Efficient Frequency Doubling of a Low-Power Femtosecond Er-Fiber Laser in BiB$_{3}$ O$_{6}$

BiB₃O₆ (BIBO) crystal has been used for efficient second-harmonic generation (SHG) of a low-power femtosecond Er-fiber laser-amplifier system operating at 56 MHz. At the maximum input power of 65 mW, an internal conversion efficiency of 23% was achieved for SHG at 782 nm, with a pulse duration of 64 fs. A comparison with beta-BaB₂O₄ reveals superior properties of BIBO for such ultrashort-pulse ultra-broadband SHG.     

180$^{circ}$ and 90$^{circ}$ Phase Shifting Networks With an Octave Bandwidth and Small Phase Errors

A new phase shifting network for both 180 $^{circ}$ and 90 $^{circ}$ phase shift with small phase errors over an octave bandwidth is presented. The theoretical bandwidth is 67% for the 180$^{circ}$ phase bit and 86% for the 90$^{circ}$ phase bit when phase errors are $pm 2^{circ}$. The proposed topology consists of a bandpass filter (BPF) branch, consisting of a LC resonator and two shunt quarter-wavelength transmission lines (TLs), and a reference TL. A theoretical analysis is provided and scalable parameters are listed for both phase bits. To test the theory, phase shifting networks from 1 GHz to 3 GHz were designed. The measured phase errors of the 180$^{circ}$ and the 90$^{circ}$ phase bit are $pm 3.5^{circ}$ and $pm 2.5^{circ}$ over a bandwidth of 73% and 102% while the return losses are better than 18 dB and 12 dB, respectively.      

High-${Q}$ Transformers in Copper-Interconnection CMOS Technology

This paper proposes the adoption of aluminum-pad (AL-pad) film to improve the performance of on-chip transformers using current CMOS technology. Two devices proposed in this paper use an AL-pad film, without adding extra process, to enhance the Q value and bandwidth in the copper-interconnection process. The first device changes the transformer's coil location to increase the peak Q value and operation bandwidth, and the second device alters the coil material to improve the Q value in the entire operating band. A foundry 0.13-mum CMOS technology is fabricated the proposed transformers. The measurement results demonstrate that the first proposed device improves the peak Q value and operation bandwidth with the values of 32.5% and 22.6%, respectively. Afterward, the second proposed device increases the peak Q value 44.7% more than the standard device.     

Zn$_{1 - x}$Mg$_{x}$ O Homojunction-Based Ultraviolet Photodetector

Zn$_{1 - {x}}$ Mg$_{x}$ O p-n photodiodes were fabricated on (0001) sapphire substrates using a pulsed laser deposition technique with different Mg contents. Ti–Au and Ni–Au metals deposited using vacuum evaporation were used as n-type and p-type contacts, respectively. The X-ray diffraction analysis showed the Zn$_{1 - {x}}$Mg$_{x}$O double layers have a single phase hexagonal wurtzite structure. The optical bandgap of Zn$_{1 - {x}}$Mg$_{x}$O films has been tuned from 3.27 to 4.26 eV by increasing the Mg content ${x} =0.0$ to ${x}=0.34$. Correspondingly, the cutoff wavelength of the resultant detectors varies from 380 to 284 nm. Zn$_{1 - {x}}$Mg$_{x}$O p-n photodiodes with different Mg contents exhibit very good performance, with a very low dark current (${≪}$ 20 pA) at the bias voltage of 10 V. The ultraviolet to visible rejection ratio is more than three orders of magnitude.      

Diplexer With Integrated Filters and Photodetector in Ge–Si Using $Gamma-{X}$ and $Gamma-{M}$ Directions in a Grating Coupler

We demonstrate a central-office-type diplexer in which the filter and photodetector are monolithically integrated on a silicon-on-insulator substrate. The photonic integrated circuit receives a 1577-nm signal from an external laser and sends it to the fiber link using a two-dimensional grating coupler. The same grating coupler receives a 1270-nm signal from the fiber link and sends it to a monolithically integrated germanium photodetector using a polarization-diversity scheme to achieve polarization independence. The grating coupler is novel in that both the $Gamma-{X}$ and $Gamma-{M}$ directions are employed. This allows the grating coupler to couple both the 1577- and 1270-nm wavelengths with a small fiber tilt angle and hence have low polarization-dependent loss.      

