Review of 1.55 μm Waveband Integrated External Cavity Tunable Diode Lasers

The 1.55 μm waveband integrated external cavity tunable diode lasers have excellent merits such as their small volume, low cost, low power consumption, wide tuning range, narrow linewidth, large side mode suppression ratio, and high output power. These merits have attracted many applications for the lasers, such as in wavelength division multiplexing, passive optical networks, mobile backhaul, and spectral sensing technology. In this paper, firstly, the basic structure and principle of integrated external cavity tunable diode lasers are introduced, and then two main integrated structures of 1.55 μm waveband external cavity tunable diode lasers are reviewed and compared in detail, namely the hybrid integrated structure and monolithic integrated structure of 1.55 μm waveband integrated external cavity tunable diode lasers. Finally, the research progress in 1.55 μm waveband integrated external cavity tunable diode lasers in the last decade are summarised, and the advantages and disadvantages of 1.55 μm waveband integrated external cavity tunable diode lasers are analysed. The results show that, with the transformation of optical communication into more complex modulation formats, it is necessary to integrate miniature 1.55 μm waveband external cavity tunable diode lasers. Low-cost integrated 1.55 μm waveband external cavity tunable diode lasers are expected to be used in the next generation of optical transceivers in small-factor modules.