Browsing by Author "Lin, GR"

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1.2-ps mode-locked semiconductor optical amplifier fiber laser pulses generated by 60-ps backward dark-optical comb injection and soliton compression
(2005-02-07)
Lin, GR
;
Chiu, IH
;
Wu, MC
;
光電工程學系
;
Department of Photonics
Optically harmonic mode-locking of a semiconductor optical amplifier fiber laser (SOAFL) induced by backward injecting a dark-optical comb is demonstrated for the first time. The dark-optical comb with 60-ps pulsewidth is generated from a Mach-Zehnder modulator, which is driven by an electrical comb at a DC offset of 0.3V(pi). Theoretical simulation indicates that the backward injection of dark-optical comb results in a narrow gain window of 60 ps within one modulating period, providing a cross-gain-modulation induced mode-locking in the SOAFL with a shortest pulsewidth of 15 ps at repetition frequency of 1 GHz. The mode-locked SOAFL pulsewidth can be slightly shortened to 10.8 ps with a 200m-long dispersion compensating fiber. After nonlinearly soliton compression in a 5km-long single mode fiber, the pulsewidth, linewidth and time-bandwidth product become 1.2 ps, 2.06 nm and 0.31, respectively. (C) 2005 Optical Society of America.
10 Gbit/s all-optical non-return to zero-return-to-zero data format conversion based on a backward dark-optical-comb injected semiconductor optical amplifier
(2006-05-15)
Lin, GR
;
Yu, KC
;
Chang, YC
;
光電工程學系
;
Department of Photonics
By using a semiconductor optical amplifier backward injected by a dark-optical-comb pulse train at 10 GHz, we demonstrate a 10 Gbit/s all-optical nonreturn-to-zero (NRZ) to return-to-zero (RZ) format conversion of an incoming optical pseudorandom binary sequence (PRBS) data strieam. Both the polarity and the wavelength of data are conserved during format conversion. Without any preamplification, the extinction ratio of degraded optical NRZ PRBS data is greatly improved from 7.13 to 13.6 dB after NRZ-to-RZ conversion. An ultralow bit-error rate of 10(-12) at a data rate as high as 10 Gbits/s is obtained with a received optical power of-18.3 dBm. The converted RZ PRBS data exhibit a negative power penalty of > 3.7 dB compared with the NRZ PRBS data at a bit-error rate of 10(-12). (c) 2006 Optical Society of America
10 Gbit/s tunable dual-wavelength nonreturn-to-zero-to-return-to-zero data-forma't transformer based on a non-direct-current-biased Fabry-Perot laser diode
(2005-05-20)
Chang, YC
;
Lin, GR
;
光電工程學系
;
Department of Photonics
We demonstrate the conversion of a nonreturn-to-zero (NRZ)-formatted electrical data stream into a wavelength-tunable return-to-zero (RZ)-formatted optical pulse code by externally seeding a synchronously sinusoidal-modulated Fabry-Perot laser diode (FPLD) with optical pseudorandom binary-sequence data at 10 Gbits/s (Gbps). The FPLD without a dc-biased current was modulated by use of a power-amplified sinusoidal wave signal (similar to 25.6 dBm) as an NRZ-to-RZ data-format transformer, which is regeneratively amplified by a closed-loop erbium-doped fiber amplifier. The gain switching and on-off keying operation of the FPLD is initiated under the seeding of self-feedback and extemal-injection signals. A maximum wavelength tuning range of 30 nm with a side-mode suppression ratio of greater than 36 dB is obtained. The power penalty of the NRZ-to-RZ data-format conversion at 10 Gbps is 1.5 dB. (c) 2005 Optical Society of America.
