A two-color, laser-diode-based, full-duplex fiber-wired and millimeter-wave (MMW)-wireless orthogonal frequency-division multiplexing (OFDM) transmission link is performed. With modal control on the two-color laser diode, a single-wavelength optical carrier is used as both the downstream and upstream transmitters to replace the dual-mode one with an optical baseband, which effectively suppresses the chromatic dispersion that occurs in fiber. The proposed system demonstrates a carrier-reused, full-duplex 28-GHz MMW dense wavelength division multiplexing passive optical network (DWDM-PON) system, providing OFDM transmission with 54 Gb/s downstream, 36 Gb/s upstream and 16 Gb/s wireless data rates. The single-wavelength optical carrier transmits data from an optical line terminal (OLT) to a remote node (RN) and then transfers into a dual-wavelength carrier for optically heterodyne beating an MMW carrier, which further wirelessly transmits the data to an optical network unit (OUN). In addition, the upstream data is carried by another slave colorless laser diode injection-locked by reusing the downstream carrier without additional data erasing, which avoids the wavelength selection problem that resulted from identifying or addressing upstream and downstream channels. Among three laser transmitters with different cavity lengths, the 600-μm embedded MMW wireless carrier can provide the lowest bit error rate (BER) after 25 km of fiber and 1.6-m free-space transmissions at 16 Gb/s, because its highest external quantum efficiency supports the optimization on self-heterodyne transferring the MMW carrier to enable the low-noise and long-distance wireless transmission.
© 2017 Chinese Laser Press
The urgent need for data transmission capacity due to emerging modern technologies such as high-definition (HD) and 4K resolution videos puts the research spotlight on fifth generation (5G) mobile wireless communication systems. To meet this demand, a millimeter-wave (MMW) carrier with high central frequency is considered for 5G applications [1–4]. Recently, Intel’s mobile and wireless group proposed two possible MMW carrier frequencies of 28 and 39 GHz that are capable of delivering the data at a bit rate of 1 Gb/s or higher over a free space distance of at least 200 m. Similarly, Samsung has also proposed a 28-GHz wireless communication system to transmit data over 2 km in free space at a data rate of 1 Gb/s . To reduce transmission loss and extend the transmission distance, the microwave-photonics-enabled MMW over fiber (MMWoF) link was recently considered a promising candidate because it is a fused optical/microwave carrier that offers advantages such as long- and low-loss propagation, broadband transmission capacity, excellent flexibility, and mobility [6–9].
To optically synthesize the MMW carrier for wireless data transmission, the sideband generation of a continuous wave (CW) light with an external modulator (EM) is currently a low-cost and mature approach . As early as 1992, O’Reilly et al. used a nonlinearly biased Mach–Zehnder modulator (MZM) with suppressed even-order sidebands to beat a 36-GHz MMW carrier [11,12]. Later, by using a dual-electrode MZM, Smith et al. demonstrated a 20-GHz MMWoF link to transmit pseudorandom binary sequence (PRBS) data at 51.8 Mb/s over an 80-km single-mode fiber (SMF) . In 2001, Ogusu et al. employed a distributed feedback laser diode (DFBLD) combined with a phase modulator (PM) to optically heterodyne a 60-GHz MMW carrier . In 2005, Jia et al. preliminarily proposed wavelength division multiplexing (WDM) data streams with 200-GHz spacing, and the central carriers were simultaneously upconverted to a 40-GHz MMW band using an optical carrier suppression (OCS) technique to show almost identical performance for all wavelengths . As late as 2010, Lin et al. proposed a 60-GHz MMW embedded transmission system with a dual-electrode MZM to transmit a 28-Gb/s 16-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) data in a 25-km SMF link . More recently, Ma et al. employed two CW lasers and three MZMs to optically transmit 110-GHz MMW carried 10-Gb/s PRBS data over 20-km SMF .
