Showing papers on "Optical Carrier transmission rates published in 2017"

Simultaneous Real-Time Ranging and Velocimetry via a Dual-Sideband Chirped Lidar

Abstract: A dual-sideband (DSB) chirped lidar for simultaneous real-time ranging and velocimetry is proposed and demonstrated, in which a Mach–Zehnder modulator (MZM) is applied to generate the required optical DSB frequency-modulated continuous-wave (FMCW) signal. The inherent opposite frequency chirp and contrary wavelength offset to the optical carrier of the two generated sidebands make it possible to measure the distance and velocity by frequency mixing without complex post digital signal processing, meanwhile, make the measurement of velocity immune to the nonlinearity of the FMCW optical signals. An experiment is carried out, in which an 8–18 GHz saw-tooth FMCW signal is used to drive an MZM, generating a wideband optical DSB FMCW signal. The distance and the velocity are simultaneously derived from the real-time frequency spectra. Accurate velocimetry with a nonlinear FMCW signal is also investigated.

Optical vector analysis based on asymmetrical optical double-sideband modulation using a dual-drive dual-parallel Mach-Zehnder modulator.

Abstract: A novel approach to perform optical vector analysis (OVA) is proposed and experimentally demonstrated with carrier-shifted optical double-sideband (ODSB) modulation based on a dual-drive dual-parallel Mach-Zehnder modulator (DD-DPMZM). The proposed method has a doubled measurement range as compared with the conventional OVA based on optical single sideband modulation (OSSB), and a much simpler and more robust configuration as compared with the previously-reported ODSB-based OVA. In addition, the proposed scheme does not generate any undesirable spikes in the measurement results. The transmission response of a sampled fiber Bragg grating in a range of 80 GHz is measured with a resolution of less than 667 kHz by using 40-GHz microwave components. The influence of the unideal frequency-shifted optical carrier generation in the DD-DPMZM on the measurement error is also investigated.

Low power consumption and continuously tunable all-optical microwave filter based on an opto-mechanical microring resonator.

Abstract: We propose and experimentally demonstrate a continuously tunable all-optical microwave filter using a silicon opto-mechanical microring resonator (MRR). By finely adjusting the pump light with submilliwatt power level, transmission spectrum of the MRR could be continuously shifted based on the nonlinear effects, including the opto-mechanical effect and thermo-optic effect. Therefore, in the case of optical single sideband (OSSB) modulation, the frequency intervals between the optical carrier (near one MRR resonance) and the corresponding resonance could be flexibly manipulated, which is the critical factor to achieve continuously tunable microwave photonic filter (MPF). In the experiment, the central frequency of the MPF could be continuously tuned from 6 GHz to 19 GHz with the pump power lower than -2.5 dBm. The proposed opto-mechanical device is competent to process microwave signals with dominant advantages, such as compact footprint, all-optical control and low power consumption. In the future, using light to control light, the opto-mechanical structure on silicon platforms might have many other potential applications in microwave systems, such as microwave switch.

Photonic Generation of a Phase-Coded Chirp Microwave Waveform With Increased TBWP

Abstract: Photonic generation of a phase-coded chirped microwave waveform with an increased time bandwidth product (TBWP) using a frequency-tunable optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The frequency-tunable OEO is implemented using a tunable laser source (TLS), a phase modulator (PM), a phase-shifted fiber Bragg grating, and a photodetector (PD), with the frequency tuning realized by tuning the wavelength of the TLS. A frequency-tunable optical sideband with a frequency that is equal to that of the optical carrier plus the OEO oscillation frequency is generated by the OEO, which is then orthogonally polarization multiplexed with the optical carrier from the TLS at a polarization beam combiner, and applied to a polarization modulator, to which a binary phase-coded parabolic electrical signal is applied. By beating the two orthogonally polarized optical signals at a PD, a phase-coded chirped microwave waveform is generated. The TBWP is significantly increased due to the increase of the temporal duration of the microwave waveform. The proposed approach is experimentally demonstrated. Two phase-coded chirped microwave waveforms with TBWPs of 58.5 and 80 000 using two phase coding signals corresponding to a 13 Barker code and a 20480-bit pseudorandom sequence are generated.