10Gbps operation of a metamorphic InGaP buffered In0.53Ga0.47As p-i-n photodetector grown on GaAs substrate - art. no. 602023
(2005)
Liao, YS
;
Lin, GR
;
Lin, CK
;
Chu, YS
;
Kuo, HC
A novel top-illuminated In0.53Ga0.47As p-i-n photodiodes (MM-PINPD) grown on GaAs substrate by using a linearly graded metamorphic InxGa1-xP (x graded from 0.49 to 1) buffer layer has been demonstrated on the SONET OC-192 receiving performance. With a cost-efficient TO-46 package, the MM-PINPD at data rate of 10 Gbit/s can be obtained at minimum optical power of -19.5 dBm. At wavelength of 1550nm, the dark current, optical responsivities, noise equivalent power, and operational bandwidth of the MM-PIND with aperture diameter of 60 mu m are 13 pA, 0.6 A/W, 3.4 x 10(-15) W/Hz(1/2), and 8 GHz, respectively. All the parameters are comparable to those of similar devices made on InP substrate or other InGaAs products epitaxially grown on an InGaAlAs buffered GaAs substrate. The performances of the MM-PINPD on GaAs are analyzed by impulse injecting of 1.2-ps pulse-train, eye pattern at 10Gbps, and frequency response from VNA.
110-pJ and 410-fs pulse at 10 GHz generated by single-stage external fiber compression of optically injection-mode-locked semiconductor optical amplifier fiber laser
(2006-05-01)
Lin, GR
;
Chiu, IH
;
光電工程學系
;
Department of Photonics
We demonstrate the high-power amplification and single-stage fiber-based pulse compression of a traveling-wave semiconductor optical amplifier (TWSOA) fiber ring laser (SOAFL), which is optically mode-locked by backward injecting the TWSOA with a dark-optical-comb at repetition frequency of 10 GHz. A negatively chirped SOAFL pulsewidth of 5.4 ps is compensated and shortened to 3.9 ps by a 75-m-long dispersion compensating fiber. With a single-stage pulse compression in a single-mode-fiber spool, the SOAFL pulses with input average power of 1.7 W can further be compressed to a pulsewidth of 410 fs, corresponding to a pulse compressing ratio of nearly ten. The maximum average output power of the amplified SOAFL pulse is up to 1.1 W, corresponding to the peak power and pulse energy of > 0.27 kW and 110 pJ, respectively.
A 3.5-ps mode-locked semiconductor optical amplifier fiber laser generated by 60-ps backward optical dark pulse-train injection
(2005)
Chiu, IH
;
Liao, YS
;
Chang, YC
;
Lin, GR
;
光電工程學系
The relationship between the backward optical injection waveform and the mode-locked Pulse shape of semiconductor optical amplifier fiber laser (SOAFL) is studied. The SOA plays both the roles of a gain medium and an optically controlled modulator in this work. The injected optical comb-like bright and dark pulse-train with 60-ps pulsewidth was generated using a Mach-Zehnder intensity modulator (MZM) which DC-biased voltage of 1.7 V and 7.2 V, respectively. The backward injection of optical dark pulse-train results in a wide gain-depletion width (and a narrow gain window) within one modulation period, which is necessary for perfect mode-locking the SOAFL. In opposite, the backward injection of short optical pulse of bright optical pulse-train only causes a less pronounced gain-depletion effect. Such a broadened gain window can hardly initiate the mode-locking process. The backward comb-like dark pulse-train modulation IS Much easier to initiate harmonic mode-locking in the SOAFL than the bright pulse-train or sinusoidal-wave, wave injection, which generates pulsewidth as short as 15 ps at 1 GHz. After propagating through 195m-long dispersion-compensating fiber, the pulsewidth of the mode-locked SOAFL can be linearly compressed to 13.5 ps. The linewidth and time-bandwidth product of the compressed SOAFL pulses are 1.78 nm and 0.8, respectively. The pulsewidth can further be nonlinearly compressed by using a 4695m-long single-mode fiber. The shortest mode-locked SOAFL pulsewidth of 3.5 ps at repetition frequency of I GHz by using cross-gain modulation technique is reported for the first time.
