High-sensitivity two-stage erbium-doped fiber preamplifier at 10Gb/s

An optical preamplifier with a record sensitivity of -38.8 dBm (102 photons/bit) at 10 Gb/s has been demonstrated. When the amplifier is employed in a practical link without an input isolator, the sensitivity is only slightly degraded to -37.6 dBm (135 photons/bit) by input coupling losses and feedback due to Rayleigh backscattering in the transmission fiber. It is predicted that this penalty can be reduced to 0.15 dB with an improved isolator in the composite EDFA     

Highly efficient integrated optical fibre amplifier module pumped by a 0.98 mu m laser diode

A small fibre amplifier module pumped by a 0.98 mu m LD has been fabricated. Using a low erbium content fibre with a 4.9 dB/mW gain coefficient, the module attained 33 dB gain at 1.535 mu m with only 80 mA drive current.<>     

10 GHz optical receiver using a travelling-wave semiconductor laser preamplifier

A 1.5 ?m optical receiver with a bandwidth of 10 GHz has been demonstrated. The receiver used a travelling-wave semiconductor laser preamplifier and had an equivalent input noise of 1 pA/?Hz) with a 3 dB bandwidth of 10 GHz. The estimated sensitivity at 15 Gbit/s was ?27 dBm.     

High-gain and high-efficiency diode laser pumped fiber amplifier at1.56 μm

Gain of an erbium-doped amplifier was optimized for operation at 1.56 μm, resulting in gains of up to 20 dB and slope efficiencies of 0.66 dB/mW. The amplifier is plug compatible with existing fiber networks. The gains of up to 20 dB were achieved using 1.48-1.49 μm laser diode pump sources with powers of 30 mW launched into the input of the system. The erbium-doped fiber used had an Er³⁺ concentration of roughly 30 p.p.m. in a GeO₂-Al₂O ₃SiO₂ host, and a core diameter of 7.0 μm     

A transimpedance APD optical receiver operating at 10 Gb/s

The authors report an optical receiver which uses a separate-absorption-and-multiplication avalanche photodiode (SAM-APD) to achieve high sensitivity at a bit rate of 10 Gb/s. A transimpedance front end incorporating HEMT devices is used for high bandwidth and low noise. The sensitivity (bit-error rate of 10^-9) is -28.7 dBm for a return-to-zero signal, and -27.0 dBm for a nonreturn-to-zero signal     

All-optical clock recovery from 2.5 Gbit/s NRZ data using selfpulsating 1.58 mu m laser diode

For the first time, all-optical clock extraction from 2.5 Gbit/s NRZ data is demonstrated using a two contact InGaAsP semiconductor selfpulsating laser diode (SP-LD) for what the authors believe to be the first time. The saturable absorber region of the device was doped with Zn ions to reduce the carrier lifetime such that strong selfpulsations at frequencies up to 4 GHz were obtained. Injection of a 10 mu W optical data signal at a wavelength approximately 15 nm lower than the lasing wavelength was sufficient to synchronise the selfpulsations to the incoming NRZ data stream. Similar effects were seen for RZ formated data. Such all-optical clock extraction techniques will find application in future multigigabit per second optical networks and for OEIC applications.<>     

Methane and carbon dioxide sensing using a DFB laser diode operating at 1.64 mu m

Selective gas sensing of CH/sub 4/ and CO/sub 2/ using a single tunable 1.64 mu m DFB laser diode is demonstrated for the first time. By precise wavelength tuning of the diode to non-coincident absorptions of the two gases in their overlapping spectral region, one can detect both using absorption spectroscopy.<>     

15 Gbit/s integrated laser diode driver using 0.3 mu m gate length quantum well transistors

An integrated laser diode driver was realised using enhancement/depletion 0.3 mu m recessed-gate AlGaAs/GaAs quantum well transistors. Fully-open eye diagrams were observed at bit rates up to 10 Gbit/s with 50 Omega loads. The maximum DC and modulation current were 25 and 45 mA, respectively. The power consumption is less than 450 mW.<>     

High-temperature optically pumped 1.55-μm VCSEL operating at 6Gb/s

Vertical cavity lasers operating at a wavelength of 1547 nm were optically pumped by a 980-nm diode laser. Continuous-wave fiber-coupled output powers of 2 mW at room temperature and 140 nW at 105°C were observed. Fiber optic transmission over 25 km at 6 Gbit/s with a power penalty of 0.3 dB was demonstrated     

Practical implementation of a highly sensitive receiver using an erbium-doped fiber preamplifier

A practical erbium-doped fiber preamplified direct detection receiver is demonstrated with which receiver input sensitivities of -46.5 dBm at 622 Mb/s and -40.7 dBm at 2.3 Gb/s have been achieved. There is no penalty from the transmission fiber Rayleigh backscattering. The bit error ratio measurements with 2/sup 23/-1 NRZ PRBS (pseudorandom bit sequence) show highly stable characteristics with no apparent error floor, owing to the polarization insensitivity of the preamplifier and to an active locking of the receiver optical filter. The tradeoff between preamplifier and avalanche gain is shown, and the influence of optical filter bandwidth and decision threshold setting is measured.<>     

Wavelength conversion at 10 Gb/s using a semiconductor opticalamplifier

Data at 10 Gb/s has been translated from an input signal wavelength to another wavelength, either longer or shorter, using gain compression in a 1.5-μm semiconductor optical amplifier for wavelength conversion. To achieve operation at such high bit rates, the probe (shifted) input must be intense enough to compress the gain of the amplifier significantly. This reduces the gain recovery time of the amplifier because of probe stimulated emission. A consequence of the intense probe is an extinction ratio deduction. Using moderate input powers, wavelength conversion is achieved over a 17-nm (2-THz) range, with 0.7-3-dB power penalties     

