Preliminary Investigation of a New Optically Pumped Atomic Rubidium Standard

TLDR: Feldman et al. as discussed by the authors used a beam device to detect the presence of gas in the air, and used it as a source of radiation for the first time in the early 1970s.

Abstract: Mark Feldman, J. C. Bergquis t , L L. Lewis, and F. L. Walls Frequency and Time Standards Group Time and Frequency D i v i s i o n Nat ional Bureau of Standards Boulder. Colorado 80303 Summary We a r e s t u d y i n g t w o t y p e s o f o p t i c a l l y pumped g l a s s c e l l s w h i c h do n o t c o n t a i n a b u f f e r gas and have no w a l l c o a t i n g i n w h i c h b e a m l i k e p r o p e r t i e s a re exp lo i t ed . The f i r s t d e v i c e i s a sealed g lass tube o f abou t 1 cm diameter and 20 cm leng th . A sinal 1 amount o f 87Rb metal i s l o c a l i z e d a t one end by temperature gradients which a lso cont ro l the vapor pressure. The c e l l has t h e p r o p e r t i e s o f a broad atomic beam f o r t h e t r a n s p o r t o f o p t i c a l l y pumped atoms from one nd t o t h e o t h e r with c o l l i m a t i o n g i v e n b y t h e a s p e c t r a t i o o f t h e t u b e . A t each end the Rb "beam" i s crossed by a l ase r . I n each i n t e r a c t i o n r e g i o n , t h e l a s e r o p t i c a l l y pumps atoms i n t o one o f t h e 5 2 S h y p e r f i n e l e v e l s , as we l l as detects populat ion kanges between the h y p e r f i n e l e v e l s . I n a second device, graphi te i n s e r t s a r e i n c l u d e d i n the g lass tube. The g r a p h i t e s t r o n g l y g e t t e r s Rb, the reby p rov id ing c o l l i m a t i o n and s i g n i f i c a n t l y r e d u c i n g s c a t t e r i n g o f l a s e r l i g h t f r o m background Rb atoms. A TE m i c r o w a v e c a v i t y i s p o s i t i o n e d between the w l a s e r i n t e r a c t i o n r e g i o n s . I n t h e b r o a d beam device we have observed the t r a n s p o r t o f o p t i c a l l y pumped atoms between t h e ends w i t h a S/N r a t i o o f 300:l i n 1 S . A tunable dye laser was used f o r t h e pumping and signal d e t e c t i o n . I n t h e c o l l i m a t e d beam device, we have obsewed microwave t rans i t ions us ing a d iode lase r f o r pumping and f luorescence detection.