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ABSTRACT: We propose an ultra-sensitive integrated photonic sensor structure using an InP-based triangular resonator, in which a surface plasmon resonance (SPR) gold film is applied on a total internal reflection mirror. We have analyzed and optimized the triangular resonator sensor structure with an extremely small SPR mirror sensing area of 3.3 × 0.35 μm<sup>2</sup>. Due to the large phase shift in the SPR mirror, a significantly enhanced sensitivity of 930 nm/RIU (refractive index unit) and the maximum peak shift of half free spectral range have been obtained at the SPR angle of 24.125° with Au thickness of 33.4 nm for the change of the refractive index Δn = 1x10<sup>-3</sup>. This value is larger than the previous largest value in micro resonator-type biosensors. Moreover, the proposed triangular resonator sensor can be easily made in a micro structure with optical source integration.
Optics Express 08/2012; 20(17):19067-74. · 3.59 Impact Factor
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ABSTRACT: We have explicated the Goos-Hänchen (GH) shift in a mum-order Kretchmann-Raether configuration embedded in an optical waveguide structure by using the finite-difference time-domain method. For optical waveguide-type surface plasmon resonance (SPR) devices, the precise derivation of the GH shift has become critical. Artmann's equation, which is accurate enough for bulk optics, is difficult to apply to waveguide-type SPR devices. This is because Artmann's equation, based on the differentiation of the phase shift, is inaccurate at the critical and resonance angles where drastic phase changes occur. In this study, we accurately identified both the positive and the negative GH shifts around the incidence angle of resonance. In a waveguide-type Kretchmann-Raether configuration with an Au thin film of 50 nm, positive and negative lateral shifts of -0.75 and + 1.0 microm are obtained on the SPR with the incident angles of 44.4 degrees and 47.5 degrees, respectively, at a wavelength of 632.8 nm.
Optics Express 11/2009; 17(23):20714-20. · 3.59 Impact Factor
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ABSTRACT: A novel biosensor structure based on the stadium shaped ring resonator (SRR) with dual photonic crystal microcavity (DPCM) is proposed and the resonance characteristics are analyzed for the first time. A Q-factor of the photonic crystal microcavity (PCM) can be significantly enhanced when single PCM or DPCM has the same resonance condition with the SRR. Here, the Q-factor of the SRR with DPCM is increased by three times in comparison with that of the directional coupler structure with single PCM. The bulk refractive index resolution of 3.03 times 10<sup>-5</sup> is observed on the SRR with DPCM.
Infrared, Millimeter, and Terahertz Waves, 2009. IRMMW-THz 2009. 34th International Conference on; 10/2009
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Doo Gun Kim,
Geum-Yoon Oh,
Woon-Kyung Choi,
Hyo Jin Kim,
Seon Hoon Kim,
Hyun Chul Ki,
Sang-Taek Kim,
Hang Ju Ko,
Tae Un Kim,
Myoung Hak Yang,
Hwe Jong Kim,
Jong Chang Yi,
Youngchul Chung,
Nadir Dagli,
Young-Wan Choi
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ABSTRACT: Novel triangular ring resonators combining extremely small multimode-interference (MMI) coupler, low loss total internal reflection (TIR) mirrors, and semiconductor optical amplifiers are reported for the first time. The MMI length of 90 microm is among the shortest reported. The incidence angle of the TIR mirror inside the resonator is 22 degrees. A free-spectral range of approximately 2 nm is observed near 1550 nm along with an on-off ratio of 17 dB. The triangular resonators with a sharp angle are very attractive components due to their promise of compact size and high levels of integration. Therefore, large numbers of resonators can be integrated on a chip to increase functionality in future optical wavelength division multiplexing system.
Optics Express 01/2009; 16(25):21053-8. · 3.59 Impact Factor
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ABSTRACT: Coupled-ring reflector laser diodes composed of squared ring waveguides are fabricated and it is demonstrated that the laser diodes exhibit single mode operation and 15 nm tuning range with SMSR exceeding 25 dB.
Optical MEMs and Nanophotonics, 2008 IEEE/LEOS Internationall Conference on; 09/2008
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ABSTRACT: We investigate the properties of the attenuated total reflection mirrors with surface plasmon resonance including Goos-hanchen shift using FDTD method to find optimum photodetector’s position and size.