In view of previous works using the dual-wavelength optical carrier to transmit data over SMF, most systems inevitably suffer from chromatic dispersion, which deteriorates their transmission capacity [13,18–20]. To overcome such a drawback, a single-wavelength carrier must be used to replace the dual-wavelength one. The single-wavelength carrier can transmit data from optical line terminal (OLT) to remote node (RN) to suppress the chromatic dispersion during optical propagation, which then transfers into a dual-wavelength carrier and self-heterodynes into an MMW carrier for further wireless transmitting the data to optical network units (ONUs). Typically, the DFBLD is a highly coherent single-mode light source in passive optical networks (PONs). However, it is difficult to be employed as a colorless and universal transmitter with controllable wavelength for dense WDM (DWDM) applications. To obtain a wavelength tunable transmitter for a cost-effective PON, the colorless laser diode exhibits long cavity length and low front-facet reflectance, which provides broaden gain spectrum, dense longitudinal modes, and high external injection efficiency to serve as the universal transmitter for all DWDM-PON channels. These are the unique features proposed for such a transmitter with a low fabrication cost . For cost-effective, high-capability, single- or dual-wavelength carrier transmission, an injection-locking technology combined with a multimode laser diode can be implemented, which also improves the output dynamics of the slave laser diode . When considering a suitable laser transmitter for an MMWoF application, a long-cavity colorless laser diode with high injection efficiency, broad gain spectrum, and dense longitudinal modes has recently been proposed to facilitate a DWDM-PON [23–26]. Such a colorless laser diode is designed and fabricated by anti-reflective coating the front-facet of a conventional Fabry–Perot laser diode (FPLD). Recently, Lin et al. used a dual-mode injection-locked colorless laser diode to achieve a baseband capacity of 36 Gb/s, which delivers a stabilized 39-GHz MMW carrier for 4-Gb/s passband transmission . Later, the resonant four-wave-mixing (FWM) suppression of a master-to-slave, injection-locked, two-wavelength colorless laser diode pair is demonstrated for 18-Gb/s baseband and 2-Gb/s passband data transmissions . However, the effect of cavity length on optical wired and microwave wireless data transmissions with the injection-locked colorless laser diode has never been previously discussed.
In this work, a downstream optical carrier that reused a full-duplex 28-GHz MMW-DWDM-PON system with an optical baseband of 54-Gb/s downstream and 36-Gb/s upstream, associated with a 16-Gb/s MMW wireless data transmission, is successfully demonstrated using a single-wavelength injection-locked colorless laser diode. To discuss the effect of laser cavity length on the wired and wireless transmission performances, three colorless laser diodes with different cavity lengths of 600, 750, and 900 μm are selected and compared. The constellation plot, error vector magnitude (EVM), signal-to-noise ratio (SNR), and bit error rate (BER) of delivered downstream and upstream 64-QAM OFDM data are analyzed and discussed. In particular, the upstream data is carried by another colorless laser diode that is injection-locked by reusing the downstream optical carrier without an additional data eraser. This approach effectively avoids the wavelength selection problem that occurred from the upstream and downstream carriers. For 28-GHz MMW wireless communication, the radio frequency (RF) spectrum of a beat MMW carrier is characterized to prove its power stability and spectral purity. Afterward, the free space data transmission performance is analyzed to realize a hybrid fiber-optic wired and 5G mobile wireless communication network with full-duplex functionality.
2. EXPERIMENTAL SETUP
The experimental setup of a carrier-reused, full-duplex MMW-DWDM-PON system based on a single-wavelength, injection-locked colorless laser diode is illustrated in Fig. 1. At the central office (CO), after properly adjusting the polarization status, a high-coherent DFBLD was used to single-mode injection-lock the slave colorless laser diode through an optical circulator for downstream transmission. Three colorless laser diodes with different cavity lengths of 600, 750, and 900 μm were employed and compared. To prevent unexpected wavelength drifting, the temperatures of all downstream laser transmitters were controlled at 22°C. For direct modulation, the 64-QAM OFDM data with subcarrier numbers of 128, 150, 171, 192, and 214 were selected to occupy bandwidths of 6, 7, 8, 9, and 10 GHz, respectively, which represents related raw data rates of 36, 42, 48, 54, and 60 Gb/s. By using a 24-GS/s arbitrary waveform generator (AWG, Tektronix 70001A) and a 10-dB pre-amplifier (Picosecond, 5828), all 64-QAM OFDM data were separately delivered and amplified, respectively. A bias tee (Picosecond, 5542) was used to combine the bias current and the amplified OFDM data to directly encode the single-wavelength downstream optical carrier. After propagating over 25 km of fiber, the optical OFDM data was received by a photodetector (PD, Nortel PP-10G) at the RN, and the recovered electrical OFDM data was amplified by an 18-dB amplifier (New Focus, 1422) for baseband analyzing. In addition, the single-mode downstream carrier with data is reused to injection-lock another 600-μm colorless laser diode to erase the downstream data and transmit the upstream data concurrently. For upstream data transmission, the pre-amplified 4-, 5-, 6-, and 7-GHz 64-QAM OFDM data with subcarrier numbers of 86, 107, 128 and 150, respectively, were selected. After 25-km fiber transmission, the upstream data was also received by the same PD at the CO.