A feedback-injected Fabry-Perot laser diode filtering technique for side-mode suppression and linewidth reduction of erbium-doped fiber lasers
(2003-07-15)
Lin, GR
;
Lee, SK
;
光電工程學系
;
Department of Photonics
By adding a fiber-pigtailed Fabry-Perot laser diode (FPLD) into a close-loop erbium-doped fiber amplifier (EDFA) ring cavity. and feedback-injecting the FPLD biased at just below threshold and the EDFA each other via directional couplers, we demonstrate a low-cost band-pass filtering technique for constructing narrow linewidth erbium-doped fiber laser (EDFL) with ultrahigh side-mode suppression ratio (SMSR). Under an output coupling ratio of 90%, the mutually injection-locked EDFL-FPLD link exhibits a maximum output power and SMSR of up to 98.6 mW and 49.6 dB at wavelength 1561.37 nm,. respectively. Wavelength tuning of up to 6 nm can be achieved by tuning the temperature and fine adjusting the below threshold driven current of FPLD. The minimum spectral linewidth at 3dB-decay of as small as 0.017 nm measuring by commercial optical spectrum analyzer with limited resolution bandwidth of 0.01 nm are observed. The stabilities in power, SMSR, peak wavelength of +/-0.01 mW, +/-0.5 dB, and +/-0.025 nm, respectively, are also determined. (C) 2003 Elsevier Science B.V. All rights reserved.
A novel phase-noise-suppressed and delay-time-tunable mode-locked erbium-doped fiber laser
(2002-10-15)
Lin, GR
;
Lai, Y
;
光電工程學系
;
Department of Photonics
A phase-noise-suppressed and delay-time-tunable actively mode-locked erbium-doped fiber ring laser is demonstrated by using voltage-controlled and frequency-discriminated phase shifter as an inherent timing module. By changing the voltage from -3.35 to 3.6 V, the maximum tuning range of phase and delay-time of 500 MHz optical pulse-train from the laser can be up to 340degrees (similar to1.9pi) and 1.9 ns (nearly 1 period), respectively. Optimized responsivity and tuning deviation are 0.27 ps/mV and less than or equal to 4%. The single-sided-band phase the laser operated at feedback controlled mode is significantly reduced to -100 dBc/Hz (measured at frequency of 10 kHz offset from center), which is at least 10 dB smaller than that of the laser operated at free-running mode. (C) 2002 Published by Elsevier Science B.V.
A pulse-compressed and harmonic mode-locked SOA-EDFA laser link with suppressed phase and supermode noises
(2005)
Lin, GR
;
Chang, YC
;
Wu, MC
;
光電工程學系
;
Department of Photonics
An optically bandpass filtered SOA-EDFL laser link with suppressed phase noise of -110 dBc/Hz and improved supermode noise suppression ratio of 90 dB after harmonic mode-locking and fiber-based pulse compression (to 3.1 ps) are demonstrated.
All-optical data format conversion in synchronously modulated single-mode Fabry-Perot laser diode using external injection-locking-induced nonlinear threshold reduction effect
(2005-06-01)
Lin, GR
;
Chang, YC
;
Lin, YH
;
Chen, JH
;
光電工程學系
High-speed all-optical data-format conversion and logic gate from a synchronously modulated Fabry-Wrot laser diode (FPLD) below threshold condition is demonstrated by using external injection-induced. nonlinear threshold reduction effect of the FPLD. A pulsed pseudoreturn-to-zero (PRZ) data with maximum extinction ratio of 14.5 dB is obtained by externally seeding the 9.953-Gb/s (OC-192) nonreturn-to-zero (NRZ) data stream to optically gain-switch the FPLD. At optimized radio frequency and optical injecting powers of 24 and 4 dBm, the root mean square timing jitter and the duty-cycle (pulsewidth) of the PRZ eye pattern are determined as 0.4 ps and 45% (44 ps), respectively. The bit-error rate (BER) can be as low as 10(-13) under the 4-dBm external injecting power. A 1.5-dB power penalty with the BER of < 10(-9) is measured at a bit rate of 9.953 Gb/s. Highest NRZ-to-PRZ conversion rate of 12.5 Gb/s is achieved by increasing biasing current of the FPLD.
