• Title/Summary/Keyword: Semiconductor optical amplifiers

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All-optical Read Only Memory Employing SOAs

  • Jung, Young-Jin;Park, Nam-Kyoo;Jhon, Young-Min;Lee, Seok
    • Journal of the Optical Society of Korea
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    • v.12 no.1
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    • pp.52-56
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    • 2008
  • An all-optical read only memory utilizing cross gain modulation in semiconductor optical amplifiers (SOAs) has been demonstrated for the first time to our knowledge. In our demonstration, an all-optical 2-to-4 line decoder constructed with SOAs has been employed for the construction of this all-optical read only memory. Storing four characters in an American standard code for information interchange (ASCII) format has been successfully carried out. Each character consisting of seven binary bits could be read out at a rate of 10 Giga characters per second.

PMD Tolerance of 10 Gbps Modulated Signals due to SOA-Induced Chirp in SOA Booster Amplifiers

  • Jang, Ho-Deok;Kim, Kyoung-Soo;Lee, Jae-Hoon;Jeong, Ji-Chai
    • Journal of the Optical Society of Korea
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    • v.12 no.4
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    • pp.232-239
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    • 2008
  • We investigated how the polarization-mode dispersion (PMD) tolerance was degraded by semiconductor optical amplifier (SOA)-induced chirp for the 10 Gb/s nonreturn-to-zero (NRZ), duobinary NRZ, return-to-zero (RZ), and carrier-suppressed RZ (CS-RZ) modulation formats. The power penalty was calculated as a measure of the system performance due to PMD for a given SOA-induced chirp. Considering only first-order PMD, all modulation formats have a similar PMD tolerance regardless of SOA-induced chirp. On the other hand, when both first- and second-order PMD are considered, the PMD tolerance of all modulation formats with the exception of the CS-RZ modulation format are degraded by SOA-induced chirp. Among all modulation formats considered here, the NRZ modulation format has the PMD tolerance with the highest sensitivity to SOA-induced chirp. When the peak-to-peak chirp induced by SOAs is $0.28{\AA}$, its PMD tolerance is degraded up to 4 dB for a differential group delay (DGD) of 50 ps. However, the PMD tolerance of the CS-RZ modulation format is largely unaffected by SOA-induced chirp.

Anti-reflection coating on the facet of a spot size converter integrated laser diode using a pair of TiO2 and SiO2 thin films (TiO2와 SiO2 박막 쌍을 이용한 광모드 변환기가 집적된 반도체 레이저 단면의 무반사 코팅)

  • 송현우;김성복;심재식;김제하;오대곤;남은수
    • Korean Journal of Optics and Photonics
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    • v.13 no.5
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    • pp.396-399
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    • 2002
  • Using a bi-layer anti-reflection coating of $TiO_2$and $SiO_2,$ we have achieved a minimum facet reflectivity of $~10^{-5}$ and a band width of 27 nm for a reflectivity of $~10^{-4}$ or less for 1.3 $\mu\textrm{m}$ spot size converter integrated semiconductor lasers. This coating is applicable to external-cavity-tuned laser sources and semiconductor optical amplifiers.

Characterization of amplified spontaneous emission light source from an $Er^{3+}$/$Tm^{3+}$co-doped silica fiber ($Er^{3+}$$Tm^{3+}$이 복합 첨가된 실리카 광섬유의 ASE 광원에 대한 특성 평가)

