Characterization and Direct Modulation of a Multi-Section PIC Suited for Short Reach Optical Communication Systems

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.

Investigation and Suppression of Fiber Nonlinearities Using Injection-Locking in OFDM-WDM System

The fiber nonlinearities play a major role in optical communication with respect to the system performance and transmission capacity. Here, fiber nonlinear impairments are investigated through consideration of several parameters of optical fiber system, such as fiber length and core effective area. We also demonstrate the mitigation of fiber nonlinearities by using single-stage injection-locking in 3 × 10 Gb/s OFDM-WDM system. This paper focuses on selection of appropriate bias current for slave laser to suppress the four wave mixing (FWM) crosstalk effects. These findings resemble the importance of single-stage injection-locking for FWM suppression for high-speed data communication.

COMPLEXITY AND SYNCHRONIZATION IN CHAOTIC INJECTION-LOCKING SEMICONDUCTOR LASERS

The chaotic complexity properties of semiconductor lasers in the chaotic synchronization systems are investigated numerically, based on the information theory based quantifier, the permutation entropy (PE). We find that, on the one hand, the degree of complexity for the master laser increases with the feedback strength firstly and then saturate at higher feedback strength, but are hardly affected by the feedback delay. On the other hand, for the slave laser, the complexity degree is closer to that for the master laser when the high quality chaos synchronization is obtained, which shows that, the PE method is a successful quantifier to evaluate the degree of complexity for the chaotic signals in chaos synchronization systems, and can be considered as a complementary tool to observe the synchronization quality.

ROLE OF HYSTERESIS ON THE MODE-SHIFT CHARACTERISTICS OF INJECTION LOCKING A LASER DIODE

Using Lang's equation for the dynamics of injection locking of a laser diode, we show that the hysteresis property of the excess carrier density has direct influence on the mode-shift characteristics, which makes the shift of the slave laser mode to be different from the frequency detune of the external master laser signal within the locking range of the slave laser. The theoretical prediction is experimentally confirmed by the measurement of the mode-shift of an injection locked Fabry-Perot laser diode.