Saturated absorption spectroscopy of acetylene gas inside large-core photonic bandgap fiber

Abstract

Saturated absorption spectroscopy is performed on the acetylene nu(1) + nu(3) band near 1532 nm inside photonic bandgap fibers of small (approximately 10 microm) and large (approximately 20 microm) core diameters. The observed linewidths are narrower in the 20 microm fiber and vary from 20 to 40 MHz depending on pressure and power. Variations in the background light transmission, attributed by others to surface modes, are significantly reduced in the 20 microm fiber. The optimum signal for use as a frequency reference in a 0.8 m long, 20 microm diameter fiber is found to occur at about 0.5 torr for 30 mW of pump power. The saturation power is found by modeling the propagation and attenuation of light inside the fiber.

Chip-scale atomic devices

“…Some related techniques for confining alkali atoms into even smaller structures with dimensions on the order of an optical wavelength have been developed. [109][110][111] While these latter types of cells appear well-suited for certain types of spectroscopy, the very small cell dimension may limit their application in microwave atomic frequency references due to relaxation from rapid collisions of the atoms with the cell walls, as discussed above.…”

“…Optical frequency references based on acetylene-filled hollow core optical fibers 109 have achieved frequency uncertainties in the range of 10 kHz near 1.5 lm.…”

Suspended-core fibres as optical gas sensing cells: study and implementation

“…The width of the resulting central dip in the absorption profile is then function of all other broadening sources but Doppler. This central dip, sometimes called Lamb dip, was observed in hollow-core fibres containing low-pressure acetylene gas 13,17 . The measured full width of the Lamb dip was ∼40 MHz in both cases and varied with input pump power, gas pressure, and diameter of the gas cell.…”

Optical frequency standard using acetylene-filled hollow-core photonic crystal fibers

“…During the last decade, I 2 , acetylene and Rb vapour cells have been widely investigated and implemented in laser stabilization using the saturated absorption spectroscopy (SAS) technique [2], often combined with frequency modulated spectroscopy [3][4][5][6][7]. Since the demonstration of the first photonic band gap guidance in air [8], the increased availability of fibers with an hollow core (HC) allowed to investigate the realization of a portable optical frequency reference based on a gas-filled HC fiber [9][10][11][12][13].…”