Enhanced Vertical Light Extraction From Ultrathin Amorphous Si–Si$_{3}$ N$_{4}$ Multilayers With Photonic Crystal Patterns

We have investigated the significant enhancement of light extraction from amorphous Si-Si₃N₄ multiple-quantum-well structures, in which two-dimensional hexagonal-lattice air-hole photonic crystals (PCs) were integrated. The vertical spectral integrated intensity of light emission around 674 nm was enhanced up to times due to strong coupling to the inherent leaky modes or radiation modes near Gamma point of PC's band structure. The experimental observations also suggested that coupling to leaky modes should be more beneficial for light extraction enhancement.     

Nitride-Based Asymmetric Two-Step Light-Emitting Diode With In$_{0.08}$ Ga$_{0.92}$ N Shallow Step

A nitride-based asymmetric two-step light-emitting diode (LED) with $hbox{In}_{0.08} hbox{Ga}_{0.92}hbox{N}$ shallow step was proposed and fabricated. It was found that the low indium content $hbox{In}_{0.08} hbox{Ga}_{0.92}hbox{N}$ layer can significantly enhance phase separation and/or inhomogeneous indium distribution in the active $hbox{In}_{0.27}hbox{Ga}_{0.73}hbox{N}$ layer. It was also found that we can enhance LED output power by a factor of 2.27 by simply inserting an $hbox{In}_{0.08} hbox{Ga}_{0.92}hbox{N}$ shallow step.      

2 MHz AO $Q$ -switched ${rm TEM}_{00}$ Grazing Incidence Laser With 3 at.% Neodymium Doped Nd:YVO$_{4}$

We present a detailed experimental and theoretical study of the ultrahigh repetition rate AO $Q$ -switched ${rm TEM}_{00}$ grazing incidence laser. Up to 2.1 MHz $Q$-switching with ${rm TEM}_{00}$ output of 8.6 W and 2.2 MHz $Q$ -switching with multimode output of 10 W were achieved by using an acousto-optics $Q$ -switched grazing-incidence laser with optimum grazing-incidence angle and cavity configuration. The crystal was 3 at.% neodymium doped Nd:YVO$_{4}$ slab. The pulse duration at 2 MHz repetition rate was about 31 ns. The instabilities of pulse energy at 2 MHz repetition rate were less than ${pm}6.7hbox{%}$ with ${rm TEM}_{00}$ operation and ${pm}3.3hbox{%}$ with multimode operation respectively. The modeling of high repetition rate $Q$-switched operation is presented based on the rate equation, and with the solution of the modeling, higher pump power, smaller section area of laser mode, and larger stimulated emission cross section of the gain medium are beneficial to the $Q$-switched operation with ultrahigh repetition rate, which is in consistent with the experimental results.      

A 67 dBm $OIP_{3}$ Multistacked Junction Varactor

A multistacked varactor is presented for ultra-linear tunable radio frequency applications. The varactor elements are applied in anti-series configuration and are characterized by an “exponential” $C$- $V _{R}$ relationship. Third-order intermodulation ($IM_{3}$) is cancelled through proper harmonic loading of the terminals of the anti-series configuration. Multiple stacking is used to further increase the power handling and to minimize the remaining fifth-order distortion. The measured output intercept point ($OIP_{3}$ ) at 2 GHz is $ > 67~{rm dBm}$ for modulated signals up to 10 MHz bandwidth, while providing a capacitance tuning ratio of 3:1 with an average quality factor of 40 and maximum control voltage of 10 V.      

