Fabrication of Butt‐Coupled SGDBR Laser Integrated with Semiconductor Optical Amplifier Having a Lateral Tapered Waveguide

We have demonstrated a high‐power widely tunable sampled grating distributed Bragg reflector (SGDBR) laser integrated monolithically with a semiconductor optical amplifier (SOA) having a lateral tapered waveguide, which is the first to emit a fiber‐coupled output power of more than 10 dBm using a planar buried heterostructure (PBH). The output facet reflectivity of the integrated SOA using a lateral tapered waveguide and two‐layer AR coating of TiO₂ and SiO₂ was lower than 3 × 10^?4 over a wide bandwidth of 85 nm. The spectra of 40 channels spaced by 50 GHz within the tuning range of 33 nm were obtained by a precise control of SG and phase control currents. A side‐mode suppression ratio of more than 35 dB was obtained in the whole tuning range. Fiber‐coupled output power of more than 11 dBm and an output power variation of less than 1 dB were obtained for the whole tuning range.     

Attenuation inner-window in the amplifier- and modulator-integrated laser diode

To better control the input power of an amplifier, which is monolithically integrated with an electroabsorptive-modulated laser, an inner window is implemented by removing a section of the waveguide to realize an attenuator. It also reduces the effect of amplified spontaneous emission on the integrated laser. Attenuation around -10 dB is obtained by adjusting the length of the inner window. Because of different focal depths, unguided stray light from the inner window is not coupled to a fiber on which the amplifier output is focused through a lens.     

High power, diffraction-limited emission from monolithically integrated active grating master oscillator power amplifier (lasers)

A novel monolithically integrated master oscillator power amplifier with a distributed amplifier/grating output coupler is demonstrated which emits 370 mW in a single-frequency diffraction-limited beam without any form of active phase control. The distributed amplifier/grating output coupler results in a guided mode power that saturates along the direction of propagation, providing a uniform carrier density to preserve the flatness of the radiated phase front.<>     

High efficiency 1.3 mu m superluminescent diode with absorbing tapered waveguide

A new type of superluminescent diode (SLD) with a tapered waveguide in the absorbing region is proposed. This SLD structure monitors output power, as it emits monitor light from the rear facet that is about one-tenth the output power from the front one. Device parameters have been determined by beam propagation methods. A 1.3 mu m SLD fabricated by liquid phase epitaxy (LPE) with an absorbing waveguide 200 mu m long and with a 6.5 degrees tapered angle can emit output power of 13.5 mW from the front facet at a 200 mA driving current without lasing.<>     

Monolithically integrated waveguide-MSM detector-HEMT amplifier receiver for long-waveguide lightwave systems

The first demonstration is reported of a long-wavelength receiver that monolithically integrates an InGaAsP waveguide, an InAlAs-InGaAs metal-semiconductor-metal (MSM) detector, and an InAlAs-InGaAs high-election-mobility transistor (HEMT) amplifier. External responsivities in response to a guided signal of 0.43 and 0.5 A/W were recorded, respectively for a 150- and a 300- mu m-long detector integrated with an InGaAsP waveguide. This corresponds to an internal quantum efficiency of about 95% after taking account of the combined external losses such as insertion loss between waveguide and fiber and propagation loss in the waveguide. A pulse response of 200 ps. corresponding to a bandwidth of about 820 MHz, was measured at the output of the HEMT amplifier. The receiver represents a major advance toward achieving high-performance integrated receiving components for long-wavelength lightwave systems.<>     

Coherent lasers turn up the power

Three categories of multiwatt, coherent laser designs are discussed. The designs are single-mode waveguides suitable for output powers in the order of 200 mW, single-mode operation of multimode lasers, which are suitable for operation between 0.5 and 1.0 W, and the monolithically integrated master-oscillator power amplifier (M-MOPA) designs that have demonstrated 4.5 W of spectrally coherent output power and more than 0.8 W of single-lobe diffraction-limited output power in a technology that is scalable to even higher output powers. Laser-diode design architectures and the unique properties of semiconductor materials are reviewed     

1.55 μm polarisation independent semiconductor optical amplifierwith 25 dB fiber to fiber gain