  • Jeong, Hoon;Oh, K.
    • Proceedings of the Optical Society of Korea Conference
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    • 2000.02a
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    • pp.96-97
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    • 2000
  • Incoherent broadband optical sources have been applied in various areas such as a light source for optical device characterization, fiber-optic gyroscopes$^{(1)}$ , and spectrum sliced light source in wavelength division multiplexing (WDM) system$^{(2)}$ . To utilize the inherent low loss in silica optical fibers, various types of incoherent light sources are being developed. Among the light sources, the amplified spontaneous emission (ASE) from a rare earth doped fiber has benefits in temperature stability, high output power, low polarization dependence over semiconductor diodes$^{(3)}$ . Recently erbium doped fibers (EDF) have been intensively researched for ASE sources as well as optical amplifiers$^{(4)}$ . The spectrum of ASE from an EDF, however, is limited in the 1520~1560 nm range in conventional configurations. In this letter we described a new broadband ASE source which included both the conventional ASE band of Er$^{3+}$ ion, 1520nm~1560nm and ASE band from Tm$^{3+}$ ions that extends the bandwidth further. For the first time, to the best knowledge of authors, a fiber ASE source based on the energy transfer between Er$^{3+}$ and Tm$^{3+}$ ions in the range of 1460~1550 nm, has been demonstrated using a single 980nm pump laser diode. (omitted)omitted)

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Widely Tunable Coupled-ring Reflector Laser Diode Consisting of Square Ring Resonators

  • Kim, Su-Hyun;Byun, Young-Tae;Kim, Doo-Gun;Dagli, Nadir;Chung, Young-Chul
    • Journal of the Optical Society of Korea
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    • v.14 no.1
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    • pp.38-41
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    • 2010
  • We design and fabricate a widely tunable laser diode made of InGaAsP-InP. The diode is monolithically integrated with a wavelength-selective coupled-ring reflector and semiconductor amplifiers. For realization of a compact size device, deeply etched multi-mode interference couplers and square ring resonators composed of total-internal-reflection mirrors are adopted and fabricated using a self-aligned process. It is demonstrated that the laser diode exhibits single mode operation and 16 nm tuning range with side-mode-suppression-ratio exceeding 20 dB.

Comb-spacing-swept Source Using Differential Polarization Delay Line for Interferometric 3-dimensional Imaging

  • Park, Sang Min;Park, So Young;Kim, Chang-Seok
    • Current Optics and Photonics
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    • v.3 no.1
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    • pp.16-21
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    • 2019
  • We present a broad-bandwidth comb-spacing-swept source (CSWS) based on a differential polarization delay line (DPDL) for interferometric three-dimensional (3D) imaging. The comb spacing of the CSWS is repeatedly swept by the tunable DPDL in the multiwavelength source to provide depth-scanning optical coherence tomography (OCT). As the polarization differential delay of the DPDL is tuned from 5 to 15 ps, the comb spacing along the wavelength continuously varies from 1.6 to 0.53 nm, respectively. The wavelength range of various semiconductor optical amplifiers and the cavity feedback ratio of the tunable fiber coupler are experimentally selected to obtain optimal conditions for a broader 3-dB bandwidth of the multiwavelength spectrum and thus provide a higher axial resolution of $35{\mu}m$ in interferometric OCT imaging. The proposed CSWS-OCT has a simple imaging interferometer configuration without reference-path scanning and a simple imaging process without the complex Fourier transform. 3D surface images of a via-hole structure on a printed circuit board and the top surface of a coin were acquired.

Characteristics of a Wavelength-swept Laser with a Polygon-based Wavelength Scanning Filter (다면체 거울 스캐닝 파장 필터를 이용한 파장 훑음 레이저의 출력 특성)

  • Ko, Myeong Ock;Kim, Namje;Han, Sang-Pil;Park, Kyung Hyun;Lee, Bong Wan;Jeon, Min Yong
    • Korean Journal of Optics and Photonics
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    • v.25 no.2
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    • pp.61-66
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    • 2014
  • We report the characterization of a wavelength-swept laser (WSL) using a polygon-based wavelength scanning filter and two semiconductor optical amplifiers (SOAs). The output intensity and scanning bandwidth of the WSL depend on the position of the two SOAs in the laser cavity and the coupling ratio of the output fiber coupler. The outputs of the WSL are characterized for coupling ratios of 10%, 30%, 50%, 70%, and 90% for the output fiber coupler. In the setup in which the output fiber coupler is located between the two SOAs, high output power and wide scanning bandwidth can be achieved with an optimized configuration. Using the optimized configuration of the WSL, the intensity increases with the coupling ratio. These results can be used to construct an optimized WSL using the polygon-based wavelength scanning filter.