Millimeter-Wave Carrier Embedded Dual-Color Laser Diode for 5G MMW oF Link

Abstract: With the use of central carrier suppressed master which contains a double sideband carrier, a directly encoded dual-color laser diode with low coherence based millimeter-wave (MMW) carrier generation for hybrid wired and wireless MMW over fiber (MMWoF) system is demonstrated. The maximal transmission capacities for optical wired band at 36 Gb/s and for MMW wireless band at 12 Gb/s are achieved in the proposed MMWoF link. Three MMW carrier frequencies of 28, 39, and 47 GHz are synthesized for implementing the fifth generation (5G) mobile network and satellite communication. The dual-color injection-locking effectively suppresses the central carrier power to –37 dBm, which provides the dual-color optical carrier with a central carrier suppression ratio of 38 dB. The 47-GHz double sideband carrier injection has shown its capability to carry 64-QAM OFDM data at 36 Gb/s with the lowest bit-error-rate (BER) of 2.1 × 10–3 over 25-km single-mode fiber, as its weakest four-wave-mixing modes greatly suppress the fiber chromatic dispersion. After optical baseband transmission, the photonic mixed 28-, 39-, and 47-GHz MMW carriers are heterodyne beat from the dual-color carrier to show similar spectral linewidth of 41 dB. The 28-GHz MMW carrier can wireless transmit 12-Gb/s 16-QAM OFDM data over 1.6-m free-space to show an average signal-to-noise ratio of 15.3 dB, an error vector magnitude of 17.1%, and a receiving BER of 3.3 × 10-3.

Generation of Phase-Coded Microwave Signals Through Equivalent Phase Modulation

Abstract: A novel approach to generate phase-coded microwave signals using a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator is proposed and experimentally demonstrated. The key component of the proposed scheme is a DP-QPSK modulator, in which, the upper dual parallel Mach-Zehnder modulator (DP-MZM) modulated by a coding signal is properly biased to implement equivalent phase modulation, while the lower DP-MZM modulated by an RF signal functions as an optical wavelength shifter. A phase-coded microwave signal is generated by beating the phase-modulated optical carrier and the wavelength-shifted optical sideband at a photodetector. The proposed approach has a compact structure and great reconfigurability. By applying different coding signals, binary or quaternary phase-coded signals can be generated. A proof-of-concept experiment is carried out. The generation of binary and quaternary phase-coded signals with a microwave carrier frequency at 8 and 13 GHz is demonstrated.

Ultra-wide bandwidth photonic microwave phase shifter with amplitude control function.

Abstract: This paper presents a new technique for realizing continuous 0°-360° RF signal phase shift over a very wide bandwidth. It is based on using single-sideband modulation together with optical filtering to largely suppress one of the RF modulation sidebands over a wide input RF frequency range, and controlling the phase of the optical carrier to shift an RF signal phase. The technique does not require expensive electrical or optical components to realize an RF signal phase shift over 2-40 GHz frequency range with a flat amplitude and phase response performance. This overcomes the current technology limitation in which no reported phase shifter structure has demonstrated the capability of operating in such a wide bandwidth. Experimental results demonstrate only ± 1 dB amplitude variation and ± 5° phase deviation from the desired RF signal phase shift over 2-40 GHz bandwidth and the RF signal amplitude control function. The phase shifter wavelength insensitive performance is also demonstrated experimentally.