Frequencies and Wavelengths From a New Far-Infrared Lasing Gas: $^{13}$ CHD$_{2}$ OH

The first laser action produced by the partially deuterated isotopic form of methanol, $^{13}$ CHD$_{2}$ OH, has been observed. With this laser medium, eight far-infrared laser emissions were discovered having wavelengths ranging from 33.8 to 80.9 $mu$m. A three-laser heterodyne system was used to measure the frequencies for these newly discovered laser lines and are reported with fractional uncertainties of ${pm}3 times 10^{-7}$. The offset frequency of the CO$_{2}$ pump laser was measured with respect to its center frequency for each $^{13}$CHD$_{2}$OH laser emission.      

Impacts of $hbox{N}_{2}$ and $hbox{NH}_{3}$ Plasma Surface Treatments on High-Performance LTPS-TFT With High-$kappa$ Gate Dielectric

Low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) with high- $kappa$ gate dielectrics and plasma surface treatments are demonstrated for the first time. Significant field-effect mobility $mu_{rm FE}$ improvements of $sim$86.0% and 112.5% are observed for LTPS-TFTs with $hbox{HfO}_{2}$ gate dielectric after $hbox{N}_{2}$ and $ hbox{NH}_{3}$ plasma surface treatments, respectively. In addition, the $hbox{N}_{2}$ and $ hbox{NH}_{3}$ plasma surface treatments can also reduce surface roughness scattering to enhance the field-effect mobility $mu_{rm FE}$ at high gate bias voltage $V_{G}$, resulting in 217.0% and 219.6% improvements in driving current, respectively. As a result, high-performance LTPS-TFT with low threshold voltage $V_{rm TH} sim hbox{0.33} hbox{V}$, excellent subthreshold swing S.S. $sim$0.156 V/decade, and high field-effect mobility $mu_{rm FE} sim hbox{62.02} hbox{cm}^{2}/hbox{V} cdot hbox{s}$ would be suitable for the application of system-on-panel.      

A TV-Band Harmonic Rejection Mixer Adopting a $g_{m}$ Linearization Technique

A TV-band harmonic rejection mixer (HRM) adopting a novel $g_{m}$ linearization technique is proposed and its harmonic rejection ratio (HRR) over the mismatch parameters is analyzed numerically using simple vector diagrams. The operational mechanism of the proposed $g_{m}$ linearization technique is described and its effectiveness is proved with both simulation and measurement. Based on the proposed idea and analysis, a TV-band HRM is implemented with 90 nm CMOS technology. Measurements show 3–6 dB IIP3 improvement and 37–52 dBc HRR at 29 mA current in 1.2 V supply voltage.      

A 20 to 24 GHz $+$16.8 dBm Fully Integrated Power Amplifier Using 0.18 $mu{rm m}$ CMOS Process

A 20-24 GHz, fully integrated power amplifier (PA) with on-chip input and output matching is realized in 0.18 mum standard CMOS process. By cascading two cascode stages, the PA achieves 15 dB small signal gain, 10.7% power added efficiency, 16.8 dBm output saturation power and high power density per chip area of 0.137 W/mm², which is believed to be the highest power density to our knowledge. The whole chip area with pads is 0.35 mm², which is the smallest one compared to all reported paper.     

A Comparative NBTI Study of $hbox{HfO}_{2}$, $hbox{HfSiO}_{x}$, and SiON p-MOSFETs Using UF-OTF $I_{rm DLIN}$ Technique

