4×25Gb/s电吸收调制器与DFB激光器集成光源阵列封装方案研究

对应用于4×25 Gb/s电吸收调制器与DFB激光器集成光源阵列的微波传输线进行了设计.通过有限元法仿真,确定其最优结构.经优化后,采用引脚封装的多路传输线在30 GHz以内的传输损耗低于0.5 dB,反射系数低于-13 dB,并有效抑制了相邻信道间的串扰.对集成光源阵列的封装方案进行了研究,提出了一种合理高效的封装方案.     

Integrated four-wavelength DFB laser array with 10 Gb/s speed and 5nm continuous tuning range

A 1.5 μm, four-wavelength DFB (distributed feedback) laser array operating at a speed of 10 Gb/s and with a continuous tuning range of 5 nm for each laser has been demonstrated. An adjacent channel electrical crosstalk penalty of 0.6 dB was measured, and the thermal tuning limitation was identified. Each laser could be modulated at a speed of 10 Gb/s with moderate electrical crosstalk penalty (~0.6 dB) from the adjacent laser. The high-speed performance was not degraded by thermal tuning up to 3.2 nm     

基于直接调制和外调制的高速半导体激光光源

直接调制和外调制的半导体激光光源在现代光纤通信系统中有着重要的应用。首先介绍了应用于10 Gb/s接入网系统的直接调制AlGaInAs多量子阱DFB激光器。由于AlGaInAs量子阱的导带不连续性较大,因此基于该材料的半导体激光器具有良好的温度特性,其特征温度达到了88 K。同时,该直接调制激光器的3 dB小信号调制响应带宽超过15 GHz。随后介绍面向40 Gb/s干线传输系统的高速DFB激光器/EA调制器集成光源。该集成光源采用同一外延层集成方案,并采用Al2O3高速微波热沉进行了管芯级封装,在3 V反向偏压下获得大于13 dB的静态消光比,3 dB小信号调制带宽超过40 GHz。     

DC to 2.5 Gb/s×4 p-i-n/HBT optical receiver array with lowcrosstalk

A multichannel optical receiver with an In_0.53Ga_0.47As p-i-n photodetector array and a monolithic transimpedance amplifier array fabricated in AlGaAs/GaAs HBT (heterojunction bipolar transistor) technology were demonstrated. Both flip-chip rear-illuminated and wire-bonded front-illuminated detector configurations were implemented. The transimpedance was 65 dBΩ, and the 3-dB bandwidth was measured to be 2.3 GHz. By using series feedback, the transimpedance gain of each cell was matched to within 0.5 dB, and the entire array operated from a single 5-V supply. A low interchannel crosstalk of less than -40 dB was measured up to a data rate of 2 Gb/s     

A high-speed eight-channel optoelectronic integrated receiver arraycomprising GaInAs p-i-n PD's and AlInAs/GaInAs HEMTs

The successful fabrication of an eight-channel optoelectronic integrated receiver array on an InP substrate, which comprises eighty elements including GaInAs p-i-n photodiodes (PDs) and AlInAs/GaInAs HEMTs, is reported. An average bandwidth of 1.2 GHz with a standard deviation of 190 MHz over the whole channel was obtained. An average responsivity was 546 V/W with a standard deviation of only 19.2 V/W. A crosstalk was less than -30 dB at frequencies between 3 and 900 MHz and as small as -28 dB even at 1 GHz. The yield of chips available for 1.0 Gb/s operation was as high as 62.5% over 2-in-diameter wafer     

Wavelength blocking filter with flexible data rates and channel spacing

This work presents a high-resolution (13.2 GHz) channel-blocking optical filter, suitable for use as a reconfigurable optical add/drop multiplexer (ROADM), which seamlessly supports data rates from 2.5 to 160 Gb/s. The filter consists of a linear array of 64 MEMS micromirrors and a high-dispersion echelle grating. The demonstrated device had an insertion loss of 9 dB, a loss ripple of 1.2 dB, and a group delay ripple of 15 ps. Data transmission through the device with various mixed data rate scenarios ranging from 2.5 to 160 Gb/s showed negligible penalty, except at 40 Gb/s where a maximum penalty of 1.5 dB was observed due to a phase coherence with the blocker filter ripple.     

