Low insertion loss and low dispersion penalty InGaAsP quantum-well high-speed electroabsorption modulator for 40-Gb/s very-short-reach, long-reach, and long-haul applications

We present a metal-organic-chemical-vapor-deposition-grown low-optical-insertion-loss InGaAsP/InP multiple-quantum-well electroabsorption modulator (EAM), suitable for both nonreturn-to-zero (NRZ) and return-to-zero (RZ) applications. The EAM exhibits a dynamic (RF) extinction ratio of 11.5 dB at 1550 nm for 3 Vp-p drive under 40-Gb/s modulation. The optical insertion loss of the modulator in the on-state is -5.2 dB at 1550 nm. In addition, the EAM also exhibits a 3-dB small-signal response (S21) of greater than 38 GHz, allowing it to be used in both 40-Gb/s NRZ and 10-Gb/s RZ applications. The dispersion penalty at 40 Gb/s is measured to be 1.2 dB over /spl plusmn/40 ps/nm of chromatic dispersion. Finally, we demonstrate 40-Gb/s transmission performance over 85 km and 700 km.     

Theoretical performance of multigigabit-per-second lightwavesystems using injection-locked semiconductor lasers

The locking conditions for multigigabit-per-second modulation are examined, and the dependence of the receiver sensitivity on the fiber dispersion coefficient-length product is investigated. With a 4.8-Gb/s NRZ (nonreturn-to-zero) modulation, a 1-dB penalty in receiver sensitivity occurs for a transmission distance of 68 km. The injected power is 0.4 mW and the frequency detuning is -35 GHz. With 10-Gb/s NRZ modulation, the allowable transmission distance is 12.5 km for an injected power of 1.0 mW and a frequency detuning of -35 GHz. These results represent increases in the transmission distances obtained with a solitary laser by factors of 3.7 at 4.8 Gb/s and 2.7 at 10 Gb/s     

Simultaneous Demodulation and Clock-Recovery of 40-Gb/s NRZ-DPSK Signals Using a Multiwavelength Gaussian Filter

We demonstrate a novel optical circuit that has the potential of simultaneous demodulation and all-optical clock-recovery of 40-Gb/s wavelength-division-multiplexing nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) signals. A key device of the circuit is an ad hoc periodic fiber Bragg grating filter that simultaneously demodulates the input signals and seeds a series of clock recovery circuits. We report the complete characterization of the proposed scheme in the whole-band using a tunable transmitter. The DPSK demodulated signals show enhanced resilience to chromatic dispersion with respect to the usual NRZ _ON-OFF keying format. On the other hand, the recovered clock signals are very stable and have around 200-fs root-mean-square time jitter.     

Payload-envelope detection and label-detection integrated photonic circuit for asynchronous variable-length optical-packet switching with 40-gb/s RZ payloads and 10-gb/s NRZ labels

A photonic integrated circuit that performs 40-Gb/s payload-envelope detection (PED) and 10-Gb/s label detection for asynchronous variable-length optical-packet switching is demonstrated. The circuit consists of an InP photonic integrated device combined with electronic GaAs and InP devices on a carrier. Asynchronous variable-length optical packets with 40-Gb/s return-to-zero (RZ) payloads and 10-Gb/s non-RZ (NRZ) labels are processed by the circuit. The circuit outputs a PED electrical signal that represents the temporal location of the payload and a 10-Gb/s electrical signal representing the optical label. The optical label is detected error free. The PED signal has a rise/fall time of 3-ns and 150-ps jitter. The PED signal was also used to erase and rewrite the optical labels error free.     

