Abstract: An optical sub-assembly is disclosed, having a mating end adapted to receive a mating fiber, and a back end provided with a converging lens establishing an expanded beam interface with an optical device. The use of an expanded beam interface provides greatly improved stability, and reduces the sensitivity to slight misalignments The optical sub-assembly comprises a receptacle for which the manufacturer thereof has full control over the optical interfaces and refractive index boundaries. The receptacle and the optical device may be manufactured separately.

Abstract: An integrated wavelength monitor and a method for obtaining such a device are disclosed. The device suitable for integration into a laser semiconductor laser module for fiber optic communication can be made in the following way: An interference filter is created directly onto a position sensitive photo detector by depositing a number of layers of different optical transparent materials forming an optical filter. The interference filter may also be created separately and subsequently mounted directly on top of the detector. The integrated position sensitive device (13) is mounted with an angle behind a laser in the same position as a normal power monitor detector. The electrically derived lateral position of light hitting the Position Sensitive Device provided with the interference filter will be dependent of the wavelength of the incident light and this derived position is used for the wavelength monitoring.

Abstract: An optical receiver and transmitter module comprises a substrate and receiver, transmitter and monitor chips mounted behind each other on the surface of the substrate. Optical waveguides extend from an edge of the substrate up to active surfaces of the receiver and transmitter chips, these active surface all having the same orientation. The waveguides extending to the transmitter chip pass in grooves in the bottom surface of the receiver chip which is placed in front of the transmitter chip. No space on the substrate is required for bends of the waveguides which all have a substantially straight configuration which allows the substrate to be made with minimum dimensions.