Showing papers in "IEEE Journal of Quantum Electronics in 2010"

Thin-Film Schottky Barrier Photodetector Models

Abstract: Phenomenological models for the internal quantum efficiency of Schottky barrier photodetectors suitable for the detection of optical radiation below the bandgap energy of the semiconductor are presented and discussed. The detection mechanism is internal photoemission from the metal film into the semiconductor substrate. Three detector configurations are considered: the first consists of a thick metal film on a semiconductor substrate forming a single Schottky barrier; the second consists of a thin metal film on a semiconductor substrate also forming a single Schottky barrier; and the third consists of a thin metal film buried in semiconductor and forming two Schottky barriers (one along each metal-semiconductor interface). In the three cases, illumination through the semiconductor substrate is assumed. The two thin-film configurations provide enhanced internal quantum efficiencies due to multiple hot carrier reflections within the metal film, with the double-barrier case providing the greatest enhancement due to emission over two barriers. The models proposed are based on assessing the emission probability of hot carriers as a function of their energy, taking into account multiple reflections within the metal film and energy losses due to internal scattering (e.g., with phonons and cold carriers). The thin-film single-barrier model was tested via comparisons with responsivity measurements reported in the literature for PtSi/p-Si and Pd2Si/p-Si detectors.

High-Saturation-Current Modified Uni-Traveling-Carrier Photodiode With Cliff Layer

Abstract: We demonstrate two modified uni-traveling carrier photodiode (MUTC) structures that incorporate a charge or “cliff” layer to attain high-saturation-current. MUTC1 achieved responsivity of 0.82 A/W and 134 mA saturation current at -6-V and 20 GHz. The MUTC2 structure, which has higher doping density in the cliff layer and thinner absorption region, exhibited a higher saturation current of 144 mA (at -5-V) and an improved 3 dB bandwidth of 24 GHz; however, the responsivity was reduced to 0.69 A/W. For MUTC2, a high-saturation-current bandwidth product of 3456 GHz mA has been achieved. An intermodulation distortion figure of merit, IP3, > dBm at 20 GHz was observed for both MUTC structures.

Strain-Balanced ${\rm Ge}_{z}{\rm Sn}_{1-z}\hbox{--}{\rm Si}_{x}{\rm Ge}_{y}{\rm Sn}_{1-x-y}$ Multiple-Quantum-Well Lasers

Abstract: We propose and analyze a strain-balanced GezSn1-z-SixGeySn1-x-y multiple-quantum-well (MQW) laser. By incorporating a proper amount of -Sn into Ge, a direct-bandgap GeSn alloy can be realized to achieve population inversion in the direct conduction band. The introduction of compressive strain into the GeSn QW can effectively modify the valence band structure to reduce the threshold carrier density. We calculate the electronic band structure and the polarization-dependent optical gain of the strained GezSn1-z-SixGeySn1-x-y MQW laser taking into account the effect of the L-conduction bands. We also present our waveguide design for index guidance and calculate the optical confinement factors of various regions. Our calculation indicates that the modal gain can reach the threshold condition and lead to lasing action.

High Peak Power, Passively $Q$ -switched Microlaser for Ignition of Engines

Abstract: The compact (electric spark plug size), diode-pumped, passively Q-switched Nd:YAG/Cr4+:YAG microlaser was developed for ignition of engines. Output energy of 2.7 mJ per pulse and 11.7 mJ per four-pulse train with a pulsewidth of 600 ps and an M 2 value of 1.2 were obtained at a pump duration of 500 ?s. The optical-to-optical conversion efficiency was 19%. Brightness of the microlaser was calculated as 0.3 PW/ sr-cm2 and optical power intensity was calculated as 5 TW/cm2 at the focal point of ignition. The enhanced combustion by the microlaser ignition was successfully demonstrated in a constant-volume chamber at room temperature and atmospheric pressure. The cross section area of a flame kernel generated by laser ignition is 3 times larger than that by a conventional spark plug at 6 ms after ignition in a stoichiometric mixture (A/F 15.2) of C 3H 8/air, even though ignition energy of the laser is 1/3 of that of the spark plug. Hundred percent ignition was successfully demonstrated in a lean mixture of A/F 17.2 by laser ignition, where electric spark plug ignition failed.

