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ABSTRACT: A precise grating profile evaluation method for distributed-feedback (DFB) laser diodes was achieved using a simple optical metrology. Spectroscopic scatterometry, an optical-wavelength light-diffraction technique, is emerging as a fast, accurate, and nondestructive means of monitoring profiles. A photoresist grating pattern on an InP substrate and an etched InP grating with periods of 0.2 and 0.24 mum were successfully evaluated by using unpolarized simple optical metrology. A precise grating profile evaluation technique with an accuracy of nanometers enabled us to obtain an accurate coupling coefficient (kappaL) for DFB laser diodes. DFB laser diodes with well-controlled kappaL are very promising for practical use in cost-effective optical networks.
IEEE Transactions on Semiconductor Manufacturing 09/2007; · 0.72 Impact Factor
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ABSTRACT: We have successfully fabricated 1.3-μm AlGaInAs strain-compensated multiple-quantum-well (MQW) buried-heterostructure (BH) lasers by narrow-stripe selective metalorganic vapor-phase epitaxy. Based on the optimization of AlGaInAs strain compensated MQW and the Al-oxidation-free BH process, we obtained a low-threshold current of 12.5 mA and a relaxation frequency of more than 10 GHz at 85°C for Fabry-Perot lasers. For distributed feedback lasers, we demonstrated a 10-Gb/s operation and transmission of over 16 Km for a single mode fiber at 100°C. Furthermore, a record-low 25.8-mA<sub>p-p</sub> modulation current for a 10-Gb/s modulation at 100°C was demonstrated with shorter cavity and high grating-coupling coefficient. A median life of more than 1×10<sup>5</sup> h at 85°C was estimated after an aging test of over 5000 h for these lasers. These superior characteristics at high temperatures were achieved by the combination of the high differential gain of AlGaInAs strain compensated MQW and the BH structure.
IEEE Journal of Selected Topics in Quantum Electronics 02/2005; · 3.78 Impact Factor
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ABSTRACT: A record-low 25.8-mA/sub p-p/ modulation current for 10-Gb/s modulation at 100/spl deg/C was demonstrated using AlGaInAs strain compensated MQW-BH-DFB lasers. A median life of more than 1/spl times/10/sup 5/ hours at 85/spl deg/C was estimated after an aging test of 4000 hours.
Optical Fiber Communication Conference, 2004. OFC 2004; 03/2004
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H. Hatakeyama,
K. Naniwae,
K. Kudo,
N. Suzuki,
S. Sudo,
S. Ae, Y. Muroya,
K. Yashiki,
K. Satoh,
T. Morimoto,
K. Mori,
T. Sasaki
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ABSTRACT: We report on the first demonstrated near-complete coverage of the S-, C-, and L-bands using six different ranges of wavelength-selectable microarray light sources (WSLs) based on a distributed-feedback (DFB) laser diode (LD) array. The six devices were fabricated on only two wafers. Each device has a tuning range of more than 15 nm, a sidemode suppression ratio of over 40 dB, and a fiber-coupled power greater than around 10 mW.
IEEE Photonics Technology Letters 08/2003; · 2.19 Impact Factor
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ABSTRACT: A process for growing a high-quality AlGaInAs MQW on a grating has been developed and applied to fabricate a 1.3-μm AlGaInAs BH DFB-LD. A low threshold current of 20 mA, a high slope efficiency of 0.31 W/A at 85°C and a high CW operating temperature of 120°C were obtained for a 250-μm-long device with antireflective and high-reflective coated facets. A clear eye opening under 10-Gb/s direct modulation was also confirmed at 85°C.
Indium Phosphide and Related Materials, 2003. International Conference on; 06/2003
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Y. Muroya,
T. Okuda,
R. Kobayashi,
K. Tsuruoka,
Y. Ohsawa,
T. Koui,
T. Tsukuda,
T. Nakamura,
A. Ito,
J. Shimizu,
K. Kobayashi
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ABSTRACT: 1.3-μm AlGaInAs BH DFB laser diodes have been developed for the first time. 100°C, 10-Gb/s operation and transmission over 16 km of SMF were demonstrated with an 80-mA operating current and a 42-mA<sub>p-p</sub> modulation current.