All-optical NRZ-to-PRZ format transformer with an injection-locked Fabry-Perot laser diode at unlasing condition
(2004-09-20)
Chang, YC
;
Lin, YH
;
Chen, JH
;
Lin, GR
;
光電工程學系
By using an optical nonreturn-to-zero (NRZ) format data-stream to injection-lock an synchronously modulated Fabry-Perot laser diode at below threshold condition (without DC driving current), an output data-stream with pseudo-return-to-zero (PRZ) format can be generated at bit rate of up to 2.488 Gbit/s. Such an NRZ-to-PRZ format transformation is due to the injection-locking induced gain-switching of the FPLD with the incoming NRZ data. The PRZ data-stream with a maximum on/off extinction ratio of 12.2 dB is obtained under the optical injecting power of -2 dBm and the RF driving power of 24.4 dBm. The best side-mode suppression ratio of 40 dB and the lowest timing jitter of 0.4 ps for the PRZ data-stream are observed. A power penalty of 1.2 dB is measured at a bit-error rate of 10(-9) after NRZ-to-PRZ transformation. In application, the demonstration of an all-optical OR logic gate using the FPLD-based NRZ-to-PRZ transformer is also reported. (C) 2004 Optical Society of America.
All-optical pulse data generation in a semiconductor optical amplifier gain controlled by a reshaped optical clock injection
(2006-05-08)
Lin, GR
;
Chang, YC
;
Yu, KC
;
光電工程學系
;
Department of Photonics
Wavelength-maintained all-optical pulse data pattern transformation based on a modified cross-gain-modulation architecture in a strongly gain-depleted semiconductor optical amplifier (SOA) is investigated. Under a backward dark-optical-comb injection with 70% duty-cycle reshaping from the received data clock at 10 GHz, the incoming optical data stream is transformed into a pulse data stream with duty cycle, rms timing jitter, and conversion gain of 15%, 4 ps, and 3 dB, respectively. The high-pass filtering effect of the gain-saturated SOA greatly improves the extinction ratio of data stream by 8 dB and reduces its bit error rate to 10(-12) at -18 dBm. (c) 2006 American Institute of Physics.
Analysis of silicon nanocrystals in silicon-rich SiO2 synthesized by CO2 laser annealing - art. no. 602020
(2005)
Lin, CJ
;
Lin, GR
;
Chueh, YL
;
Chou, LJ
;
光電工程學系
The localized synthesis of 4.2-5.6 nm-Si nanocrystals (nc-Si) in Si-rich SiO2 (SRSO) by CO, laser annealing at laser intensity of below ablation-threshold (6 kW/cm(2)) is demonstrated. Since the SRSO exhibits a high absorption coefficient of up to 0.102 cm(-1) at wavelength of 10.6 mu m, a direct-writing CO, laser annealing system with focusing spot 2 size of 0.2 mm(2) is used to locally anneal the SRSO and precipitate the nc-Si. A thermophysical model reveals that the surface temperature of SRSO ranging from 130 degrees C to 3350 degrees C is achieved by varying the laser power densities from 1.5 to 13.5 kW/cm(2). The CO2 laser-ablation-threshold power density is about 6 kW/cm(2). corresponding to the optimized annealing temperature 1285 degrees C at the ablation threshold. The CO2 laser annealing is capable of the precise control on power density and spot size, which benefits from the in-situ and localized annealing temperature control of SRSO film, and also prevents from the eternal damage of the other electronic devices nearby the annealing site. The nc-Si dependent photoluminescence (PL) were observed at 806 nm or longer, whereas the laser-ablation damaged SRSO film exhibits significant blue PL at 410 nm due to the oxygen-related structural defects. The refractive index of the laser-treated SRSO film is increasing from 1.57 to 2.31 as the laser intensity increases from 1.5 to 6.0 kW/cm(2) which is mainly attributed to the increasing density of nc-Si embedded in SRSO. High resolution transmission electron microscopy (HRTEM) analysis reveals that the average size of nc-Si embedded in SRSO film is about 5.3 nm, which correlates well with the theoretical prediction of a corresponding PL at 806 nm. The HRTEM estimated square density of the nc-Si in SRSO film under the laser intensity of 6 kW/cm(2) is about 10(18) cm(-3).
