Abstract: An optical wavelength-division multiplexing (“WDM”) device utilizing a mechanism of folded optical-path includes multiple collimators, optical filters, prism, and glass plate. The collimators are capable of collimating optical lights for facilitating free-space optical communication. The optical filters optically coupled with the collimators provide filtering functions to separate optical wavelengths in accordance with the configurations or characteristics of optical filters. The prism having an interface surface and two side surfaces is configured to direct or redirect optical beams based on the angle of incidence (“AOI”) of each optical beam received. The glass plate, in one embodiment, physically configured to be situated in parallel with the collimators is capable of providing free-space optical paths for facilitating separation of wavelengths.

Abstract: Method and multiport free-space wavelength division multiplexing (“WDM”) device capable of handling multiple optical signals carried in multiple wavelengths (“?n”) using a relay lens are disclosed. The WDM device includes an optical filter, collimator, optical relay, and a relay optical filter. The optical filter is able to receive an optical beam containing multiple ?n and subsequently extract a first wavelength (“?1”) from ?n. A second optical beam is formed by the remaining of ?n. The collimator, in one example, receives ?1 from the optical filter. Upon receiving the second optical beam, the optical relay collimates the second optical beam with minimal loss due to light divergence. The relay optical filter, in one aspect, is configured to receive the collimated second optical beam and redirects the collimated second optical beam to a predefined intended orientation.

Abstract: A multiport free-space wavelength division multiplexing (“WDM”) device is capable of handling multiple optical signals carried in multiple wavelengths (“?n”) using a prism. The WDM device includes an input collimator, prism, and optical filter. The input collimator receives an optical beam containing multiple wavelengths ?n traveling through free-space. The prism uses at least two (2) surfaces to generate a first optical beam which travels in opposite direction of the optical beam. The optical filter is situated at a predefined angle with respect to the interface surface of the prism for facilitating frequency separation as well as extracts a first wavelength (“?1”) from ?n to form a first light signal with ?1 and form a second optical beam with the remaining wavelengths of ?n. A collimator is used to guide the first light signal to a port.