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Herein, a lucid meta-holographic approach leveraging geometric phase metasurfaces and photonic crystal surface-emitting lasers is presented. Such a straightforward technique inherently enables polarized structured light projection with opposite circular polarization states, effectively doubling the field of view for depth sensing applications. Furthermore, the innate polarization state of projected light provides enhanced resistance to environmental interference. To demonstrate the practical utility of this method, an integrated depth sensing system based on the geometric phase meta-hologram has been developed and successfully detects targets at an operating distance of 75 cm, paving the way for advanced 3D sensing applications in various fields.

We put forward and demonstrate a steerable optical beam visible light communication (VLC) system combining orthogonal frequency division multiplexing (OFDM) and non-orthogonal multiple access (NOMA) schemes, and utilizing a spatial light modulator (SLM)-based reconfigurable intelligent surface (RIS) for beam steering. When utilizing the SLM as RIS for optical beam steering, its operation principle, maximum achievable steering angle (i.e., field-of-view, FOV), as well as the corresponding loss should be analyzed. We theoretically and experimentally analyzed in detail the characters of SLM when acting as the RIS. Experimental results demonstrate the flexibility of both active beam control and data rate allocation for multiple users. The SLM-based RIS can independently and simultaneously control multiple beams, and significantly reduce the deploying cost of the increase in the devices for the multi-beam handling scenario. All of the specified channels under evaluation satisfy the pre-forward error correction bit-error rate limit (pre-FEC BER = 3.8 × 10−3).

In the paper, a hybrid Mach-Zehnder interferometer (MZI) and Rayleigh backscattering (RB) injection is designed and applied in the erbium-doped fiber (EDF) ring laser configuration. The MZI scheme and RB-induced signal can accomplish the single-longitudinal-mode (SLM) oscillation and narrow the linewidth to kHz target for each generated wavelength over the available wavelength-tuning bandwidth. In the measurement, the output power, optical signal to noise ratio (OSNR) and wavelength linewidth of the designed fiber laser are also executed and discussed.

We put forward and provide the first illustration of a high capacity and high spectral efficient free space optical communication (FSOC) system using digital domain power division multiplexing orthogonal-frequency-division-multiplexed (DDPD-O-OFDM) signal utilizing 10-GHz class optical components. In the proof-of-concept demonstration, a data rate of 2 × 30.8 Gbit/s can be achieved for each polarization multiplexed wavelength channel, fulfilling the pre-forward-error-correction bit-error-ratio (pre-FEC BER = 3.8 × 10−3). By employing the DDPD-O-OFDM here, the FSOC per channel capacity can be enhanced not only allowing the spectral overlapping of different orthogonal subcarriers, as in the case of OFDM; but also allowing channel multiplexing in the power domain to increase the spectral efficiency. The principle of DDPD-O-OFDM is discussed; and BER and signal-to-noise ratio (SNR) of different DDPD channels are experimentally measured.

We propose to utilize a commercially available DIALux lighting design software for simulation and planning of machine learning (ML) based angle-of-arrival (AOA) visible light positioning (VLP) systems. Here, different ML models, for example, second order linear regression (LR), artificial neural-network (ANN), and convolutional neural-network (CNN) are employed. The proposed VLP simulator works well with different ML algorithms. The results show that the proposed scheme can acts as an effective indoor VLP planning and design tool. Besides, it may also alleviate the training data collection in ML based VLP systems.

Inthe work, we study and express a new wavelength-division-multiplexing passive optical network (WDM-PON) architecture with fiber fault protection. The designed optical network unit (ONU) module and periodic spectrum of 2 × N array waveguide grating (AWG) are applied to produce the self-protected mechanism. Here, we employ the free space optical communication (FSO)- and fiber-based connection between two adjacent ONUs to achieve signal relink. Moreover, the corresponding signal performances of downstream and upstream are also analyzed and discussed.

We propose and demonstrate a 100 Gbit/s silicon photonic (SiPh) coherent receiver (Rx) with advanced digital signal processing (DSP) for dual-polarization quadrature-phase-shift-keying (DP-QPSK) transmission. It employs integrated 2D polarization-splitting grating couplers (2D-GCs), modified hybrid mixers and high speed silicon-germanium (SiGe) photodiodes (PDs). The 2D-GC replaced the polarization beam splitters and rotators needed in traditional coherent Rx. Moreover, the SiGe PD has the bandwidth >50 GHz.

