High Saturation Output Power Research Articles

New SOA Design With Large Gain, Small Noise Figure, and High Saturation Output Power Level

New SOA Design With Large Gain, Small Noise Figure, and High Saturation Output Power Level

Active multi-mode interferometer semiconductor optical amplifier on quantum dots toward high saturated output power under high temperature

A semiconductor optical amplifier (SOA) is wildly used as gain media in a photonic integrated circuit, as it is integrable with various devices, including wavelength filter, on the same wafer. Quantum dots (QD) have been known to realize high-temperature operation without using a thermo-cooler, the saturated output power was not high due to the limited density of state in QD. To realize high saturated output power under high temperatures, we have exploited the active multi-mode interferometer (active-MMI) configuration on QD SOA. We fabricated active-MMI SOA using a 1.31 μm InAs/GaAs QD active layer with the design of approximately 5 times larger footprint compared to a single stripe, whereas it holds regular single transverse mode output. As a result, a significant improvement of 15 dB saturated output power at 75 °C was substantiated successfully.

A high power X‐band internally‐matched power amplifier with 705 W peak power and 51.7% PAE

A high power and high efficiency fully internally-matched GaN power amplifier operating at X-band is proposed. The device is realized by matching four GaN power bars of 18-mm gate periphery. To reduce the size, single layer capacitors with high permittivity are used, and the impedance matching circuits are fabricated on Al2O3 ceramic substrate. The device exhibits saturated output power of more than 660 W with power gain above 9.8 dB within the frequency range of 8.2–8.8 GHz, based on the pulse mode of 100 μs pulse width and 10% duty. In addition, the highest saturated output power and power added efficiency reach 705 W and 51.7% with packaging compact size (26 mm × 17.4 mm).

A Monolithically Integrated Single-Input Load-Modulated Balanced Amplifier With Enhanced Efficiency at Power Back-Off

In this article, the design of a power amplifier (PA) using a simple but effective architecture, namely, load-modulated balanced amplifier (LMBA), is presented. Using this architecture for PA design, it can achieve not only a relatively high saturated output power but also an excellent efficiency enhancement at the power back-off (PBO) region. To prove that the presented approach is feasible in practice, a PA is designed in a 1- μm gallium arsenide (GaAs) HBT process. Operating under a 5-V power supply, the PA can deliver more than 31-dBm saturated output power with 36% collector efficiency (CE) at 5 GHz. Moreover, it also achieves 1.2 and 1.23 times CE enhancement over an idealistic Class-B PA at 6- and 9-dB PBO levels, respectively. Finally, the designed PA supports 64-quadrature amplitude modulation (QAM) with 80 Msys/s at 22-dBm average output power while still maintaining an error vector magnitude (EVM) and adjacent channel power ratio (ACPR) better than -29.5 dB and -29.4 dBc, respectively.

Performance Analysis of a Low-Noise, Highly Linear Distributed Amplifier in 500-nm InP/InGaAs DHBT Technology

This article is an extension of the previous report on an ultrawideband distributed amplifier (DA) in the InP double heterojunction bipolar transistor (DHBT) technology. With the choice of a tricode unit cell, the Miller capacitance is reduced and a larger bandwidth (BW) is obtained. Measured S-parameters show a 3-dB BW of near dc to >170 GHz with a gain of 12 dB. In addition, the circuit operates in low dc bias conditions, thus yielding a low measured noise figure (NF) of 8 dB over the frequency range of 5–50 GHz and 12 dB at 135 GHz. Within the 5–50-GHz frequency range, the NF is only 0.5 dB higher than the NF of a similar DA with cascode unit cell. When the circuit is measured for large-signal condition, it reaches a 1-dB output compression point, $P_{\mathrm {1\,dB}}$ , of 8.4 dBm at 150 GHz, a saturated output power of approximately 10 dBm, and an associated maximum power-added efficiency (PAE) of 6%. This is the best linearity as well as the highest saturated output power and PAE reported at this frequency for DAs. When measured at 20 GHz, the circuit shows a $P_{\mathrm {1\,dB}}$ , of 9 dBm and output referred third-order intercept point of 22 dBm, a saturated output power of 11 dBm, and an associated maximum PAE of 6%, thereby proving its uniform large-signal character within the full band. In short, this circuit brings in the unique combination of low NF, highly linear characteristics, and high PAE simultaneously together over large BW. Furthermore, the circuit consumes 180 mW of dc power only.