Nonlocal Nonlinear Electro-Optic Phase Dynamics Demonstrating 10 Gb/s Chaos Communications

Abstract: We report on successful 10 Gb/s transmission of a message hidden in a chaotic optical phase over more than 100 km of an installed fiber optic network. This represents the best performance to date for so-called optical chaos communication, a physical layer oriented optical data encryption technique. Such performances was achieved through the use of a recently developed electro-optic nonlinear delay phase dynamics, inspired from differential phase modulation techniques. The setup appears as a superior alternative to the most popular architectures, i.e., the ones involving laser rate equations subjected to delayed feedback. It is compatible with standard dispersion compensation techniques and optical amplification, as shown by two field experiments over installed fiber optic networks.

Analysis of an Optically Injected Semiconductor Laser for Microwave Generation

Abstract: The nonlinear dynamical period-one oscillation of an optically injected semiconductor laser is investigated analytically. The oscillation is commonly observed when the injection is moderately strong and positively detuned from the Hopf bifurcation boundary. The laser emits continuous-wave optical signal with periodic intensity oscillation. Since the oscillation frequency is widely tunable beyond the relaxation oscillation frequency, the system can be regarded as a high-speed photonic microwave source. In this paper, analytical solution of the oscillation is presented for the first time. By applying a two-wavelength approximation to the rate equations, we obtain mathematical expressions that characterize the oscillation. The analysis explains the physical origin of the periodic intensity oscillation as the beating between two wavelengths, namely, the injected wavelength and the cavity resonance wavelength. As the injection strength increases, the optical gain reduces, the cavity is red-shifted through the antiguidance effect, and so the beat frequency increases continuously. The theoretical analysis is useful for designing the system for photonic microwave applications.

Highly Efficient Wavelength Converter Using Direct-Bonded PPZnLN Ridge Waveguide

Abstract: We fabricated a periodically poled and ZnO-doped LiNbO3 ridge waveguide by employing direct bonding and dry etching techniques. We obtained a second-harmonic generation (SHG) conversion efficiency of 2400%/W, and converted 92% of the pump light into SH light at a pump power of 160 mW. We developed a fiber-coupled module using the fabricated ridge waveguide. The high conversion efficiency and high damage resistance of the ridge waveguide result in the parametric amplification of the signal and converted signal lights. The low insertion loss of the module (-4 dB) and sufficient parametric conversion gain (+8 dB) enable us to achieve a wavelength converter with + 4 dB fiber-to-fiber gain, which means the wavelength converter operates without loss.

Tb/s Optical Logic Gates Based on Quantum-Dot Semiconductor Optical Amplifiers

Abstract: The performance of an ultrafast all-optical logic gate based on quantum-dot semiconductor optical amplifier (QD-SOA) has been theoretically analyzed in this paper. We introduce a novel approach to accelerate the gain recovery process with a control pulse (CP) using the cross-gain modulation (XGM) effect. It is shown that the optical XOR gate in a Mach-Zehnder interferometer-based structure is feasible at Tb/s speeds with proper quality factor. The operation capability at 2.5 Tb/s with a Q-factor of 4.9 and 2 Tb/s with a Q -factor of 8.8 is reported for the first time. This capability indicates great potential for ultrafast all-optical signal processing and switching.

Effect of P-Type Last Barrier on Efficiency Droop of Blue InGaN Light-Emitting Diodes

Abstract: P-type doping in the last barrier is proposed to improve the efficiency droop of the blue InGaN light-emitting diodes (LEDs). The light-current curves, energy band diagrams, carrier concentrations, radiative recombination efficiency, and internal quantum efficiency of the blue LEDs under study are investigated. The simulation results show that the efficiency droop is significantly improved when the last undoped GaN barrier in a typical blue LED is replaced by a p-type GaN barrier. The simulation results suggest that the improvement in efficiency droop is mainly due to the decrease of electron current leakage and increase of hole injection efficiency.

