Future mobile and terrestrial communication systems B5G/6G are strongly expected to heterogeneously realize typically diversified performances, i.e. high-data-rate, high-mobility, low-latency, high-capacity, massive-connectivity and low-energy in order to satisfy the highly diversified application requirements. To achieve those goals the operation band of B5G/6G should be primarily in the millimeter-wave (mmW) range. Generation and distribution of mmW with traditional methods is limited by electronic bottleneck and associated complexity. Consequently broad bandwidth, simple, efficient, and cost-effective photonic mmW-over-fiber (mmWoF) transmission systems are solutions for B5G/6G. The spectral purity of mmW carriers is necessary. Numerous approaches have been proposed to generate pure mmW signals. Compared with other technologies, quantum dash or dot (QD) coherent comb lasers (QD CCLs) have great advantages for mmW generation because QD-CCLs with low power consumption and chip-scale integration capacity with silicon can provide multiple highly correlated and low noise optical channels. In this paper we will present our developed InAs/InP QD-CCLs around 1550 nm with the channel spacing from 10 GHz to 1000 GHz and the output power up to 50 mW. By using a C-band QD CCL and based on the single- and dual-optical carrier modulation schemes, an up to 16-Gb/s mmWoF optical heterodyne wireless signal at 28 GHz through a 25-km single mode fiber before the mmW carrier is optically synthesized remotely for detection over a 2-m free space. The data capacity and performance of the proposed mmWoF link can be significantly increased by utilizing a duplex mmWoF link with MIMO and WDM technique, which provides a cost-efficient and promising solution for Terabit/s capacity mmWoF fronthaul systems of B5G/6G networks.
This work has proposed and compared several millimeter wave (mmWave) radio-over-fiber (RoF) frequency multiplexing techniques based on InAs/InP quantum dash (QD) mode locked laser (MLL). QD-MLL is capable of generating tens of highly coherent optical carriers simultaneously with same frequency difference. After heterodyne detection, the RF phase noise of QD-MLL can be as low as 15kHz. In this paper, four different RoF based mmWave frequency multiplexing architecture is proposed and compared in experimentation. The EVM of two 2GBaud/s 16-QAM mmWave signal can be as low as 7.1% after demultiplexing in the experimentation.
A directly modulated quantum dash mode-locked laser is proposed for a 50-GHz millimeter-wave over fiber architecture. This advancement offers enhanced fiber-wireless communication capabilities, facilitating coverage of 15-km SMF and 2-m wireless QPSK transmissions. By utilizing the directly modulated laser (DML), we have successfully achieved an optical heterodyne mmW frequency of 50 GHz with exceptional stability. Notably, the measured RF beat-note 3-dB linewidth of the QDash DML is significantly reduced to 2.4 kHz, without the need for any optical feedback scheme. This DML-based hybrid architecture demonstrates the potential to seamlessly integrate with existing optical and wireless networks for next-generation indoor and short-reach mobile communications.
In this work, we have investigated self-injection locking effects on a full spectral system with selective single-channel injection and full-channel injection in a quantum dot mode-locked comb laser through an optical feedback loop. It has been noticed that self-injection locking can not only improve the performance of a single-channel laser system but also has a strong effect on the whole spectral behavior. In the case of single-channel self-injection, we investigated the effects under a locked regime above the injection-locking threshold PSIL. The locked lines were strongly enhanced with intensities high above the broad spectrum and also intensified even outside of the original spectral bandwidth. The typical feature is a big dip (or hole) appearing on the high-energy side of the lines if it is within the free-running spectral region. We have investigated this asymmetric phenomenon. It is considered that the locked modes are highly intensified at the expense of higher energy carriers excited by currents. The locking process transferred the energy from the lasing mode to the locked mode. For the full channel self-injection, the system was set under a controllable self-injection locking condition. A bandwidth enhancement phenomenon can be observed when injected power reaches the self-injection locking threshold PSIL, and the broadening gets stronger till to the locked regime. Finally, the original spectral bandwidth had been significantly broadened. This bandwidth broadening goes to both sides of the free-running spectrum and the broadening is remarkable.
In this work, we demonstrate the establishment of a self-injection locking threshold in a quantum dot (QD) comb laser with a Fabry-Perot cavity and an external feedback loop. This process involves controlling injection power and polarization to inject a controlled fraction of lasing power back into the QD laser source. The study is focused on the single line self-injection locking effects. The self-injection locking process was characterized by a self-injection locking threshold power (PSIL) and a locked power (Plocked). The self-injection locking process begins from the threshold power PSIL and followed by a magnified enhancement till it reaches the locked power (Plocked). Once in the locked region, the enhancement effect starts to stabilize and is only weakly influenced by injection power. The established threshold provides a distinctive condition for the measurements of the modified optical properties of the coupled cavity system. Additionally, the locked single lines tested at different currents indicated a very broad spectral coverage which are much larger than the original bandwidth of free running QD laser.
To support enhanced mobile broadband (eMBB) communication, 5G is going to use new radios (NRs) at frequencies above 24.25 GHz in the millimeter-wave (mm-wave) bands with abundant available bandwidths. The photonic generation, modulation and distribution of such ultra-high speed broadband RF signals in the optical domain is more promising compared to the bandwidth limiting electrical technology, however, it requires low noise coherent optical sources. In this paper, we present a highly coherent low noise InP-based p-n block buried heterostructure (BH) C-band InAs/InP quantum dash (QD) passively mode-locked laser (MLL) for photonic aided broadband wireless communication systems. The device features repetition rates of 25 GHz resulting in an optical coherent frequency comb (CFC) with a 6-dB optical bandwidth of around 9 nm providing over 46 channels. Each individual channel of the CFC exhibits an average phase noise and integrated relative intensity noise (RIN) of less than 500 kHz and -130 dB/Hz in the frequency range from 10 MHz to 20 GHz, respectively. Its timing jitter and RF beat-note linewidth between any two adjacent channels are as low as 5.53 fs and 3 kHz, respectively. By using this QD MLL, a photonic aided radio-over-fiber (RoF) broadband quadrature amplitude modulated (QAM) signal wireless delivery at around 25 GHz (K-band) is successfully demonstrated over 2-m free space wireless distance through 25.22 km standard single-mode fiber (SSMF) with a total link capacity of 16Gbit/s and error vector magnitude (EVM) below the standard requirements of 12.5%.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.