基于同一外延层结构的10Gb/s单片集成光发射模块

利用同一外延层集成工艺方法制作了10Gb/s电吸收调制器/分布反馈(DFB)半导体激光器单片集成光发射模块.在器件中引入增益耦合机制以提高单模成品率,并采用感应耦合等离子体干法刻蚀技术以降低调制器电容.集成器件阈值电流为12mA,在-2V偏置时的消光比为15dB,器件的小信号调制带宽超过10GHz.在10Gb/s调制速率下经过35km单模光纤传输后,误码率为10-12时的功率代价小于1dB.     

10Gb/s EML Module Based on Identical Epitaxial Layer Scheme

A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupling mechanism is employed to improve the single mode yield of the DFB laser,while inductively coupled plasma dry etching technique is utilized to reduce the modulator capacitance.The integrated device exhibits a threshold current as low as 12mA and an extinction ratio over 15dB at －2V bias.The small signal modulation bandwidth is measured to be over 10GHz.The transmission experiment at 10Gb/s indicates a power penalty less than 1dB at a bit-error-rate of 1e－12 after transmission through 35km single mode fiber.     

Fabrication and Characteristics of 40-Gb/s Traveling-Wave Electroabsorption Modulator-Integrated DFB Laser Modules

We have developed 40-Gb/s traveling-wave electroabsorption-modulator-integrated distributed feedback laser (TW-EML) modules using several advanced technologies. First, we have adopted a selective area growth (SAG) method in the fabrication of the 40-Gb/s EML device to provide active layers for the laser and the electroabsorption modulators (EAMs) simultaneously. The fabricated device shows that the measured 3-dB bandwidth of electrical-to-optical (E/O) response reaches about 45 GHz and the return loss (S₁₁) is kept below -10 dB up to 50 GHz. For the module design of the device, we mainly considered electrical and optical factors. The measured S₁₁ of the fabricated 40 Gb/s TW-EML module is below -10 dB up to about 30 GHz and the 3-dB bandwidth of the E/O response reaches over 35 GHz. We also have developed two types of coplanar waveguide (CPW) for the application of the driver amplifier integrated 40 Gb/s TW-EML module, which is a system-on-package (SoP) composed of an EML device and a driver amplifier device in a module. The measured S₁₁ of the two-step-bent CPW is below -10 dB up to 35 GHz and the measured S₁₁ of the parallel type CPW is below -10 dB up to 39 GHz.     

Modulation bandwidth enhancement in monolithic integrated two-section DFB lasers based on the detuned loading effect

Modulation bandwidth enhancement in a directly modulated two-section distributed feedback (TS-DFB) laser based on a detuned loading effect is investigated and experimentally demonstrated. The results show that the 3-dB bandwidth of the TS-DFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24. Compared to the absence of a detuned loading effect, there is a 4.6 GHz increase and a 2.45 reduction, respectively. After transmitting a 10 Gb/s non-return-to-zero (NRZ) signal through a 5-km fiber, the modulation eye diagram still achieves a large opening. Eight-channel laser arrays with precise wavelength spacing are fabricated. Each TS-DFB laser in the array has side mode suppression ratios (SMSR) > 49.093 dB and the maximum wavelength residual < 0.316 nm.     