To implement the wireless communication, the downstream carrier after erbium-doped fiber amplifier (EDFA) amplification was converted into a dual-mode optical carrier with a nully biased MZM at the RN. Then, a high-speed PD (U2T, XPDV2020R) converts the dual-mode carrier into a 28-GHz MMW carrier to wirelessly transmit 16-QAM OFDM data with a 4-GHz bandwidth ranged from 1 to 5 GHz. Moreover, a 40-dB MMW amplifier (Quinstar, QLW-24403336) was selected to amplify the MMW carried data to compensate the power attenuation during wireless communication. After wireless transmitting and receiving with a pair of horn antennas (A-INFO, LB-28-25), the 16-QAM OFDM data was frequency downstream converted using a balanced mixer (Quinstar, QMB-Ka) with a local oscillation frequency of 28 GHz. Both the fiber-wired baseband and the wireless transmitted data were sampled by a 100-GS/s digital serial analyzer (DSA, Tektronix 71604C) and decoded with a homemade MATLAB program.
3. RESULTS AND DISCUSSION
In the following discussions, the carrier-reused, full-duplex MMW-DWDM-PON system based on the single-wavelength injection-locked colorless laser diode is divided into fiber-wired downstream baseband, fiber-wired upstream baseband, and MMW-wireless passband transmissions.
A. Fiber-Wired Downstream Baseband Transmission
To compare the property of the colorless laser diodes with different cavity lengths, Fig. 2 shows the power-to-current responses of three free-running devices with same front-facet reflectance of 1% and different cavity lengths of 600, 750, and 900 μm. The cavity lengths of 600, 750, and 900 μm lead to corresponding mode spacings of 0.58, 0.48, and 0.38 nm, and threshold currents of 17, 18, and 20 mA, respectively. Among them, the 600-μm colorless laser diode shows the largest power-to-current slope of 75 mW/A to exhibit its highest external quantum efficiency, which is expected to provide the best modulation efficiency and transmission performance.
To discuss the allowable transmission capacity of these colorless laser diodes under 0-dBm injection-locking, the constellation plots of their delivered 64-QAM OFDM data with different bandwidths after downstream 25-km fiber transmission are shown in Fig. 3. For the 600-μm case, by increasing the encoded OFDM bandwidth from 6 to 10 GHz, the constellation plot gradually becomes blurred with its related EVM degrading from 7.0% to 10.1%. When lengthening the colorless laser diode cavity to 750 μm, it delivered 64-QAM OFDM data that reveals an EVM deterioration from 7.8% to 11.3% with increasing OFDM bandwidth from 6 to 10 GHz. The allowable OFDM bandwidth shrinks by lengthening the cavity length of the colorless laser diode. Because the worse external quantum efficiency induced by lower extinction between stimulated and spontaneous emissions seriously degrades the transmission performance, the 900-μm device provides the highest EVM degrading from 8.2% to 12.1% when broadening the OFDM bandwidth from 6 to 10 GHz.
Moreover, the subcarrier SNRs of decoded 64-QAM OFDM data with different bandwidths delivered by the 600-μm device are shown in Fig. 4(a). When the data bandwidth is increased from 6 to 10 GHz, the average SNR is decreased from 23.1 to 19.9 dB because of the declined laser throughput response at high frequencies. To meet the SNR of 21.2 dB required by forward error correction (FEC) criterion, a maximal allowable OFDM bandwidth of 9 GHz is observed, as its average SNR is beyond 21.23 dB, which enables a raw data rate of 54 Gb/s. Lengthening the cavity to 750 μm slightly degrades the average SNR from 22.2 to 18.9 dB for the delivered 64-QAM OFDM data with the corresponding bandwidth increasing from 6 to 10 GHz, as shown in Fig. 4(b). The SNR degradation inevitably reduces the maximal allowable OFDM bandwidth to 7 GHz with a raw data rate of 42 Gb/s. In comparison, Fig. 4(c) shows that the 900-μm device delivers the same data with its average SNR, reducing from 21.8 to 18.32 dB by expanding the OFDM bandwidth from 6 to 10 GHz, and the supported transmission is 6-GHz 64-QAM OFDM data with a 36-Gb/s raw data rate.