Bit rate and wavelength transparent all-optical clock recovery scheme for NRZ-coded PRBS signals

All-optical clock recovery from 40-Gb/s nonreturn-to-zero (NRZ) pseudorandom binary sequence data streams based on self-pulsating lasers is presented. A compact preprocessing circuit is utilized to convert an NRZ signal to a pseudoreturn-to-zero sequence before injecting into the optical clock. It comprises a semiconductor optical amplifier followed by a periodical wavelength-division-multiplexing demultiplexer filter. A stable sinusoidal clock signal with a root-mean-square jitter below 700 fs is detected at the output of the self-pulsating laser within data dynamic range of more than 8 dB. The performance of the all-optical clock recovery scheme is investigated by varying the bit rates between 39.81 and 43.02 Gb/s as well as for various wavelengths in the C-band.     

NRZ versus RZ in 10-40-Gb/s dispersion-managed WDM transmissionsystems

We compare nonreturn-to-zero (NRZ) with return-to-zero (RZ) modulation format for wavelength-division-multiplexed systems operating at data rates up to 40 Gb/s. We find that in 10-40-Gb/s dispersion-managed systems (single-mode fiber alternating with dispersion compensating fiber), NRZ is more adversely affected by nonlinearities, whereas RZ is more affected by dispersion. In this dispersion map, 10- and 20-Gb/s systems operate better using RZ modulation format because nonlinearity dominates. However, 40-Gb/s systems favor the usage of NRZ because dispersion becomes the key limiting factor at 40 Gb/s     

Dispersion tolerance and transmission distance of a 40-Gb/sdispersion management soliton transmission system

We investigate the tolerance of the variation of average dispersion in a 40-Gb/s dispersion-managed soliton (DMS) transmission system. It is theoretically shown that dispersion tolerance is governed by pulse broadening and soliton interaction, and that the largest dispersion tolerance can be achieved by optimizing the pulse energy depending on the transmission distance. We construct a 40-Gb/s recirculating loop transmission system and show that the dispersion tolerance of over 180 ps/nm, which is much larger than that of a linear nonreturn-to-zero (NRZ) format system, can be realized by the optimization of the pulse energy at a transmission distance of more than 1000 km     

A 10 Gb/s high sensitivity, monolithically integrated p-i-n-HEMToptical receiver

A high-sensitivity, monolithically integrated optical receiver, composed of a p-i-n-PD and high electron mobility transistors (p-i-n-HEMTs) is described. The receiver sensitivity is -17.3 dBm at a bit error rate of 1×10^-9 for a 10-Gb/s non-return-to-zero (NRZ) lightwave signal. This value is the best result yet reported for 10-Gb/s monolithically integrated receivers. The sensitivity is -30.6 dBm if an erbium-doped fiber amplifier (EDFA) is placed ahead of the p-i-n-NEMT receiver. A transmission experiment using a 150-km dispersion-shifted fiber (DSF) indicates no degradation in the bit error rate characteristics or the eye pattern. This verifies the practicality of the p-i-n-HEMT optical receiver for high-speed transmission systems     

InP HBT driver circuit optimization for high-speed ETDMtransmission

The design of high-speed circuits and optimization of function of technological and geometrical parameters are presented. Various modeling aspects are discussed, such as model accuracy for InP heterojunction bipolar transistor and modeling with technological and geometrical parameters. MUX-driver design and optimization for 40-Gb/s ETDM transmission is presented. The impact of collector thickness (W_c ) on driver performances is evaluated and assessed by circuit fabrication and measurements. Results of 40-Gb/s electrical measurements and optical experiment with realized MUX-driver module are presented     

Optical Clock Recovery and 3R Regeneration for 10-Gb/s NRZ Signal to Achieve 10 000-hop Cascadability and 1 000 000-km Transmission

This letter experimentally demonstrates all-optical clock recovery and optical 3R regeneration for a 10-Gb/s nonreturn-to-zero (NRZ) format. The 3R regenerator has achieved 10 000-hop cascadability and 1 000 000-km transmission for a pseudorandom bit sequence (PRBS) of$2 ^7 -1$. A semiconductor-optical-amplifier-based Mach–Zehnder interferometer (SOA-MZI) as an NRZ to pseudoreturn-to-zero converter and a Fabry–PÉrot filter perform the all-optical clock recovery from an NRZ signal. A pair of SOA-MZIs combined with a synchronous modulator provides the 2R regeneration and retiming functions. The cascadablity of the 3R regenerator is investigated in a recirculating loop transmission experiment by eye diagram, bit-error rate, and$Q$-factor measurements. Transmission with the 3R regenerator shows significant performance improvement over that without 3R regeneration. A 100-hop cascadability is also demonstrated for PRBS$2 ^31 -1$, enabling 10 000-km error-free transmission with a low power penalty of 1.2 dB.     

