Integrated MQW optical amplifier/noise-filter/photodetectorphotonic circuit

A monolithically integrated photonic circuit with an InGaAs/InGaAsP multiple-quantum-well (MQW) traveling-wave optical amplifier, a Bragg reflection grating-folded noise filter, and an MQW photodetector has been demonstrated. This photonic circuit offers potential as a preamplified lightwave receiver in high-data-rate applications because of its compactness and potentially low cost     

Photonic Microwave Bandpass Filter With Negative Coefficients Using a Polarization Modulator

A novel photonic microwave bandpass filter with negative coefficients implemented using a polarization modulator (PolM) is proposed and experimentally demonstrated. In the proposed filter, a lightwave from a tunable laser source (TLS) is sent to a PolM, with the incident lightwave adjusted to have its polarization direction aligned at an angle of plusmn45deg to the principal axes of the PolM. A microwave signal is applied to the PolM through its RF port. Thanks to the polarization modulation in the PolM, two complementary microwave signals with identical amplitudes carried by two optical carriers with orthogonal polarizations are generated. The two complementary optical microwave signals are then sent to an optical delay line consisting of one section or two sections of polarization-maintaining fiber (PMF), with the polarization directions aligned with the fast and slow axes of the PMF. A photonic microwave bandpass filter with two or four taps is obtained     

1.5 μm optical filter using a two-section Fabry-Perot laserdiode with wide tuning range and high constant gain

The 1.5-μm optical filter exhibits a tuning range as wide as 188 GHz (15 Å), with 23-dB constant gain and 5-GHz constant bandwidth. A 25-channel wavelength selection with less than -10-dB crosstalk is expected with this filter. The wavelength-tunable optical filter has applications in wavelength-division multiplexing lightwave transmission systems and wavelength division photonic switching systems     

Reconfigurable Optical Add‐Drop Multiplexer Using a Polymer Integrated Photonic Lightwave Circuit

We have developed a fully functional reconfigurable optical add‐drop multiplexer (ROADM) switch module using a polymer integrated photonic lightwave circuit technology. The polymer variable optical attenuator (VOA) array and digital optical switch array are integrated into one polymer PLC chip and packaged to form a 10‐channel VOA integrated optical switch module. Four of these optical switch modules are used in the ROADM switch module to execute 40‐channel switching and power equalization. As a wavelength division multiplexer (WDM) filter device, two C‐band 40‐channel athermal arrayed waveguide grating WDMs are used in the ROADM module. Optical power monitoring of each channel is carried out using a 5% tap PD. A controller and firmware having the functions of a 40‐channel switch and VOA control, optical power monitoring, as well as TEC temperature control, and data communication interfaces are also developed in this study.     

Dynamic gain equalisation filter based on integrated optical transversal filter with asymmetric combiner

A compact dynamic gain equalisation filter on a silica-based planar lightwave circuit has been fabricated. The filter is based on the authors' newly developed optical transversal filter that uses an asymmetric combiner. This device flattened the amplified spontaneous emission spectrum of an erbium-doped fibre amplifier to a ripple of /spl sim/1 dB over a wavelength range of 30 nm.     

光有源器件中的光集成技术演变

从光集成技术在光有源器件中的应用与发展的角度出发,结合硅光平台、平面光回路、光子集成回路以及光电子集成回路等基本的光集成技术平台,分析了光有源器件中的光集成技术的演变趋势,并给出了对未来光集成技术发展的展望。     

Integrated optical digital-to-analogue converter and itsapplication to pulse pattern recognition

An optical digital-to-analogue converter that enables optical pulse pattern recognition, fabricated on the silica-based planar lightwave circuit, is proposed. The converter features an optical transversal filter with a multimode interference combiner. Various kinds of four-bit pulse patterns at 10 Gbit/s have been successfully recognised with the fabricated converter     

光子晶体绿光滤波器的研究

利用传输矩阵法设计了一种适用于绿光波段的光子晶体窄带滤波器,并研究了影响滤 波器特性的多种因素。结果表明:适当选取光子晶体结构参数,可将滤波器的中心波长移到绿光波段的532nm处,谱线线宽可达0. 0131nm。此外,随着光子晶体周期层数的增加,线宽进一步变窄;当缺陷层厚度减小时,滤波器的中心波长向短波段移动而谱线宽度几乎保持不变;当入射角增大时,滤波器的谱线宽度变窄但变化幅度不大且在小角度范围( 0～3°)内宽度几乎保持不变。这种绿光窄带滤光器有望在蓝绿光通信中得到应用。     

