A circuit module can include a substrate, a photonic conversion unit placed on the substrate; and a retention assembly. The retention assembly can include a heat sink in thermal contact with the photonic conversion unit and a fastener. The fastener can be mechanically coupled to both the substrate and the heat sink, and configured to press the heat sink against the photonic conversion unit. The photonic conversion unit is removably secured to the substrate by the retention assembly without the use of a bonding material.