Furthermore, the effect of cavity length on the corresponding BERs of the data delivered by three injection-locked colorless laser diodes after back-to-back (BtB) and 25-km fiber transmissions are shown in Fig. 5. To specifically discuss the data degradation induced by chromatic dispersion, the same receiving power of is set for both cases. Increasing the data bandwidth from 6 to 10 GHz, the BtB transmitted BER of the 600-μm device delivered data is degraded from to , whereas the 750-μm and 900-μm-long colorless laser diode further enlarge their BERs from to and from to , respectively. After transmitting a 25-km fiber, the allowable 64-QAM OFDM data bandwidths for a 600-, 750-, and 900-μm device are up to 9/7/6 GHz with a corresponding raw data rate of 54/42/36 Gb/s to reveal a BER of , respectively. All three cases meet the FEC-required BER of , but the 600-μm case exhibits the highest data rate of 54 Gb/s due to its optimal external quantum efficiency.
To discuss the receiving power sensitivity in more detail, Fig. 6 shows the BER curves as a function of the receiving power for the BtB and 25-km fiber transmitted 64-QAM OFDM data carried by the 600-, 750-, and 900-μm laser transmitters. At the FEC-required BER of , a BtB receiving power sensitivity of is observed for the 54 Gb/s data carried by the 600-μm device, which is degraded to after propagating over 25-km fiber with a 0.9-dB power penalty. For the 750-μm device carrying 42 Gb/s data, the receiving power sensitivity is at BtB transmission and a power penalty of 2.0 dB is observed after 25-km fiber transmission. By lengthening the colorless laser diode to 900 μm for carrying 36 Gb/s data, the receiving power sensitivities of and can be obtained at BtB and 25-km fiber cases, respectively, revealing a power penalty of 1.99 dB.
B. Fiber-Wired Upstream Baseband Transmission
After 25-km fiber transmission, the single-mode downstream optical carrier without additional data erasing is reused to injection-lock another 600-μm slave colorless laser diode for upstream transmission [10,29], in a full-duplex DWDM-PON system. In fact, the colorless laser diode at the RN functions simultaneously as the upstream transmitter and the downstream data eraser. Most important, the injection-locking induced data erasing results in a different output compared to that induced by the gain-saturation. Such a data erasing based on injection-locking has been reported [30,31] and its operation principle is illustrated in Fig. 7, which shows quite different behavior from the CW injection-locking case. The optical data stream greatly suppresses its on/off extinction ratio after injecting into the colorless laser diode, which almost switches off (or significantly smooths) the waveform of the data stream due to nearly identical power-to-current response and finite recovery time of the injection-locked colorless laser diode at highly biased condition.
To investigate the allowable upstream data bandwidth, the constellation plots and related subcarrier SNRs of 25-km fiber transmitted 64-QAM OFDM data carried by the upstream injection-locked colorless laser diode at different bandwidths are shown in Fig. 8. The downstream carrier is directly encoded by a 5-GHz 64-QAM data, which is spectrally filtered by the AWG-based WDM and DWDM couplers before injection-locking the upstream colorless laser diode. Note that the upstream received constellation plot exhibits an increased EVM from 5.7% to 10.3% when extending the data bandwidth from 4 to 7 GHz, and the related average SNR is also degraded from 24.8 to 19.8 dB. To meet the FEC requested EVM and SNR of 8.7% and 21.2 dB, respectively, the maximal allowable upstream data bandwidth can be increased up to 6 GHz with a corresponding data rate of 36 Gb/s.
After 25-km fiber transmission, the corresponding BERs of upstream 64-QAM OFDM data at different bandwidths are shown in Fig. 9. Increasing the modulation bandwidth from 4 to 7 GHz deteriorates the BER from to , and the downstream injection-locked upstream slave colorless laser diode successfully increases its capacity to 36 Gb/s.
The power penalty between BtB and 25-km fiber cases of the upstream transmitted 36 Gb/s data is extracted from the BER responses of BtB and 25-km fiber transmitted responses, as shown in Fig. 10. Under FEC criterion, the BtB receiving power sensitivity is observed at , and there is a power penalty of 1.5 dB after 25-km fiber transmission.