40-Gb/s Direct Modulation With High Extinction Ratio Operation of 1.3-μm InGaAlAs Multiquantum Well Ridge Waveguide Distributed Feedback Lasers

Direct modulation at 40 Gb/s of a 1.3-mum InGaAlAs distributed feedback ridge waveguide laser is experimentally demonstrated. By combination of the high differential gain of an InGaAlAs multiquantum well active layer, a short cavity length of 100 mum, and a low-resistance notch-free grating, it achieves high bandwidth of 29 GHz and high-extinction ratio of 5 dB at 40-Gb/s modulation. Moreover, the laser operates at a record maximum ambient temperature of 60degC under 40-Gb/s directly modulation. It also achieves 40-Gb/s modulated transmission over 2 km with a low power penalty of 0.25 dB at 25degC .     

MEMS-based channelized dispersion compensator with flat passbands

This paper describes a continuously variable and independently addressable channelized dispersion compensator. The optical system is a free-space grating-based system used in a four-pass configuration to ensure flat passbands. The variable dispersion is produced by an array of thermally adaptable curvature micromechanical mirrors. A per-channel variable dispersion greater than +/-400 ps/nm has been demonstrated, with 58 GHz +/-0.4 dB flat passband on 85 GHz spacing. The group delay ripple is less than 7 ps and the penalty with 40 Gb/s CSRZ is 0.7 dB.     

Parallel optical interconnection for uncoded data transmission with1 Gb/s-per-channel capacity, high dynamic range, and low powerconsumption

The design, realization, and characterization of a multichannel dc-coupled ECL-voltage compatible parallel optical interconnection with a bit rate of up to 1 Gb/s-per-channel is reported. The transmitter module consists of an array of laser diodes with low threshold currents and the 50 Ω matching network, the receiver module of a photo diode array and an amplifier array. All the opto-electronic and electronic components are fabricated as arrays with a pitch of 250 μm. The total power consumption is 110 mW per channel, For a BER <10¹⁴ the dynamic range is 15 dB for a bit rate per channel of 200 Mb/s, 13 dB for 630 Mb/s, and 8 dB for 1 Gb/s. The channel crosstalk is below -48 dB (electrical). The size of the opto-electronic parts (12 channels, without electrical connectors) is only 10 mm (length)×5 mm (width)×4 mm (height)     

Monolithically integrated multichannel SiGe/Si p-i-n-HBTphotoreceiver arrays

A low-power, short-wavelength eight-channel monolithically integrated photoreceiver array, based on SiGe/Si heterojunction bipolar transistors, is demonstrated. The photoreceiver consists of a photodiode, three-stage transimpedance amplifier, and passive elements for feedback, biasing and impedance matching. The photodiode and transistors are grown by molecular beam epitaxy in a single step. The p-i-n photodiode exhibits a responsivity of 0.3A/W and a bandwidth of 0.8 GHz at λ=0.88 μm. The three-stage transimpedance amplifier demonstrates a transimpedance gain of 43 dBΩ and a -3 dB bandwidth of 5.5 GHz. A single channel monolithically integrated photoreceiver consumes a power of 6 mW and demonstrates an optical bandwidth of 0.8 GHz. Eight-channel photoreceiver arrays are designed for massively parallel applications where low power dissipation and low crosstalk are required. The array is on a 250-μm pitch and can be easily scaled to much higher density. Large signal operation up to 1 Gb/s is achieved with crosstalk less than -26 dB. A scheme for time-to-space division multiplexing is proposed and demonstrated with the photoreceiver array     

Ultrafast time-division demultiplexer based on electrooptic on/offgates

Electrooptic on/off gate-based demultiplexers for high-bit-rate optical transmission systems are reported. The electrooptic demultiplexing of a TDM 49.6 Gb/s fixed pattern data stream is demonstrated, using two cascaded Ti:LiNbO₃ electroabsorptive multi-quantum-well intensity modulators driven at 6.2 GHz. Error-free 10 Gb/s demultiplexing to 5 Gb/s is achieved using cascaded Mach-Zehnder (MZ) modulators driven at 1.25 GHz. The power penalty due to the interchannel crosstalk is 0.3 dB at the bit error rate of 10^-9     

Four channel integrated DFB laser array with tunable wavelengthspacing and 40-Gb/s signal transmission capacity