In this study, a symmetric polarization-division-multiplexing (PDM) wavelength-division-multiplexing passive optical network (WDM-PON) with fiber to the extension (FTTE) architecture is presented and investigated. The proposed PON can also avoid the Rayleigh backscattering (RB) interference noise. Here, each WDM wavelength can produce 25 Gbit/s on-off keying (OOK) and 10 Gbit/s OOK modulation channels simultaneously in x- and y-polarizations (Polx and Poly) through PDM method for 25 and 105 km single-mode fiber (SMF) transmissions without dispersion compensation. The measured minimal power budget of 25 and 10 Gbit/s downstream and upstream signals are 29 and 35.1 dB and 29.8 and 31.5 dB, respectively, at the forward error correction (FEC) target. Therefore, the proposed PDM WDM-PON architecture can not only offer symmetric 35 Gbit/s downstream and upstream connections by the dual-polarized wavelength, but also can avoid the RB-induced interference noise. In addition, the presented dual-polarized downstream signal also can provide information security in physical layer, when the unauthorized user occupies unlawfully.

We put forward and demonstrate a angle-of-arrival (AOA) based visible-light-positioning (VLP) system using quadrant-solar-cell (QSC) and third-order ridge regression machine learning (RRML) to improve the positioning accuracy.

We put forward and experimentally demonstrate a second order machine-learning (ML) based visible-light-positioning (VLP) system using simple linear interpolation algorithm to reduce the training samples required in the ML algorithm. Algorithms of the second order regression ML model using 2,430 training samples; and using the reduced training samples of 570 with and without the proposed linear interpolation are compared and discussed. We can observe that the positioning accuracy of using training samples of 570 with the proposed interpolation can have similar performance when compared with using 2,430 training samples. The training samples are reduced by ~76.5%. Here, off-the-shelf LED lamps and low bandwidth electrical and optical components are employed; and the system is cost-effective. Good quality on-off keying (OOK) identifier (ID) signals are retrieved after frequency down-conversion from 20 kHz, 40 kHz and 60 kHz without and with optical background noises respectively.

We propose and experimentally demonstrate a non-orthogonal multiple access (NOMA) visible light communication (VLC) system using non-Hermitian symmetry (NHS) inverse-fast-Fourier-transform (IFFT)/FFT size efficient (SE) orthogonal frequency division multiplexing (OFDM). Fix power allocation and successive interference cancellation (SIC) algorithms are realized. The power ratio between different users, transmission distance, network cell coverage are investigated. The proposed scheme is also compared with the HS based direct-current optical (DCO)-OFDM NOMA-VLC system.

In this paper, we present experimentally an erbium-doped fiber (EDF) laser system to accomplish the single-longitudinal-mode (SLM) and wavelength-upconverted output by using nonlinear effect. To accomplish the SLM output, a short length of unpumped EDF saturable absorber (SA) is applied inside the EDF laser cavity for filtering densely multi-mode noise. In accordance with the designed EDF laser system, the lasing wavelength can be upconverted to a longer wavelength position. In addition, the output characteristics of output power, optical signal to noise ratio (OSNR), tunability, stability and linewidth in the EDF laser are also discussed.

We propose and experimentally demonstrate a color-shift-keying embedded direct-current-optical-orthogonal-frequency-division-multiplexing (CSK-DCO-OFDM) scheme for the VLC systems. The proposed scheme can provide not only non-flickering aggregated optical power to reduce human health concerns, but also offers additional modulation dimension or flexibility to the CSK by including high data rate OFDM signal. The data rate is increased from 10 Mbit/s in the original CSK signal to 70.43 Mbit/s in the CSK-DCO-OFDM signal, and both the CSK and OFDM signals satisfy the forward-error-correction (FEC) threshold.

In this research, we present and study an erbium fiber laser with triple-fiber-ring (TFR) scheme for continuous-wave (CW) wavelength-selection. The designed TFR not only can achieve single-longitudinal-mode (SLM) oscillation, but also can spread the tuning range from 1519.0 to 1583.0 nm covering C- and part of L-bands. Moreover, 0 dB power fluctuation can be obtained from 1523.0 nm to 1559.0 nm for flattened operation based on the compound-ring configuration. The Lorentzian laser linewidths of 22 to 29 kHz are also attained in the entire wavelength-tunable range.

