Wide temperature (-20°C-95°C) operation of an uncooled2.5-Gb/s 1300-nm DFB laser

This letter describes a 2.5-Gb/s 1300-nm distributed feedback laser that can operate in a wide temperature range of -20°C to 95°C. We present RF and DC characteristics of the device and the statistical distribution of threshold current and slope efficiency at high temperature. Finally, we demonstrate the device performance in a 2.5-Gb/s small-form-factor module up to 85°C     

Chirp characteristics of 10-Gb/s electroabsorption modulatorintegrated DFB lasers

We present a complete large-signal dynamic model of electroabsorption modulator integrated (EAMI) distributed feedback (DFB) lasers using the time-dependent transfer matrix method. With this model, it is possible to analyze dynamic characteristics depending on optical feedback and spatial hole burning. Also, we can separately calculate the laser and modulator chirp including the voltage-dependent modulator chirp parameter, the grating phase at the end of the laser section, the length of the waveguide region, and electrical coupling. Therefore, our model can provide better predictions regarding the laser and modulator chirp. The calculated large-signal chirp using our model has similar characteristics to the measured large-signal chirp for 10-Gb/s EAMI-DFB lasers     

Performance of directly modulated DFB lasers in 10-Gb/s ASK, FSK,and DPSK lightwave systems

A comparison is presented of the performance of amplitude-shift-keying (ASK), frequency-shift keying (FSK), and differential-phase-shift-keying (DPSK) lightwave systems which operate at 10 Gb/s with directly modulated 1550-nm distributed feedback (DFB) laser transmitters and conventional 1310-nm dispersion-optimized fiber. Computer modeling techniques were used to accurately simulate the amplitude modulation response and the frequency modulation response of DBF lasers. The system performance is evaluated from simulated eye patterns for both direct and heterodyne detection. With the narrow-optical spectral widths of these signal formats, fiber chromatic dispersion limits up to 70 km were obtained for transmission at 1550-nm using conventional 1310-nm optimized fiber     

Yield estimation of 10-Gb/s electroabsorption modulator-integratedDFB lasers due to chirp

We investigate the yield of 10-Gb/s electroabsorption modulator integrated-distributed feedback (EAMI-DFB) lasers for 40- and 60-km transmissions due to the chirp. The yield has been estimated from the effective positive chirp (EPC) capable to transmit signals over 40 and 60 km within 2-dB dispersion power penalty. The signals with EPC of 0.48 and 0.24 Å can be transmitted over 40 and 60 km with less than 2-dB power penalty, respectively. The chirp is calculated from a large signal dynamic model of EAMI-DFB lasers using the time-dependent transfer matrix method (TMM). The results suggest that the yield is mostly dependent on coupling constant (κL) and should be set around 1.3 for high yield while maintaining low facet reflectivity at modulator     

Transport performance of an 80-Gb/s WDM regional area transparentring network utilizing directly modulated lasers

The transport performance of a regional area wavelength division multiplexing (WDM) transparent optical network is studied. We present excellent performance results (Q factors for all received signals greater than 10 with small power penalties) for a ring network based on application-optimized cost-effective optical layer components and fiber. The network consists of six network nodes, interconnected with 86.5-km spans of uncompensated negative dispersion fiber, resulting in a maximum transmission distance around the ring of 519 km, and it supports 32 directly modulated channels operating at 2.5 Gb/s (80-Gb/s network capacity). The novel design of the network nodes ensures great flexibility in terms of scalability and transparency, as well as great performance. To our knowledge, the capacity-length product of this transparent network, using cost-effective directly modulated lasers (DMLs) and no dispersion compensation, is the highest ever reported     

Power stabilisation of uncooled 980 nm pump laser modules from 10to 100°C

Efficient fibre Bragg grating wavelength and power stabilisation of 980 nm pump lasers at high fibre-coupled output power (250 mW at 10°C and 95 mW at 100°C) over a wide temperature range of 90°C is demonstrated     

10 Gbit/s transmission over 50 km nonzero dispersion-shifted fibreusing 1.3 μm directly modulated uncooled transmitters

A 1.3 μm uncooled transmitter with wide-open eye diagrams at laser temperatures of 20, 50, and 85°C is presented. Using this transmitter, it is demonstrated that 10 Gbit/s transmission is possible over a 50 km nonzero dispersion-shifted Lucent TrueWave-RS fibre. This result is compared with transmission over a 55 km standard singlemode fibre     

