ɪt mˈeɪ mˈiːn ðætðə ɡˈeɪn ʌvðə lˈeɪzɚ mˈiːdiəm ʃˌʊd biː dˈʌbəld, fɔːɹ ɛɡzˈæmpəl, dˈʌblɪŋ ðə pˌɑːpjʊlˈeɪʃən ʌvðɪ ˌʌpɚ lˈeɪzɚ lˈɛvəl ɪn ɐ kwˈeɪzaɪtˈuː lˈɛvəl sˈɪstəm ɐsˈuːmɪŋ nˈɛɡlɪdʒəbəl ɐbsˈoːɹpʃən ʌvðə ɡɹˈaʊndstˈeɪt.
It may mean that the gain of the laser medium should be doubled, for example, doubling the population of the upper laser level in a quasi-two level system (assuming negligible absorption of the ground-state).