Lighting device with plurality of stacked luminescent concentrators

A lighting device comprising:

• a plurality of luminescent concentrators including at least a first luminescent concentrator and a second luminescent concentrator, each luminescent concentrator of the plurality of luminescent concentrator comprising an elongated light transmissive body having a first face and a second face defining a length of the elongated body, the elongated body comprising one or more side edges, wherein one or more side edges comprise one or more radiation input faces, wherein the second face comprises a radiation exit window;
• the elongated light transmissive body comprising a luminescent material configured to convert at least part of a pump radiation received at the one or more radiation input faces into luminescent material light, and each luminescent concentrator configured to couple at least part of the luminescent material light out at the radiation exit window as converter light;
• a plurality of light sources configured to provide light source radiation as first pump radiation to the one or more radiation input faces of a first luminescent concentrator;
• said first luminescent concentrator comprising a first luminescent material configured to convert at least part of the first pump radiation into first luminescent material light, and configured to couple at least part of the first luminescent material light out at the first radiation exit window as first converter light;
• said second luminescent concentrator configured parallel to the first luminescent concentrator with a side edge of the first luminescent concentrator configured parallel to a side edge of the second luminescent concentrator, wherein the second luminescent concentrator is configured to receive at said side edge of the second luminescent concentrator one or more of said first pump radiation and said first luminescent material light escaping from said side edge of said first luminescent concentrator as second pump radiation, the second luminescent concentrator comprising a second luminescent material configured to convert at least part of the second pump radiation into second luminescent material light, and configured to couple at least part of the second luminescent material light out at the second radiation exit window as second converter light;
• and
• wherein one or more of the luminescent concentrators are longer than one or more of the other luminescent concentrators, thereby providing one or more luminescent concentrator extending parts extending relative to the one or more other luminescent concentrators, and wherein a subset of one or more light sources is configured to provide light source radiation to the one or more luminescent concentrator extending parts.