The time, temperature, and oxide-field dependence of negative-bias temperature instability is studied in $hbox{HfO}_{2}/hbox{TiN}$, $ hbox{HfSiO}_{x}/hbox{TiN}$, and SiON/poly-Si p-MOSFETs using ultrafast on-the-fly $I_{rm DLIN}$ technique capable of providing measured degradation from very short (approximately microseconds) to long stress time. Similar to rapid thermal nitrided oxide (RTNO) SiON, $hbox{HfO}_{2}$ devices show very high temperature-independent degradation at short (submilliseconds) stress time, not observed for plasma nitrided oxide (PNO) SiON and $hbox{HfSiO}_{x}$ devices. $hbox{HfSiO}_{x}$ shows lower overall degradation, higher long-time power-law exponent, field acceleration, and temperature activation as compared to $hbox{HfO}_{2}$, which are similar to the differences between PNO and RTNO SiON devices, respectively. The difference between $ hbox{HfSiO}_{x}$ and $hbox{HfO}_{2}$ can be attributed to differences in N density in the $hbox{SiO}_{2}$ IL of these devices.      

A 10 MS/s 11-bit 0.19 mm $^{2}$ Algorithmic ADC With Improved Clocking Scheme

A 10 MS/s 11-bit algorithmic ADC with an active area of 0.19$~{hbox{mm}}^{2}$ is presented. Using an improved clocking scheme, this design overcomes the speed limit of algorithmic ADCs. The proposed ADC employs amplifier sharing, DC offset cancellation, and input memory effect suppression, resulting in reduced area and power, and high linearity. The ADC implemented in a 0.13$~mu{hbox{m}}$ thick gate-oxide CMOS process achieves 69 dB SFDR, 58 dB SNR, and 56 dB SNDR, while consuming 3.5 mA from a 3 V supply.      

Chalcogenide As$_{2}$S$_{3}$ Suspended Core Fiber for Mid-IR Wavelength Conversion Based on Degenerate Four-Wave Mixing

A chalcogenide optical fiber of special design is proposed to convert a short-wavelength infrared radiation (around 2 $mu$m) up to a second transparency window of atmospheric air (around 4.5 $mu$ m) by degenerate four-wave mixing. The fiber supports a small core surrounded by three large air holes. The zero-dispersion wavelength is shifted down to 2 $mu$m in this fiber by properly tailoring the fiber core. We demonstrate by solving the nonlinear SchrÖdinger equation that efficient wavelength-conversion can be obtained by pumping the fiber with a Tm : SiO$_{2}$ pulsed fiber laser.      

Dual-Gate Graphene FETs With $f_{T}$ of 50 GHz

A dual-gate graphene field-effect transistor is presented, which shows improved radio-frequency (RF) performance by reducing the access resistance using electrostatic doping. With a carrier mobility of 2700 cm²/V · s, a cutoff frequency of 50 GHz is demonstrated in a 350-nm-gate-length device. This f_T value is the highest frequency reported to date for any graphene transistor, and it also exceeds that of Si MOS field-effect transistors at the same gate length, illustrating the potential of graphene for RF applications.     

$C$ -Band Optical 90$^{circ}$ -Hybrids Based on Silicon-on-Insulator 4 $times$ 4 Waveguide Couplers

We demonstrate 4times4 multimode interference couplers in a silicon-on-insulator rib waveguide technology that enable compact integrated fully passive optical 90deg-hybrid devices with operation across the C-band.     

Eigendecomposition of Images Correlated on $S^{1}$, $S^{2}$, and $SO(3)$ Using Spectral Theory

Eigendecomposition represents one computationally efficient approach for dealing with object detection and pose estimation, as well as other vision-based problems, and has been applied to sets of correlated images for this purpose. The major drawback in using eigendecomposition is the off line computational expense incurred by computing the desired subspace. This off line expense increases drastically as the number of correlated images becomes large (which is the case when doing fully general 3-D pose estimation). Previous work has shown that for data correlated on S ¹ , Fourier analysis can help reduce the computational burden of this off line expense. This paper presents a method for extending this technique to data correlated on S ² as well as SO(3) by sampling the sphere appropriately. An algorithm is then developed for reducing the off line computational burden associated with computing the eigenspace by exploiting the spectral information of this spherical data set using spherical harmonics and Wigner-D functions. Experimental results are presented to compare the proposed algorithm to the true eigendecomposition, as well as assess the computational savings.