Frequency-Dependent Complex Conductivities and Dielectric Responses of Indium Tin Oxide Thin Films From the Visible to the Far-Infrared

Abstract: Transparent and conducting indium tin oxide (ITO) thin films form an integral part for various optoelectronic devices. In this paper, we report the frequency-dependent complex conductivities and dielectric responses of several sputtered ITO thin films with thicknesses in the range of 189-962 nm by using terahertz time domain spectroscopy (THz-TDS), optical reflectance spectroscopy, and electrical measurements. The plasma frequencies are verified to be from 1590 to 1930 rad·THz, while the scattering times are in the range 6-7 fs based on the Drude free-electron model. The mobilities of the above ITO thin films are calculated to be 32.7-34.2 cm2 V-1 s-1, whereas the carrier concentrations lie in the range 2.79-4.10× 1020 cm-3. The electrical properties derived from the THz-TDS technique agree well with those determined by Hall measurement. Parameters for the complex dielectric function suitable for ITO in the range 0.2-2 and 4-450 THz are also determined.

Mode-Locking in Semiconductor Fabry-Pérot Lasers

Abstract: We theoretically study the dynamics and the mode-locking properties of semiconductor Fabry-Perot lasers with intracavity saturable absorber by using a travelling-wave model and a time-domain description of the optical response of the semiconductor materials. Our description enables us to incorporate important features as for instance the abrupt spectral variations of the absorption in the saturable absorber. We analyze the influence of several key parameters that affect the stability of the mode-locking regime and show that this modelling approach can be used, upon proper fitting of the material parameters, for optimization of the design of semiconductor mode-locked lasers.

Coherent Polarization Beam Combination

Abstract: A new, scalable coherent beam combination architecture has been developed and experimentally verified. Coherent Polarization Beam Combination (CPBC) relies on the combination of multiple beams through a coherent superposition of orthogonal polarization states. By actively controlling the phases and polarizations of individual beams, the creation of new polarization states at polarization beam combiners enables the coherent combination of any number of beams with arbitrary power ratios. A four-beam CPBC was experimentally demonstrated at low laser power level, with 96% combining efficiency, nearly diffraction-limited beam quality, and variable polarization of the output beam. The CPBC method will enable power scaling of master oscillator power amplifier laser systems.

Active Region Design for High-Speed 850- nm VCSELs

Abstract: Higher speed short-wavelength (850 nm) VCSELs are required for future high-capacity, short-reach data communication links. The modulation bandwidth of such devices is intrinsically limited by the differential gain of the quantum wells (QWs) used in the active region. We present gain calculations using an 8-band k·p Hamiltonian which show that the incorporation of 10% In in an InGaAs/AlGaAs QW structure can approximately double the differential gain compared to a GaAs/AlGaAs QW structure, with little additional improvement achieved by further increasing the In composition in the QW. This improvement is confirmed by extracting the differential gain value from measurements of the modulation response of VCSELs with optimized InGaAs/AlGaAs QW and conventional GaAs/AlGaAs QW active regions. Excellent agreement is obtained between the theoretically and experimentally determined values of the differential gain, confirming the benefits of strained InGaAs QW structures for high-speed 850-nm VCSEL applications.

Temperature Dependence of Avalanche Breakdown in InP and InAlAs

Abstract: Simple analytical expressions for temperature coefficients of breakdown voltage of avalanche photodiodes (APDs) utilizing InP or InAlAs are reported. The work is based on measurements of temperature dependence of avalanche breakdown voltage in a series of InP and InAlAs diodes at temperatures between 20 and 375 K. While avalanche breakdown voltage becomes more temperature sensitive with avalanche region thickness for both materials, the InAlAs diodes are less sensitive to temperature changes compared to InP diodes.

Systematic Engineering of Waveguide-Resonator Coupling for Silicon Microring/Microdisk/Racetrack Resonators: Theory and Experiment

Abstract: A systematic engineering of waveguide-resonator coupling for optimum phase matching and field-overlap is proposed to achieve critical coupling and strong over-critical coupling for microring, micro racetrack and microdisk resonators on silicon-on-insulator (SOI) platform. The impact of the waveguide-resonator dimensions, their spacing and interaction length on the strength of the coupling are investigated. We show that by optimization of the dimension of the waveguide-resonator structure, the coupling strength can be engineered to be insensitive to fabrication errors. Based on our optimization techniques, critical coupling to low Q resonators (Q ~ 104) as well as ultra-high Q resonators (Q ~ 3.1 x 106) is experimentally demonstrated.