A Hybrid Solution for Simultaneous Transfer of Ultrastable Optical Frequency, RF Frequency, and UTC Time-Tags Over Optical Fiber

Abstract: We describe a fiber-optic solution for simultaneous distribution of all signals generated at today’s most advanced time and frequency laboratories, i.e., an ultrastable optical reference frequency derived from an optical atomic clock, a radio frequency precisely linked to a realization of the SI-Second, and a realization of an atomic timescale, being the local representation of the virtual, global UTC timescale. In our solution both the phase of the optical carrier and the delay of electrical signals (10-MHz frequency reference and one-pulse-per-second time tags) are stabilized against environmental perturbations influencing the fiber link instability and accuracy. We experimentally demonstrate optical transfer stabilities of $5 \times 10^{-19}$ and $2 \times 10^{-15}$ for 100 s averaging period, for optical carrier and 10-MHz signals, respectively.

Low-power all-optical microwave filter with tunable central frequency and bandwidth based on cascaded opto-mechanical microring resonators.

Abstract: We propose and experimentally demonstrate an all-optical microwave filter with tunable central frequency and bandwidth based on two cascaded silicon opto-mechanical microring resonators (MRRs). Due to the Vernier effect, transmission spectrum of the cascaded MRRs is a series of notch bimodal distribution. In the case of intensity modulation with optical double-sideband (ODSB) signals, the optical carrier is fixed between the two resonant peaks of one notch bimodal distribution. By injecting two pump powers to control the above two resonance red-shifts based on the nonlinear effects in opto-mechanical MRRs, the frequency intervals between the optical carrier and the two resonances could be flexibly manipulated for tunable microwave processing. In the experiment, with the highest required pump powers of 1.65 mW and 0.96 mW, the central frequency and bandwidth of the notch microwave photonic filter (MPF) could be tuned from 5 GHz to 36 GHz and 6.7 GHz to 10.3 GHz, respectively. The proposed opto-mechanical device is competent to process microwave signals with dominant advantages of all-optical control, compact footprint, wide tuning range and low-power consumption, which has significant applications in on-chip microwave systems.

Generation of a frequency-quadrupled phase-coded signal using optical carrier phase shifting and balanced detection.

Abstract: A novel approach for photonic generation of a frequency-quadrupled phase-coded signal using optical carrier shifting and balanced detection is proposed and demonstrated. The key component of the scheme is an integrated dual-polarization quadrature phase shift-keying (DP-QPSK) modulator. In the modulator, an RF signal is applied to the upper QPSK modulator to generate high-order optical sidebands, while an electrical coding signal is applied to the bottom QPSK modulator to perform optical carrier phase shifting. After that, a frequency-quadrupled phase-coded signal with an exact π-phase shift is generated through balanced detection. The proposed scheme has a simple, compact structure and good tunability. Besides, a phase-coded pulse can be directly obtained when a three-level rectangular coding signal is applied. A proof-of-concept experiment is carried out. The generation of a 2-Gbit/s phase-coded signal with a frequency tuning from 12.12 to 28 GHz is experimentally demonstrated, and the generation of a phase-coded microwave pulse is also verified.

224 Gb/s Optical Carrier-Assisted Nyquist 16-QAM Half-Cycle Single-Sideband Direct Detection Transmission over 160 km SSMF

Abstract: We demonstrate 224 Gb/s single polarization direct detection transmission over 160 km standard single mode fiber with Nyquist 16-ary quadrature amplitude modulation half-cycle single-sideband (SSB) signal at C -band. The net bit rate is 203.4 Gb/s considering frame redundancy and hard-decision forward error correction (HD-FEC) with 7% overhead. After 160 km transmission, the bit error rate (BER) is 3.6 × 10−3, which is less than the BER threshold of 4.5 × 10–3 for 7% HD-FEC. To our best knowledge, it is the first report of C -band 200G single channel and single photodiode direct detection transmission, which sets a record of fiber link length for such systems. In our experiment, the optical carrier is added with an additional laser at the transmitter side, which is delivered along with the signal. For short reach transmission, the nonlinear interactions between the carrier and the signal are usually insignificant. Therefore, our scheme is equivalent to heterodyne coherent detection with a local oscillator and a single-ended photodiode. The system performance is studied by deducing the relationship between electrical signal-to-noise ratio and optical signal-to-noise ratio of an SSB signal. The spectrum efficiency and hardware complexity of our experiment are compared with other direct detection schemes. The signal–signal beat interference induced by the square-law detection of a single-ended photodiode is compensated by an iterative technique at the receiver side. The equalization-enhanced in-band noise in bandwidth-limited systems is compensated using a digital post filter together with maximum likelihood sequence decision. The demonstrated scheme can provide a promising technique for beyond 100G high-speed direct detection transmission aiming to datacenter interconnecting and some metropolitan area applications.