C. Heterodyne MMW Generation and Wireless Data Transmission
Figure 11 illustrates the optical spectra of the injection-locked colorless laser diode with cavity lengths of 600, 750, and 900 μm, including those before and after 25-km fiber transmission, with and without optical dual-mode generation (at an MMW frequency spacing of 28 GHz). After injection-locking, the side-mode suppression ratios (SMSRs) of the 600-, 750-, and 900-μm colorless laser diodes are determined as 50, 45, and 42 dB, respectively. At the same bias current ratio, the colorless laser diode with longer cavity length provides more cavity gain to induce stronger mode competition, which inevitably leads to a smaller injection-locking efficiency. For the 25-km case, an EDFA accompanied with an optical bandpass filter is necessary for enlarging MMW power and minimizing the ASE-induced intensity noises after heterodyne detection.
Note that the optical power of the downstream injection-locked 600-μm colorless laser diode is decreased to after 25-km fiber transmission. For the optical heterodyne generation of the 28-GHz MMW carrier, the downstream transmitted single-mode carrier is transferred into a central carrier-suppressed double sideband (CCS-DSB) carrier using an MZM biased at the null point. Such a transfer inevitably weakens the peak power of the CCS-DSB carrier to . To compensate, an EDFA is employed to amplify the power level of the CCS-DSB carrier. However, the EDFA may induce intensity noise to degrade the data performance. Therefore, it is necessary to investigate the appropriate receiving power for the wireless transmitted data. Figure 12 shows the BER versus the receiving power for the 1-GHz 16-QAM OFDM at a raw data rate of 4 Gb/s carried by the CCS-DSB carrier after 25-km fiber and 0.2-m free space transmissions. Without EDFA amplification, a BER of is observed. With the aid of EDFA to increase the receiving power to , the BER can be suppressed to . On the other hand, the overly increased receiving power from to 0 dBm deteriorates the BER to because of the intensity noise induced by the amplified spontaneous emission of the EDFA. Therefore, the optimal receiving power of is set for the MMW generation and wireless communication.
In addition, the RF spectra of the 28-GHz MMW carriers generated from three downstream colorless laser diodes transmitters with different cavity lengths at a resolution bandwidth (RBW) of 1 Hz are shown in Fig. 13. Note that the same peak power of and spectral linewidth of 1.2 Hz are observed for three MMW. Furthermore, a similar noise floor of also leads to the same carrier-to-noise ratio (CNR) of 55 dB, indicating that the three colorless laser diodes generated 28-GHz MMW carriers reveal identical stability and purity.
With the use of the same MZM biased at a null point and modulated with a 14-GHz local oscillator (LO) signal, the injection-locked 600-, 750-, and 900-μm colorless laser diodes can deliver the optical dual-sideband carrier with 28-GHz MMW frequency spacing. Figure 14 shows the RF spectra of the remotely heterodyned 28-GHz MMW carrier with 3-GHz OFDM data delivered from the injection-locked 600-, 750-, and 900-μm colorless laser diodes after an electrical amplification with a power gain of 40 dB.
Note that the same peak power of for the 28-GHz MMW carriers delivered by three colorless laser diodes is observed. Moreover, the upconverted OFDM data covering 3-GHz bandwidth with a peak power of and a power-to-frequency slope of can be observed.
For implementing the wireless communication at different distances, the BERs of 25-km fiber transmitted 4-Gb/s 16-QAM OFDM data carried by the 28-GHz MMW carrier at free space distance ranged from 0.2 to 1.6 m for three colorless laser diodes are shown in Fig. 15. For the 900-μm colorless laser diode, the BER is increased from to by lengthening the distance from 0.2 to 1.6 m. In contrast, the 750-μm colorless laser diode delivered wireless data degrades its BER from to . Among these laser transmitters, the 600-μm one provides the lowest BER degraded from and , because its best optical baseband transmission performance also guarantees the optimal result of MMW wireless communication.
Under 1.6-m wireless transmission, the bandwidth of 16-QAM OFDM data is enlarged from 1 to 5 GHz to further increase the wireless transmission capacity, which increases the raw data rate from 4 to 20 Gb/s, as shown in Fig. 16. The BER of the 28-GHz MMW carried data transferred from the 900-μm colorless laser diode is increased from to when increasing the data bandwidth from 1 to 5 GHz.
