Frequency tuning characteristics and WDM channel access of thesemiconductor three-branch Y3-lasers

We describe frequency tuning and channel access characteristics of the new, widely-tunable, multi-quantum-well three-branch Y3-lasers. The Y3-lasers are tuned discretely with two independent current controls: coarse tuning (5.5 nm, 680 GHz tuning steps) selects the desired optical frequency range, fine tuning selects the desired frequency channel (0.4 nm, 50 GHz channel spacing). For example, we demonstrate access to 50 channels over the ~31 nm free spectral range of the Y3-laser; 36 contiguous channels are accessed using three independent current controls. The coarse/fine “digital” tuning makes Y3-lasers very useful for wavelength-division-multiplexed (WDM) multi-channel optical communication systems     

Highly selective and widely tunable 1.55-μm InP/air-gapmicromachined Fabry-Perot filter for optical communications

The authors report, for the first time, a highly selective and widely tunable optical filter at 1.55 μm using a Fabry-Perot resonator with micromachined InP/air-gap distributed Bragg reflectors. The minimum resonance full-width at half-maximum (FWHM), as measured by microreflectivity experiments, is close to 0.4 mm (around 1.55 μm) and is compatible with wavelength-division multiplexing specifications of optical telecommunications. The tuning range is 62 nm for a tuning voltage of 14 V. The FWHM is kept below 1 nm over a 40 nm tuning range     

Single frequency electrooptical tuning of an extended cavity diodelaser at 1500 nm wavelength

A wavelength-tunable, single-frequency GaInAsP-InP laser diode using an intracavity electrooptic LiNbO₃ crystal as the wavelength selective component is discussed. Wavelength tuning is achieved by applying a driving voltage on the crystal electrodes. First results indicate a tuning rate of 1 GHz/V over a tuning range of about 4 nm. This performance was obtained using a nonoptimized X-cut, Z-propagating LiNbO₃ crystal. A potential tuning rate of 6.5 GHz/V is possible with reasonable improvements     

可用于差拍法珀干涉仪的633nm可调谐外腔半导体激光器

为更好地改善差拍法 珀干涉仪用于对纳米干涉仪进行非线性比对和校准场合的性能 ,提出用 6 33nm外腔半导体激光器代替He Ne激光器 ,并针对差拍法 珀干涉仪对工作激光器的要求 ,设计和实现了 6 33nm可调谐外腔半导体激光器。用前端镀增透膜的 6 37nm量子阱结构半导体激光器件及工作于Littrow自准直状态的光栅作为反馈元件 ,构成外腔激光器。实验结果表明 ,该激光器具有比较窄的光谱线宽 ;通过控温和旋转光栅 ,获得了覆盖 6 33nm的 4nm的调谐范围 ;通过控制频率调谐器 ,得到了 1 8GHz的连续调谐范围。     

Frequency modulation and spectral characteristics for a 1.5?m phase-tunable DFB laser

Frequency modulation (FM) and spectral characteristics for a 1.5?m phase-tunable DFB (PT DFB) laser have been studied experimentally. As tuning current was increased, light output, lasting wavelength, FM efficiency and spectral linewidth changed periodically. The continuous-wavelength tuning range was over l.2nm (150 GHz). A high FM efficiency, more than 16GHz/mA, and a flat FM response, up to 100MHz, were obtained.     

Alternate and simultaneous generation of 1-GHz dual-wavelengthpulses from an electrically tunable harmonically mode-locked fiber laser

A new scheme of producing dual-wavelength mode-locked pulses from a fiber laser is proposed and experimentally demonstrated. In addition to the simultaneous generation of two selected wavelength components, the scheme also allows the alternate generation of mode-locked pulses at different wavelengths. The alternate switching of wavelengths is demonstrated at 1 GHz, and has been achieved over an electrical tuning range of 13.1 nm using the dispersion-tuning approach. A constant mode spacing of 7.1 nm is maintained during the tuning process     

Low noise broadband tunerless waveguide sis receivers for 440–500 GHz and 630–690 GHz

We have developed broadband SIS heterodyne receivers for the frequency ranges from 440 to 500 GHz and 630 to 690 GHz. The mixerblocks contain a punched waveguide cavity which forms a fixed backshort. The substrate channel is sawed across the waveguide. The horn antenna is flanged to the mixerblock. The blocks are easy and quickly to manufacture even for the small dimensions needed in the submm wavelength range. We use Nb-Al₂O₃-Nb junctions with areas of 0.8 µm² and integrated three step niobium tuning structures. With this design we achieve instantaneous double sideband receiver noise temperatures around 120 K over the frequency range from 660 to 690 GHz and around 80 K from 440 to 500 GHz. The mixer performance agrees well with the design calculations for the tuning structures.     