Low threshold, room temperature laser diode pumped Sb-based VECSEL emitting around 2.1 /spl mu/m

The operation of a diode-pumped AlGaAsSb/GaInAsSb type-I quantum-well vertical external cavity surface emitting laser (VECSEL) emitting near 2.1 /spl mu/m is reported. The epitaxial structure, grown on GaSb by molecular beam epitaxy consists of a GaSb/AlAsSb Bragg reflector and a GaInAsSb/AlGaAsSb active region. A TEM/sub 00/ low-divergence laser operation is demonstrated in quasi-CW (10 /spl mu/s pulses, 10% duty cycle) from 250 up to 350 K. A threshold as low as 390 W/cm/sup 2/ at 250 K combined with a T/sub 0/ around 33 K has been measured.     

1.47 /spl mu/m Tm/sup 3+/:ZBLAN fibre laser pumped at 1.064 /spl mu/m

A large core area (1257 /spl mu/m/sup 2/) Tm/sup 3+/-doped ZBLAN fibre laser operated at 1.47 /spl mu/m is demonstrated. The pump source is a Nd:YAG laser operated at 1.064 /spl mu/m. A laser output power of 1.56 W continuous wave was obtained for 5.2 W of launched pump power. The slope efficiency with respect to the launched pump power was measured to be 33%.     

A 10 Gb/s optical heterodyne detection experiment using a 23 GHzbandwidth balanced receiver

A balanced receiver for multigigabit-per-second coherent optical transmission systems is described. A balanced optical receiver with a frequency bandwidth of 23 GHz is achieved by connecting an InGaAs twin-p-i-n photodiode to a 0.5-30.0 GHz GaAs monolithic distributed amplifier fabricated with a soldier bump flip-chip interconnection technique. An experiment which demonstrated that this receiver has the potential for use in 10-Gb/s optical CPFSK (continuous-phase frequency shift keying) heterodyne detection systems was conducted     

High performance 1.5 mu m multiple-quantum-well DFB-DC-PBH-LDs at 30 mW output power for Gb/s range coherent systems

Long cavity (1200 mu m) MQW-DFB-DC-PBH-LDs have been developed. The devices simultaneously showed less than 1 MHz spectral linewidth, lower than 15 kHz FM dip frequency, moderate FM efficiency (250-300 MHz/mA at 100 MHz modulation frequency), as well as 10-GHz FM bandwidth (6 dB down level from the peak), at 30 mW output power condition. Such LDs will be suitable for Gb/s continuous phase frequency shift keying (CPFSK) current optical fiber communication systems.<>     

A 1.25 Gb/s laser diode driver with pulse width optimization

A 1.25 Gb/s laser diode driver(LDD) with pulse width optimization has been implemented in a 0.6-μm BiCMOS process.This paper illustrates the relation between the pulse width distortion(PWD) of the output eye diagram and the driving amplitude from the second pre-amplifier.Also,a specific current setting circuit working together with an LDD is proposed to generate the optimum driving amplitude and to avoid device nonlinearity,temperature variation and process deviation.The measured results show a maximum c...     

具有脉冲宽度优化的1.25Gb/s激光驱动器

A 1.25 Gb/s laser diode driver (LDD) with pulse width optimization has been implemented in a 0.6-μ m BiCMOS process. This paper illustrates the relation between the pulse width distortion (PWD) of the output eye diagram and the driving amplitude from the second pre-amplifier. Also, a specific current setting circuit working together with an LDD is proposed to generate the optimum driving amplitude and to avoid device nonlinearity, temperature variation and process deviation. The measured results show a maximum crossing deviation of –3% and indicate the desired independence and stability.     

消光比对10Gb/s光接收模块灵敏度的影响

10Gb/s光通信用光接收模块前端常采用APD-TIA组件.理论表明,具有该组件的10Gb/s光接收模块的光灵敏度,主要取决于光纤耦合效率、APD偏置电压、光倍增、过剩噪声和暗电流和消光比等.测试表明,当其它相关因素不变,消光比由5.0dB变到11.0dB时,光接收灵敏度发生2.0～5.0dBm的优化,指出了获得较佳光...     

Effects of laser diode parameters on power penalty in 10 Gb/soptical fiber transmission systems

A composite tradeoff study based on the influence of key laser diode parameters on frequency chirp induced power penalty, extinction induced power penalty, the turn-on delay, and the dispersion transmission limit is presented for 10 Gb/s optical fiber transmission systems. The simulated results reveal that an optimum range of differential gain and nonlinear gain coefficient exists, and it is advantageous to set an extinction ratio that minimizes both the total power penalty and the turn-on delay. In addition, it is shown that a reduction of chirp and maximization of the dispersion transmission limit can be realized by designing the laser diode with a linewidth enhancement factor near -0.8     

Optical demultiplexing at 6 Gb/s using a semiconductor laser amplifier as an optical gate

A semiconductor laser amplifier (SLA) has been employed successfully for optical demultiplexing in two-channel optical time division multiplexed system experiments at 6 and 2 Gb/s. Demultiplexing of 6-Gb/s (2-Gb/s) signals was demonstrated with a power penalty of 1.6 dB (3.0 dB) at bit error rates of 10/sup -9/. It is also shown that a reduction of the generated amplified spontaneous emission can be obtained by optical gating/demultiplexing for systems incorporating inline amplifiers. A 0.5-dB improvement in sensitivity was achieved as a result of using an SLA for demultiplexing from 2.0 to 1.0 Gb/s in a system with one inline Er/sup 3+/-doped fiber amplifier.<>