To meet the demand of FEC criterion (), the 900-μm device can support MMW wireless data transmission at a bandwidth of 3 GHz with a BER of to support a raw data rate of 12 Gb/s. Similarly, the 750-μm device also allows a data bandwidth of 3 GHz to give a BER of . Note that the BER of the 750-μm device delivered data is lower than that of 900-μm device delivered one because the 750-μm device exhibits a steeper power-current curve with better external quantum efficiency to enhance the ratio of simulated and spontaneous emissions. With the use of a 600-μm colorless laser diode, the MMW delivered wireless data rate can be further increased to 16 Gb/s with a requested data bandwidth of 4 GHz, which results in a BER of . The highest external quantum efficiency makes the 600-μm colorless laser diode the highest wireless data rate when compared to other cases.
For fair comparison, the Fig. 17 illustrates the subcarrier SNRs of 1.6-m wireless transmitted 12-Gb/s 16-QAM OFDM data carried by three colorless laser diodes with different cavity lengths. All the received data exhibit clear constellation plots with EVMs of 12.7%, 13.3%, and 13.5% obtained for the cases delivered with 600-, 750-, and 900-μm colorless laser diodes, and the average SNRs are 17.9, 17.5, and 17.4 dB, which all pass the FEC-required SNR of 15.2 dB.
To extend the MMW wireless transmitted data bandwidth up to 4 GHz under the same propagation distance of 1.6 m, the constellation plots and related subcarrier SNRs of 16-Gb/s data carried by three colorless laser diodes are shown in Fig. 18, which exhibit blurred constellation patterns compared to that with a 4-GHz data bandwidth. Both Figs. 17 and 18 are for the MMW free-space transmission with same data format of 16-QAM OFDM. Note that the estimated EVMs are 14.6%, 18.2%, and 17.3% for the data delivered by the 600-, 750-, and 900-μm colorless laser diodes, and the retrieved average SNRs are 15.2, 14.8, and 14.6 dB. The optically heterodyned MMW carrier cannot afford 64-QAM OFDM transmission. To perform the free-space MMW wireless transmission after 25-km fiber wired transmission, the QAM-level of the MMW-carried OFDM data must reduce down to 16 under degraded SNR. Note that the 750- and 900-μm colorless laser diodes fail to deliver the data passed the FEC criterion. Only the 600-μm colorless laser diode is qualified to enable the full-duplex MMW-DWDM-PON transmission after 25-km fiber with a baseband 54-Gb/s downstream and 36-Gb/s upstream, and to support the 28-GHz MMW wireless 16-Gb/s transmission over 1.6 m free space.
According to previous work , the orthogonally polarized dual-mode optical carrier with single-mode modulation was made by a delay interferometer and a polarization beam combiner, under the construction of a complex structure with high-cost elements. To perform that work, the polarization of the optical carriers needs to be controlled accurately. In contrast, a single-mode injection-locking and modulation is performed in this work without using dual-mode master control; hence, the modulated data suffers from the least dispersion effect after passing fiber. This suppresses the power-fading- induced distortion when compared to the dual-mode case.
With the modal control on a specifically designed two-color laser diode, the carrier reused full-duplex 28-GHz MMW-DWDM-PON system with a baseband 54-Gb/s downstream and 36-Gb/s upstream, associated with a 28-GHz MMW band 16-Gb/s wireless data transmissions, is demonstrated using the single-wavelength optical carrier. At the RN, the single-wavelength optical carrier transfers into a dual-wavelength carrier to optically heterodyne beat the 28-GHz MMW carrier with a 55-dB CNR to further wirelessly transmit the data to the OUN. When compared to the 750-μm and 900-μm colorless laser diodes, the 600-μm one shows the highest external quantum efficiency, which provides the best modulation efficiency and highest capacity of 54 Gb/s for optical baseband downstream transmission. Moreover, the receiving power sensitivities of and are obtained at back-to-back and 25-km fiber cases, respectively, at the FEC-required BER of . In comparison, the 750-μm and 900-μm devices can only support downstream transmission capacities of 42 and 36 Gb/s, respectively. For upstream transmission, the data is carried by another 600-μm colorless laser diode injection-locked by reusing the downstream carrier without additional data erasing. The upstream transmitted OFDM data can achieve 36-Gb/s capacity to exhibit a receiving power penalty of only 1.5 dB. For the 28-GHz MMW carriers delivered by three colorless laser diodes at the same receiving power of , the same peak power of and spectral linewidth of 1.2 Hz are observed. The 600-μm colorless laser diode embedded MMW wireless carrier can provide the lowest BER after 25-km fiber and 1.6-m free space transmissions because its best baseband transmission performance also supports the optimization on the self-heterodyne transferred MMW carrier to enable low-noise and long-distance wireless transmission. Afterward, the 28-GHz MMW wireless transmission can reach the data rate of up to 16 Gb/s.
