Yutaka Chaen

All-optical flip-flop operation based on asymmetric active-multimode interferometer bi-stable laser diodes

We demonstrate fast and low energy all optical flip-flop devices based on asymmetric active-multimode interferometer using high-mesa waveguide structure. The implemented devices showed high speed all-optical flip-flop operation with 25 ps long pulses. The rising and falling times of the output signal were 121 ps and 25 ps, respectively. The required set and reset pulse energies were only 7.1 fJ and 3.4 fJ, respectively.

Low Wavelength Dependency Design for MMI (Multi-Mode Interference) Mode Converter

Mode-division multiplexing (MDM) is widely researched, and we are researching mode converter by using multi-mode interference (MMI) waveguide. Wavelength division multiplexing (WDM) must be used in addition to the MDM, however, wavelength dependency exits for MMI in general as it works based on the interference of light. In this paper, we analyze the wavelength dependency of the MMI 0th to 1st mode-converter theoretically. As a result, we clarify the design scheme to suppress the wavelength dependency. Moreover, we show the sufficient performance of less than 1.0 dB in entire C-band for highly confined waveguide (Si/SiO2 waveguide) as a design example.

Design criteria for wavelength independent MMI mode converter

The design criteria that achieve the excess loss of less than 1.0 dB in entire C-band has been clarified for MMI mode converter. As a result, we have confirmed that MMI width in addition to access waveguide width ratio over MMI width are the important design criteria.