Method for Computing the Nonlinear Refractive Index via Keldysh Theory

Abstract: A procedure for computation of the nonlinear refractive index of a gaseous medium from the intensity dependence of the ionization rate is reported. The ionization rate is calculated from Keldysh theory via a Kramers-Kronig transform. Peremolov-Popov-Terent'ev (PPT) theory is analyzed in the perturbative limit of multiphoton ionization for a completely analytical expression for the nonlinear refractive index. The method requires knowledge of only the particle density and the ionization energy of the gas. Example calculations are performed for the inert gases and compared to experimental data and atomic model calculations for the hyperpolarizability of the respective media. Excellent agreement between reference data and the computed values derived from the Kramers-Kronig transform is found in the visible and infrared spectral range. Additionally, higher-order nonlinear refraction is discussed.

Minimizing Heat Generation in Solid-State Lasers

Abstract: Novel high-power ytterbium YAG lasers are described. These lasers incorporate the principle of anti-Stokes fluorescence cooling to reduce or eliminate detrimental heating. Lasers with net heating and net cooling are demonstrated. By balancing the spontaneous and stimulated emission, we have reduced the net thermal loading to below 0.01% of the laser's average output power. Design, testing, and analysis are reported for lasers up to 500 W average power and pulsed operation up to 30 s. Issues and limitations of this approach are discussed.

Numerical Investigation of the ASE and Power Scaling of Cladding-Pumped Er–Yb Codoped Fiber Amplifiers

Abstract: The influence of the amplified spontaneous emission (ASE) on the performance of high-power, cladding-pumped Er-Yb codoped fiber amplifiers (EYDFAs) are investigated numerically. The results show that the counter-pump-propagating Yb-band ASE is the main reason that limits the efficiency of an EYDFA at high pump power. By introducing a co-pump-propagating Yb-band signal at proper wavelength, the counter-pump-propagating Yb-band ASE can be effectively suppressed and thus the available power of the EYDFA can be remarkably improved. This method is also helpful to improve the stability of high power EYDFAs.

Tunable Fiber Laser Using a MEMS-Based in Plane Fabry-Pérot Filter

Abstract: We propose a tunable erbium doped fiber laser based on a Fabry-Perot (F-P) cavity tuned by an electrostatic actuator. The device is made of single crystalline silicon. The F-P cavity consists of two Bragg mirrors, one being displaced by a comb-drives actuator. The F-P cavity, grooves for optical fibers and electro-mechanical structure are fabricated by deep reactive ion etching on a 70 μm silicon on insulator wafer and are integrated in a ring fiber laser. The resulting tunable fiber laser has a tuning range of 35 nm in the C-band and a spectral width of less than 0.06 nm. The maximum applied voltage for full tuning of the laser is 37 V. The mechanical resonance frequency of the actuated mirror is 14.4 kHz allowing fast tuning of the laser. The maximum output power is 1.8 mW.

Taper-Integrated Multimode-Interference Based Waveguide Crossing Design

Abstract: We present a design technique for a compact waveguide crossing by using a 90° multimode-interference (MMI) based waveguide crossing sandwiched by four identical miniaturized tapers where the power of the input guided mode is coupled into even modes of the MMI section at a specific power ratio and with different phases, thereby reducing the dimension of this waveguide crossing with imperceptible loss and crosstalk. Using the finite difference time domain method, we demonstrate that the MMI-based waveguide crossing embedded in short Gaussian tapers has a size 5426 nm × 5426 nm, insertion loss 0.21 dB, and crosstalk -44.4 dB at the wavelength of 1550 nm and broad transmission spectrum ranging from 1500 to 1600 nm.

Tandem Cladding-Pumping for Control of Excess Gain in Ytterbium-Doped Fiber Amplifiers

Abstract: We theoretically detail and explain how to control unwanted excess gain for higher order modes in cladding-pumped large-core ytterbium-doped fiber amplifiers operating on the fundamental mode by using a small inner cladding and pumping close to the emission wavelength in a so-called tandem-pump configuration. Such excess gain can otherwise limit the core size. We study this experimentally by comparing the level of amplified spontaneous emission at the edge of the core in a conventional diode-pumped and tandem-pumped large-core ytterbium-doped multimode fiber. We also discuss the potential benefits of tandem pumping in reducing fiber photodarkening.

A Switchable Liquid-Crystal Optical Channel Waveguide on Silicon

Abstract: An integrated optical switch based on liquid crystal on silicon is reported. The switch consists of an optical waveguide, whose core is made of nematic liquid crystal E7 infiltrated in a SiO2/Si V-groove. The electrooptic effect allows us to control the waveguide propagation condition by means of ITO and Si electrodes. A voltage as low as 2 V applied to the driving electrodes turns the waveguide on. Since the output intensity increases with voltage, the waveguide behaves also as a variable optical attenuator. A maximum ON-OFF extinction ratio in excess of 44 dB was measured.