Radio-over-fiber (ROF)-based mobile fronthaul network supporting the baseband unit and simple remote radio head is a promising network architecture for future wireless networks. In this paper, we propose and demonstrate a silicon photonics (SiPh)-based remote radio frontend (RRF) for the mm-wave ROF systems. The proposed SiPh-based RRF consisted of an integrated Mach-Zehnder modulator and a micro-ring modulator, producing a single-sideband 40 GHz millimeter-wave orthogonal-frequency-division-multiplexing ROF signal, which is robust against fiber chromatic dispersion in the mobile fronthaul transmission. The RRF is fabricated using SiPh platform and could be potentially low cost. High split-ratios can be potentially achieved. Data rate of 7.813 Gbit/s per wavelength channel is achieved in the experiment. Numerical analysis is also performed; there are good matches of the simulation and experimental results.

In this work, for the first time, we demonstrate a 1250 Mbit/s on-off keying white-light visible light communication (VLC) transmission in a free space transmission length of 1 m by utilizing a yellow-phosphor laser diode (LD). Here, the blue optical filter, which is used to enhance the data rate by removing the yellow color component, is not required to. Besides, the wireless transmission lengths, illuminations, and modulation traffic rates of the proposed LD-based VLC system are analyzed and discussed.

To achieve the high traffic rate of a GaN LED-based visible light communication (VLC), a 4 × 4 color-polarization-multiplexing system is demonstrated by using two blue and two green LEDs. In the measurement, an available bandwidth of blue and green LEDs can be greater than 465 MHz for VLC modulation traffic by using the suitable analogy front end circuit. Hence, the proposed VLC system can deliver 1.7 to 2.3 Gbit/s on-off keying traffic rates in the free space transmission length of 1-4 m under the extremely low illumination of 6.9-136.1 lux for the indoor application. Moreover, the measured BER of each LED is less than the forward error correction target of 3.8 × 10-3 to maintain the better signal performance.

We propose and demonstrate a CMOS rolling-shutter pattern decoding scheme based on two newly introduced schemes, named row grayscale redistribution and differential grayscale packet selection to improve the performance in decoding the CMOS rolling-shutter pattern in translational or rotational motions. Results show that even the CMOS image sensor is in translational or rotational motions, no significant signal degradation is observed at wireless transmission distance up to 150 cm. The maximum visible light communication data rate at different wireless transmission distances is also analyzed.

The demand of higher data rates has made it attractive to consider a low-cost laser diode (LD), such as vertical-cavity-surface-emitting laser (VCSEL) for use in visible light communication (VLC) transmitters (Tx) due to their higher electrical-to-optical modulation bandwidth, beam convergence, and energy efficiency. Many reported LD-based VLC systems only had a solitary downstream transmission. We demonstrate a 3-m bidirectional signal remodulated VCSEL-based VLC system using visible-light modulator to produce the upstream signal. The visible-light external modulator usually has limited modulation bandwidth. By using the predistortion, the upstream remodulated data rate is enhanced by ~2.8 times. Hence, the VCSEL-based VLC system with 10.64-Gb/s downstream signal and 5-Mb/s upstream remodulated signal can be achieved. We also analyze via numerical simulations how the predistorted signal can enhance the transmission data rate by mitigating the intersymbol interference introduced by the bandwidth limitation of the upstream modulator.

In this paper, we propose and experimentally illustrate a wavelength-switchable erbium-doped fiber (EDF) dual-ring (DR) laser with stable single-longitudinal-mode (SLM) oscillation. In the experiment, a silicon-micro-ring-resonator (SiMRR) is applied in the proposed DR cavity for tuning different output wavelengths, when the birefringence loss is adjusted correctly. To compress the densely multilongitudinal-mode oscillations, the DR scheme together with a 2-m unpumped EDF-based saturable absorber is acted as the mode filter. The DR also can produce self-injection loop for an SLM operation. The wavelength tunability is between 1532.61 to 1557.98 nm and the measured 3-dB output linewidth is ~22.5 kHz. Moreover, the output stabilizations of the proposed SiMRR-based EDF DR laser are also analyzed and discussed.

We propose and demonstrate a visible light communication (VLC) system using a light-panel and a mobile-phone camera. We also propose the rolling-shutter-effect (RSE) pattern synchronization and demodulation algorithms. By using our developed mobile-phone application program, the RSE pattern can be demodulated even at very low illuminance. As the light-panel will have different advertisements on it, we also define a noise-ratio (NR) as the figure-of-merit; hence, different VLC data rates can be adjusted according to different advertisement NR values. Experimental bit error rate measurements at different free-space transmission distances and different NRs are performed.