10-Gb/s transmission and beyond

The authors outline obstacles encountered in the development of 10-Gb/s (STM-64, OC-192) systems. Technologies to overcome these obstacles are presented and compared, taking into account real field environments. A perspective on 40-Gb/s systems technologies is also given     

100/spl deg/C 10 Gbit/s directly modulated InGaAsP DFB lasers with Ru-doped semi-insulating buried heterostructure

A directly modulated 1.3 /spl mu/m InGaAsP DFB laser with a simple buried structure using Ru-doped semi-insulating InP is presented. The high relaxation oscillation frequency of 10 GHz was obtained at 95/spl deg/C. Clear eye openings under 10 Gbit/s direct modulation were achieved from 0 to 100/spl deg/C.     

WDM PON using 10-Gb/s DPSK downstream and re-modulated 10-Gb/s OOK upstream based on SOA

A signal remodulation scheme of 10-Gb/s differential phase-shift keying(DPSK) downstream and 10-Gb/s on-off keying(OOK) upstream using a semiconductor optical amplifier(SOA) and a Mach-Zehnder intensity modulator(MZ-IM) at the optical networking unit(ONU) side for wavelength division multiplexed passive optical network(WDM PON) is proposed.Simulation results indicate that error-free operation can be achieved in a 20-km transmission,and the receiver sensitivity of return-to-zero differential phase-shift keying(RZ-DPSK) is higher than nonreturn-to-zero differential phase-shift keying(NRZ-DPSK) in the proposed scheme.     

A CMOS multichannel 10-Gb/s transceiver

We describe a CMOS multichannel transceiver that transmits and receives 10 Gb/s per channel over balanced copper media. The transceiver consists of two identical 10-Gb/s modules. Each module operates off a single 1.2-V supply and has a single 5-GHz phase-locked loop to supply a reference clock to two transmitter (Tx) channels and two receiver (Rx) channels. To track the input-signal phase, the Rx channel has a clock recovery unit (CRU), which uses a phase-interpolator-based timing generator and digital loop filter. The CRU can adjust the recovered clock phase with a resolution of 1.56 ps. Two sets of two-channel transceiver units were fabricated in 0.11-/spl mu/m CMOS on a single test chip. The transceiver unit size was 1.6 mm /spl times/ 2.6 mm. The Rx sensitivity was 120-mVp-p differential with a 70-ps phase margin for a common-mode voltage ranging from 0.6 to 1.0 V. The evaluated jitter tolerance curve met the OC-192 specification.     

4-Gb/s PSK homodyne transmission system using phase-lockedsemiconductor lasers

Homodyne detection of 4-Gb/s pilot-carrier binary-phase-shift-keyed (BPSK) optical signals using external-cavity semiconductor lasers synchronized by a linear phase-locked loop is discussed. A 2¹⁵-1 pseudorandom binary sequence (PRBS) has been transmitted through a short fiber with a receiver sensitivity of -44.2 dBm or 72 photons/bit. After transmission through 167 km of standard single-mode fiber, the sensitivity is -43.6 dBm or 83 photons/bit. A balanced PIN/HEMT transimpedance receiver which has a 3-dB bandwidth from 100 kHz to 10.1 GHz and an average equivalent input noise current of 10.8 pA/√Hz is used     

Transmission properties of 1.3-/spl mu/m InGaAlAs MQW FP lasers in 10-gb/s uncooled operation

Limitations on transmission by an uncooled InGaAlAs Fabry-Perot (FP) laser in 10-Gb/s operation are experimentally and theoretically investigated. The InGaAlAs laser has both high relaxation-oscillation frequency and superior light-current characteristics over a wide temperature range, making it suitable for uncooled operation at 10 Gb/s. Over most of the temperature range used in transmission testing with standard-dispersion fiber, a small power penalty of 1 dB for a bit error rate (BER) of 10/sup -12/ was obtained in transmission over 4-7 km at the measured temperature range, whereas an error floor was seen in transmission over greater distance, despite the negative chromatic dispersion between the fiber and laser light. Theoretical analysis of these results indicates that mode-partition noise (MPN) imposes the major limitation on transmission distance. Moreover, the minimum transmission distance was estimated as 2.1 km, even when the production tolerance of lasing characteristics and zero-dispersion range of installed fiber are taken into account.     