Using a tapered in width square active waveguide and bulk InGaAsP/InP material we demonstrate a polarisation independent amplifier structure operating at 1550 nm with a reduced far-field divergence. Improvement of coupling efficiency enables us to achieve a 25 dB fiber to fiber gain together with 9 dBm fiber saturation output power for 150 mA bias current. A 200 ps gain recovery time allows fast gating or wavelength conversion     

Realisation of monolithically integrated single frequency MQW laser and booster amplifier at 1.5 mu m wavelength

The fabrication and performance of a 1.5 mu m wavelength multiquantum well distributed feedback laser monolithically integrated with a booster amplifier are described. Single longitudinal mode operation was achieved at output powers exceeding 45 mW. A minimum spectral linewidth of 2.3 MHz was obtained, with powers of 35 mW being reached before linewidth rebroadening occurred.<>     

Tunable external-cavity semiconductor laser using monolithicallyintegrated tapered amplifier and grating coupler for collimation

A novel lensless tunable external-cavity laser using monolithically integrated tapered amplifier, grating coupler (GC) and an external half mirror is proposed and demonstrated. It can be fabricated by a simple process and emits a collimated output beam. By making use of wavelength dispersion of the GC, the lasing wavelength can be angle tuned. Wavelength tuning over a wide range of 21.5 nm by 4.5° device rotation and an 84-mW output power were achieved under continuous-wave operation. A well-collimated output beam with a divergence angle as small as 0.3° was maintained over the entire tuning range     

选择外延技术研制1.5μm DFB激光器和自对准模斑转换器集成器件

利用选择外延技术研制了1.5μm DFB激光器和自对准模斑转换器单片集成器件.激光器的上限制层与垂直方向上楔型波导的模斑转换器同时选择性生长 ,这样的方法不仅可以分别优化有源区和模斑转换器的材料,同时可以降低选择性生长对接结构的难度.所研制集成器件的阈值为4.4mA,在49.5mA下的输出功率为10.1mW,边模抑制比为33.2dB,垂直方向和水平方向上的远场发散角分别为9°和15°,1dB偏调容差分别为3.6μm和3.4μm.     

选择外延技术研制1.5μm DFB激光器和自对准模斑转换器集成器件

利用选择外延技术研制了1.5μm DFB激光器和自对准模斑转换器单片集成器件.激光器的上限制层与垂直方向上楔型波导的模斑转换器同时选择性生长 ,这样的方法不仅可以分别优化有源区和模斑转换器的材料,同时可以降低选择性生长对接结构的难度.所研制集成器件的阈值为4.4mA,在49.5mA下的输出功率为10.1mW,边模抑制比为33.2dB,垂直方向和水平方向上的远场发散角分别为9°和15°,1dB偏调容差分别为3.6μm和3.4μm.     

InGaAsP/InP超辐射集成光源

为提高半导体超辐射器件的输出功率 ,采用直接耦合的方法 ,将超辐射发光管 (SL D)与半导体光放大器 (SOA)单片集成 ,制得了 1.3μm超辐射集成光源 ,其脉冲输出功率为 50 m W,光谱宽度 (FWHM)为 2 8.9nm。通过对放大器增益特性的讨论 ,得出了既能稳定器件性能 ,又可以提高输出功率的有效工作方案。     

Tapered thickness MQW waveguide BH MQW lasers

We propose and demonstrate a novel 1.3 μm InGaAsP/InGaAsP multiple-quantum-well (MQW) BH Fabry-Perot laser diode monolithically integrated with a MQW tapered thickness waveguide. A selective area growth (SAG) technique is used to fabricate the tapered thickness waveguide with low absorption loss and to integrate it with the MQW gain region with a high coupling efficiency. We achieve very narrow vertical and lateral far-field FWHM of 11.8° and 8.0°, with low threshold current of 19 mA and high slope efficiency of 0.25 mW/mA     

11 dBm photonic millimetre-wave generation at 100 GHz usinguni-travelling-carrier photodiodes

