Performance enhancement of an optically-injected-semiconductor-laser-based optoelectronic oscillator by subharmonic microwave modulation

Abstract

An approach to enhancing the performance of an opticallyinjected-semiconductor-laser-based optoelectronic oscillator (OEO) is proposed by subharmonic microwave modulation. A free-running OEO is first established based on period-one dynamics of an optically injected semiconductor laser. The oscillation frequency can be tuned in the range of 8.87 to 18.41 GHz by controlling the injection strength, but the output signal suffers from strong side modes and poor frequency stability. To address these problems, subharmonic microwave modulation is applied to the injected semiconductor laser. In the experiment, microwave modulation with 1/2, 1/4, and 1/6 subharmonics is demonstrated. The side-mode suppression ratio is improved by over 40 dB, while the phase noise at a 1 kHz offset is reduced by about 18 dB. Furthermore, the frequency drift over a period of 20 min, which characterizes the long-term stability, is reduced from 8.7 kHz to less than 1 Hz, indicating a significant reduction of over three orders.

Characteristics of microwave photonic signal generation using vertical-cavity surface-emitting lasers with optical injection and feedback

“…The phase noise can also increase the linewidth of the generated microwave, which affects the performance in radio over fiber (RoF) applications and the maximum detection range in Doppler velocimeters [20], [21]. To solve this problem, many methods have been introduced, such as using double-locking with a microwave source [12], [22], [23], optoelectronic feedback [24], [25] and optical feedback [9], [26]- [28]. Among all of these schemes, optical feedback is a simple and low-cost method to reduce the phase noise and linewidth.…”

Tunable Photonic Microwave Up-Converter Using Opto-Electronic Oscillator Based on Monolithic Integrated Three-Section Laser

“…In this study, the phase noise reaches the level of -99.8 dBc/Hz@1kHz and -130 dBc/Hz@10kHz at 22.7 GHz, as shown in Fig.3(b). With such a low phase noise, the OEO based on the integrated laser is superior or at least comparable to those based on discrete devices [27,28] Firstly, a sinusoidal IF of 2 GHz at -10 dBm is modulated on SL via an EC, and two modulated sidebands appear accordingly, resulting in two beating frequencies of 16 GHz and 20 GHz. Benefitting from the high-quality IF, the phase noises of the converted sinusoidal frequencies are -132 dBc@10kHz and -135 dBc@10kHz respectively, which are slightly better than the oscillation frequency and worse than the IF, as shown in Fig.…”

Period-One Laser Dynamics for Photonic Microwave Signal Generation and Applications

“…In addition, the phase noise performance at low offset frequencies deteriorates. In [38], Zhou et al proposed combining the advantages of subharmonic microwave modulation and dual-loop optoelectronic feedback to stabilize the P1 oscillation signal of OISLs, as shown in Figure 7. Therefore, both the performance of the spectral purity and frequency stability were significantly improved.…”