Arsenic-implanted GaAs: An alternative material to low-temperature-grown GaAs for ultrafast optoelectronic applications
(1998)
Pan, CL
;
Lin, GR
;
光電工程學系
;
Department of Photonics
Arsenic-ion-implanted GaAs (or GaAs:As+), with excess-arsenic-related deep level defects, has recently emerged as a potential alternative to low-temperature molecular-beam-epitaxy (LTMBE) grown GaAs for ultrafast optoelectronic applications. In this paper, we review results of our structural, ultrafast optical and optoelectronic investigations of as-implanted and thermally annealed GaAs:As+. Picosecond photoconductive switching responses are reported for devices fabricated on thermally-annealed low-dose and high-dose implanted GaAs:As+. Novel sign reversals in near-bandgap ultrafast optical responses were observed and explained.
As+-implanted AlGaAs oxide-confined VCSEL with enhanced oxidation rate and high performance uniformity
(2004-06-01)
Laih, LH
;
Kuo, HC
;
Lin, GR
;
Laih, LW
;
Wang, SC
We report the utilization of an As+-implanted Al-GaAs region and regrowth method to enhance and control the wet thermal oxidation rate for 850-nm oxide-confined vertical-cavity surface-emitting laser (VCSEL). The oxidation rate of the As+-implanted device showed a four-fold increase over the nonimplanted one at the As+ dosage of 1 x 10(16) cm(-3) and the oxidation temperature of 400 degreesC. 50 side-by-side As+-implanted oxide-confined VCSELs fabricated using the method achieved very uniform performance with a deviation in threshold current of DeltaI(th) similar to 0.2 mA and slope-efficiency of DeltaS.E. similar to 3%.
Broad-band (>= 20 GHz) laser-diode-based optoelectronic microwave phase shifter
(1998-10-01)
Lin, GR
;
Hwang, TS
;
Chuang, YH
;
Wang, SC
;
Pan, CL
We demonstrate a new type of broad-band microwave phase shifter with superior performance at frequencies up to 20 GHz. This is implemented by simply adding an offset voltage prior to the loop filter (LF) in a laser-diode-based digital optoelectronic phase-locked loop (OEPLL), Accurate control of the phase of microwave signals with a continuously tunable range exceeding 640 degrees (similar to 3.6 pi) is achieved. The phase fluctuation and long-term drift of ally desired phase shift are as small as +/-0.4 degrees and 0.08 degrees, respectively, at 20 GHz, The relative phase instability can be maintained within 0.09 degrees while operating in a phase-shift-keying (PSK) scheme, We also demonstrate accurate control of relative phase difference between dual phase-locked microwave sources using the phase shifter. Our results indicate potential application of this broad-band optoelectronic phase shifter in a phased-array antenna system.
Characterization of optically excited terahertz radiation from arsenic-ion-implanted GaAs
(2001-01-01)
Lin, GR
;
Pan, CL
;
光電工程學系
;
Department of Photonics
This work characterizes the optically excited terahertz (THz) radiation from arsenic-ion-implanted GaAs (GaAs:As+). We observed phase reversal in the emitted THz radiation field after the semi-insulating GaAs substrate was implanted. The peak amplitude of the emitted THz field increased from 25 mV/cm to 100 mV/cm after thermal annealing. This trend confirms the recovery in crystallinity of the as-implanted GaAs :As+ after annealing. By introducing a magnetic field, we observe a blue shift of the center frequency in the THz power spectrum from 0.57 THz for the as-implanted CaAs : As+ to 1 THz for furnace-annealed samples. Analysis of the blue-shifted spectra and unsymmetrical pulse shapes allows us to infer the increasing importance of the contribution of another unknown mechanism to the THz radiation from the GaAs:As+ samples after annealing. This is also explained satisfactorily by the crystallinity of the as-implanted and furnace-annealed GaAs : As+. Further, the effective carrier mobilities of as-implanted, rapid-thermal-annealed, and furnace-annealed GaAs : As+ are determined for the first time as 0.6, 2, and 15 cm(2)/Vs respectively according to the THz data.
