Wavelength-locked Fabry-Perot Laser Diode Research Articles

MC-CDMA Enhanced LR-PON Using Widely Wavelength Lockable FPLD With Low Facet Reflectance

By using a widely wavelength lockable Fabry-Perot laser diode (FPLD) with low facet reflectance under intensity modulation and direct detection, a multicarrier code division multiple access (MC-CDMA) enhanced long-reach passive optical network (LR-PON) architecture is demonstrated to perform the dense-spectral-utilized transmission with orthogonal frequency division multiplexing (OFDM) format. Enlarging the power injected into the low-facet-reflectance FPLD enables the broadening of operational wavelength margins at a cost of slightly increased bit-error rate (BER). After LR-PON transmission, the signal-to-noise ratio among subcarriers strongly correlates with the frequency chirp of the wavelength-locked FPLD, which affects the allowable wavelength locking range. By substituting MC-CDMA for the typical OFDM format and using the minimum-mean-squared-error-based multicode interference cancellation processing, the BER degradation is minimized, accompanied by a 16% extension on the lockable wavelength margin achieved under 3 dBm injection. Such a widely wavelength lockable FPLD-based MC-CDMA enhances the LR-PON with a power penalty reduction of 1 dB as compared to the typical OFDM LR-PON after 60 km transmission.

Lasing wavelength shift of ASE-injected wavelength-locked F-P LD in WDM-PON

The lasing wavelength shift characteristics of amplified spontaneous emission (ASE)-injected wavelength-locked Fabry-Perot laser-diodes used in the wavelength division multiplexed passive optical network are studied. The lasing wavelength shift at different injected-ASE powers and different bias currents are experimentally evaluated. The saturation effect has been found as the bias current increases. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26088

A WDM-PON with an 80 Gb/s capacity based on wavelength-locked Fabry-Perot laser diode

We investigate a high capacity WDM-PON based on wavelength-locked Fabry-Perot laser diodes. A color-free transmission of 2.5 Gb/s per channel is achieved with a polarization independent F-P LD and a decision threshold control circuit at the receiver. Then, we demonstrate an 80 Gb/s capacity (2.5 Gb/s x 32 channels) WDM-PON with transmission length of 20 km. We also investigate impairments in transmission.

Bidirectional 2.5-Gb/s WDM-PON Using FP-LDs Wavelength-Locked by a Multiple-Wavelength Seeding Source Based on a Mode-Locked Laser

We experimentally investigate the operation of a cost-effective wavelength-division-multiplexed passive optical network (WDM-PON) based on wavelength-locked Fabry-Perot laser diodes (FP-LDs). A single quantum-dash passively mode-locked laser (QD-MLL) is combined with an arrayed waveguide grating in WDM-PON architecture to provide a low-noise, coherent multiwavelength seeding source to injection-lock the FP-LDs for both downstream and upstream. The results show that the QD-MLL-injected FP-LD has the same performance when compared to the case of injection-locking by a low-noise external cavity laser. Error-free bidirectional transmission over 25 km for 16 channels with 42.7-GHz channel spacing is demonstrated at 2.5 Gb/s in the C -band and an optical budget higher than 30 dB is reached.

Decision Threshold Control Method for the Optical Receiver of a WDM-PON

We demonstrate an improvement of optical receiver performance for an optical signal with beat noises. The decision threshold level is adjusted automatically according to the detected average optical power. This simple method improves optical receiver performance under a wide range of input signal conditions, e.g., beat noise level and extinction ratio. Thus this proposed method is useful to optical receivers for WDM-PONs. By employing this control circuit, we successfully demonstrate a WDM-PON based on a wavelength-locked Fabry–Perot laser diode at 1.25 Gb/s per channel with 100 GHz spacing.

1.25-Gb/s Operation at 50-GHz Channel Spacing Based on Intensity Noise Suppression of Wavelength-Locked Fabry–PÉrot Laser Diode

We demonstrate 1.25-Gb/s operation at 50-GHz channel spacing and 10-km single-mode fiber, which is based on a wavelength-locked Fabry-Perot laser diode (F-P LD) and an intensity noise suppression by a gain saturation of F-P LD in front of the receiver. The wavelength-locked F-P LD employs the spectrum-sliced incoherent light with narrow bandwidth of 35 GHz. The intensity noise of wavelength-locked F-P LD is suppressed about 6 dB by the F-P LD in the front of the receiver. As a result, the bit-error-rate curves exhibit the error-free performances over the detuning conditions to cover a whole mode spacing period of F-P LD.