The design and characterisation of a millimetre-wave uni-travelling-carrier photodiode with a monolithically integrated matching (impedance transform) circuit utilising a coplanar-waveguide short-stub are presented. The device with the matching circuit shows ~50% higher efficiency than one with a 50 Ω load design. The maximum saturation output power obtained is 13.6 mW at 100 GHz     

Analysis of monolithic integrated master oscillator poweramplifiers

An analysis of a novel, monolithic integrated master oscillator power amplifier (M-MOPA) is presented. The M-MOPA consists of a DBR master oscillator which injects power into a linear chain of amplifiers and detuned second-order grating output couplers. The analysis self-consistently includes amplified spontaneous emission buildup and residual reflections throughout the amplifier stages. It predicts that output powers in excess of 1 W can be expected from a single-lateral-mode waveguide multistage amplifier less than 1 cm in length, injected with less than 15 mW of input power. In addition to the signal gain of >25 dB, the signal-to-noise ratio at 1-W output exceeds 15 dB. Because of the small reflections associated with the grating output couplers, and gain saturation by the injected signal, the amplifier self-oscillation threshold is suppressed to current densities above 15 kA/cm²     

Monolithically integrated semiconductor LED-amplifier for applications as transceivers in fiber access systems

We have fabricated a monolithically integrated LED-amplifier chip for application as a high-power broad-band transmitter. Amplified LED output of 10 mW and fiber-coupled power of 4 mW was demonstrated. The device can be used as a spectrally-sliced transmitter for wavelength-division-multiplexed networks or as a broad-band transmitter in subcarrier multiple-access systems to eliminate optical beat interference. The amplifier section in the integrated device can also be used as a photodetector. The performance of the device as a transceiver in a WDM multiple-access system operating at a typically proposed local-access data rate of 10 Mb/s was successfully demonstrated.     

一种新颖的毫米波集成功率合成器

本文介绍一种结构新颖的毫米波Ｅ面混合集成功率合成器及其设计方法。功率合成器电路由鳍线和Ｅ面线构成,输出端口为标准矩形波导。具有结构紧凑、调试简便的优点。采用两耿氏管,在Ｋａ波段,６３０ＭＨｚ的机械调谐带宽内连续波输出功率大于２００ｍＷ,最大输出功率为２９３ｍＷ。     

Efficient EM Simulation of GCPW Structures Applied to a 200-GHz mHEMT Power Amplifier MMIC

The behaviour of grounded coplanar waveguide (GCPW) structures in the upper millimeter-wave range is analyzed by using full-wave electromagnetic (EM) simulations. A methodological approach to develop reliable and time-efficient simulations is proposed by investigating the impact of different simplifications in the EM modelling and simulation conditions. After experimental validation with measurements on test structures, this approach has been used to model the most critical passive structures involved in the layout of a state-of-the-art 200-GHz power amplifier based on metamorphic high electron mobility transistors (mHEMTs). This millimeter-wave monolithic integrated circuit (MMIC) has demonstrated a measured output power of 8.7 dBm for an input power of 0 dBm at 200 GHz. The measured output power density and power-added efficiency (PAE) are 46.3 mW/mm and 4.5 %, respectively. The peak measured small-signal gain is 12.7 dB (obtained at 196 GHz). A good agreement has been obtained between measurements and simulation results.     

Diode-pumped and packaged acoustooptically tunableTi:Er:LiNbO3 waveguide laser of wide tuning range

Design, fabrication, and properties of an acoustooptically tunable Ti:Er:LiNbO₃ waveguide laser of up to 31-nm tuning range in the wavelength band 1530 nm<λ<1575 nm are discussed. The laser cavity is formed by an Au mirror and a dielectric mirror as output coupler, both vacuum-deposited on the polished waveguide endfaces. As tunable intracavity wavelength filter with zero frequency shift, two monolithically integrated single-stage acoustooptical TE-TM-mode converters are used together with two polarization splitters operated as TE- and TM-pass polarizers, respectively. The minimum threshold of about 54 mW (coupled) pump power is obtained at λ≈1561-nm emission wavelength for diode laser pumping at λ_p≈1480 nm. With about 110-mW coupled pump power, up to 320-μW output power is achieved; the emission linewidth is 0.3 nm