CO2 laser annealing synthesis of silicon nanocrystals buried in Si-rich SiO2
(2005)
Lin, CJ
;
Chueh, YL
;
Chou, LJ
;
Kuo, HC
;
Lin, GR
Localized synthesis of 3-8 nm Si nanocrystals (nc-Si) in PECVD-grown Si-rich SiO2 (SRSO) film is demonstrated using CO2 laser annealing at an intensity below the ablation-threshold (6.0 kW/cm(2)). At an optimized surface temperature of 1285 degrees C, the precipitated nc-Si in CO2-laser-annealed SRSO film results in near-infrared photoluminescence (PL) at 806 ran, whereas the ablation damage induced at higher laser intensities as well as temperatures results in blue PL at 410 nm related to structural defects. The refractive index of the laser-annealed SRSO at 633 nm increases from 1.57 to 2.31 as the laser intensity increases from 1.5 to 6.0 kW/cm(2). Transmission electron microscopy analysis reveals that the average size and volume density of Si nanocrystals embedded in the SRSO film are about 6 nm and 4.5 x 10(16) cm(-3), respectively. The CO2 laser annealing with controlled intensity and spot size can potentially accomplish in-situ, localized annealing of the SRSO film without causing irreversible damage to nearby electronics.
Comparison of high-resistivity ZnO films sputtered on different substrates
(2002-04-01)
Lin, GR
;
Wang, SC
;
光電工程學系
;
Department of Photonics
The structural and electrical properties of (002)-oriented high-resistivity ZnO films with luminescent peaks ranging from 3 80 nm to 415 nm grown on SiO2/Si, Si and Coming 7059 glass substrates by radio-frequency magnetron-assisted sputtering are determined. The X-ray diffraction results reveal that the ZnO/glass sample has a narrow normalized intensity of full-width at half maximum (FWHM) compared to other samples. The photoluminescence spectra show that the band-gap energy of the ZnO/glass sample is similar to that of the ZnO bulk standard; however, a smaller band-gap energy of 2.987 eV of the ZnO/SiO2/Si sample due to the defect-induced lattice expansion effect is observed. The ZnO/glass sample has better crystallinity, but exhibits lower contact resistance and sheet resistance. In particular, the metal-semiconductor-metal diode fabricated on the ZnO/Si sample is found to exhibit a relatively larger contact resistance, sheet resistance, and specific contact resistivity of 1.02 x 10(9) Omega, 3.8 x 10(10) Omega/square, and 1.54 x 10(3) Omega-cm(2), respectively.
Comparison on the noise and jitter characteristics of harmonic injection-locked and mode-locked erbium-doped fiber lasers
(2005)
Wu, MC
;
Chang, YC
;
Lin, GR
;
光電工程學系
;
Department of Photonics
We compare the noise characteristics of optical pulses generated from an actively mode-locked (AML) erbium-doped fiber laser (EDFL) with a semiconductor optical amplifier and an injection-locked EDFL with a gain-switched Fabry-Perot laser diode (FPLD). The mode-locked EDFL pulse exhibits a phase noise of -110.1 dBc/Hz (at 1 MHz offset frequencies from the carrier), the timing jitter of 1.16 ps, and a supermode noise suppression ratio of 47.5 dB. The injection-locked EDFL pulse exhibits a phase noise of -121.1 dBc/Hz (at 1 MHz offset frequencies from the carrier), a timing jitter of 0.31 ps, and a supermode noise suppression ratio of 51 dB. It is demonstrated that the injection-locked EDFL with a gain-switched FPLD has lower noise characteristics than the AML-EDFL.