Opto-Electronics and Communications Conference, 2008 and the 2008 Australian Conference on Optical Fibre Technology. OECC/ACOFT 2008. Joint conference of the; 08/2008
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ABSTRACT: Optical logic gates with AND, OR, and INVERT functionality are demonstrated by vertical cavity lasers with depleted optical thyristor structure using our differential switching operation schemes which control a reference input light.
Optical Internet, 2007 and the 2007 32nd Australian Conference on Optical Fibre Technology. COIN-ACOFT 2007. Joint International Conference on; 07/2007
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ABSTRACT: Novel rectangular ring lasers containing active and passive sections are fabricated and characterized. The rectangular laser cavity is formed using four low-loss total internal reflection (TIR) mirrors and an output coupler made out of passive three coupled waveguides. The fabrication process is exactly the same as for other active and passive devices except for one deep etch step for TIR mirror fabrication. Two different lasers having active section lengths of 250 and 350 mum and total cavity lengths of 580 and 780 mum are fabricated. For both devices, lasing thresholds of 38mA are obtained at room temperature and under continuous-wave operation. Lasing is predominantly single-mode with a sidemode suppression ratio better than 20 dB. The power loss of a single TIR mirror is also determined to be about 0.5 dB. Such low-loss TIR mirrors enabled lasers with very small footprints
IEEE Photonics Technology Letters 04/2007; 19(5):306-308. · 2.19 Impact Factor
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ABSTRACT: The switching characteristics of an electroabsorption modulator fabricated on a waveguide-coupled micro-ring-cavity resonator were investigated. The ring cavity resonator consists of ridge waveguide regions, total internal reflector mirrors, and a coupling region. The coupling region is implemented with a multimode interferometer (MMI) waveguide to enhance the coupling coefficient. The total internal reflection mirrors were fabricated by self-aligned RIBE process resulting in minimal insertion losses of around 0.7 dB/mirror. The gain medium was a 1.55 μm InGaAsP MQW ridge waveguide, and the passive waveguide was a re-grown 1.4 μm InGaAsP ridge structure. The sharp variation of the optical transmission through the micro-ring-cavity resonator near the resonance wavelength was utilized to realize efficient semiconductor optical modulators with a high extinction ratio. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
physica status solidi (c) 03/2007; 4(5):1649 - 1652.
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ABSTRACT: Latching optical switches and optical logic gates with AND and OR functionality are demonstrated for the first time by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure. The thyristors have a low threshold current of 0.65 mA and a high on/off contrast ratio of more than 50 dB. By simply changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR. The thyristor laser fabricated by using the oxidation process and has achieved high optical output power efficiency and a high sensitivity to the optical input light.
Optics Express 12/2006; 14(24):11833-8. · 3.59 Impact Factor
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ABSTRACT: Optical switches and optical logic gates with AND and OR functionality are demonstrated by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure. The thyristors have a low threshold current of 0.65 mA and a high on/off contrast ratio of more than 50 dB. By simply changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR.
Nanotechnology Materials and Devices Conference, 2006. NMDC 2006. IEEE; 11/2006
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ABSTRACT: The authors show that the optical properties of selectively oxidized vertical cavity lasers with a depleted optical thyristor structure have a low threshold current and high sensitivity to input optical light. The oxidized thyristor laser clearly shows a nonlinear s-shaped current-voltage and lasing characteristics. A switching voltage of 5.24 V, a holding voltage of 1.50 V, and a very low threshold current of 0.65 mA are measured, making these devices attractive for optical processing applications.
Applied Physics Letters 09/2006; 89(12):121117-121117-3. · 3.84 Impact Factor
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ABSTRACT: We investigate the properties of novel ring cavity resonator based on InGaAsP material system using various multimode interference lengths. Optimum multimode interference length and on-off ratio are 110 mum and 13 dB, respectively.