High-performance Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As MSM-HEMT receiver OEIC grown by MOCVD on patterned InP substrates

Reports the first demonstration of a new long-wavelength receiver OEIC comprising an AlInAs/GaInAs MSM detector and an AlInAs/GaInAs HEMT preamplifier. The layer structure was grown by LP-MOCVD on patterned InP substrates, which allowed independent optimisation of the MSM detector and HEMT preamplifier. The MSM detector showed the lowest leakage current yet reported and the HEMT exhibited a transconductance of 260 mS/mm. An excellent receiver response to 1.7 Gbit/s NRZ signals has been obtained.<>     

Photoreceiver module using an InP HEMT transimpedance amplifier for over 40 gb/s

We developed a photoreceiver module for over 40 Gb/s that uses two ultrahigh- speed device technologies: an InP HEMT transimpedance amplifier (TIA) and a uni-traveling-carrier photodiode (UTC-PD). The TIA was designed to have a wide dynamic range by using cascade HEMT topology for the output buffer. We found that reducing the standing wave at the PD-TIA interface by decreasing the change of arg(S/sub 11/) of the TIA within the required frequency region is important for increasing the bandwidth of the module. We obtained a minimum sensitivity of -7.6 dBm and a dynamic range of 11 dB for 43-Gb/s nonreturn-to-zero optical input signal. Error-free operation of the module was confirmed at a data rate of 50 Gb/s.     

Low-noise current optoelectronic integrated receiver with internalequalizer for gigabit-per-second long-wavelength optical communications

An equalizer, which is essential in order to improve the sensitivity of receiver optoelectronic integrated circuits (OEICs) at a gigabit-per-second data rate, has been monolithically integrated on an InP substrate with a p-i-n photodiode and a high-impedance high-electron-mobility-transistor (HEMT) amplifier. The receiver operated up to 1.6 Gb/s and showed low noise current characteristics. The minimum noise current is less than 4 pA/√Hz. The sensitivity calculated from the noise current characteristics is -28.4 dBm for 1.6-Gb/s signals. The receiver chip, which was assembled on a ceramic mount, exhibited a sensitivity of -30.4 dBm at 1.2 Gb/s and 1.3-μm wavelength. The performance is as good as those of receiver OEICs with an external equalizer and sufficient for practical use in gigabit-per-second optical communication system     

EAM-integrated DFB laser modules with more than 40-GHz bandwidth

Electroabsorption modulator (EAM)-distributed feedback (DFB) modules with record-high bandwidth of 41 GHz have been developed. 40-Gb/s nonreturn to zero (NRZ) operation with 12-dB extinction ratio and -1.6-dBm average output power have been successfully achieved by optimizing the EAM length and detuning. A clearly opened eye diagram was maintained even after 80-km nonzero dispersion shifted fiber (NZ-DSF) transmission with dispersion compensation, 40-GHz short pulse trains with 6-ps pulsewidth have been also generated by sinusoidal electrical modulation     

An analog front-end chip set employing an electro-optical mixeddesign on SPICE for 5-Gb/s/ch parallel optical interconnection

