Some quality issues of low-cost 1300nm laser diode packaged-in receptacles

Laser diodes packaged in receptacles are attractive candidates for the deployment of optics in the Access Network because of their simple design and easy handling. Nevertheless, such devices may suffer from specific issues which affect their output power stability. Two different types of receptacle technologies based respectively on the FC/PC and the EC connector concepts have been carefully investigated. The electro-optic characterization has mainly consisted in the recording of P(I) over a large temperature range and in the measurement of mating repeatability. In addition, the inner ''optical. structure'' of each type of device has been investigated by low coherence reflectometry. The results obtained show that the EC concept makes it possible to design laser diode receptacles with good properties : repeatability (approximate to 0.1dB) and random mating (approximate to 0.5dB). On the other hand, FC/PC receptacles exhibit random mating higher than 1dB, a fact which illustrates the strong impact of the patchcord on coupled power. In addition, depending upon the patchcord and temperature of testing, P(I) curves of FC/PC receptacles may exhibit strong non-linearities. The investigation of such devices with low coherence reflectometry shows that they are due to multiple optical reflections in the cavity formed by the front facet laser and the fiber end. Such a behaviour highlights the weakness of the basic concept of FC/PC receptacles. That physical contact is difficult to maintain whatever the patchcord and the environmental temperature conditions.