Microwave photonic system for instantaneous frequency measurement based on principles of “frequency-amplitude” conversion in fiber Bragg grating and additional frequency separation

Abstract: This article describes the design principles of optoelectronic system (OES) for instantaneous frequency measurement (IFM) of microwave signals based on the use of amplitude-phase modulation conversion of single optical carrier into symmetrical dual-frequency signal for additional frequency separation, its modulation by unknown frequency and subsequent “frequency-amplitude” measurement conversion in Fiber Bragg Grating (FBG) with Gaussian reflection profile. Such approach allows increasing of measurement resolution at low frequencies.

Linearized phase-modulated analog photonic link with the dispersion-induced power fading effect suppressed based on optical carrier band processing.

Abstract: A linear phase-modulated photonic link with the dispersion-induced power fading effect suppressed based on optical carrier band (OCB) processing is proposed. By introducing a proper phase shift to the OCB, the third-order intermodulation distortion (IMD3) component of the signal transmitted over a length of fiber is effectively suppressed, while the fundamental component is shifted to be away from the notch point of the transmission response. The IMD3 and the dispersion-induced power fading effect are effectively suppressed simultaneously to realize a linear phase-modulated photonic link, and the simplicity is preserved. Theoretical analyses are taken and an experiment is carried out. Simultaneous suppression of IMD3 and dispersion-induced power fading effect is achieved. An improvement of larger than 10 dB in third-order spurious-free dynamic range (SFDR3) for both the RF frequency around the notch point and the peak point of the transmission response curve for a 20-km link is realized, as compared with the traditional phase-modulated photonic link without the OCB processing.

Optical single sideband modulation with tunable optical carrier-to-sideband ratio using a modulator in a Sagnac loop

Abstract: We propose and experimentally demonstrate a cost-effective approach to achieve optical single sideband (OSSB) modulation with tunable optical carrier-to-sideband ratio (OCSR) based on a bi-directional use of an OSSB modulator. The key concept of the proposed scheme is to use an OSSB modulator which is incorporated in a Sagnac loop where a light wave is modulated in the form of SSB modulation along the clock-wise direction while the orthogonal light is not modulated along the counter clock-wise direction due to the velocity mismatch. The signals along two directions are combined together at the output of the Sagnac loop via a polarization beam splitter (PBS). Thus a partial orthogonal SSB (PO-SSB) modulated signal is obtained. The generated signal is then sent into a polarization controller (PC) followed by a polarizer. An OSSB-modulated signal with tunable OCSR from −10 to 27 dB is achieved by adjusting the PC in the experiment. The proposed scheme is wavelength independent, which can support low microwave bandwidth and achieve flexible wavelength tunability.

Broadband Microwave Photonic Sub-Harmonic Downconverter with Phase Shifting Ability

Abstract: A microwave photonic signal processor that is capable of simultaneously realizing sub-harmonic frequency down conversion and IF signal phase shifting operation is presented The IF signal generated by the frequency down conversion process is obtained by the beating of the second-order local oscillator (LO) sideband with the fundamental RF signal sideband at the photodetector The phase of the IF signal can be tuned continuously from 0° to 360° by controlling the optical phase of the RF signal sideband The optical carrier is eliminated at the signal processor output to achieve high conversion efficiency mixing operation The signal processor can be designed to have a very wide bandwidth as it only involves optical components Experimental results are presented that demonstrate frequency down conversion with > 88 dB conversion efficiency over 6 to 40 GHz RF signal bandwidth and 005 to 10 GHz IF signal bandwidth, and a continuous 0° to 360° phase shift on the output IF signal

