser system that is highly resistant to vibrations.

Moreover, tunable FBGs are also applicable in fiber-pigtailed semiconductor lasers for external cavity wavelength tuning.

Fig.3. A tunable fiber laser, designed with an 'all-fiber'

laser cavity configuration

Fig.4. DFB single frequency fiber laser can be tuned by TFBG.

Fig.5. Fiber-pigtailed semiconductor laser can be tuned by TFBG.

Fig. 6. Output spectra from tunable fiber lasers at different wavelength bands.

(a) Er-doped fiber laser; (b) Tm-doped fiber laser; (c) Yb-doped fiber laser.

3. Fiber Optic Sensors

FBGs have demonstrated successful applications in fiber optic sensors, particularly for strain and temperature measurements. They excel in sensing various physical parameters, such as displacement, load, pressure, and more through the measurement of strain. Our FBG tuning technique can be adapted for the advancement of transducers in fiber optic sensor applications. The remarkable linearity and significant achievable wavelength shifts will substantially enhance the measurement range of FBG-based sensors."

Fig. 7. The wavelength shift of the FBG depends on the displacement of the actuator. The tuning structure can be configured to sense various physical parameters, including displacement, load, pressure, and more.

Fig. 8. The wavelength shift of an FBG has a linear dependence on the displacement of the actuator; a wavelength shift range of around 50 nm is available.

Please contact us for your needs, we will be happy to work with you to meet your application needs.