Ryosuke Goto

All optical mode locking of Fabry–Perot laser diode via mutual injection locking between two longitudinal modes

A method to mode lock a Fabry–Perot laser diode (F–P LD) by purely optical means is proposed. Two F–P modes are mutually injection locked with the aid of injected cw light at the center frequency of the two modes. The other F–P modes are cascadingly mode locked owing to the cavity-enhanced nondegenerate four-wave mixing in the F–P LD. The principle of the method was confirmed by observing the linewidth narrowing of the lasing longitudinal modes and the generated optical pulse train at the repetition frequency of one F–P mode spacing.

Generation of Squeezed Vacuum Using Wavelength-Tunable Soliton Pulse and Nonlinear Polarization Interferometer

We demonstrate the generation of squeezed vacuum using a wavelength-tunable soliton pulse and nonlinear polarization interferometer (NOPI). Since the soliton pulse is ideal for squeezed vacuum generation and the wavelength of the soliton pulse can be tuned easily, it is expected that we can demonstrate large squeezing over a wide wavelength range. Using NOPI, since it is possible to generate squeezed light by only passing the optical pulse through the optical fiber without spatial alignment, the squeezed light can be generated easily and stably. A maximum noise reduction of -2.46 dB below shot noise level was observed. Considering the effect of quantum efficiency, the corresponding magnitude of squeezing is estimated to be -4.22 dB. The squeezing was observed when the center wavelengths were 1625 nm and 1650 nm.

Generation of Squeezed Vacuum using Spectral Filter by Spatial Light Modulator and Nonlinear Polarization Interferometer

We have demonstrated squeezed vacuum generation using an optical fiber, spectral filter consisting of the spatial light modulator (SLM), and a nonlinear polarization interferometer (NOPI). In the SLM filter, we can suppress the classical amplitude noise and modulate the amplitude and phase of incident pulses simultaneously. The NOPI is the easy and stable squeezed light generator. When the incident pulse is optimized using a feedback algorithm, the maximum noise reduction of -2.0 dB is observed and the corresponding magnitude of squeezing is -3.2 dB. The effects of the SLM filter such as classical amplitude noise reduction and phase optimization are confirmed.