Widely tunable Q-switched dual-wavelength synchronous-pulsed Tm-doped fiber laser emitting in the 2  μm region.

We demonstrate a widely tunable Q-switched dual-wavelength fiber laser emitting synchronized pulses in the 2 μm spectral range. Owing to the use of a Tm-doped rod-type fully aperiodic large pitch fiber, together with an acousto-optic modulator and two volume Bragg gratings (VBGs), the wavelength separation was shown to be continuously tunable from 1 to 120 nm (∼0.1-10  THz).

Noninvasive characterization of optical fibers.

Capillary optical fibers with hole diameters of several micrometers are important for novel plasmonic applications and medical diagnosis. In order to ensure the optical functionality of these fibers, the diameter of the capillary hole needs to be realized with high accuracy. Here, we introduce a novel and noninvasive methodology to characterize optical fibers and discuss it for the assessment of capillaries.

Independently tunable dual-wavelength fiber oscillator with synchronized pulsed emission based on a theta ring cavity and a fiber Bragg grating array.

We present a fiber-integrated laser enabling independent tuning of two emission wavelengths with a synchronized pulsed emission. The discrete tuning concept comprises a theta cavity fiber laser (TCFL), a fiber Bragg grating (FBG) array as a versatile spectral filter, facilitating tailored tuning ranges, and optical gating to control the emission spectrum. A novel electrical driving scheme uniquely enables independently tunable multi-wavelength emission from a single laser oscillator.

Discrete tuning concept for fiber-integrated lasers based on tailored FBG arrays and a theta cavity layout.

We demonstrate a novel tuning concept for pulsed fiber-integrated lasers with a fiber Bragg grating (FBG) array as a discrete and tailored spectral filter, as well as a modified laser design. Based on a theta cavity layout, the structural delay lines originating from the FBG array are balanced, enabling a constant repetition rate and stable pulse properties over the full tuning range. The emission wavelength is electrically tuned with respect to the filter properties based on an adapted temporal gating scheme using an acousto-optic modulator.

All-fiber 10 MHz acousto-optic modulator of a fiber Bragg grating at 1060 nm wavelength.

Acousto-optic modulation of a 1 cm fiber Bragg grating at 10.9 MHz frequency and 1065 nm wavelength is demonstrated for the first time. A special modulator design is employed to acoustically induce a dynamic radial long period grating which couples power of the fundamental mode to the higher-order modes supported by the Bragg grating.

Fiber-integrated concept to electrically tune pulsed fiber lasers based on step-chirped fiber Bragg grating arrays.

We present a novel method to discretely tune the emission wavelength of pulsed fiber-integrated lasers. As spectral filter, a step-chirped fiber Bragg grating (FBG) array is employed combining a monolithic structure with an unrivaled design freedom enabling large tuning bandwidths as well as tailored spectral characteristics towards fingerprint tuning features. Together with an electrical control mechanism ensuring programmable operation, this tuning method promotes fiber-integrated lasers to access new fields of applications e.

All-fiber time-delay spectrometer for simultaneous spectral and temporal laser pulse characterization in the nanosecond range.

We have realized a modified time-delay spectrometer based on a step-chirped fiber Bragg grating array. This method allows simultaneous spectral and temporal characterization of pulsed light sources in the nanosecond regime, which can also be applied to the investigation of single pulses. With a spectral resolution in the 100 pm range, pulse spectrograms are measured and exemplarily used to explore the emission behavior of a wavelength-stabilized laser diode directly modulated in the nanosecond range.