Optical Fiber Communications Conference, 2003. OFC 2003; 04/2003
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ABSTRACT: Clarifies that phase shift value in directly modulated distributed feedback laser diodes (DFB-LDs) affects their chirp characteristics and resistance to external optical feedback because of the feedback effect of mirror loss (FEML). Comparing λ/8, λ/4, and 3/λ8 phase-shifted DFB-LDs, theoretically and experimentally, showed that the negative FEML in λ/8 phase-shifted DFB-LDs improves their transmission performance and makes them more resistant to external optical feedback. It was demonstrated with 2.5-Gb/s directly modulated 1.55-μm λ/8 phase-shifted DFB-LDs that a very low-power penalty for 100-km transmissions (less than 1 dB for BER=10<sup>-10</sup>) can be obtained within a wide extinction ratio from 8.5 to 14.5 dB. Excellent resistance to optical feedback was also demonstrated using λ/8 phase-shifted DFB-LDs: isolator-free 80-km transmission was successful under -14-dB external optical feedback. In addition, the relation of transmission characteristics to coupling coefficient κL and detuning between oscillation wavelength and gain maximum was also discussed here for designing low chirp λ/8 phase-shifted DFB-LDs.
IEEE Journal of Quantum Electronics 12/2002; · 1.88 Impact Factor
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K. Yashiki,
K. Kudo,
T. Morimoto,
S. Sudo, Y. Muroya,
T. Tamanuki,
M. Ishizaka,
T. Hosoda,
Y. Furushima,
H. Hatakeyama,
Y. Yokoyama,
K. Mori,
T. Sasaki,
M. Yamaguchi
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ABSTRACT: In this letter, we have simultaneously fabricated five wavelength-selectable microarray light sources (WSLs), each having a different wavelength range integrated with an electroabsorption (EA) modulator on a single wafer. We also introduced a novel device configuration scheme for wavelength-independent modulation. The five EA-WSLs fully covered the entire C-band and had a low uniform threshold current of 6 /spl plusmn/ 1 mA at 25/spl deg/C. Wavelength-independent extinction characteristics were obtained over a tuning wavelength range of 8 nm, and 2.5-Gb/s transmission over 600 km was successfully achieved.
IEEE Photonics Technology Letters 03/2002; · 2.19 Impact Factor
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ABSTRACT: We developed high-performance distributed feedback array-based wavelength-selectable light sources (WSLs), covering the entire C-band with five simultaneously fabricated devices. We fabricated five different range WSLs on a wafer, each with a unique 8-nm tuning range to cover 40 100-GHz-spaced channels. Uniform characteristics, such as an Ith of 8.3/spl plusmn/1.2 mA, a sidemode suppression ratio of over 45 dB, and a fiber-coupled power greater than 8.5 mW were obtained.
IEEE Photonics Technology Letters 11/2001; · 2.19 Impact Factor
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ABSTRACT: It was verified for the first time that phase-shift value in directly modulated DFB laser diodes (LDs) affects their chirping characteristics and external optical feedback resistance due to the feedback effect of mirror loss (FEML). Theoretical and experimental results clarified that the negative FEML achieved in /spl lambda//8 phase-shifted DFB-LDs was able to improve the transmission performances and make the LDs more robust to external optical feedback. Isolator-free 80-km transmissions with a very low power penalty of less than 1-dB at bit error rate (BER)=10/sup -10/ was demonstrated with 2.5-Gb/s directly modulated 1.55-/spl mu/m /spl lambda//8 phase-shifted DFB-LDs.
IEEE Photonics Technology Letters 04/2001; · 2.19 Impact Factor
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ABSTRACT: We developed multi-range wavelength-selectable light sources (WSLs) with an all-selective MOVPE (ASM) grown microarray planar-buried-hetero (MPBH) structure. We simultaneously fabricated five WSLs, each with a unique 8-nm tuning range, to cover forty 100-GHz-spaced channels (the entire C-band). Uniform characteristics, such as an I/sub th/ of 8.3 /spl plusmn/ 1.2 mA, an SMSR of over 45 dB, and a fiber-coupled power up to 15 mW, were obtained.
Optical Fiber Communication Conference and Exhibit, 2001. OFC 2001; 02/2001
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K. Yashiki,
K. Kudo,
T. Morimoto,
N. Suzuki,
S. Sudo, Y. Muroya,
T. Tamanuki,
K. Sato,
Y. Ohsawa,
Y. Hisanaga,
K. Mori,
T. Sasaki
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ABSTRACT: We have developed a wavelength-selectable light source (WSL) based on microarray DFB-LD configuration that enables high fiber-coupled power operation. The WSL was grown in only two steps without any complicated semiconductor etching. Using the WSL, fiber-coupled power of more than 20 mW and stable single-mode oscillations with an SMSR of more than 50 dB were obtained for all 23 addressable ITU-T channels on a 50-GHz grid.
