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A multi-section active photonic integrated circuit (PIC) is characterized in detail to gauge its suitability as a transmitter for short reach applications. The PIC is 1.5 mm long and consists of two lasers integrated in a master-slave configuration, which enables optical injection locking (OIL) of the slave laser. The beneficial impact of the injection is characterized by static and dynamic measurements. The results show a reduction of the optical linewidth from 8 MHz to 2 MHz, a relative intensity noise (RIN) value as low as −154.3 dB/Hz and a 45% improvement of the slave laser modulation bandwidth from 9.5 GHz to 14 GHz. This frequency response enhancement allows the direct modulation of the slave gain section at a data rate of 10.7 Gb/s and an error-free transmission over 25 km of standard single-mode fiber (SSMF). Transmission performance of the injected case shows a 2 dB improvement in the minimum optical power required to achieve a bit error rate of 3.8×10−3 (hard decision forward error correction limit). These results demonstrate that the multi-section PIC can serve as an attractive cost-efficient transmitter in a wide variety of low-cost short-reach data communication applications.

We demonstrate a novel directly modulated transmitter, based on a six-section photonic integrated circuit. The device uses a unique master-slave configuration with a variable optical attenuator in between, allowing decoupling of cavities and independent control of the injection power. The VOA also provides the ability to find an optimum injection level that balances the trade-off between the extinction ratio and the chirp of the transmitted signal. Using the device, an error-free transmission of a 10 Gb/s non-return-to-zero signal over 25 km and 50 km standard single mode fibre is achieved.

The authors present the complete characterization of two cost-efficient photonically integrated slotted lasers that offer regrowth free manufacturing. Furthermore, the application of these devices, as multi-carrier transmitters is also investigated. In particular, the authors employ gain switching, an optical frequency comb (OFC) generation technique based on the direct modulation. The first device used is a dual section discrete mode index patterned device. It comprises two sections, implemented in a master-slave configuration to achieve optical injection locking (OIL) of the slave section. The second, a foursection device, consists of two regrowth-free Fabry-Perot lasers, also forming a master-slave configuration. The authors demonstrate that the additional sections give finer control over the OIL parameters of the device. Results show that the OIL leads to the enhancement of the modulation bandwidth, which in turn can be used to generate a broader OFC. The generated OFC is characterized to demonstrate additional improvements brought