<title>Beam characterization and measurement of propagation attributes</title>

Scattered light imaging method (SLIM) for characterization of arbitrary laser beam intensity profiles

“…Here we confirmed the difficulty of determining the diameter of an arbitrary beam, as was remarked by Sasnett and Siegman [3,9]. Therefore M 2 is not a good metric for characterizing an arbitrary laser beam.…”

“…However, the laser beam cannot be characterized completely using only the M 2 value [3][4][5][6][7] because M 2 does not provide information about the intensity profile of an arbitrary laser beam. M 2 1 indicates an ideal laser beam, i.e., one having the single-mode TEM 00 [3,8,9], which has a Gaussian intensity profile. For a laser beam with M 2 > 1, the beam can be formed by either a highorder mode or a mixture of modes (multimode) [3,10], and its intensity profile presents an arbitrary shape that can be very far from that of an ideal laser beam.…”

Single-mode operation of a coiled multimode fiber amplifier

“…This calculation applies to a step-index fiber with an NA of 0.08 (a typical value for a low-NA fiber) and L = 10 m. The attenuation coefilcients for modes of order higher than LPI, are larger than ctll, and these modes will therefore be even more effectively suppressed in the coiled amplifier. Figure 1 indicates that, depending on the acceptable level of LPO1bend loss, >10 dB of suppression for the higher-order modes is possible for core diameters of 50-100 pm (V numbers of [12][13][14][15][16][17][18][19][20][21][22][23][24]. The corresponding bend radii are calculated to be 1.7-3.7 cm, which is compatible with compact packaging of the amplifier.…”

Fabrication and application of soft glass micro-optical elements for midIR fiber optics

“…On the basis of the measurements, it was established that for lenses of 10 mm focus length the minimal beam waist is 30 m. Parametr M 2 (M squared) (Fig. 2) defined as [7]:…”