Fast Transmission Matrix Measurement of a Multimode Optical Fiber With Common Path Reference

Abstract

We report an improved scheme for the measurement of the transmission matrix of multimode waveguides in which the reference field co-propagates with the signal wave. The performance of the technique is demonstrated with the measurement of a 1.6 m long multimode optical fiber guiding 104 LP modes at 1064nm. The transmission matrix permitted efficient focusing of the light delivered at the fiber exit as well as shaping in the fiber's transmission channels.

Efficient Switchable Common Path Interferometer for Transmission Matrix Characterization of Scattering Medium

“…This method strictly ensures the common path similar to those reported in Ref. [20], [24], [36]. Different from the traditional method, the reference is introduced to characterize the TM of the scattering medium only, and can be switched off afterwards during the imaging and focusing of the signal, avoiding the negative effect from the reference beam after the TM characterization.…”

“…However, the holographic method needs to introduce an additional reference light, which reduces the stability and limits application range of the measurement system. To overcome this shortcoming, the co-propagation phase shift method is proposed and demonstrated by S. M. Popoff et al in 2010 [20], [24], [36], [37]. In this method, the signal beam and the reference beam propagate along the common path, which enhances the stability of the system.…”

Shaping of amplified beam from a highly multimode Yb-doped fiber using transmission matrix

“…This configuration mitigates the differential phase drift between signal and reference fields on the duration of the measurement as they share the same propagation medium. The TM measurement technique is similar to the one previously described in [27]. Figure 1 shows the experimental setup.…”

“…In the following sections, we report the TM measurement of a highly multimode fiber with gain for the first time, using the co-propagative reference scheme [26,27]. TM was further used for input wavefront profiling to get output beam focusing and shaping in amplification regime.…”

Machine learning method to measure the transmission matrix of a multimode optical fiber without reference beam for 3D beam tailoring

“…This coherent control has opened up new perspectives for MMFs [1] and expanded their fields of application, such as in optical telecommunications [2][3][4], bio-imaging [5][6][7], spectroscopy [8], quantum signal processing [9] or laser sources [10]. To shape a laser beam from an MMF, there are four main types of processes: digital phaseconjugation [11], adaptive control in a feedback loop [12], neural networks (NN) for image propagation [13][14][15], or modal decomposition [16] and transmission matrix (TM) measurement [17,18].…”