A chip set composed of a laser-diode driver (LDD) and an optical receiver (RCV), which incorporates a full 2D (reshape, regenerate) function, has been developed by using silicon bipolar technology for a four-channel 5-Gb/s parallel optical transceiver. An electro-optical mixed design on SPICE of the LDD and the LD is accomplished by describing the rate equations of the LD as an electrical circuit. This design accommodates easy connectivity of the LDD chip to the LD in the optical transmitter module without the need for adjustment of the optical waveform. A pseudobalanced transimpedance amplifier (TIA) and feedforward automatic decision threshold control (ATC) in the RCV minimize the number of off-chip bypass capacitors, eliminate the need for any off-chip coupling capacitors, and keep crosstalk less than -50 dB and low cutoff frequency less than 80 kHz. A prototype parallel optical transmitter module and a prototype receiver module, based on the chip set, demonstrated asynchronous four-channel 5-Gb/s operation. The chip set has a throughput of 20 Gb/s with a power dissipation of 1.3 W at a 3.3-V supply     

On-the-Fly All-Optical Contention Resolution for NRZ and RZ Data Formats Using Packet Envelope Detection and Integrated Optical Switches

We present a packet-by-packet contention resolution scheme that combines packet detection, optical space switching, and wavelength conversion performed in the optical domain by integrated optical switches. The packet detection circuit provides the control signals required to deflect and wavelength-convert the contending packets so that all the packets are forwarded to the same output without any collision or packet droppings. We demonstrate the compatibility of the scheme with both nonreturn-to-zero (NRZ) and return-to-zero (RZ) modulation formats by recording error-free operation for 10-Gb/s NRZ and 40-Gb/s RZ packet-mode traffic     

An ultra-high-speed optoelectronic integrated receiver forfiber-optic communications

An ultra-high-speed optoelectronic integrated receiver consisting of a GaInAs p-i-n photodiode and a transimpedance AlInAs-GaInAs high-electron-mobility-transistor amplifier was successfully fabricated on an InP substrate. A 3-dB bandwidth of 6 GHz with a transimpedance of 50 dBΩ was achieved for the receiver with a feedback resistance of 750 Ω. Measured noise currents of the receiver were analyzed and found to be dominated by the low-frequency noise and the induced gate noise. A sensitivity of -21.2 dBm for 8.0-Gb/s NRZ signals was deduced from the noise current characteristics     

Clock and data recovery IC for 40-Gb/s fiber-optic receiver

The integrated clock and data recovery (CDR) circuit is a key element for broad-band optical communication systems at 40 Gb/s. We report a 40-Gb/s CDR fabricated in indium-phosphide heterojunction bipolar transistor (InP HBT) technology using a robust architecture of a phase-locked loop (PLL) with a digital early-late phase detector. The faster InP HBT technology allows the digital phase detector to operate at the full data rate of 40 Gb/s. This, in turn, reduces the circuit complexity (transistor count) and the voltage-controlled oscillator (VCO) requirements. The IC includes an on-chip LC VCO, on-chip clock dividers to drive an external demultiplexer, and low-frequency PLL control loop and on-chip limiting amplifier buffers for the data and clock I/O. To our knowledge, this is the first demonstration of a mixed-signal IC operating at the clock rate of 40 GHz. We also describe the chip architecture and measurement results.     

An AlGaAs/InGaAs pseudomorphic HEMT modulator driver IC with lowpower dissipation for 10-Gb/s optical transmission systems

An optical modulator driver integrated circuit (IC) has been developed for 10-Gb/s optical communication systems. To achieve both high-frequency (HF) operation and low power dissipation, 0.2-μm T-shaped gate AlGaAs/InGaAs pseudomorphic high electron-mobility transistors (HEMTs) have been employed for their large transconductance g_m of 610 mS/mm and high cutoff frequency f_T of 67.5 GHz. In addition, optimizing input logic swing, switching transistor size in the output driver, and using cascode-current mirror circuits with small output conductance enable power dissipation as low as 1 W to be achieved at a 10-Gb/s nonreturn-to-zero (NRZ) signal output with 3 V_p._p. This is the lowest value ever reported for power dissipation. As an additional function, the output-voltage swing can be controlled in the range from 2 to 3.3 V_p._p. by the current mirror circuit for the purpose of adjusting the optical-output-signal duty factor through an optical modulator