Light-emitting-diode transmitter and complementary-metal-oxide-semicon-ductor (CMOS) image sensor receiver based visible light communication is a promising scheme for an optical wireless communication. During the demodulation of the rolling shutter pattern obtained from the CMOS image sensor Rx, due to the high signal fluctuation introduced by the uneven light exposure, special thresholding schemes are needed to correctly identify the data logic. In this work, we propose and demonstrate a modified adaptive scheme (MQA) for the demodulation of the rolling shutter pattern. Experimental bit-error-ratio (BER) measurements using different thresholding schemes at different illuminance are analyzed. The results show that the proposed MQA scheme can provide much lower BER, with similar process latencies when compared with other schemes.

In this work, we demonstrate a wavelength-tunable erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here using the self-injection method and unpumped EDF-based saturable absorber can suppress other densely sidemode to achieve SLM. Hence, the output power and optical signal-to-noise ratio of proposed EDF ring laser are between -7.1 and 2.1 dBm and 30.1 and 36.5 dB in the tuning range of 1525.0 to 1574.0 nm, respectively. According to the proposed EDF laser structure, the wavelength operation range can extend to shorter L-band from C-band. Moreover, the output stability of the proposed EDF ring laser is also executed experimentally.

Mobile-phone based visible light communication (VLC) is an attractive method for optical wireless communication. However, the data rate is typically limited by the complementary metal-oxide-semiconductor image sensor frame rate and the processing time gap in the rolling shutter mode operation. Here, we propose and demonstrate a packet-reconstruction scheme, known as beacon jointed rolling shutter pattern scheme. The mobile-phone based VLC data rate can be increased to a record 10.32 kb/s. The implementation algorithm is discussed; and the bit-error-rate experimental evaluations at different transmission distances and horizontal offsets are performed.

Visible light communication (VLC) is regarded as relatively secure communication when compared with other wireless communications using radio frequency (RF). However, due to the visual nature, the VLC signals are still subject to eavesdropping when they are emitted by the light source. Here, we propose a light encryption scheme using devices having light-emitting diode (LED) and a camera image sensor, such as a mobile phone. The original visible signal sending from the lamp can be first received by the proposed light encrypter. The information can be encrypted and then emitted. The light encrypter acts as an encryption gateway for signals in optical domain. The rolling shutter effect of the complementary metal--oxide semiconductor (CMOS) camera in the mobile phone can be used. By demodulating the rolling shutter pattern, the data information can be obtained. We also propose and demonstrate using the Otsu thresholding scheme to define the data logic in the rolling shutter pattern. We show that the Otsu scheme is effective for estimating the bit error rate (BER). The optimum number of intervals (segmentations) and the process time of the Otsu method are also studied.

We propose an electronic label and sensor system using visible light communication (VLC). The downlink signal is transmitted by a white-light light-emitting diode (LED) lamp that can provide lighting, VLC, and energy harvesting for mobile devices. The downlink is received by a solar cell. The uplink can be captured by a surveillance camera image sensor. However, using the camera image sensor as a VLC receiver (Rx) is challenging since the data rate is limited by the frame rate and due to uneven light exposure. The rolling shutter effect of the image sensor can be used to increase the data rate. In this paper, we propose and demonstrate how to demodulate the obtained rolling shutter pattern using a second-order polynomial (SOP) extinction ratio (ER) enhancement scheme, together with iterative and modified quick adaptive thresholding schemes. The ER enhancement scheme can significantly reduce the large ER fluctuation. Experimental results show that by using the proposed SOP ER enhancement scheme, the bit error rate (BER) improvement can be up to two orders of magnitude. We also believe that the proposed electronic label and sensor system may be applicable to Internet-of-Things sensing networks for connecting a number of mobile devices.

In this demonstration, we propose and investigate a stable and tunable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser structure. Here, in order to achieve the SLM output, the “eye-type” triple-ring scheme is designed in this EDF laser to suppress the densely spaced longitudinal modes. In the measurement, the output power and optical-signal-to-noise ratio (OSNR) are between 8.35 and 8.92 dBm and 33.2 and 35.7 dB, respectively, in the wavelength range of 1530 to 1560 nm. The proposed EDF laser architecture not only has free tuning step but provides stabilized and flattened output power spectrum as well.

We propose and experimentally demonstrate an indoor positioning system which combines identity positioning and the radio frequency carrier allocation technique in order to reduce the signal interference from nearby light-emitting diodes (LEDs) and improve the accuracy of positioning. In addition, the solar cell is used as an optical receiver for the visible light positioning system. Due to the benefits of solar cells such as low-cost, high light sensitivity, and ease in integration with wearable devices, the proposed system could be an energy-efficient and environmentally friendly choice for indoor positioning in the future.