160 Gbit/s soliton data transmission over 200 km

Polarisation- and time-domain-multiplexed 160 Gbit/s soliton signals have been successfully transmitted over 200 km for the first time. The soliton source was a 10 GHz regeneratively modelocked fibre laser and a planar lightwave circuit was used for optical multiplexing. The soliton pulse width was ~1.5 ps. A polariser and a nonlinear loop mirror were used for demultiplexing from 160 to 10 Gbit/s     

Multitap Photonic Microwave Filters With Arbitrary Positive and Negative Coefficients Using a Polarization Modulator and an Optical Polarizer

A novel multitap photonic microwave filter with arbitrary positive and negative coefficients implemented using an electrooptic polarization modulator (PolM) and an optical polarizer is proposed and experimentally demonstrated. In the proposed filter, the optical polarizer is connected at the output of the PolM with its transmission axis aligned at an angle of 45 to one principal axis of the PolM. By adjusting the polarization direction of the input lightwave to be 45 or 135 to one principal axis of the PolM, an inverted or noninverted intensity-modulated optical microwave signal is obtained at the output of the optical polarizer, which leads to the generation of a negative or positive coefficient. A time delay difference between adjacent taps is generated by using a wavelength-dependent delay line. A five-tap photonic microwave filter with arbitrary positive and negative coefficients is demonstrated. The reconfigurability of the filter is also investigated.     

1/spl times/4 optical switch based on transversal filter configuration with constant power consumption

An optical switch based on a transversal filter configuration is demonstrated. The switch consists of cascaded 3 dB optical power splitters and a phase shifter array. By using a silica-based planar lightwave circuit, a 1/spl times/4 optical switch was realised. A characteristic of the switch is that its power consumption is constant regardless of the output selection.     

WDM-PON module using a planar lightwave circuit with a coated WDM filter

We have presented a new configuration of a planar lightwave circuit (PLC) module coated directly with a filter which divides 1310/1550-nm wavelength bands for a wavelength-division-multiplexing passive optical network module in order to improve the conventional insertion process of thin film filter into the narrow trench located at the Y-junction of a PLC platform. The broadly tapered output facet width of a V-shaped waveguide was designed to be 12 /spl mu/m to minimize the reflected loss. The receiver module integrated with a PIN-photodiode on a silicon optical bench was fabricated. Data transmission of 2.5-Gb/s was demonstrated with clear eye diagrams.     

Experimental demonstration of OCDMA traffic over optical packet switching network with hybrid PLC and SSFBG en/decoders

The transmission of coherent optical code division multiple access (OCDMA) traffic over optical-code-based optical packet switching (OPS) network has been proposed and successfully demonstrated in experiment. Full function of the OPS node has been successfully demonstrated in the experiment with coherent OCDMA traffic. A hybrid using planar lightwave circuit and superstructured fiber Bragg grating en/decoder for packet label and OCDMA-payload encoding/decoding has been verified as well. Error-free (<10/sup -12/) transmissions have been achieved for the 10- and 40-Gb/s payload data and up to two OCDMA channels.     

Novel realization of monotonic Butterworth-type lowpass, highpass,and bandpass optical filters using phase-modulated fiber-opticinterferometers and ring resonators

A novel realization of monotonic Butterworth-type lowpass, highpass, and bandpass optical filters (from their electrical digital filter characteristics) by cascading the all-pole and all-zero resonators is presented. A graphical method for fast derivation of the transfer functions, quick inspection of the resonance effects, and important characteristics of any photonic circuits is described. It is shown that incorporation of the optical amplifiers and optical phase modulators into the delay lines of two basic optical resonators, whose pole and zero can be adjusted independently of each other, provides great design flexibility which would otherwise not possible using conventional passive optical resonators. Possible applications of these optical filters as optical pulse equalizers and receiver shaping filters in long-haul coherent lightwave transmission systems are discussed. Possible application of basic resonators comprising of optical phase modulators as tunable optical filters for spectrum analyzers is also considered     

