Conclusions
	• Saturated absorption is readily achievable in photonic bandgap fibers with power <10 mW. • We have characterized linewidth in terms of pressure and power. • Linewidth dominated by transit-time broadening. – larger-core photonic bandgap fibers desirable. • Counter-propagation prone to noise- careful polarization control required • We have got Satuation Power to be somewhere between     25 to 50 mW. • We have also spliced the fiber outside the vacuum chamber and got very good splice.