Low-Chirp 85-Gb/s Duobinary Modulator in InP Using Electroabsorption Modulators

In 2005, Griffin showed that an InP phase-shift-keying/duobinary Mach–Zehnder interferometer (MZI) modulator could achieve good transmission performance at 10 Gb/s, despite modest residual amplitude modulation in the phase modulators in the MZI (ratio of real to imaginary part of index change was $sim$0.1). Here we show that even strong amplitude modulation in the “phase” modulators (ratio of real to imaginary part of index change is $sim$ 1.0) gives good transmission performance. Allowing for strong amplitude modulation allows a significant increase in modulator bandwidth. We demonstrate low-chirp 85.4-Gb/s optical duobinary generation in a fully packaged InP photonic integrated circuit.      

Nonlinearity Limitations When Mixing 40-Gb/s Coherent PDM-QPSK Channels With Preexisting 10-Gb/s NRZ Channels

We investigate the penalties onto a 40-Gb/s polarization-division-multiplexing (PDM)-quadrature phase-shift keying caused by PDM, wavelength-division multiplexing and 10-Gb/s nonreturn-to-zero neighbor channels. Besides, we optimize the carrier phase estimation process and introduce bandgaps in the multiplex in order to contain limitations caused by cross nonlinear effects.     

10-Gb/s Operation of RSOA for WDM PON

We report on the 10-Gb/s operation of the reflective semiconductor optical amplifier (RSOA) for the next-generation wavelength-division-multiplexed passive optical network (WDM PON). The bandwidth of the RSOA used in this experiment is merely 2.2 GHz. Nevertheless, a clear eye opening is obtained at 10 Gb/s by using the electronic equalizer processed offline. We investigate the impacts of the network's operating conditions (such as the injection power to the RSOA and the fiber length) on the performances of these equalizers. The results show that the RSOA-based WDM PON is operable at 10 Gb/s and the maximum reach can be extended to ${>}$ 20 km with the help of the forward error correction codes.      

Wide temperature operation of 40-Gb/s 1550-nm electroabsorption modulated lasers

Electroabsorption modulated lasers (EMLs) exploiting the quantum confined Stark effect need thermoelectric coolers to achieve stable output power levels and dynamic extinction ratios. Temperature-independent operation is reported between 20/spl deg/C and 70/spl deg/C for InGaAlAs-InP-based monolithically integrated 1550-nm EMLs exploiting a shared active area at 40 Gb/s by actively controlling the electroabsorption modulator bias voltage. Dynamic extinction ratios of at least 8 dB and fiber-coupled mean modulated optical power of at least 0.85 mW are obtained over the mentioned temperature range.     

10-Gb/s modulator drivers with local feedback networks

A novel intrinsic collector-base capacitance (C/sub CB/) feedback network (ICBCFN) was incorporated into the conventional cascode and series-connected voltage balancing (SCVB) circuit configurations to implement 10-Gb/s modulator drivers. The drivers fabricated in 0.35-/spl mu/m SiGe BiCMOS process could generate 9 V/sub PP/ differential output swings with rise/fall time of less than 29 ps. Also, the ICBCFN was modified as an intrinsic drain-gate capacitance feedback network (IDGCFN) to implement drivers with differential output swing of 8 V/sub PP/ in 0.18-/spl mu/m CMOS process. The power consumption is as low as 0.6 W. The present work shows that the driving capability is greater than that of the currently reported silicon-based drivers.     

A GaAs HBT 16×16 10-Gb/s/channel crosspoint switch

A 16×16 crosspoint switch IC has been designed and implemented in a 2-μm GaAs heterojunction bipolar transistor (HBT) technology. The IC is a strictly nonblocking switch with broadcast capability and asynchronous data paths. The IC has fully differential internal circuitry and is packaged in a custom high-speed assembly. Test results confirmed that the IC achieves a 10-Gb/s/channel (or 160-Gb/s aggregate) capacity, the highest reported to date for a 16×16 crosspoint switch IC