Solid microlaser passively switched by a saturable absorber and its production process

Abstract

The invention relates to a microlaser cavity ( 10 ) having: a solid active medium ( 2 ) emitting at least in a wavelength range between 1.5 and 1.6 μm, and a saturable absorber ( 4 ) of formula CaF 2 :Co 2+ or MgF 2 :Co 2+ or SrF 2 :Co 2+ or BaF 2 :Co 2+ or La 0.9 Mg 0.5-x Co x Al 11.433 O 19 or YalO 3 :Co 2+ (or YAl 5-2x Co x Si x O 3 YAl (1-2x) Co x Si x O 3 ) or Y 3 Al 5-x-y Ga x Sc y O 12 :Co 2+ (or -3 Al 5-x-y2z Ga x Sc y Co z Si z O 12 Y 3 Al 5-x-y-2z Ga x Sc y Co z Si z O 12 ) or Y 3-x Lu x Al 5 O 12 :Co 2+ (or Y 3-x Lu x Al 5-2y Co y Si y O 3 ) or Sr 1-x Mg x La y Al 12-y O 12 :Co 2+ (or Sr 1-x Mg x-y Co y La z Al 12-z O 12 , with 0<y<x) Sr 1-x La x Mg x Al 12-x O 19 :Co 2+ ( or Sr 1-x La x Mg x-y Co y Al 12-x O 19 , with 0<y<x ).

We claim:  
     
       1. Microlaser cavity incorporating: 
       a solid active medium emitting at least in a wavelength range between 1.5 and 1.6 μm and  
       a saturable absorber of formula CaF 2 :Co 2+  or MgF 2 :Co 2+  or SrF 2 :Co 2+  or BaF 2 :Co 2+  or La 0.9 Mg 0.5-x Co x Al 11.433 O 19  or YAlO 3 :Co 2+  or YAl 5-2x Co x Si x O 3 YAl (1-2x)   Co   x   Si   x   O   3  or Y 3 Al 5-x-y Ga x Sc y O 12 :Co 2+  or Y 3 Al 5-x-y-2z Ga y Sc z Co z Si z O 12 Y 3   Al   5-x-y-2z   Ga   x   Sc   y   Co   z   Si   z   O   12  or YLuAlO:Co 2+  or Y 3-x Lu x Al 5 12 CoSiO Y 3-x   Lu   x   Al   5   O   12   :Co   2+    or Y   3-x   Lu   x   Al   5-2y   Co   y   Si   y   O   12  or Sr 1-x Mg x La y Al 12-y O 12 :Co 2+  or Sr 1-x Mg x-y Co y La z Al 12-z O 12 , (with o<y<x Sr 1-x   La   x   Mg   x   Al   12-x   O   19   :Co   2+    or Sr   1-x   La   x   Mg   x-y   Co   y   Al   12-x   O   19 , ( with  0 <y<x  for the latter compound).  
     
     
       2. Microlaser cavity according to  claim 1 , the saturable absorber being in the form of a film. 
     
     
       3. Microlaser cavity according to  claim 2 , the film having a thickness between 1 and 150 μm. 
     
     
       4. Microlaser cavity according to  claim 2  or  3 , the film having been obtainable by the sol-gel method, or by molecular beam or liquid phase epitaxy. 
     
     
       5. Microlaser cavity according to  claim 1 , the solid active medium being constituted by a base material chosen from among Y 3 Al 5 O 12  (YAG), LaMgAl 11 O 19  (LMA), Y 2 SiO 5  (YSO), GdVO 4 , Y 3 Sc 2 Ga 3 O 12  (YSGG), SrY 4 (SiO 4 ) 3 O (SYS), Ca 2 Al 2 SiO 7  (CAS) and doped either with erbium or with chromium or with an erbium-ytterbium codoping, or an erbium-ytterbium-cerium codoping. 
     