Optical Communication, 2001. ECOC '01. 27th European Conference on; 02/2001
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ABSTRACT: Based on a novel large-signal dynamic analysis, external optical feedback resistant single-mode LD's were designed and realized. Under -14 dB external optical feedback, isolator-free 2.5-Gb/s 45-km transmission was demonstrated over a wide temperature range from -40/spl deg/C to +80/spl deg/C for the first time.
IEEE Photonics Technology Letters 12/1999; · 2.19 Impact Factor
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ABSTRACT: We developed EA-modulator integrated DFB-LDs covering 1.56-μm
to 1.61-μm wavelengths on a single wafer, and tested them in
long-distance transmission experiments for the first time to our
knowledge. Transmissions at 2.5 Gbit/s over 600 km and 10 Gbit/s over
500-ps/nm dispersion were successfully demonstrated
Optical Fiber Communication Conference, 1999, and the International Conference on Integrated Optics and Optical Fiber Communication. OFC/IOOC '99. Technical Digest; 02/1999
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ABSTRACT: Using partially corrugated waveguide laser diodes (PC-LDs) with
robust and high-yield external optical feedback resistance,
isolator-free 2.5-Gbit/s,45-km transmission was demonstrated over a wide
temperature range from -40°C to +80°C under -14 db external
optical feedback
Optical Fiber Communication Conference, 1999, and the International Conference on Integrated Optics and Optical Fiber Communication. OFC/IOOC '99. Technical Digest; 02/1999
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ABSTRACT: 1.56-1.61 μm range modulator-integrated distributed-feedback
laser diodes (DFB/MODs) of different wavelengths are successfully
demonstrated for applications in 1.58 μm band WDM systems. They were
fabricated on a single wafer by using narrow-stripe selective MOVPE with
a novel growth-time-modulation (GTM) technique. Uniform and
high-performance characteristics such as a threshold current less than 5
mA and an extinction ratio larger than 16 dB at -2 V were achieved
Electronics Letters 11/1998; · 0.96 Impact Factor
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ABSTRACT: We have demonstrated higher coupling efficiency InGaAsP
single-longitudinal-mode partially corrugated MQW laser diodes (PC-LDs)
with an active tapered stripe and chirped grating. The coupling
efficiency was improved by 2.5 dB over conventional straight stripe LDs
without sacrificing light output efficiency at high temperatures. This
performance is promising for the development of cost-effective optical
modules
Optical Fiber Communication Conference and Exhibit, 1998. OFC '98., Technical Digest; 03/1998
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ABSTRACT: Eight-wavelength 1.55-μm DFB-LD array modules with 1.6-nm
wavelength spacing have been made by self-aligned assembly using a
stripe-type solder bump flip-chip bonding, and the fiber output optical
power for each channel was greater than ~20 dBm. These modules are
attractive low-cost multiwavelength light sources for use in WDM systems
Integrated Optics and Optical Fibre Communications, 11th International Conference on, and 23rd European Conference on Optical Communications (Conf. Publ. No.: 448); 10/1997
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ABSTRACT: Precise wavelength control of a multiple-wavelength DFB InGaAsP strained MQW laser-diode (LD) array was achieved using weighted-dose allocation variable-pitch EB-lithography (WAVE) and highly uniform MOVPE. Multiple-wavelength 1.3 μm λ/4-shifted DFB LD arrays with wavelength spacing of 2.0 nm were successfully demonstrated. The standard deviation of the wavelength was as low as 0.37 nm over 2-in wafers.
IEEE Photonics Technology Letters 04/1997; · 2.19 Impact Factor
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ABSTRACT: An internal distortion cancellation mechanism in DFB-LDs caused by
relaxation oscillation and longitudinal spatial hole burning has been
revealed to realise low intermodulation distortion laser diodes used at
high modulation frequencies. Extremely low distortion characteristics
(IMD<sub>3</sub>⩽-80 dBc) were achieved at up to 2.2 GHz owing to
the internal distortion cancellation effect
Electronics Letters 12/1995; · 0.96 Impact Factor