L-Band Quantum-dash Self-Injection Locked Multiwavelength Laser Source for Future WDM Access Networks

Abstract: We propose and demonstrate a compact, cost-effective, multiwavelength laser source employing self-injection locking scheme on InAs/InP quantum-dash (Qdash) laser diode. The device is shown to exhibit Fabry–Perot modes or subcarriers selectivity of 1 to 16 between ∼1600–1610 nm, with corresponding mode power (side mode suppression ratio) variation of ∼10 (∼38) to ∼−2.5 (∼22) dBm (dB), and able to extend beyond 1610 nm, thereby encompassing >30 optical carriers. Then, we utilized a single self-locked optical carrier at 1609.6 nm to successfully transmit 128 Gb/s dual-polarization quadrature phase shift keying signal over 20 km single mode fiber with ∼−16 dBm receiver sensitivity. To stem the viability of unifying the transceivers and addressing the requirements of next generation access networks, we propose self-seeded Qdash laser based wavelength division multiplexed passive optical network, capable of reaching a data capacity of 2.0 Tb/s ( ${\rm{16\,\times \,128\, Gb/ s}}$ ) in L-band.

Non-optical Carrier SSB-OFDM PONs With the Improved Receiver Sensitivity and Potential Transmission Nonlinearity Tolerance

Abstract: Receiver sensitivity can be improved by optical heterodyne reception. For our investigations, we implement a passive optical network (PON) to demonstrate the heterodyne reception scheme. In this paper, a novel non-optical carrier single-sideband orthogonal frequency division multiplexing (NOC-SSB-OFDM) scheme is proposed for intensity modulation and heterodyne detection-based passive optical networks (PONs). We study the effect of signal-signal beating interference (SSBI) for different guard bands (GBs), the line-width of the laser, and the carrier to signal power ratio (CSPR) on the performance of the proposed scheme. It is shown that the receiver sensitivity can be improved by about 4 dB at a bit error rate (BER) of 1 × 10 -3 after 100-km single mode fiber (SMF) transmission by using the proposed NOC-SSB-OFDM scheme compared with the traditional SSB-OFDM scheme.

Two-color laser diode for 54-Gb/s fiber-wired and 16-Gb/s MMW wireless OFDM transmissions

Abstract: 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.

Analog Photonic Link With Tunable Optical Carrier to Sideband Ratio and Balanced Detection

Abstract: Optical carrier to sideband ratio (CSR) optimization and balanced detection are two effective techniques to improve the performance of an analogy photonic link (APL). Here, we proposed an APL where tunable optical CSR and balanced detection can both be implemented. A single integrated polarization division multiplexing Mach–Zehnder modulator (PDM-MZM) is used to generate a polarization multiplexed signal containing an optical carrier and two radio frequency modulated sidebands, and the optical CSR can be tuned from –15 to 15 dB by simply adjusting the direct current bias of the modulator. By optimizing the optical CSR in the proposed link, the link gain and noise figure (NF) are improved by 12 and 6.8 dB compared with conventional quadrature biased link. In addition, after balanced detection in the proposed link, the link gain, NF, third-order spurious free dynamic range (SFDR), and especially the second-order SFDR are further improved.

Radiophotonic method for instantaneous frequency measurement based on principles of “frequency-amplitude” conversion in Fiber Bragg grating and additional frequency separation

Abstract: This article describes the design principles of optoelectronic system (OES) for instantaneous frequency measurement (IFM) of microwave signals based on the use of amplitude-phase modulation conversion of single optical carrier into symmetrical dual-frequency signal for additional frequency separation, its modulation by unknown frequency and subsequent “frequency-amplitude” measurement conversion in Fiber Bragg Grating (FBG) with Gaussian reflection profile. Such approach allows increasing of measurement resolution at low frequencies.

