Polymer semiconductors are usually depicted as bundles of loosely bound chains of conjugated carbon atoms. Interchain interactions are far from negligible in their photophysics and separating inter-chain from intra-chain contribution is an important issue in organic photonics research area. Here, we focus on the class of emitting polymers threaded with sugar macrocycles. The dynamics of the excited states confined on isolated conjugated segments are relevant to photonic applications. Supramolecular chemistry is a reliable tool for controlling chain interactions. Non-covalent encapsulation of conjugated polymers by means of cyclodextrin macrocycles (rotaxination) has been demonstrated to yield effective control of the secondary interactions between conjugated polymer chains and to inhibit the generation of charges in the threaded polymeric backbone under optical excitation. Allowing for inter-chain separation even in densely packed solid-state samples is crucial in order to preserve important characteristics of the material for applications, whilst sometimes leads to new functionalities. Here, a combined spectroscopy study (ultrafast pump-probe, cw-PIA and time resolved photoluminescence) and amplified spontaneous emission characterization of a rotaxinated conjugated polymer is presented together with detailed analysis. We show that optical amplification over a bandwidth of more than 30 nm and amplified spontaneous emission under quasi-cw laser pumping (1 ms pulse width) can be achieved in supramoleculary encapsulated polymer film. We have recently shown that supramolecular encapsulation of conjugated polymers is an effective means to suppress intermolecular interactions, which leads to enhanced spectral properties such as higher luminescence quantum yield and blue shifted emission. Ultrafast spectroscopy and cw-PIA results show that supramolecular threading reduces the generation of long-lived states, thus broadening the gain bandwidth and enabling for quasi-continuous wave optical pumping for optical amplification. Here, we show how the emitting properties of conjugated polyrotaxanes lead to a high impact photonic application that finds its natural location as the active medium in lasing systems and optical amplifiers for wavelength division multiplexing. Furthermore, the material investigated here represents the first step (and demonstration of proof-of-principle) towards organic lasers operating under quasi-continuous optical pumping. The optical properties are expected to be strongly improved through appropriate encapsulation as well as device geometries optimizations.