Ministry of Science and Technology, Taiwan (MOST) (MOST 103-2218-E-002-017-MY3, MOST 103-2221-E-002-042-MY3, MOST 104-2221-E-002-117-MY3, MOST 105-2218-E-005-003-).
1. S. Mumtaz, K. M. S. Huq, and J. Rodriguez, “Direct mobile-to-mobile communication: paradigm for 5G,” IEEE Wireless Commun. 21, 14–23 (2014). [CrossRef]
2. M. Farooq, M. I. Ahmed, and U. M. Al, “Future generations of mobile communication networks,” Acad. Contemp. Res. J. 2, 15–21 (2013).
3. A. M. Mousa, “Prospective of fifth generation mobile communications,” Int. J. Next-Gener. Netw. 4, 11–30 (2012). [CrossRef]
4. S. Hossain, “5G wireless communication systems,” Am. J. Eng. Res. 2, 344–353 (2013).
5. S. K. Mohapatra, B. R. Swain, N. Pati, and A. Pradhan, “Road towards milli meter wave communication for 5G network: a technological overview,” Trans. Mach. Learn. Artif. Intell. 2, 48–60 (2014). [CrossRef]
6. J. Yao, “Microwave photonics,” J. Lightwave Technol. 27, 314–335 (2009). [CrossRef]
7. M. Sauer, A. Kobyakov, and J. George, “Radio over fiber for picocellular network architectures,” J. Lightwave Technol. 25, 3301–3320 (2007). [CrossRef]
8. H. Harada, K. Sato, and M. Fujise, “A radio-on-fiber based millimeter-wave road-vehicle communication system by a code division multiplexing radio transmission scheme,” IEEE Trans. Intell. Transp. Syst. 2, 165–179 (2001). [CrossRef]
9. K. Ikeda, T. Kuri, and K. Kitayama, “Simultaneous three band modulation and fiber-optic transmission of 2.5-Gb/s baseband, microwave-, and 60-GHz-band signals on a single wavelength,” J. Lightwave Technol. 21, 3194–3202 (2003). [CrossRef]
10. L. Chen, H. Wen, and S. Wen, “A radio-over-fiber system with a novel scheme for millimeter-wave generation and wavelength reuse for up-link connection,” IEEE Photon. Technol. Lett. 18, 2056–2058 (2006). [CrossRef]
11. J. J. O’Reilly, P. M. Lane, R. Heidemann, and R. Hofstetter, “Optical generation of very narrow linewidth millimeter wave signals,” Electron. Lett. 28, 2309–2311 (1992). [CrossRef]
12. J. J. O’Reilly and P. M. Lane, “Remote delivery of video services using mm-wave and optics,” J. Lightwave Technol. 12, 369–375 (1994). [CrossRef]
13. G. H. Smith, D. Novak, and Z. Ahmed, “Overcoming chromatic-dispersion effects in fiber-wireless systems incorporating external modulators,” IEEE Trans. Microw. Theory Tech. 45, 1410–1415 (1997). [CrossRef]
14. M. Ogusu, K. Inagaki, and Y. Mizuguchi, “60 GHz millimeter-wave source using two-mode injection-locking of a Fabry–Perot slave laser,” IEEE Microw. Wireless Compon. Lett. 11, 101–103 (2001). [CrossRef]
15. Z. Jia, J. Yu, and G.-K. Chang, “All-optical 16 2.5 Gb/s WDM signal simultaneous up-conversion based on XPM in an NOLM in ROF systems,” IEEE Photon. Technol. Lett. 17, 2724–2726 (2005). [CrossRef]
16. C.-T. Lin, J. Chen, P.-T. Shih, W.-J. Jiang, and S. Chi, “Ultra-high data-rate 60 GHz radio-over-fiber systems employing optical frequency multiplication and OFDM formats,” J. Lightwave Technol. 28, 2296–2306 (2010). [CrossRef]
17. J. Ma, R. Zhang, Y. Li, Q. Zhang, and J. Yu, “Full-duplex RoF link with broadband mm-wave signal in W-band based on WDM-PON access network with optical mm-wave local oscillator broadcasting,” Opt. Commun. 336, 248–254 (2014). [CrossRef]