In this paper, we propose using an energy-efficient and low-cost 682-nm vertical-cavity surface-emitting laser (VCSEL) with 1-GHz modulation bandwidth for high-speed wireless visible light communication (VLC). Moreover, by using spectral-efficient orthogonal frequency division multiplexing (OFDM) modulation with bit-and-power-loading algorithm, we successfully demonstrate VCSEL-based transmission at 11.1 Gbps (10.2 Gbps in a raw data rate) over a free-space length of 1.2 m under small bias current of 3.5 mA. Furthermore, decreasing the bias current as low as 2 mA, we can also demonstrate 10.5 Gbps (9.7 Gbps in a raw data rate) OFDM VLC transmission over a 1.2-m free-space link. This proposed VCSEL-based OFDM transmission system could be viewed as a cost-effective and energy-efficient approach for high-speed (> 10 Gbps) laser diode wireless VLC application.

Network architectures to combine the fiber network outside the building and the visible light communication (VLC) access network inside the building are important for effectively distributing the high-capacity data to different users. In this paper, we propose a bidirectional network combining the VLC access network and the time-wavelength-division-multiplexed passive optical network (TWDM-PON). Orthogonal frequency division multiplexed modulation is used since it offers high spectral efficiency for both the TWDM-PON and the VLC access network. Low-cost phosphor-based white-light light-emitting diodes are (LEDs) used; hence, the VLC access network can combine with the lighting systems.

The phosphor light-emitting diode (LED) has been widely used not only for indoor illumination but for the optical transmitter (Tx) as well in visible light communication (VLC). However, the transmission data rate is significantly limited by the modulation bandwidth of LED because of the low-speed response of phosphor. In order to enhance the data rate of the VLC system, we demonstrate a 3 × 3 imaging multiple-input multiple-output (MIMO) VLC system. Besides, the pre-equalizer circuit is used to extend the bandwidth of the LED Tx. Orthogonal frequency division multiplexing (OFDM) with bit-loading algorithm is used. By using the proposed scheme, the original 1 MHz bandwidth commercially available phosphor white light LED can achieve 1 Gbps data rate over 1-m free-space transmission distance.

In this paper, a flexible and reliable 40-Gb/s time and wavelength division multiplexing passive optical network (TWDM-PON) architecture is proposed and demonstrated. Here, a 4 × 10 Gb/s orthogonal frequency-division multiplexing (OFDM) downstream signal is achieved by utilizing four 2.5-GHz directly modulated lasers in the optical line terminal. A reflective optical semiconductor amplifier is utilized in each optical network unit to serve as upstream transmitter (Tx) transmitting 2.5-Gb/s on-off keying (OOK) and 10-Gb/s OFDM upstream traffic, respectively. In addition, the dynamic bandwidth (capacity) allocation and fiber fault protection also can be achieved by applying the new proposed PON architecture with software-defined networking approach.

An optical distribution network (ODN) sharing scheme to integrate mobile backhaul networks with the existing passive optical network (PON) systems is proposed and demonstrated. With the ODN sharing scheme, the expense of building new fibers for the next-generation fifth-generation (5G) mobile backhaul networks can be reduced. As many wavelengths are allocated to the already deployed PON systems, there remain limited wavelengths for the mobile backhaul systems. Hence, to efficiently increase the serving cell sites of the 5G systems, spectral-efficient orthogonal frequency-division multiplexing (OFDM) is adopted in the mobile backhaul systems. In order to reduce the latency of the system, adaptive adjustment of the OFDM signals for different transmission distances is averted. The OFDM signals are transmitted only using specific available bandwidth. The available bandwidth for each wavelength is studied according to the power fading relationship between the transmission distances and the chirp induced from signal modulation. A proof-of-concept demonstration experiment has been performed. In our results, 20.17 Gb/s with a bit error rate (BER) lower than 3.8 × 10-3 was realized with a split ratio of 256 and a 40-km transmission distance of the PON ODN. Hence, each wavelength can support about 20, six, and two nodes for the IMT-advanced, current Long-Term Evolution-Advanced (LTE-A) systems, and the expected 5G systems, respectively.