High-Performance O-Band Quantum-Dot Semiconductor Optical Amplifiers Directly Grown on a CMOS Compatible Silicon Substrate

High gain and high saturation output power silicon-based semiconductor optical amplifiers (SOAs) are essential elements in future large-scale silicon photonic integrated circuits (PICs) to compensa...

Linear and Nonlinear Noise Characterisation of Dual Stage Broadband Discrete Raman Amplifiers

We characterise the linear and nonlinear noise of dual stage broadband discrete Raman amplifiers (DRAs) based on conventional Raman gain fibres. Also, we propose an optimised dual stage DRA setup that lowers the impact of nonlinear noise (generated in the amplifier) on the performance of a transmission link (with 100-km amplifier spacing). We numerically analyse the design of a backward pumped cascaded dual stage 100-nm DRA with high gain (∼20 dB) and high saturated output power (>23 dBm). We show that the noise figure (NF) of the dual stage DRA is mainly dominated by the first stage irrespective of the type of gain fibre chosen in the second stage, and we also demonstrate that optimising the length and the type of Raman gain fibre can have significant impact on the size of inter/intrasignal nonlinearities generated. Here, we report a theoretical model to calculate the nonlinear noise power generated in transmission spans with dual stage DRAs considering piecewise signal power evolution through the Raman gain fibres. The predicted signal-to-noise ratio (SNR) performances are calculated from the combined contributions from NF and nonlinear product power obtained using the proposed analytical model for transmission systems deployed with 100-km transmission span compensated by different dual stage DRAs. Finally, an optimised IDF 6 km–SMF 10 km dual stage configuration has been identified using the theoretical model, which allows maximum SNR of 14.6 dB at 1000 km for 1 THz Nyquist wavelength division multiplexed signal and maximum transmission reach of 3400 km at optimum launch power assuming 8.5 dB HD-FEC limit of the Nyquist PM-QPSK signal.

Large mode-volume, large beta, photonic crystal laser resonator

We propose an optical resonator formed from the coupling of 13, L2 defects in a triangular-lattice photonic crystal slab. Using a tight-binding formalism, we optimized the coupled-defect cavity design to obtain a resonator with predicted single-mode operation, a mode volume five times that of an L2-cavity mode and a beta factor of 0.39. The results are confirmed using finite-difference time domain simulations. This resonator is very promising for use as a single mode photonic crystal vertical-cavity surface-emitting laser with high saturation output power compared to a laser consisting of one of the single-defect cavities.

1310nm Raman amplifier utilizing high-power, quantum-dot pumping lasers

Abstract The Raman amplifier can be used to increase the range of 1310 nm transmission. In the paper, we present detailed studies regarding the design and performance of the 1310 nm Raman amplifier utilizing quantum-dot pumping lasers. We design and investigate performance of the QD laser based 1310 nm Raman amplifier with a single and double pump configuration, different fiber lengths and 1240/1310 nm coupler types (CWDM or circulator). The 1310 nm Raman amplifier gain as a function of wavelength is presented showing the amplification bandwidth of about 14–16 nm. Further, we achieved a gain of 17.7 dB and a noise figure of 4.5 dB in a QD-laser pumped 1310 nm Raman amplifier in a double pump configuration and 12.3 dB in a single pump configuration. Application of the 1240/1310 nm CWDM coupler allows for about 1–2 dB higher gain than circulator, however, with the potential trade off of the amplification bandwidth. We compare the 1310 nm Raman amplifier with the 1310 nm SOA, proving the comparable gain, higher saturation output power and lower noise figure of the Raman amplifier. Finally, we show that joined SOA-Raman amplifier can provide the bandwidth up to 85 nm.

