[CITIC Securities: Optical module temperature control is being upgraded from a "supporting link" to a "performance-determining link"] On September 30, CITIC Securities pointed out that with the large-scale ramp-up of 800G optical modules and 1.6T entering the first year of mass production, single module power consumption and requirements for temperature control accuracy are significantly increasing, and optical module temperature control is being upgraded from a "supporting link" to a "performance-determining link." Optical module temperature control forms a three-layer system of chip-level precise temperature control (Micro-TEC + ceramic substrate heat sink), interface thermal conductivity (TIM gel/graphene gasket), and module-level heat distribution (VC soaking plate/cold plate). The value of single-module temperature control increases systematically with speed iterations; with the superposition of CPO/NPO architecture, optical engines and switching chips dissipate heat in the same area, and the industry is experiencing both volume and price increases. In terms of competition, core links such as TEC and ceramic substrates have been dominated by Japanese manufacturers for a long time. Domestic manufacturers are accelerating breakthroughs, and there is broad room for domestic substitution. CITIC Securities recommends focusing on three main lines of segmented investment: TEC and ceramic substrates, TIM and graphene thermal conductive materials, VC vapor chambers and liquid cooling structural parts.