Naofumi Shimizu

A 40-GHz 0.9-ps regeneratively mode-locked fiber laser with a tuning range of 1530-1560 nm

A stable 40-GHz pulse train was successfully generated from a regeneratively mode-locked fiber laser. The laser was locked to an external signal by a phase-locked loop (PLL) technique. The output pulsewidth was as short as 0.9 ps using a soliton effect in the fiber cavity and the wavelength was tunable between 1530 and 1560 nm.

Photodiode-integrated microstrip antenna array for subterahertz radiation

The radiation characteristics of subterahertz (sub-THz) electromagnetic waves emitted from an antenna array integrated with photodiodes are investigated. The element of the fabricated array antenna was a 300-GHz microstrip antenna integrating a uni-traveling carrier photodiode. It was observed that the beamwidth of a 3 /spl times/ 1 antenna array is about half that of the single microstrip antenna. We also confirmed that the radiation direction changed by 20/spl deg/ when 2/spl pi//5 of phase difference was added to the input optical signal for each antenna element. These results demonstrated that sub-THz waves emitted by each element of the array were coherently superimposed and the power combining of the sub-THz radiation occurred in the microstrip antenna array. The measured output power of each radiation element is about 120 /spl mu/W, and a total output power of 1 mW can be estimated for a fabricated 3 /spl times/ 3 array in an ideal radiation condition.

High-repetition frequency pulse generation at >100 GHz using mode-locked lasers integrated with electroabsorption modulators

Summary form only given. We demonstrated high frequency pulse generation by using a modelocked semiconductor laser integrated with electroabsorption (EA) modulators. Pulses of 2.4 ps at 102 GHz repetition frequencies were obtained. We measured low timing jitter of 0.36 ps by means of a mixing technique.