Optical Signal Processor Using Electro-Optic Polymer Waveguides

We have investigated an optical signal processor using electro-optic polymer waveguides operating at a wavelength of 1.55 $mu$m. Due to recent developments, many useful optical devices have become available such as optical filters, modulators, switches, and multiplexers. It will be useful to have a single optical device, which is reconfigurable to implement all of these functions. We call such a device an “optical signal processor,” which will play a similar role to digital signal processors in electrical circuits. We realize such an optical device in a planar lightwave circuit. Since the planar lightwave circuits are based on the multiple interference of coherent light and can be integrated with significant complexity, they have been implemented for various purposes of optical processing such as optical filters. However, their guiding waveguides are mostly passive, and the only viable mechanism to reconfigure their functions is thermal effects, which is slow and cannot be used for high-speed applications such as optical modulators or optical packet switches. On the other hand, electro-optic polymer has a very high electro-optic coefficient and a good velocity match between electrical and optical signals, thus, permitting the creation of high-speed optical devices with high efficiency. Therefore, we have implemented a planar lightwave circuit using the electro-optic polymer waveguides. As a result, the structure is complex enough to generate arbitrary functions and fast enough to obtain high data rates. Using the optical signal processor, we investigate interesting applications including arbitrary waveform generators.      

Influence of Frequency Allocations and Optical Filters on FDM Optical Fiber Communications

In long-haul frequency-division-multiplexing (FDM) lightwave transmission systems, transmission characteristics are degraded by four-wave mixing (FWM) generated in optical fibers. To date, equally spaced (ES), unequally spaced (US), and repeated US (RUS) allocations have been demonstrated in FDM lightwave transmission systems. It has already been theoretically and experimentally revealed that intensities of generated FWM lights with f_FWM=f_i for RUS are lower than those for ES, and a total bandwidth of signal lights for RUS is narrower than that for US, where f_FWM is a frequency of an FWM light, and f_i is a frequency of a signal light with a channel index i. Moreover, to overcome RUS, ES RUS (ERUS) and US RUS (URUS) have been proposed as modified RUSs and theoretically analyzed. In this paper, ES, RUS, ERUS, and URUS allocations are studied from the viewpoint of a transmission bandwidth of an optical filter. It is revealed that FWM noises are reduced in URUS more than in ES, RUS, and ERUS with a decrease in a transmission bandwidth of an optical filter. The upper limit of a filter transmission bandwidth to achieve a bit error rate of 10^-9 is also obtained.     

A Programmable 8-bit Optical Correlator Filter for Optical Bit Pattern Recognition

We demonstrate a compact reconfigurable 8-bit optical matching filter fabricated using 4% delta high-index-contrast silica-on-silicon waveguides. This planar lightwave circuit is based on an eighth-order tap-and-delay finite impulse response architecture. Multimode interference-based splitters/combiners along with variable optical attenuators and phase shifters allow us to tune and dynamically reconfigure all the taps and delays (filter coefficients) in the filter using a simple automated algorithm. The filter is designed to recognize 8-bit patterns in 40-Gb/s data streams and we demonstrate its working principle by successfully correlating 8-bit binary phase-shift-keyed patterns.     

A PLC‐Based Optical Sub‐assembly of Triplexer Using TFF‐Attached WDM and PD Carriers

We have fabricated a planar lightwave circuit (PLC) hybrid‐integrated optical sub‐assembly of a triplexer using a thin film filter (TFF)‐attached wavelength division multiplexer (WDM) and photodiode (PD) carriers. Two types of TFFs were attached to a diced side of a silica‐terraced PLC platform, and the PD carriers with a 45° mirror on which pin‐PDs were bonded were assembled with the platform. A clear transmitter eye‐pattern and minimum receiver sensitivity of ‐24.5 dBm were obtained under 1.25 Gb/s operation for digital applications, and a second‐order inter‐modulation distortion (IMD2) of‐70 dBc was achieved for an analog receiver.     

Hybrid integration of eight channel PD-array on silica-based PLCusing micro-mirror fabrication technique

A novel micro-mirror for vertical optical output has been successfully fabricated in a singlemode silica-based planar lightwave circuit (PLC) on Si. An eight channel planar photodiode array was assembled on this PLC. The assembled PLC exhibited an average responsivity of 0.92 A/W and a responsivity deviation of 0.34 dB at a wavelength of 1.31 μm     

80 Gbit/s soliton data transmission over 500 km with unequalamplitude solitons for timing clock extraction

Single-polarisation 80 Gbit/s soliton data signals have been successfully transmitted over 500 km. The soliton source was a modelocked fibre laser and a planar lightwave circuit was used for stable optical multiplexing. A nonlinear loop mirror was used for demultiplexing, in which unequal amplitude solitons were used for clock extraction