Generation of very high-order high purity Gaussian modes via spatial light modulation

Abstract

We experimentally demonstrate the conversion of a fundamental TEM00 laser mode at 1064 nm to higher order Hermite-Gaussian modes (HG) of arbitrary order via a commercially available liquid crystal Spatial Light Modulator (SLM). We particularly studied the HG5,5/HG10,10/HG15,15 modes. A two-mirror plano-spherical cavity filters the higher-order modes spatially. We analyze the cleaned modes via a three-mirror diagnosis cavity and measure a mode purity of 96/93/78% and a conversion efficiency of 6.6%/3.7%/1.7% respectively. The generated high-purity Hermite-Gaussian modes can be employed for the mitigation of mirror thermal noise in optical cavities for both optical clocks and gravitational wave (GW) detectors. HG modes are then converted into high order LG modes which can be of particular interest in cold atom physics.

Increased Sensitivity of Higher-Order Laser Beams to Mode Mismatches

“…The results are analytically derived for a small mismatch and shown to be valid against numerical solutions. These results are consistent with the evidence discussed in [14], the decreased mode purity and power observed in [13] and experimental observations [31].…”

“…Advanced LIGO operates with a high degree of mode matching to ensure power couples efficiently between the resonators; however, some degree of mismatch is always present. The HG55 mode has been proposed as a possible option for revisiting a higher order mode carrier, to reduce thermal noise [13].…”

“…There are proposals to use a spatial Higher-Order Mode (HOM) as the carrier mode in the interferometer to mitigate thermal noise [10][11][12] in gravitational-wave detectors. This technique may also be of interest to other thermal-noise limited optical cavities [13]. Sorazu et al studied the use of a Laguerre-Gauss 3,3 (LG33) mode in a 10 m suspended optical resonator [14] and noted that astigmatism caused the break up of the LG33 mode into component Hermite-Gauss (HG) modes with similar, but not equal round trip Gouy phase, which resulted in distorted control signals and a poor power coupling into the resonator.…”

“…This paper revisits the subject of higher-order mode to resonator matching, in the context of HG modes, and derives an increased sensitivity to mode mismatch which scales monotonically with mode index. Hermite-Gauss modes are naturally astigmatic, therefore, they may be more compatible with the long baseline optical resonators used in gravitational-wavedetectors [13]. The HG55 has been discussed [13] and in this case, the losses due to waist-size mismatch would be 31 times worse than for the fundamental mode.…”

“…Hermite-Gauss modes are naturally astigmatic, therefore, they may be more compatible with the long baseline optical resonators used in gravitational-wavedetectors [13]. The HG55 has been discussed [13] and in this case, the losses due to waist-size mismatch would be 31 times worse than for the fundamental mode. Our results are derived using a computer algebra system [24] and shown to match numeric integration.…”