Simple delay-limited sideband locking with heterodyne readout

Abstract: We present a robust sideband laser locking technique ideally suited for applications requiring low probe power and heterodyne readout. By feeding back to a high-bandwidth voltage-controlled oscillator, we lock a first-order phase-modulation sideband to a high-finesse Fabry-Perot cavity in ambient conditions, achieving a closed-loop bandwidth of 3.5 MHz (with a single integrator) limited fundamentally by the signal delay. The measured transfer function of the closed loop agrees with a simple model based on ideal system components, and from this we suggest a modified design that should achieve a bandwidth exceeding 6 MHz with a near-causally limited feedback gain as high as 4 × 107 at 1 kHz. The off-resonance optical carrier enables alignment-free heterodyne readout, alleviating the need for additional lasers or optical modulators.

Mitigation of Optical Interference Noise by Optical Carrier Cancelation in Self-Coherent Reflective PON Uplink Transmission

Abstract: Optical interference noise (OIN), including optical beating interference and Rayleigh back-scattering noise, severely degrades transmission performance in self-coherent reflective passive optical network uplink transmission systems. A simple, cost-effective, and optical interferometry-based optical carrier cancelation method is proposed to reduce OIN. In this experiment, we demonstrate the cancelation of optical carriers, which is a major cause of OIN, up to 29 dB. Under the conditions of higher fiber input power and longer transmission distance, a remarkable improvement in transmission performance in terms of the eye-pattern and bit-error-rate was achieved.

SSB (Single Side Band)-OOFDM (Optical Orthogonal Frequency Division Multiplexing) link implementation method and system for beat interference cancellation

Abstract: The invention provides a DD (Direct Detection)-SSB (Single Side Band)-OOFDM (Optical Orthogonal Frequency Division Multiplexing) link implementation method and system for beat interference cancellation, and relates to the field of optical communication. In a DD-OOFDM system, a polarization modulator and an optical band-pass filter generate a cross-polarized SSB-OOFDM signal; the SSB-OOFDM signal is injected to a single side beat interference (SSBI) cancellation receiver (BICR) after optical fiber transmission, a polarization beam splitter (PBS) splits the cross-polarized optical carrier and OOFDM side band in the SSB-OOFDM signal into two linearly-polarized SSB-OOFDM signals, a balance photo-detector (BPD) performs photoelectric conversion, differential photocurrent output by a subtracter only contains an RF (Radio Frequency)-OFDM (Orthogonal Frequency Division Multiplexing) signal, while the SSBI component is completely canceled, so that the guard interval between the optical carrier and the OOFDM side band is greatly reduced and the spectral efficiency of the system is improved. The BICR has the advantages of simple structure, low cost and insensitivity to signal wavelength, and is significant for improving the performance of the DD-OOFDM system.

Digital Domain Power Division Multiplexed Dual Polarization Coherent Optical OFDM Transmission

Abstract: Capacity is the eternal pursuit for communication systems due to the overwhelming demand of bandwidth hungry applications. As the backbone infrastructure of modern communication networks, the optical fiber transmission system undergoes a significant capacity growth over decades by exploiting available physical dimensions (time, frequency, quadrature, polarization and space) of the optical carrier for multiplexing. For each dimension, stringent orthogonality must be guaranteed for perfect separation of independent multiplexed signals. To catch up with the ever-increasing capacity requirement, it is therefore interesting and important to develop new multiplexing methodologies relaxing the orthogonal constraint thus achieving better spectral efficiency and more flexibility of frequency reuse. Inspired by the idea of non-orthogonal multiple access (NOMA) scheme, here we propose a digital domain power division multiplexed (PDM) transmission technology which is fully compatible with current dual polarization (DP) coherent optical communication system. The coherent optical orthogonal frequency division multiplexing (CO-OFDM) modulation has been employed owing to its great superiority on high spectral efficiency, flexible coding, ease of channel estimation and robustness against fiber dispersion. And a PDM-DP-CO-OFDM has been theoretically and experimentally demonstrated with 100Gb/s wavelength division multiplexing (WDM) transmission over 1440km standard single mode fibers (SSMFs). Two baseband quadrature phase shift keying (QPSK) OFDM signals are overlaid together with different power levels. After IQ modulation, polarization multiplexing and long distance fiber transmission, the PDM-DP-CO-OFDM signal has been successfully recovered in the typical polarization diversity coherent receiver by successive interference cancellation (SIC) algorithm.

