Novel high precision alignment technique for polarisation maintaining fibres using a frequency modulated tunable laser

Wavelength-dependent orientation of the principal axes of photonic crystal fibers measured by windowed Fourier-transform spectral interferometry

“…The orientation of a given axis was retrieved using the p 1 parameter of the cosine function fit (see Eqs. (15) and (16)). This parameter provides the angle β directly.…”

“…The final step of the evaluation was a cosine function fit to these data according to Eqs. (15) and (16) [Fig. 4].…”

“…There are more precise methods, based on monitoring the change in the phase difference between the polarization modes, which rely on the rotation of the polarization plane of the light beam [5] or the rotation of the fiber itself [6]. Other techniques combine the rotation with external perturbations of the fiber, which are often achieved by heating [7][8][9][10][11], applying transversal stress [12], pressure [13] or with a frequency-tunable laser [14,15]. Interferometric methods employing a Michelson-interferometer [16] or a fiber interferometer [17] are also used especially for alignment during fiber splicing.…”

Wavelength Tunable Laser Diodes and Their Applications

“…Continuously wavelength tunable lasers are also useful for various measurement and sensing applications [6,7,8]. Among these, two representative applications will be discussed briefly.…”

“…From quantitative evaluation it turns out that, particularly for multisection DBR devices and TTG lasers with their passive tuning sections, 6.vIRSN represents the essential contribution to the excess linewidth broadening [39,41]. Since, for a fixed laser geometry, 6.vIRSN is approximately proportional to the tuning range squared, it becomes most essential for the large range tunable devices. It should be noted, however, that this broadening effect does not occur by the thermal tuning, even if it is induced by the tuning current.…”