     
       6. Microlaser cavity according to  claim 1 , the solid active medium being a phosphate glass doped with erbium and ytterbium, the erbium an ytterbium doping operations being respectively at between 0.5 and 0.9 and between 15 and wt. % oxide. 
     
     
       7. Microlaser cavity according to  claim 1 , the cavity being stable. 
     
     
       8. Microlaser cavity according to  claim 7 , having an input mirror and an output mirror, at least one of the two mirrors being concave. 
     
     
       9. Microlaser cavity according to  claim 1 , also having a microlens directly formed on the laser material. 
     
     
       10. Process for the production of a microlaser cavity involving the production of a saturable absorber of formula CaF 2 :Co 2+  or MgF 2 :Co 2+  or SrF 2 :Co 2+  or BaF 2 :Co 2+  or La 0.9 Mg 0.5-x Co x Al 11.433 O 19  or YAlO 3 :Co 2+  or YAl 5-2x Co x Si x O 3 YAl (1-2x)   Co   x   Si   x   O   3  or Y 3 Al 5-x-y Ga x Sc y O 12 :Co 2+  or Y 3 Al 5-x-y-2z Ga x Sc y Co z Si z O 12  or Y 3-x Lu x Al 5 O 12 :Co 2+  or Y 3-x Lu x Al 5-2y Co y Si y O 12  or Sr 1-x Mg x La y Al 12-y O 12 :Co 2+  or Sr 1-x Mg x-y Co y La z Al 12-z O 12  (with o<y<x Sr 1-x   La   x   Mg   x   Al   12-x   O   19   :Co   2+    or Sr   1-x   La   x   Mg   x-y   Co   y    Al   12-x   O   19   , (with  0 <y<x  for the latter compound). 
     
     
       11. Process according to  claim 10 , also involving the conditioning to a predetermined thickness of the constituent material of the solid active medium. 
     
     
       12. Process according to one of the claims  10  or  11 , the saturable absorber being produced in film form. 
     
     
       13. Process according to  claim 12 , the film having a thickness between 1 and 150 μm. 
     
     
       14. Process according to  claim 12 , the saturable absorber being produced by epitaxy or the sol-gel method. 
     
     
       15. Process according to  claim 12 , the saturable absorber being produced from a solid material conditioned in thin strip form. 
     
     
       16. Process according to  claim 15 , the thin strip being bonded to the active laser material. 
     
     
       17. Process according to  claim 15 , the thin saturable absorber strip and the laser active medium being assembled by bonding, intimate contact or molecular adhesion. 
     
     
       18. Process according to  claim 12 , the film being directly produced on the active laser medium. 
     
     
       19. Process according to  claim 12 , the film being previously deposited on a substrate, which is then assembled with the laser medium. 
     
     
       20. Process according to  claim 19 , the substrate then being removed. 
     
     
       21. Laser telemetry device operating on the principle of the measurement of the travel time of a light pulse, characterized in that it comprises: 
       a passively switched microlaser having a microlaser cavity according to  claim 1 ,  
       means for receiving a light pulse reflected by an object and detection of the reception time of said pulse,  
       means for detection of the emission time of a pulse from the microlaser,  
       a device for measuring the time interval separating the emission time of a microlaser pulse from the reception time of a reflected beam.  
     
     
       22. Car equipped with a telemeter according to  claim 21 . 
     
     
       23. Process according to  claim 10 , the solid active medium constituted by a base material being chosen from among Y 3   Al   5   O   12  ( YAG ) , LaMgAl   11   O   19  ( LMA ) , Y   2   SiO   5  ( YSO ) , GdVO   4   , Y   3   Sc   2   Ga   3   O   12  ( YSGG ) , SrY   4 ( SiO   4 ) 3   O  ( SYS ) , Ga   2   Al   2   SiO   7  ( CAS )  and doped either with erbium or with chromium or with an erbium - ytterbium codoping, or an erbium - ytterbium - cerium codoping.