Root-Cause Analysis of Peak Power Saturation in Pulse-Pumped 1100 nm Broad Area Single Emitter Diode Lasers

Abstract: Many physical effects can potentially limit the peak achievable output power of single emitter broad area diode lasers under high current, pulse-pumped operation conditions. Although previous studies have shown reliable operation to high pump levels (240 A, 300 ns, and 1 kHz), power was found to saturate. We present here results of a systematic study to unambiguously determine the sources of this power saturation. A combination of detailed measurements and finite element device simulation were used for the diagnosis. We find that the measured power saturation is dominated by electron leakage caused by band bending at high bias due to the low mobility of the p-type waveguide. However, the power saturation is only fully reproduced when longitudinal spatial hole-burning is included. Higher powers are expected to be achieved if higher energy barriers and lower confinement factors are used to mitigate leakage and longitudinal hole-burning, respectively.

Broadband MEMS-Tunable High-Index-Contrast Subwavelength Grating Long-Wavelength VCSEL

Abstract: A widely-tunable single-mode 1.3 μm vertical-cavity surface-emitting laser structure incorporating a microelectromechanical system-tunable high-index-contrast subwavelength grating (HCG) mirror is suggested and numerically investigated. A linear tuning range of 100 nm and a wavelength tuning efficiency of 0.203 are predicted. The large tuning range and efficiency are attributed to the incorporation of the tuning air gap as part of the optical cavity and to the use of a short cavity structure. The short cavity length can be achieved by employing a HCG design of which the reflection mechanism does not rely on resonant coupling. The absence of resonance coupling leads to a 0.59 λ-thick penetration depth of the HCG and enables to use a 0.25 λ-thick tuning air gap underneath the HCG. This considerably reduces the effective cavity length, leading to larger tuning range and efficiency. The basic properties of this new structure are analyzed, and shown to be explained by analytical expressions that are derived in the paper. In this context, the penetration depth of the HCG is introduced and shown to be an important characteristic length scale. Throughout the tuning wavelength range, strong single mode operation was maintained and uniform output power is expected.

Extremely High Saturation Current-Bandwidth Product Performance of a Near-Ballistic Uni-Traveling-Carrier Photodiode With a Flip-Chip Bonding Structure

Abstract: In this study, we demonstrate near-ballistic uni-traveling carrier photodiodes (NBUTC-PDs) with an optimized flip-chip bonding structure, wide 3-dB optical-to-electrical (O-E) bandwidth (> 110 GHz), and extremely high saturation current-bandwidth product performance (37 mA, > 110 GHz, > 4070 mAmiddot GHz). NBUTC-PDs with different active areas (28-144 mum2) are fabricated and flip-chip bonded with coplanar waveguides onto an AlN-based pedestal. The overshoot drift velocity of the electrons in the collector layer of the NBUTC-PD means that both the thicknesses of the collector layer and active areas of our device can be increased to reduce the density of the output photocurrent, compared to that of the traditional UTC-PD. This improves the high power performance without seriously sacrificing the speed performance. According to the measured O-E frequency responses, devices with even a large active area (144 mum2 ) can still have a flat O-E frequency response, from near dc to 110 GHz. A three-port equivalent circuit model for accurately extracting the 3-dB bandwidth of the devices is established. The extracted 3-dB O-E bandwidth of a device with a small active area (28 mum2) can be as high as 280 GHz under a load of 25 Omega . In addition, the saturation current measurement results indicate that after inserting a center bonding pad on the pedestal (located below the p-metal of the NBUTC-PD for good heat sinking), the saturation current performance of the device becomes much higher than that of the control device (without the center bonding pad), especially for the device with a small active area (28 mum2 ). The measurement and modeling results indicate that a device with a 144 mum2 active area and optimized flip-chip bonding pedestal can achieve an extremely high saturation current-bandwidth product (6660 mA-GHz, 37 mA, 180 GHz).