Design and performance of a robust 180 nm CMOS standalone VCO and the integrated PLL

The design details of a low power/wide tuning range phase locked loop (PLL) is presented in 180 nm CMOS together with the simulated and post fabrication measured performance. The PLL has been specifically designed for applications requiring a wide tuning range (1.55–2.28 GHz) while maintaining low power consumption (18 mW) and good phase noise (−100.9 dBc/Hz at 1 MHz). The tuning range represents significant improvement over other reported PLL CMOS implementations. To illustrate the robustness of the architecture, a 90 nm CMOS design is included with a 5.8–9.45 GHz tuning range (48%), phase noise of −111.7 dBc/Hz, and power consumption of 18.6 mW. The stand alone voltage controlled oscillator (VCO) and the PLL were fabricated on a single 180 nm die providing a unique opportunity to analyze and measure both the stand alone VCO phase noise performance and the integrated PLL phase noise performance. The contributions to the PLL phase noise (phase detector, charge pump, VCO, divider, and reference source) are delineated and both the theoretical and measured PLL phase noise performance is discussed. Design tradeoffs are included such as effect of loop bandwidth on phase noise contributions.     

Fully integrated SiGe VCOs with powerful output buffer for 77-GHz automotive Radar systems and applications around 100 GHz

It is demonstrated that SiGe bipolar technologies are well suited for voltage-controlled oscillators (VCOs) in 77-GHz automotive radar systems. For this, the design of a VCO with powerful output buffer (with good decoupling capability and high output power), comparatively wide tuning range, and reasonably low phase noise is described. To achieve the required high output power, the potential operating range of the output transistors, limited by high-current effects and avalanche breakdown, respectively, had to be exploited using adequate transistor models. The VCOs need a single supply voltage only and have been fully integrated (including resonant circuit and output buffer) on a single small (1 mm/sup 2/) chip, demonstrating their low-cost potential. Experimental results showed, at a center frequency of around 77 GHz, a usable tuning range of 6.7 GHz and a phase noise of -97 dBc/Hz at 1-MHz offset frequency averaged over this range. In addition, the center oscillation frequency can be coarsely adjusted within a wide range by cutting links in the upper metallization layer. The total signal power delivered by both buffer outputs together is as high as 18.5 dBm at a power consumption of 1.2 W. Simulations let us expect a potential doubling of the output power (for two or four outputs) by extension of the output buffer. To get an impression of the maximum frequency achievable with the circuit concept and technology used, a second VCO (again with buffered output) has been developed. To the best of the authors' knowledge, the measured maximum oscillation frequency of about 100 GHz, at 12.4-dBm total output power (14.3 dBm at 99 GHz), is a record value for SiGe VCOs with buffered output operating at their fundamental frequency. The usable tuning range is still 6.2 GHz.     

A 1.3-V 5-mW fully integrated tunable bandpass filter at 2.1 GHz in 0.35-/spl mu/m CMOS

A 2.1-GHz 1.3-V 5-mW fully integrated Q-enhancement LC bandpass biquad programmable in f/sub o/, Q, and peak gain is implemented in 0.35-/spl mu/m standard CMOS technology. The filter uses a resonator built with spiral inductors and inversion-mode pMOS capacitors that provide frequency tuning. The Q tuning is through an adjustable negative-conductance generator, whereas the peak gain is tuned through an input G/sub m/ stage. Noise and nonlinearity analyses presented demonstrate the design tradeoffs involved. Measured frequency tuning range around 2.1 GHz is 13%. Spiral inductors with Q/sub o/ of 2 at 2.1 GHz limit the spurious-free dynamic range (SFDR) at 31-34 dB within the frequency tuning range. Measurements show that the peak gain can be tuned within a range of around two octaves. The filter sinks 4 mA from a 1.3-V supply providing a Q of 40 at 2.19 GHz with a 1-dB compression point dynamic range of 35 dB. The circuit operates with supply voltages ranging from 1.2 to 3 V. The silicon area is 0.1 mm/sup 2/.     

Widely tunable chaotic fiber laser for WDM-PON detection

A widely tunable high precision chaotic fiber laser is proposed and experimentally demonstrated. A tunable fiber Bragg grating （TFBG） filter is used as a tuning element to determine the turning range from 1533 nm to 1558 nm with a linewidth of 0.5 nm at any wavelength. The wide tuning range is capable of supporting 32 wavelength-division mul- tiplexing （WDM） channels with 100 GHz channel spacing. All single wavelengths are found to be chaotic with 10 GHz bandwidth. The full width at half maximum （FWHM） of the chaotic correlation curve of the different wave- lengths is on a picosecond time scale, thereby offering millimeter spatial resolution in WDM detection.     

宽频率范围的单子带压控振荡器设计

基于TSMC 180 nm CMOS工艺,提出了一种振荡频率为2～3 GHz的宽频率范围、低相位噪声的单子带压控振荡器(VCO).采用双平衡吉尔伯特混频结构,将单子带5～6 GHz压控振荡器与固定频率3 GHz压控振荡器进行下混频,可得到振荡频率为2～3 GHz的单子带压控振荡器,实现相对带宽从18.18％到40％的展...     

