A light generating system comprising a first light generating device , a second light generating device , a first luminescent material , a window element , and a light mixing chamber , wherein: - the first light generating device is configured to provide first device light ; wherein the first light generating device comprises one or more of a laser and a superluminescent diode; - the second light generating device is configured to generate second device light ; wherein the second light generating device comprises a solid state light source; - the light mixing chamber is defined by the window element and reflective walls, wherein the reflective walls having an average reflectivity for the second device light of at least 50 %; - the window element comprises (i) a first window element part comprising the first luminescent material , wherein the first window element part is configured in a light receiving relationship with the first light generating device , and (ii) a second window element part , wherein the second window element part is translucent for the second device light , and wherein the second window element part is configured in a light receiving relationship with the second light generating device ; wherein the first window element part and the second window element part are configured in thermal contact with each other; wherein the first window element part and the second window element part differ in material composition; - the first luminescent material is configured to convert at least part of the first device light into first luminescent material light ; - the reflectivity of the second window part is selected from the range of 30 - 70 % for the second device light ; and - wherein the second window element part does not comprise a luminescent material that is configured to convert the second device light . - the first light generating device is configured to provide first device light ; wherein the first light generating device comprises one or more of a laser and a superluminescent diode; - the second light generating device is configured to generate second device light ; wherein the second light generating device comprises a solid state light source; - the light mixing chamber is defined by the window element and reflective walls, wherein the reflective walls having an average reflectivity for the second device light of at least 50 %; - the window element comprises (i) a first window element part comprising the first luminescent material , wherein the first window element part is configured in a light receiving relationship with the first light generating device , and (ii) a second window element part , wherein the second window element part is translucent for the second device light , and wherein the second window element part is configured in a light receiving relationship with the second light generating device ; wherein the first window element part and the second window element part are configured in thermal contact with each other; wherein the first window element part and the second window element part differ in material composition; - the first luminescent material is configured to convert at least part of the first device light into first luminescent material light ; - the reflectivity of the second window part is selected from the range of 30 - 70 % for the second device light ; and - wherein the second window element part does not comprise a luminescent material that is configured to convert the second device light . <EOS>