Highly Reliable High-Speed 1.1- $\mu$ m-Range VCSELs With InGaAs/GaAsP-MQWs

Abstract: In this paper, we describe high-speed 1.1-μm-range oxide-confined vertical-cavity surface-emitting lasers (VCSELs) for large-scale optical interconnection applications. For achieving high data rates up to 25 Gbit/s under high temperature, we applied InGaAs/GaAsP strain-compensated multiple quantum wells (SC-MQWs) as the active layer. The developed device showed 25 Gbit/s error-free operation at 100°C. We also examined reliability of the VCSELs through accelerated life tests. The result showed an extremely long lifetime of about 10 thousand hours in MTTF under an ambient temperature of 150°C and a current density of about 19 kA/cm2. The level of reliability either equaled or surpassed that of conventional 0.85-μm VCSELs. Moreover, we revealed a typical failure mode of the device, which was caused by ≪110≫ dark line defects (DLDs) generated in the n-DBR layers under the current aperture area.

Self-Phase Modulation in Semiconductor Optical Amplifiers: Impact of Amplified Spontaneous Emission

Abstract: This paper presents a detailed theoretical and experimental study of the impact of amplified spontaneous emission (ASE) on self-phase modulation in semiconductor optical amplifiers (SOAs). A theoretical model of pulse propagation in SOAs is developed that includes the ASE power and its effect on gain-saturation and gain-recovery. We study the impact of ASE on the nonlinear phase shift, frequency chirp, spectrum, and shape of amplified picosecond pulses at a range of drive currents. We verify our predictions experimentally by launching gain-switched picosecond pulses with 3-mW peak power into a commercial SOA exhibiting 9-ps gain-recovery time at a current of 500 mA. Understanding the impact of ASE on SOAs is important for applications that employs SOAs for all-optical signal processing and as data-network amplifiers.

High Switching-Speed Operation of Optical Memory Based on Polarization Bistable Vertical-Cavity Surface-Emitting Laser

Abstract: Operation conditions of all-optical buffer memories based on polarization bistable vertical-cavity surface-emitting lasers (VCSELs) were investigated. The switching power dependence on the frequency detuning of the input optical signal was measured for a 980-nm polarization bistable VCSEL. The proper operating conditions for 10-Gb/s memory operation were also measured and found to be on the negative detuning side. Calculations based on a two-mode rate-equation model successfully explained the measured characteristics of the switching power dependence on the frequency detuning and the operating conditions. Maximum data rates for the memory operation strongly depended on the Q factor (i.e., photon lifetime) of the VCSELs. A possibility of 40-Gb/s memory operation using a polarization bistable VCSEL with a Q factor as low as 500 was shown.

Coupled-Wave Theory for Square-Lattice Photonic Crystal Lasers With TE Polarization

Abstract: We present a coupled-wave analysis for square-lattice photonic crystal lasers with transverse electric polarization. A model consisting of eight plane waves coupled by Bragg diffraction is used to describe two-dimensional optical coupling. The resonant frequencies and threshold criteria for the modes of oscillation have been determined for the case of index periodicity with a lattice of circular holes. The spatial intensity distributions of these resonant modes have also been calculated. For the fundamental modes, we have investigated how the intensity distribution varies as a function of coupling strength. The dependence of the threshold gain of these modes on hole size has also been elucidated. This semianalytical approach provides a comprehensive understanding of square-lattice photonic crystal lasers and allows more effective optimization of their cavity design.

A Frequency-Dependent LOD-FDTD Method and Its Application to the Analyses of Plasmonic Waveguide Devices

Abstract: Detailed frequency-dependent formulations are presented for several efficient locally one-dimensional finite-difference time-domain methods (LOD-FDTDs) based on the recursive convolution (RC), piecewise linear RC (PLRC), trapezoidal RC (TRC), auxiliary differential equation, and \mmb Z transform techniques. The performance of each technique is investigated through the analyses of surface plasmon waveguides, the dispersions of which are expressed by the Drude and Drude-Lorentz models. The simple TRC technique requiring a single convolution integral is found to offer the comparable accuracy to the PLRC technique with two convolution integrals. As an application, a plasmonic grating filter is studied using the TRC-LOD-FDTD. The use of an apodized and a chirped grating is found quite effective in reducing sidelobes in the transmission spectrum, maintaining a large bandgap. Furthermore, a plasmonic microcavity is analyzed, in which a defect section is introduced into a grating filter. Varying the air core width is shown to exhibit tunable properties of the resonance wavelength.