18. H. Schmuck, “Comparison of optical millimeter-wave system concepts with regard to chromatic dispersion,” Electron. Lett. 31, 1848–1849 (1995). [CrossRef]
19. U. Gliese, S. Ngrskov, and T. N. Nielsen, “Chromatic dispersion in fiber-optic microwave and millimeter-wave links,” IEEE Trans. Microw. Theory Tech. 44, 1716–1724 (1996). [CrossRef]
20. A. F. Elrefaie, R. E. Wagner, D. A. Atlas, and D. G. Daut, “Chromatic dispersion limitations in coherent lightwave transmission systems,” J. Lightwave Technol. 6, 704–709 (1988). [CrossRef]
21. M.-C. Cheng, C.-T. Tsai, Y.-C. Chi, and G.-R. Lin, “Direct QAM-OFDM encoding of a L-band master-to-slave injection-locked WRC-FPLD pair for 28·20 Gb/s DWDM-PON transmission,” J. Lightwave Technol. 32, 2981–2988 (2014). [CrossRef]
22. M.-C. Cheng, Y.-C. Chi, Y.-C. Li, C.-T. Tsai, and G.-R. Lin, “Suppressing the relaxation oscillation noise of injection-locked WRC-FPLD for directly modulated OFDM transmission,” Opt. Express 22, 15724–15736 (2014). [CrossRef]
23. S.-G. Mun, J.-H. Moon, H.-K. Lee, J.-Y. Kim, and C.-H. Lee, “A WDM-PON with a 40 Gb/s (32 × 1.25 Gb/s) capacity based on wavelength-locked Fabry–Perot laser diodes,” Opt. Express 16, 11361–11368 (2008). [CrossRef]
24. Y.-H. Lin, G.-C. Lin, H.-L. Wang, Y.-C. Chi, and G.-R. Lin, “Compromised extinction and signal-to-noise ratios of weak-resonant-cavity laser diode transmitter injection-locked by channelized and semiconductor-optical-amplifier bleached spontaneous-emission light source,” Opt. Express 18, 4457–4468 (2010). [CrossRef]
25. G.-R. Lin, Y.-H. Lin, C.-J. Lin, Y.-C. Chi, and G.-C. Lin, “Reusing a data-erased ASE carrier in a weak-resonant-cavity laser diode for noise-suppressed error-free transmission,” IEEE J. Quantum Electron. 47, 676–685 (2011). [CrossRef]
26. C.-H. Yeh, C.-W. Chow, Y.-F. Wu, S.-P. Huang, Y.-L. Liu, and C.-L. Pan, “Performance of long-reach passive access networks using injection-locked Fabry–Perot laser diodes with finite front-facet reflectivities,” J. Lightwave Technol. 31, 1929–1934 (2013). [CrossRef]
27. C.-Y. Lin, Y.-C. Chi, C.-T. Tsai, H.-Y. Wang, and G.-R. Lin, “39-GHz millimeter-wave carrier generation in dual-mode colorless laser diode for OFDM-MMWoF transmission,” IEEE J. Sel. Top. Quantum Electron. 21, 1801810 (2015). [CrossRef]
28. H.-Y. Chen, Y.-C. Chi, C.-Y. Lin, C.-T. Tsai, and G.-R. Lin, “Four-wave-mixing suppression of master-to-slave injection-locked two-wavelength FPLD pair for MMW-PON,” J. Lightwave Technol. 34, 4810–4818 (2016). [CrossRef]
29. Z. Xu, Y.-J. Wen, W.-D. Zhong, M. Attygalle, X. Cheng, Y. Wang, T.-H. Cheng, and C. Lu, “WDM-PON architectures with a single shared interferometric filter for carrier-reuse upstream transmission,” J. Lightwave Technol. 25, 3669–3677 (2007). [CrossRef]
30. Y.-C. Su, Y.-C. Chi, H.-Y. Chen, and G.-R. Lin, “Data erasing and rewriting capabilities of a colorless FPLD based carrier-reusing transmitter,” IEEE Photon. J. 7, 7201212 (2015). [CrossRef]
31. Y.-C. Su, Y.-C. Chi, H.-Y. Chen, and G.-R. Lin, “All colorless FPLD-based bidirectional full-duplex DWDM-PON,” J. Lightwave Technol. 33, 832–842 (2015). [CrossRef]
32. H.-Y. Wang, Y.-C. Chi, and G.-R. Lin, “Dual-mode laser diode carrier with orthogonal polarization and single-mode modulation for remote-node heterodyne MMW-RoF,” Opt. Lett. 41, 4676–4679 (2016). [CrossRef]