A four-channel distributed-feedback (DFB) laser array integrated with four heating filaments has been fabricated for high-density wavelength-division-multiplexing systems. The DFB lasers have a threshold current of 4 mA at room temperature. By changing the power in the heater, the wavelength of each laser can be continuously tuned by as much as 5 nm. Therefore, a tunable wavelength spacing anywhere from 1 nm to 2 nm can be achieved. Each laser can operate at 10 Gb/s. However, the bias current has to be increased to avoid the degradation of the eye pattern as the wavelength is thermally tuned over 2 nm. An electric crosstalk of 0.6 dB is measured when two adjacent lasers are modulated at 10 Gb/s simultaneously     

高信噪比环形腔光纤光辉器

本文介绍了一种改善环形腔掺铒光纤激光器信噪比的简单方法,信噪比提高了5.2dB。用该激光器做WDM系统的光源,守成了1.2Gb/s的归零码和2.5GHz、5GHz的模拟信号以100km的传输实验。     

Broad-band GaAs monolithic equalizing amplifiers formultigigabit-per-second optical receivers

The authors discuss the development of ICs (integrated circuits) for a preamplifier, a gain-controllable amplifier, and main amplifiers with and without a three-way divider for multigigabit-per-second optical receivers using a single-ended parallel feedback circuit, two (inductor and capacitor) peaking techniques, and advanced GaAs process technology. An optical front-end circuit consisting of a GaAs preamplifier and an InGaAs p-i-n photodiode achieves a 3-dB bandwidth of 7 GHz and -12-dBm sensitivity at 10 Gb/s. Moreover, a gain-controllable amplifier obtains a maximum gain of 15 dB, a gain dynamic range of 25 dB, and a 3-dB bandwidth of 6.1 GHz by controlling the source bias of the common-source circuit. Gain, 3-dB bandwidth, and output power of the main amplifier with the three-way divider are 17.4 dB, 5.2 GHz, and 5 dBm, respectively. These ICs can be applied to optical receivers transmitting NRZ signals in excess of 7 Gb/s     

Compact asymmetric strongly gain-coupled DFB laser array withintegrated BFM array for simultaneous 4-λ 2.5 Gb/s 100 km WDMtransmission

A low-cost and high-performance 4-λ wavelength division multiplexing distributed feedback (WDM-DFB) laser array (or WDM4), employing a newly developed asymmetric strongly gain-coupled (A-SGC) laser structure, and a novel compact packaging approach was developed for optical network applications. The WDM4 laser array is capable of simultaneous 4-λ 100 km transmission through a standard nondispersion-shifted fiber, with a simultaneous and independent direct modulation at 2.5 Gb/s for each of the four WDM channels spaced by 200 GHz     

8-element linear array monolithic p-i-n MODFET photoreceivers usingmolecular beam epitaxial regrowth

An 8-element linear array of single-stage integrating front-end photoreceivers using molecular beam epitaxial (MBE) regrowth was investigated. Each element consisted of a p-i-n In_0.53Ga_0.47As photodiode integrated with a selectively regrown pseudomorphic In_0.65Ga_0.35As/In_0.52Al_0.48 As MODFET. Cutoff frequencies of 1.0-μm discrete regrown MODFETs were f_t=24 GHz and f_max=50 GHz. Transconductance of the regrown MODFETs was as high as 495 mS/mm with a current density (I_ds) of 250 mA/mm. The 3-dB bandwidth of the photoreceiver was measured to be 1 GHz. The bit rate sensitivity at 1 Gb/s was -31.8 dBm for BER 10^-9 using 1.55 μm excitation for a photoreceiver with an anti-reflection coating. The single-stage amplifier exhibited up to 25 dB flatband gain of the photocurrent, and a two-stage amplifier was up to 31 dB of gain. Good uniformity between each photoreceiver element in the array was achieved. Electrical crosstalk between photoreceiver elements was estimated to be ~-34 dB