Apparatus and method for full-light generation of frequency-multiplication triangular wave

Abstract: The invention, which belongs to the technical field of microwave and optical communication, discloses an apparatus and method for full-light generation of a frequency-multiplication triangular wave. The apparatus and method are applied to generation of a frequency-multiplication triangular wave. According to the method, a light source 1, a radio-frequency signal source 2, a power amplifier 3, power dividers 4, 5, and 7, electric phase shifters 6 and 8, a bi-polarized quadrature phase-shift keying modulator 9, a polarization controller 10, a polarization beam splitter 11, and a balanced photoelectric detector 12 are arranged as a figure shown. A bias voltage is adjusted; an optical carrier and a positive-negative four-order sideband are generated at one polarization state and a positive-negative two-order sideband is generated at the other polarization state; after polarization multiplexing, processed signals are sent to the balanced photoelectric detector for beat frequency processing, thereby generating a full-cycle triangular pulse. The pulse repetition rate is twice as large as a radio-frequency signal frequency. Because polarization multiplexing is realized by using an integrated device and no optical band pass filter is needed, the generated frequency-multiplication triangular pulse has high stability and repetition tunability.

Adjacent Channel Beating With Recombined Dual-Mode Colorless FPLD for MMW-PON

Abstract: By delivering a reference carrier through adjacent dense-wavelength-division-multiplexing (DWDM) channel to remotely beat with the downstream transmitted optical carrier, a full-duplex millimeter-wave DWDM passive-optical-network (MMW-DWDM-PON) is demonstrated to transmit 36- ${\text{Gb/s}}$ data over 25-km single-mode fiber (SMF) and to remotely deliver a 28-GHz MMW carrier for wireless 6- ${\text{Gb/s}}$ data transmission. Such a remotely recombined dual-mode beating scheme provides baseband 36- ${\text{Gb/s}}$ data with corresponding bit error rate (BER) of 2.7 × 10 −3, which is better than the directly dual-mode injection-locked colorless Fabry-Perot laser diode (FPLD) does because of the less fiber chromatic dispersion during 25-km SMF transmission. In a hybrid 25-km SMF-wired and 1.6-m wireless link, it successfully transmits 4- ${\text{Gb/s}}$ data to fit the forward error correcting criterion. By maintaining the free-space distance at 1.6 m, the allowable raw data rate for MMW wireless transmission can be increased up to 6 ${\text{Gb/s}}$ with BER of 1.9×10−3. For optical baseband upstream transmission, the 36- ${\text{Gb/s}}$ data is also directly encoded onto the upstream colorless FPLD injection-locked by reusing the downstream pure carrier delivered through adjacent DWDM channel, and the received data reveals a BER of 2.9 × 10 −3.

Optical signal suppression by a cascaded SOA/RSOA for wavelength reusing reflective PON upstream transmission

Abstract: An optical signal suppression technique based on a cascaded SOA and RSOA is proposed for the reflective passive optical networks (PONs) with wavelength division multiplexing (WDM). By suppressing the downstream signal of the optical carrier, the proposed reflective PON effectively reuses the downstream optical carrier for upstream signal transmission. As an experimental demonstration, we show that the proposed optical signal suppression technique is effective in terms of the signal bandwidth and bit-error-rate (BER) performance of the remodulated upstream transmission.

Enhanced self-coherent optical OFDM using stimulated Brillouin scattering

Abstract: We experimentally demonstrate the first self-coherent optical OFDM (SCO-OFDM) based on received optical carrier amplification by stimulated Brillouin scattering. Compared to the conventional CO-OFDM, SCO-OFDM has similar performance with 9.6-Gb/s (16-QAM) enhanced data rate.