Optical Internet and Next Generation Network, 2006. COIN-NGNCON 2006. The Joint International Conference on; 08/2006
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ABSTRACT: The reflection properties of a coupled-ring reflector (CRR) are analyzed using the transfer matrix method. The CRR is composed of two coupled rings that are coupled to a bus waveguide. Depending on the combination of the cross-coupling ratios of the couplers, the reflection spectrum shape changes greatly. In the lossless case, the reflection spectrum has four peaks when the ring-bus coupling ratio is small. When the ring-bus coupling ratio is more than half and the ring-ring coupling is very small, the four peaks broaden, forming a single peak with still considerably narrow reflection spectrum, which makes the CRR attractive in applications requiring compact reflectors such as for single-mode laser diodes. The dependence of the propagation and insertion losses of the couplers on the reflection spectrum is also investigated, and the design guidelines are presented.
Journal of Lightwave Technology 05/2006; 24(4):1865- 1874. · 2.78 Impact Factor
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ABSTRACT: A coupled-ring reflector (CRR), which is composed of two coupled rings both of which are coupled with a straight waveguide, is applied to a widely tunable laser diode. When the radii of two rings are slightly different, the peak reflection wavelength of the CRR can be widely tuned over a few tens nanometers by a small amount of refractive index change. It is shown that a few tens nanometers of tuning with a sidemode suppression ratio exceeding 45 dB both for adjacent cavity mode and for adjacent ring mode is achievable in the widely tunable CRR laser diode.
IEEE Photonics Technology Letters 10/2005; · 2.19 Impact Factor
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ABSTRACT: Novel ring resonators combining very small multimode interference (MMI) couplers, low loss total internal reflection (TIR) mirrors, and a semiconductor optical amplifier in InGaAsP material system are reported for the first time. The MMI length of 113 μm is among the shortest reported. Average TIR mirror loss is about 1.1 dB per mirror. The material platform and fabrication process used are the same used for other active and passive devices except for a deep etch step. Hence, such resonators are easily integrated with other active and passive devices. A free spectral range of approximately 2 nm is observed near 1568 nm along with an on-off ratio of 14 dB, a full-width at half-maximum of about 0.3 nm, a finesse of more than 6, and a Q-factor of more than 4900.
IEEE Photonics Technology Letters 10/2005; · 2.19 Impact Factor
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ABSTRACT: This study demonstrates the lasing characteristics of InGaAs/InGaAsP multiple-quantum-well waveguide-type depleted optical thyristor using the vertical window. The measured switching voltage and current are 3.36 V and 10 μA, respectively. The lasing threshold current is 131 mA at 25 °C. The output peak wavelength is 1570 nm at a bias current of 1.22 Ith and there is no input signal. The vertically injected depleted optical thyristor shows very good isolation between input and output signals.
Applied Physics Letters 01/2005; 86(2):021108-021108-3. · 3.84 Impact Factor
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ABSTRACT: We designed, fabricated and characterized total internal reflection mirrors on InGaAsP/InP using a self aligned process with two etch steps. Experimental results show that additional loss per mirror is 0.71 ± 0.06 dB.
06/2004;
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ABSTRACT: We present a demonstration of a waveguide-type depleted optical thyristor laser diode with InGaAs/InGaAsP multiple-quantum-well structure. The measured switching voltage and current are 4.63 V and 10 μA, respectively. The holding voltage and current are, respectively, 0.59 V and 20 μA. The lasing threshold currents at 25 °C and 10 °C are 111 mA and 72.5 mA, respectively. The lasing wavelength is centered at 1.561 μm at a bias current equal to 1.41 times threshold. © 2003 American Institute of Physics.
Applied Physics Letters 01/2003; 82(2):158-160. · 3.84 Impact Factor
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ABSTRACT: The wide tuning characteristics of double-ring coupled lasers with/without an extended waveguide are analyzed and optimized using the scattering matrix formalism. To obtain the optimum design schemes of the tunable laser diodes, the cross coupling ratios of two rings, the tuning enhancement factor, the propagation loss of passive waveguides, the optical gain of an active region, and the back and front-facet reflectivity of the waveguide are taken into account. When the coupling ratio of the ring and input/output waveguides is fixed, the extinction ratio and the linewidth are decreased as the tuning enhancement factor is increased, while the tuning range is increased.
Optics Communications 282(13):2516-2523. · 1.49 Impact Factor