All-Optical Gray Code to Binary Coded Decimal Converter (전광 그레이코드 이진코드 변환기)

  • Jung, Young-Jin;Park, Nam-Kyoo;Jhon, Young-Min;Woo, Deok-Ha;Lee, Seok
    • Korean Journal of Optics and Photonics
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    • v.19 no.1
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    • pp.60-67
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    • 2008
  • An all-optical 4-bit Gray code to binary coded decimal (BCD) converter by means of commercially available numerical analysis tool (VPI) was demonstrated, for the first time to our knowledge. Circuit design approach was modified appropriately in order to fit the electrical method on an all-optical logic circuit based on a cross gain modulation (XGM) process so that signal degradation due to the non-ideal optical logic gates can be minimized. Without regenerations, Q-factor of around 4 was obtained for the most severely degraded output bit (least significant bit-LSB) with 2.5 Gbps clean input signals having 20 dB extinction ratio. While modifying the two-level simplification method and Karnaugh map method to design a Gray code to BCD converter, a general design concept was also founded (one-level simplification) in this research, not only for the Gray code to BCD converter but also for any general applications.

All Optical Wavelength Converters Based on XGM for Wide Input Power Dynamic Range (넓은 입력 다이너믹 영역을 가지는 상호이득변조 방식의 전광 파장전환기)

  • Bang, Joon-Hak;Lee, Sang-Rok;Lee, Sung-Un;Lee, Jong-Hyun
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.8
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    • pp.62-67
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    • 1999
  • In this letter, a scheme for increasing the input power dynamic range of wavelength converters based on cross-gain modulation (XGM) in semiconductor optical amplifiers (SOA/s) is proposed. We investigate the effect of input pump and probe powers on the power penalty, the measure of performance for the wavelength converters. As a result, we show that the optimal bit error rate (BER) performance can be obtained when the probe power is kept 3 dB weaker than the pump power. Using this characteristic, we propose the wavelength converter scheme that controls the probe power level by monitoring the input pump power and adjusting the bias current of probe source accordingly. Consequently, the wavelength converter for wide input power dynamic range can be implemented. We show that an input power dynamic range of more than 20 dB at 2.5 Gb/s is achievable.

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Giga WDM-PON based on ASE Injection R-SOA (ASE 주입형 R-SOA 기반 기가급 WDM-PON 연구)

  • Shin Hong-Seok;Hyun Yoo-Jeong;Lee Kyung-Woo;Park Sung-Bum;Shin Dong-Jae;Jung Dae-Kwang;Kim Seung-Woo;Yun In-Kuk;Lee Jeong-Seok;Oh Yun-Je;Park Jin-Woo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.5 s.347
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    • pp.35-44
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    • 2006
  • Reflective semiconductor optical amplifiers(R-SOAs) were designed with high gain, wide optical bandwidth, high thermal reliability and wide modulation bandwidth in TO-can package for the transmitter of wavelength division multiplexed-passive optical network(WDM-PON) application. Double trench structure and current block layer were introduced in designing the active layer of R-SOA to enable high speed modulation. The injection power requirement and the viable temperature range of WDM-PON system are experimentally analysed in based on Amplified Spontaneous Emission(ASE)-injected R-SOAs. The effect of the different injection spectrum in the gain-saturated R-SOA was experimentally characterized based on the measurements of excessive intensity noise, Q factor, and BER. The proposed spectral pre-composition method reduces the bandwidth of injection source below the AWG bandwidth and thereby avoids spectrum distortion impeding the intensity noise reduction originated from the amplitude squeezing.