Effects of In-Band Crosstalk in Wavelength-Locked Fabry–PÉrot Laser-Diode-Based WDM PONs

We investigated the impact of in-band crosstalk on the system's performance in wavelength-locked Fabry-Perot laser-diode (FP-LD)-based wavelength-division-multiplexed passive optical networks (WDM PONs). As expected, wavelength-locked FP-LD, which was injected by using an incoherent broadband light source, was more tolerant to in-band crosstalk than distributed-feedback (DFB) laser diode. A 1-dB power penalty in the wavelength-locked FP-LD-based PON system was observed when the crosstalk-to-signal ratio was ~-9 dB. We also compared the measured power penalties with the calculated power penalties. It has been shown that the in-band crosstalk-induced power penalty in wavelength-locked FP-LD-based WDM PON could be estimated properly by taking into account both effects of power addition and signal-crosstalk beat noise.

Noise Characteristics of a Wavelength-Locked Fabry–Perot Laser Diode

We derived a theoretical model of a wavelength-locked Fabry-Perot laser diode (F-P LD) to a sliced spectrum of externally injected amplified spontaneous emission (ASE) from wave equations. The model explains the dynamics of the wavelength-locked F-P LD. Using this model, we investigated the noise characteristics of a wavelength-locked F-P LD with respect to the various parameters, such as, the injected ASE power, the bias current of F-P LD, and the wavelength detuning. We also investigated intensity noise increment by spectral filtering in optical access networks based on wavelength-locked F-P LDs.

Dispersion penalty analysis using light injection method in the feedforward optical transmitter for WDM/SCM radio-over-fiber systems

We have experimentally and theoretically demonstrated the transmission performance of a feedforward optical transmitter using an external light injection technique. The feedforward compensation method shows 31 dB intermodulation distortion suppression and 2.2 dB noise reduction. The feedforward architecture used a wavelength-locked Fabry–Perot laser diode whose side-mode suppression ratio about 35 dB over a 12-nm range. The suppression characteristics of the intermodulation distortion for various wavelength differences and transmission lengths were measured and analyzed as the evaluation criteria for the system performance in WDM/SCM based radio-over-fiber systems.

A WDM-PON with a 40 Gb/s (32 × 125 Gb/s) capacity based on wavelength-locked Fabry-Perot laser diodes

We investigate a high capacity WDM-PON based on wavelength locked Fabry-Perot laser diodes. An error-free transmission of 1.25 Gb/s per subscriber was achieved with a flat-top passband AWG and a laser diode with low reflectivity. Then, we demonstrate a WDM-PON of 40-Gb/s capacity of 32 channels over 15 km of single mode fiber. It also shows that color-free operation within conventional C-band wavelength. The observed dispersion penalty after 30 km transmission was 0.5 dB. The demonstrated WDM-PON shows a robust transmission performance on the optical back reflection.

WDM-PON Based on Wavelength Locked Fabry-Perot Laser Diodes and Multi-Branch Optical Distribution Network

We demonstrate a wavelength division multiplexing passive optical network (WDM-PON) based on wavelength-locked Fabry-Perot laser diodes and thin-film filters. Twelve Fast Ethernet signals are bi-directionally transmitted over the multi-branch optical distribution network (ODN). The ODN has distributed branch nodes and bus networks.

Intensity Noise in a Wavelength-Locked Fabry–Perot Laser Diode to a Spectrum Sliced ASE

We derived analytic expression for the relative intensity noise (RIN) of a wavelength-locked Fabry-Perot laser diode (FP LD) in a single mode region. The RIN of the wavelength-locked output is a function of the photon density and the photon life time. It also depends on the wavelength detuning and the injected amplified spontaneous emission (ASE) power. We investigated the modulation transfer function of the wavelength-locked FP LD and its dependence on wavelength detuning. The analytic result has good agreement with the simulation result.

Effects of Back-Reflection in WDM-PONs Based on Seed Light Injection

We investigate the effects of back-reflection in wavelength-division-multiplexing passive optical networks having an injected seed light for color-free operation of an optical network unit. The back-reflection-induced penalty is reduced as the linewidth of the seed light is increased. The wavelength-locked Fabry-Perot laser diode to an injected spectrum-sliced amplified spontaneous emission light shows a high robustness on the back-reflections, while a coherent seed light exhibits a high-reflection-induced penalty. We also estimate the maximum allowable fiber loss according to the linewidth of the seed light.

