Future 5G and beyond services rely on the network slicing concept, in which underlying network elements are split and/or aggregated to compose a synthetic network infrastructure (the slice) to satisfy the requirements of services that will be executed on top. Generally speaking, end-to-end network slices comprise multiple network segments, including optical and data centers networks. Therefore, the provisioning of end-to-end network slices is a challenging task that has to consider the characteristics of the different technologies to satisfactorily map the requirements coming/imposed from the services to be deployed. This requires that offers towards the fulfillment of the services to be supported are properly parametrized, enabling the possibility to translate them into specific slice and network services characteristics to be finally materialized in concrete infrastructure resources. On the other hand, there is a rising trend of quality assurance at all levels to satisfy the requirements of services deployed, requiring the runtime maintenance of quality of service/experience of the deployed slices. Due to the dynamic nature of services, it becomes essential to monitor the associated Key Performance Indicators (KPIs), derive from them current quality levels and implement the necessary mechanisms to steer the behavior of the slices towards the maintenance of optimal quality levels. Given such scenarios, in this paper we present a framework that enables the provisioning and orchestration of network slices in multi-domain/segment optical networks as well as an approach to proactively manage the maintenance of the required slices quality. The presented framework is validated through several experimental results.