20–40 GHz dual‐gate frequency doubler using 0.5 μm GaAs pHEMT technology

A Ka-band dual-gate frequency doubler using 0.5 μm GaAs enhancement-mode pHEMT process is presented. The cascode circuit is equalised to the dual-gate frequency doubler and the relationship between bias and output matching is discussed to obtain the maximum output power and conversion efficiency. Since a pinch-off gate-to-source bias is driven at the input gate node, the frequency doubler consumes little DC power when injecting a low-power fundamental signal. Based on the analysis, the designed dual-gate doubler has a 3 dB bandwidth of 5.6 GHz, from 36 to 41.6 GHz. The fundamental suppressions are better than 15 dB. The measured maximum conversion gain is −0.9 dB at an injected power of 7 dBm. A high saturation output power is 7 dBm with a conversion efficiency of 14.3%. The measured results confirm the validity of the proposed analysis method.

A high output power V-band GaAs HEMT push–pull power amplifier using meandering baluns technology

A broadband, high saturation output power 0.15-μm gate length GaAs pseudomorphic high-electron mobility transistor push-pull V-band power amplifier has been demonstrated using meandering balun designs. Two meandering low-loss planar three-coupled-line baluns were used to form push–pull mechanism for both stages. The meandering baluns provide 180° differential outputs from the applied single-ended input at the V-band and the size was reduced for 23% compared to traditional design. The proposed push–pull amplifier achieved a peak small-signal gain of 16.8 dB at 58 GHz, a 3 dB bandwidth of 55–62 GHz, and a peak power added efficiency of 13.8%.

Dynamic and static gain characteristics of quantum-dot semiconductor optical amplifiers operating at [formula omitted

We investigate the dynamic and static gain characteristics of quantum-dot semiconductor optical amplifiers (QD-SOAs) operating at 1.55μm based upon the experimental measurements performed on an InAs/InGaAsP/InP QD-SOA and simple modeling tools. A two-level rate equation model proved to be sufficient to explain the experimental gain dynamics as a function of current. The simple model allowed the derivation of the saturation power of QD-SOAs in the static regime. We show that the saturation power of QD-SOAs, in contrast to bulk and quantum well amplifiers, is enhanced by a factor of roughly two that depends on the material and device parameters. Our modeling tools are based on the experimentally obtained quantities and facilitates the analysis of different devices' designs and the identification of the parameters that play a key role in the fast QD-SOA gain recovery and its high saturation output power, namely, a fast capture time of carriers into the dot and a large energy difference between wetting layer and quantum dot states.

Output Level Control of SOA Using On-Chip Heater for High Output Power Operation

A novel gain control scheme of semiconductor optical amplifiers (SOAs) using a heater-mounted SOA was investigated. In our proposal, a simple SOA gain control using an on-chip heater provides a high saturation output power over an entire gain control range of 10 dB. This scheme widely expands the usable power range in output level control of a 10 Gbps NRZ-OOK signal, compared to that of a conventional gain control operated by drive current. As a result, the heater-mounted SOA exhibited a large input power dynamic range (IPDR) of > 17 dB up to the output power of +8.0 dBm in level control operation.

Monolithically Integrated 8:1 SOA Gate Switch With Large Extinction Ratio and Wide Input Power Dynamic Range

A monolithic 8:1 SOA gate switch that integrates an 8-ch SOA gate array, an 8:1 optical coupler, and a 1-ch SOA gate was developed for use in a large scale optical packet switching system. A 250-mum-long compact field-flattened coupler (FFC) produces a very small channel-imbalance together with a compact total chip size of 3.0 times 1.0 mm. The device exhibited a large ON-state gain of >14.3 dB and a small total gain deviation of 3.0 dB. The optimized passive waveguide structure successfully suppressed the stray light, which resulted in a record-high ON-OFF extinction ratio of >70 dB. We used a thin tensile-strained multi-quantum well (MQW) active layer which can attain high-saturation output power, low noise, and polarization insensitivity for SOA gates. Due to the coexistence of a high saturation output power and a low noise figure, the device exhibited a very wide input power dynamic range of 20.5 dB for a 10-Gb/s NRZ signal.