A 240 km Reach DWDM-PON of 8-Gb/s Capacity using an Optical Amplifier

We demonstrate a 240 km reach DWDM-PON at 8-Gb/s capacity based on wavelength-locked Fabry-Perot laser diodes and a bidirectional EDFA. We achieve a packet-error-free transmission in both the 64 upstream and 64 downstream channels, guaranteeing a 125 Mb/s symmetric data rate per user. There is no noticeable dispersion penalty. The power penalty due to the crosstalk induced by the DWDM transmission and detuning between AWGs is less than 1.2 dB, when the detuning is within ${\pm}0.12 nm$ .

Fault-detection technique in a WDM-PON

We propose and demonstrate a new in-service fault-localization method for a wavelength division multiplexing passive optical network (WDM-PON). This scheme uses a tunable OTDR realized by a wavelength-locked Fabry-Perot laser diode. We successfully detect the faults both at the feeder fiber and the drop fibers. The resolution and the dynamic range are 100 m and 12 dB, respectively. In addition, the crosstalk induced by the OTDR signal to the transmission data is negligible.

A self-restorable architecture for bidirectional wavelength-division-multiplexed passive optical network with colorless ONUs

We propose and experimentally demonstrate a novel protection scheme for wavelength-division-multiplexed passive optical network (WDM-PON) employing colorless optical transceivers. The proposed network employs 2 x N arrayed waveguide grating (AWG) to utilize its routing characteristics. The colorless operation is achieved by using wavelength-locked Fabry-Perot laser diodes (FP-LDs) injected with spectrum-sliced amplified spontaneous emission (ASE) light. The experimental results show that the restoration can be achieved within 8 ms against the feeder fiber fault and the power penalty introduced by the restoration process is negligible.

Optimization of Spectrum-Sliced ASE Source for Injection-Locking a Fabry–PÉrot Laser Diode

We experimentally study the impact of filter bandwidth of a spectrum-sliced amplified spontaneous emission (ASE) source on the injection-locking of a Fabry-Perot laser diode (FPLD) for passive optical network application. Optimal bandwidth of a spectrum-sliced ASE source was found in terms of receiver sensitivity after transmission. We also investigate the impact of intensity noise (IN) of the spectrum-sliced ASE source and its suppression for a wavelength-locked FPLD using a semiconductor optical amplifier. Experiment results show that the output performance of a wavelength-locked FPLD is improved by IN suppression

Performance analysis of a wavelength-locked Fabry-Perot laser diode by light injection of an external spectrally sliced Fabry-Perot laser diode

We have analyzed and experimentally demonstrated the performance of a wavelength-locked Fabry-Perot laser diode (FP-LD) with a spectrally sliced FP-LD as an external-injection optical source. A high side-mode suppression ratio exceeding 30 dB was obtained, and the noise characteristic of the wavelength-locked FP-LD was analyzed in terms of both mode partition noise and interferometric noise. The measured relative intensity noise had a minimum value of -140 dB/Hz. We also investigated the transmission characteristics such as the Q factor and extinction ratio for a 622 Mbits/s and 2.5 Gbits/s baseband digital signal.

Optimisation of remote seeding optical source in wavelength-locked FP-LD bidirectional WDM access optical link

The optimised characteristics of a wavelength-locked Fabry-Perot laser diode (FP-LD) have been analysed and demonstrated experimentally using remote seeding continuous wave (CW) optical source at central office (CO). The important issues of mode partition noise (MPN) of an FP-LD and Rayleigh backscattering arising from the same wavelength bidirectional transmission are investigated. The Q factor, sidemode suppression ratio (SMSR), and power penalty of a wavelength-locked FP-LD against signal-to-backscattering-power ratio (SBR) were measured. They can be optimised for the SBR range between 22 dB and 31 dB. From the measurements, both the MPN and Rayleigh backscattering can be controlled well owing to remote seeding of an FP-LD and hence use feasibly a wavelength-locked FP-LD in a wavelength division multiplexing-passive optical network (WDM-PON) optical link.

Effects of the Injected ASE Bandwidth on the Performance of Wavelength-locked Fabry-Perot Laser Diodes

We investigate effects of the injected ASE (Amplified spontaneous emission) bandwidth on the performance of the wavelength-locked Fabry-Perot laser diodes (F-P LDs) under constant injection power density and constant injection power. For the constant injection power density, we can determine the minimum injection bandwidth by the required intensity noise or the bit-error rate (BER) performance. On the other hand, there exists the optimal ASE bandwidth for the constant injection power to minimize the intensity noise.