Yu-Dong Bae

Investigation of optical feedback in high-speed electroabsorption modulated lasers with a window region

The optimum waveguide design for optical feedback reduction in a 10-Gb/s electroabsorption modulated laser has been discussed. A device with a 30-/spl mu/m-long window region exhibited as much as 10-15-dB reduction, which is verified by experimental results and the beam propagation calculation. Using a tilted waveguide with the window region, the feedback factor is reduced to as low as -40 dB. Besides low optical feedback, the tilted-and-straight modulator has a sufficient dc extinction ratio and a far-field profile allowing larger than 60% fiber-coupling efficiency.

Operation of 1550-nm electroabsorption-Modulated laser at 40/spl deg/C for 10-gb/s, 40-km transmission

Semicooled operation at 40/spl deg/C of electroabsorptive modulator integrated laser (EML) for intermediate reach communication has been demonstrated. Reproducible operation at the elevated temperature was achieved through a device parameter optimized based on the temperature dependence of the dc characteristics of EML and a design of multi-quantum-well structure providing both relevant output power and high-frequency bandwidth at 40/spl deg/C. Good eye pattern and near zero chirp with the average power over 0 dBm are obtained at 40/spl deg/C, with an estimated lifetime over 20 years.

Monitor-photodiode integration in the amplifier- and modulator-integrated DFB laser diode

Monitor photodiode (MPD) is monolithically integrated in the antireflection output window region of the amplifier- and modulator-integrated laser diode. The MPD is electrically isolated from the other components by semi-insulating InP regrowth with total leakage current less than 1 /spl mu/A. The MPD responsivity to the output power is tailored through its location and size, and about half decibel power loss is achieved for 4% responsivity. The reliability is demonstrated through the accelerated aging test.

Towards Multimodal Affective Feedback: Interaction between Visual and Haptic Modalities

We explored how emotional cues presented in visual and haptic modalities interact. We constructed an affective haptic dataset, and used the emotional visual stimuli from the International Affective Picture System (IAPS). Participants were asked to rate the visual stimuli, haptic stimuli and visualhaptic stimuli. Analysis of the results indicates that the presence of haptic stimulus affects the arousal of the visual stimulus, but does not affect the valence significantly. We further explored this interaction in terms of the intensity, frequency, waveform and rhythm of the haptic stimuli. We then provide a set of guidelines on visual-haptic interaction that could be used in design of multimodal affective feedback.

Design of amplifier- and modulator-integrated laser diode for 10-Gb/s 80-km transmission

We present the amplifier- and modulator-integrated laser diode designed for 10-Gb/s transmission over 80-km distance. An antireflection window structure is implemented at the tilt facet of the amplifier to reduce optical feedback by 40 dB. A monitor photodiode is monolithically integrated in the antireflection window region for accurate power regulation. To better control the amplifier input power and to reduce the feedback of amplified spontaneous emission, an attenuation inner-window is incorporated by removing a section of the waveguide. The reproducibility of the chip fabrication process is tested to confirm the design margin. Through amplifying the modulated signals and reducing modulator chirp by amplifier saturation, high-power optical transmission is demonstrated.

Attenuation inner-window in the amplifier- and modulator-integrated laser diode

To better control the input power of an amplifier, which is monolithically integrated with an electroabsorptive-modulated laser, an inner window is implemented by removing a section of the waveguide to realize an attenuator. It also reduces the effect of amplified spontaneous emission on the integrated laser. Attenuation around -10 dB is obtained by adjusting the length of the inner window. Because of different focal depths, unguided stray light from the inner window is not coupled to a fiber on which the amplifier output is focused through a lens.

High-power wide temperature range (-40°C ~100°C) operation of 1300-nm InGaAsP DFB lasers with asymmetric MQWs

We demonstrate 1.25 Gbps 1300 nm InGaAsP/InP DFB lasers employing asymmetric MQWs structures operable over a wide temperature range of -40°C to 100°C, which has an optical power of 10 mW and a side mode suppression ratio (SMSR)and a Fabry-Perot suppression ratio (FPSR) of >30dB.

InGaAsP SSC LD for low cost uncooled FTTH module with bandwidth over 4GHz

By optimum design of spot-size converter regarding the cavity length, active volume and taper type, we achieved SSC LD with 13degtimes14deg FFP, 3.5 dB coupling loss and 3 dB bandwidth over 4 GHz applicable to uncooled E-PON FTTH modules