The generation of femtosecond optical vortex beam based on direct wave-front modulation with phase-only liquid crystal spatial light modulator is demonstrated. The spatial and temporal properties of the generated femtosecond vortices are investigated in detail. The experimental results show remarkable agreement with the results of the theoretical analysis and simulations, and indicate that the method we utilized can efficiently generate femtosecond optical vortex beam of arbitrary topological charge. The temporal and spectral properties of the femtosecond pulsed beam are hardly affected by the phase dislocation imposed on the wave-front.
Both in-phase and out-phase radially polarized femtosecond-pulse (RPFP) beams have been generated with one phase-only liquid crystal spatial light modulator, which effectively modulates the phase retardation distributions of a pulse beam wavefront by two reflections. The intensity distributions and polarizing properties of both in-phase and out-phase RPFP beams are detected, and the temporal properties of in-phase RPFP beams are investigated in detail. Experimental results indicate that we effectively produce an RPFP beam. And the temporal duration of the output in-phase RPFP beam is 183 fs about 14 fs shorter than the input Gaussian femtosecond-pulse beam. The temporal durations of arbitrary polarized components of an in-phase RPFP beam vary less than 3.5%.
With both ultrafast optical properties of femtosecond pulse and cylindrically symmetric polarization properties of
radially polarized light, the radially polarized femtosecond pulse beam has significant applications in super-high density
optical storage and ultra-intense lasers. A scheme for generating radially polarized femtosecond pulse beam by a
polarization plates array is proposed, in which a phase-only liquid crystal spatial light modulator (LC-SLM) is used to
load different phase retardation distribution in transverse into linearly polarized femtosecond pulse beam. Associated
with a quarter wave plate, the input linearly polarized femtosecond pulse beam will be converted to radially polarized
femtosecond pulse beam at the back of the polarization plates array. The experimental results indicate that the scheme
can be well used to generate radially polarized light, and more effective results can be obtained with the increase of
sectored polarization plates.
Tree-type network composed of optical splitters and optical combiners, according to
the corresponding link rule, plays an important role in the all-optical communication and optical
information processing. Based on the matured polarization control technology to realize routing
and switching of signal beams, a novel tree-type interconnection network using phase spatial light
modulator (PSLM), polarizing beam-splitter (PBS) and mirror, is proposed, including 1×2, 1×4,
and 2×1, 4×1 switch elements. It is able to perform any arbitrary interconnection pattern, which
has the advantages of compact in structure, efficient in performance, small size, and
polarization-independent due to exploiting the building block pattern. The theoretical analysis
shows the functional experimental prototype with large number of input/output ports should be
helpful in the optimization and design of large-scale optical switch matrix.