In this investigation, we propose and demonstrate a stable and wavelength-tunable self-injected reflective semiconductor optical amplifier (RSOA)-based laser by using the Faraday rotator mirror (FRM) and the fiber mirror (FM) serving as a reflected element, respectively. Here, a 1.2-GHz RSOA can be enhanced to ~3 GHz by utilizing a self-injected mechanism. In the measurement, applying the optical orthogonal frequency-division multiplexing quadrature amplitude modulation (OFDM-QAM)with a bit-loading algorithm on the self-injected RSOA directly, the proposed laser can achieve a 3.5-Gb/s data rate in a 20-km single-mode-fiber transmission below a forward error correction (FEC)threshold. Moreover, the related output performance of the proposed RSOA-based laser is also discussed, whereas the FRM and the FM are utilized for comparisons.

Visible light communication (VLC) is attractive as a supplementary method for future fifth-generation (5G) wireless communication owing to the shortage of radio-frequency bandwidth in conventional wireless communications. The VLC systems reported in the literature are mainly based on PIN receivers (Rxs). It is highly desirable if these VLC signals can be detected by using built-in complementary metal-oxide-semiconductor (CMOS) cameras as Rxs to provide flexible and low-cost wireless communications. However, using the CMOS camera is challenging. In this paper, we propose and demonstrate a VLC link using a CMOS mobile phone camera as Rx. By using the rolling shutter effect of the CMOS sensor, the VLC data rate can be significantly enhanced. We first use a second-order polynomial fitting to mitigate the “blooming effect” (saturation of pixels) of the CMOS sensor. In order to extend the VLC transmission distance and mitigate the influence of the background noise, we also propose and demonstrate using histogram equalization and Sobel filter to enhance VLC signal performance. Finally, a third-order polynomial fitting is used to define the threshold. The experimental results show that significant improvement of bit error rate (BER) for about an order of magnitude under different illuminances can be achieved.

Light-emitting diodes (LEDs) have been deployed for various applications in our daily lives. Similarly, image sensors or cameras integrated into mobile phones have become common. Hence, visible light communication (VLC) using LED and mobile phone cameras is attractive and provides low-cost wireless communication. In this paper, we propose and demonstrate a VLC system using color-shift-keying (CSK) modulation and code-division multiple-access (CDMA) technology simultaneously for the first time; a mobile phone camera is used as the receiver (Rx). CSK is used to enhance the VLC system capacity and to mitigate the single color light interference, whereas CDMA allows multiple users to access the network. The system design and operation mechanism of the proposed CSK-CDMA VLC system are discussed. A proof-of-concept demonstration is performed, and error-free transmission is achieved for multiple-access users. A 3-dB transmission gain is also obtained in each user when compared with the traditional on-off keying (OOK) modulation.

In this paper, we propose and investigate an injection-locked Fabry-Pérot laser diode (FP-LD) with 10% front-facet reflectivity by using orthogonal frequency-division multiplexing-quadrature amplitude modulation (OFDM-QAM) in each optical network unit (ONU) for colorless operation in the carrier-distributed passive optical network (PON). Here, the 10-Gb/s 16-QAM OFDM upstream traffic can be generated via a 2.5-GHz-bandwidth injection-locked FP-LD for the short-reach (SR)-to-long-reach (LR) transmission. In this measurement, the CW injection power of -12 dBm for an injection-locked FP-LD is required to achieve 100-km single-mode fiber (SMF) transmission. Hence, error-free transmissions of 20-, 50-, 75-, and 100-km fiber lengths are achieved with the power penalties of 0.33, 0.86, 1.20, and 1.76 dB at the bit error rate (BER) of 3.8 × 10-3, respectively, for upstream traffic. Moreover, the relationship of CW injection power and signal-to-noise ratio (SNR) of each OFDM subcarrier in the injection-locked FP-LD has also been analyzed.

We propose and demonstrate a 250-GHz high-repetition-rate mode-locked Er-doped fiber laser, which utilizes a silicon micro-ring resonator (SMRR). The SMRR acts as an optical comb filter to help achieve passive mode-locking through the dissipative four-wave-mixing effect induced by a piece of high nonlinear fiber. A short section of polarization-maintaining fiber is inserted in the cavity to induce birefringence filtering to significantly enhance the stability of the proposed laser through the combined effects of optical filtering and nonlinear spectral broadening. The laser can operate about 2 and 6 nm in the case of 1.48-ps and 875-fs output pulsewidth, with 3-dB bandwidth, respectively. The laser can remain mode locked, during our measurement time, without any cavity length or temperature feedback control.