基于半导体光放大器交叉增益调制效应的主动锁模光纤激光器

提出一种腔内损耗小的基于半导体光放大器(SOA)交叉增益调制效应(XGM)的主动锁模光纤激光器结构。使用光环行器成功减小了激光器的腔内损耗,提高了激光器的输出功率。从理论上对有理数谐波锁模过程中腔内脉冲复合的物理机制进行了详细分析。利用有理数谐波锁模技术,在调制频率为10 GHz下,得到了重复频率为30 GHz的皮秒级光脉冲序列输出,其峰值功率约0.5 mW。由于半导体光放大器的宽增益谱与滤波器的较大可调谐范围,使得激光器输出可以在较大的波长可调谐范围内保持较大功率输出。成功实现了调制频率为20 GHz的谐波锁模短光脉冲输出,可调谐范围达40 nm,峰值功率大于0.65 mW。半导体光放大器和激光器的短腔长保证了激光器的长期稳定性。     

Two-electrode DFB laser filter used as a wide tunable narrow-bandFM receiver: tuning analysis, characteristics and experimental FSK-WDMsystem

Characteristics of a two-electrode DFB laser filter are studied both theoretically and experimentally. Using a matrix analysis of spontaneous emission, a continuous tuning range of 6.7 Å is achieved by changing both net field gains of the two electrodes. A total discontinuous tuning range of over 10 nm comprising alternating mode jumps and continuous tuning range of 4 Å are measured experimentally. The laser filter presents a FWHM bandwidth of 5 GHz which depends on the optical input power. In addition, it is demonstrated that a DFB laser filter can act as a frequency discriminator/photodetector, i.e., a narrow-band FM receiver, with a uniform bandwidth of 1.5 GHz. Using the two-electrode DFB laser for both transmitter and receiver, a two-channel FSK-WDM transmission system utilizing the discontinuous tuning range is reported. The advantage of such a device is the simplicity as compared to the heterodyne technique     

电控宽带连续调谐外腔半导体激光器

介绍了一种电控调谐的外腔半导体激光器，并对其连续调谐特性进行了理论和实验分析。压电陶瓷（ＰＺＴ）（双晶片）的电扫描角度可达１°，采用适当的外腔结构，靠ＰＺＴ可同时改变外腔腔长和光栅衍射角，实现输出波长的调谐。该器件调谐范围最大可达１５ｎｍ，连续调谐范围（无跳模）为５０ＧＨｚ     

Miniature packaged external-cavity semiconductor laser with 50 GHzcontinuous electrical tuning range

Miniature, packaged, grating-external-cavity lasers have been developed for use in PSK and DPSK coherent transmission systems at 1.5 μm. The outside dimensions of the package are 30×30×50 mm and the optical cavity length is nominally 30 mm, resulting in a spectral linewidth <100 kHz. The lasing wavelength is mechanically adjustable over the range 1510-1560 nm and electrically tunable over the range of 0.8 nm. With appropriate control of the grating piezos, a continuous (hop-free) tuning range of 50 GHz (0.4 nm) can be obtained     

SiGe Bipolar VCO With Ultra-Wide Tuning Range at 80 GHz Center Frequency

A SiGe millimeter-wave VCO with a center frequency around 80 GHz and an extremely wide (continuous) tuning range of 24.5 GHz ( ap 30%) is presented. The phase noise at 1 MHz offset is -97 dBc/Hz at the center frequency (and less than -94 dBc/Hz in a frequency range of 21 GHz). The maximum total output power is about 12 dBm. A cascode buffer improves decoupling from the output load at reasonable VCO power consumption (240 mW at 5 V supply voltage). A low-power frequency divider (operating up to 100 GHz) provides, in addition, a divided-by-four signal. As a further intention of this paper, the basic reasons for the limitation of the tuning range in millimeter-wave VCOs are shown and the improvement by using two (instead of one) varactor pairs is demonstrated.     

Tuning range and spectral selectivity of the distributed forwardcoupled (DFC) laser

The tuning performance and spectral filtering mechanism in the distributed forward-coupled (DFC) laser diode are investigated. This widely tunable device is based on codirectional mode coupling along the entire laser length by a gain/loss grating perturbation. Due to the transverse integration, even rather short (L≈300-600 μm) DFC lasers may achieve side-mode suppression superior to that of previous codirectionally coupled devices over similar tuning ranges. Model calculations yield a tuning range above 100 nm at 1.5-μm wavelength with a side-mode suppression ratio around 30 dB     

Wavelength-Tunable Short-Pulse Diode-Laser Fiber-Amplifier System Around 1.06$muhbox m$

We report the first actively mode-locked diode-laser fiber-amplifier system with wide wavelength tuning around 1.06$muhbox m$. Tuning is achieved over 45 nm via a feedback grating. Pulses with a repetition rate of 1.4 GHz and a pulse duration of 30 ps are generated with up to 9.5 W of average output power.     

Wavelength-tunable short-pulse diode-laser fiber-amplifier system around 1.06 /spl mu/m

We report the first actively mode-locked diode-laser fiber-amplifier system with wide wavelength tuning around 1.06 /spl mu/m. Tuning is achieved over 45 nm via a feedback grating. Pulses with a repetition rate of 1.4 GHz and a pulse duration of 30 ps are generated with up to 9.5 W of average output power.