Schottky Barrier Diode Circuits in Silicon for Future Millimeter-Wave and Terahertz Applications

This paper presents Schottky barrier diode circuits fully integrated in a 0.13- mum SiGe BiCMOS process technology. A subharmonically pumped upconverter and a frequency doubler are demonstrated that operate beyond 100 GHz without the need of external components. The upconverter has a size of 430 times 780 mum2 including on-chip matching elements and bond pads. It has a conversion gain of - 6 to - 7 dB from 100 to 120 GHz. The upconverter achieves a high single-sideband saturated output power of - 4 dBm from 100 to 120 GHz and a high linearity with a 1-dB compression point of - 6 dBm. The frequency doubler has a size of 360 times 500 mum2 and can deliver up to 2.5 dBm at 110 GHz.

Highly Uniform Eight-Channel SOA-Gate Array With High Saturation Output Power and Low Noise Figure

A high-power eight-channel semiconductor optical amplifier gate array was developed for application as an optical switch in broadcast-and-select-type optical packet switching systems. The device exhibited a low polarization-dependent gain (<0.8 dB), a high extinction ratio (>60 dB), a low noise figure (<6.2 dB), and a high saturation output power (> +18.2 dBm) for all eight channels. It also exhibited very high interchannel uniformity of less than 0.3 dB for all characteristics.

Record high saturation output power (+20 dBm) and low NF (6.0 dB) polarisation-insensitive MQW-SOA module

A polarisation-insensitive semiconductor optical amplifier module with a thin tensile-strained multiple quantum well active layer is developed. The module exhibited a record high saturation output power of +20.0 dBm and a low noise figure of 6.0 dB at 1550 nm together with a small polarisation-dependent gain of 0.6 dB.

C-band GaAs FET power amplifiers with 70-W output power and 50% PAE for satellite communication use

This paper describes a successfully developed high-power and high-efficiency C-band GaAs FET amplifier for satellite communication systems. To realize high efficiency in a high-power amplifier, an HFET well-designed for high-power applications is developed, and precise design for an amplifier is carried out. The HFET employed achieves reduction in a gate leakage current while maintaining a high maximum drain current. For precise design of an amplifier, large-signal FET model parameters are extracted using pulsed I-V and S-parameter measurements. Based on this model, second harmonic impedances as well as fundamental impedances are determined for obtaining high efficiency and input- and output-matching circuits which are assembled in a compact package are designed to achieve a high-efficiency internally matched amplifier. As a result, the amplifier delivers a high saturated output power of 70 W and a high power-added efficiency of 51%. These characteristics are the record power performance in C-band in terms of simultaneous achievement of high power and high efficiency. A low third order intermodulation distortion of -35 dBc is also obtained at a drain voltage of 10 V.

Record high saturation power (+22 dBm) and low noise figure (5.7 dB) polarization-insensitive SOA module

A polarization-insensitive semiconductor optical amplifier (SOA) module that achieves both a high saturation output power and a low noise figure (NF) was developed by applying a multiple-quantum-well SOA in a polarization diversity configuration. The compact and low-loss SOA module exhibited a gain of 15 dB, a polarization dependence of 0.5 dB, a record-high saturation output power of +22 dBm, and a low NF of 5.7 dB at a wavelength of 1550 nm. Over the wavelength range covering four coarse wavelength-division-multiplexing channels (1471, 1491, 1511, and 1531 nm), the module gain was greater than 15 dB, the gain variation is less than 2 dB taking into account both its wavelength dependence and polarization dependence, the module saturation output power was greater than +18.7 dBm, and the module NF was less than 7.4 dB.

A broad-band MQW semiconductor optical amplifier with high saturation output power and low noise figure

A broad-band semiconductor optical amplifier (SOA) that achieves both a high chip saturation output power and a low chip noise figure (NF) was developed by using a thin multiquantum well with low internal loss. The SOA exhibited a high chip saturation output power of >+19.6 dBm and a low chip NF of <4.5 dB over a 3-dB gain bandwidth of 120 nm (1450-1570 nm). For the amplification of optical signals modulated at 40-Gb/s nonreturn-to-zero format, a penalty-free amplification was confirmed up to an average chip output power of +18.1 dBm.