K. Oe

Optical narrow-band filters using optical amplification with distributed feedback

The amplification characteristics of the distributed-feedback (DFB) laser amplifier are studied. The amplifier has a narrow, single-frequency gain-bandwidth product and the maximum-gain frequency tunability. With these advantages, the amplifier can be applied as an optical narrowband filter. This filter has optical frequency selectivity with an extinction ratio of better than -15 dB for optical inputs separated by 9.8 GHz having different optical input powers. By using a multielectrode DFB laser amplifier, the wide-range tunability of a gain maximum frequency (33.3 GHz) can be obtained while maintaining a constant gain and a constant gain-bandwidth product. Optical frequency selection with an extinction ratio of better then -20 dB can be obtained for two optical inputs separated by 15.4 GHz and having the same input power. >

Tunable optical-wavelength conversion using an optically-triggerable multielectrode distributed feedback laser diode

Tunable optical-wavelength conversion with tunability greater than 5 AA using a multielectrode distributed-feedback laser diode (DFB LD) with a saturable absorber is discussed. This device is not dependent on input polarization and can operate at up to 500 MHz. Preliminary results of an optical switching experiment using the tunable wavelength converter and optical narrowband filter with a DFB LD amplifier are also reported. >

Finely tunable 10-Gb/s signal wavelength conversion from 1530 to 1560-nm region using a super structure grating distributed Bragg reflector laser

Finely tunable wavelength conversion of a 10-Gb/s signal is demonstrated to wavelengths ranged from 1530 to 1560 nm with spacings of 0.5 nm and accuracy of /spl plusmn/0.05 nm, where the Er/sup 3+/ doped optical fiber amplifier has optical gain, by using a super structure grating distributed Bragg reflector laser. Transmission of a wavelength-converted 10-Gb/s signal within the entire target wavelength range over a 100-km optical fiber is also demonstrated using a dispersion-shifted optical fiber.

Wavelength chirping in wavelength conversion of 10 Gb/s signal with semiconductor laser converter

The chirping effects of wavelength converted 10 Gb/s signals in semiconductor wavelength converter on the waveform degradation after optical fiber transmission are investigated. The 10 Gb/s converted signal can be transmitted over 100 km with less than 2 dB power penalty in the converted wavelength region of 1.524 to 1.564 /spl mu/m when a broadly tunable SSG-DBR laser wavelength converter and a dispersion shifted fiber are used. It is also discussed how waveform degradation can be reduced when linewidth enhancement factor (/spl alpha/-parameter) of semiconductor laser wavelength converter is reduced by using modulation-doped strained MQW DFB lasers.

Suppression of wavelength drift and thermal crosstalk in a tunable duplex integrated light source

In summary, we have developed a wavelength-tunable duplex integrated light source with thermal drift compensators. Thermal-transient induced wavelength drift of the distributed Bragg reflector laser diodes (DBR-LDs) and thermal crosstalk between the DBR-LDs are effectively suppressed by using the integrated compensators.

Broad-range tunable wavelength conversion of a 10 Gbit/s signal using a super structure grating distributed Bragg reflector laser

Wavelength conversion devices will play an important role in future optical transmission or optical signal processing systems. Wavelength conversion in the 1.55-µm range has been achieved using single-mode semiconductor lasers [1]-[6] or semiconductor laser amplifiers. [7]-[9] From a systems point of view, it is preferable to have a converted signal wavelength that is arbitrarily selectable. Wavelength conversion using semiconductor laser amplifiers alone cannot change the converted signal wavelength. [7]-[9] On the other hand, tunable wavelength conversion using single-mode lasers can easily be performed and was achieved by using a multielectrode distributed feedback (DFB) laser [1] and by using a distributed Bragg reflector (DBR) laser.

Optical-wavelength switching using distributed-feedback laser diodes

An optical-wavelength converter with tunability greater than 5 AA has been demonstrated using a multielectrode distributed-feedback laser diode (DFB LD) with a saturable absorber. The buried heterostructure GaInAsP/InP LD with first-order grating was fabricated using a MOVPE/LPE (metalorganic vapor-phase epitaxy/liquid-phase epitaxy) hybrid growth method. The p-type electrode was divided into three 100- mu m sections, which can be excited independently through the electrodes. The device emits coherent light only when light input is injected into the saturable absorber, and output wavelength is continuously tuned by the driving currents. This device has high optical gain (input power approximately 330 mu W and output power approximately 1 mW) and can operate at up to 500 MHz. A narrowband optical filter was constructed using the DFB LD amplifier. The DFB LD amplifier selectively amplifies one optical frequency, which can be changed by changing the LD bias current. Extinction ratios greater than 15 dB were obtained for the two optical inputs with a 9.8-GHz frequency difference. The use of the device for optical wavelength-division switching was investigated. >