A lighting device comprising: - one or more light sources configured to provide light source light; - a luminescent element comprising an elongated light transmissive body having a first face and a second face defining a length of the light transmissive body, the light transmissive body comprising one or more radiation input faces and a first radiation exit window, wherein the second face comprises the first radiation exit window; the elongated light transmissive body comprising a luminescent material configured to convert at least part of light source light received at one or more radiation input faces into luminescent material light, and the luminescent element configured to couple at least part of the luminescent material light out at the first radiation exit window as converter light; wherein the light transmissive body has a first index of refraction n1; - a beam shaping optical element optically coupled with the first radiation exit window, the beam shaping optical element comprising a radiation entrance window configured to receive at least part of the converter light; wherein the beam shaping optical element has a second index of refraction n2; wherein: - 0.75≤n1/n2≤1.25; - an optical connector configured between the elongated light transmissive body and the beam shaping optical element, characterized by the optical connector comprising a glass material, wherein the glass material has acomposition selected from a range defined in the ternary B 2 O 3 -Bi 2 O 3 -ZnO diagram by the following compositions indicating the quadrilateral corner points of the range: mol% B 2 O 3 mol% Bi 2 O 3 mol% ZnO 25 mol% 7.5 mol% 67.5 mol% 80 mol% 20 mol% 0 mol% 65 mol% 35 mol% 0 mol% 22.5 mol% 20 mol% 57.5 mol% - wherein the beam shaping optical element comprises an optical element material different from the glass material, - and wherein the optical connector comprises a glass frit connection. - one or more light sources configured to provide light source light; - a luminescent element comprising an elongated light transmissive body having a first face and a second face defining a length of the light transmissive body, the light transmissive body comprising one or more radiation input faces and a first radiation exit window, wherein the second face comprises the first radiation exit window; the elongated light transmissive body comprising a luminescent material configured to convert at least part of light source light received at one or more radiation input faces into luminescent material light, and the luminescent element configured to couple at least part of the luminescent material light out at the first radiation exit window as converter light; wherein the light transmissive body has a first index of refraction n1; - a beam shaping optical element optically coupled with the first radiation exit window, the beam shaping optical element comprising a radiation entrance window configured to receive at least part of the converter light; wherein the beam shaping optical element has a second index of refraction n2; - 0.75≤n1/n2≤1.25; - an optical connector configured between the elongated light transmissive body and the beam shaping optical element, characterized by the optical connector comprising a glass material, wherein the glass material has acomposition selected from a range defined in the ternary B 2 O 3 -Bi 2 O 3 -ZnO diagram by the following compositions indicating the quadrilateral corner points of the range: mol% B 2 O 3 mol% Bi 2 O 3 mol% ZnO 25 mol% 7.5 mol% 67.5 mol% 80 mol% 20 mol% 0 mol% 65 mol% 35 mol% 0 mol% 22.5 mol% 20 mol% 57.5 mol% - wherein the beam shaping optical element comprises an optical element material different from the glass material, - and wherein the optical connector comprises a glass frit connection.