Noriaki Onodera

Optical beat-note frequency stabilization between two lasers using a radio frequency interferometer in the gigahertz frequency band

Abstract. A beat-note frequency stabilization system using a distributed-feedback laser and external cavity laser diode has become a very important technique for laser spectroscopy, where highly stabilized high-frequency beat notes are required. We have developed a simple and versatile system capable of stabilizing the high-frequency beat notes (3 to 11 GHz) of two lasers using a delayed radio frequency self-heterodyne interferometer and have confirmed its basic operation. The frequency stability of the obtained beat notes is higher than 1 MHz in the 3- to 11-GHz frequency range with an average time of 20 s.

Frequency stabilization of two orthogonally polarized external cavity laser diodes using a novel γ-type optical configuration consist of a phase modulator and a Faraday rotator mirror

We propose a novel method to stabilize two external cavity lasers for optical generation of microwave and millimeter wave signals. In our method, two 1550-nm, servo-locked external cavity laser diodes (ECLDs) are simultaneously locked to two resonance frequencies of a single Fabry-Perot optical cavity. The stabilization of two lasers are realized by introducing classical FM sideband technique. In .-type optical configuration, two wavelengths from the ECLDs with orthogonal polarization are simultaneously phase modulated by a phase modulator with a Faraday rotator mirror. The .-type optical configuration is designed as a compact, stable and double-pass phase modulation apparatus with same modulation index for two orthogonally polarized signals transmitted through a polarization maintaining fiber. We obtain short-term stability of 200 kHz at an averaging of 10ms, which is measured with the square root of the Allan variance from the beat note between frequency stabilized lasers.

RF-wave generation using external cavity laser diodes frequency-stabilized to single optical cavity by using orthogonal polarized modes

We propose a novel stabilization technique for two 1550-nm band external cavity laser diodes (ECLDs) used in optical generation of microwave and millimeter wave signals. Using FM sideband technique, those two ECLDs are simultaneously locked to two resonant modes of a single Fabry-Perot cavity. In the scheme, a new Υ-type optical configuration is used for simultaneous phase modulation of orthogonally polarized two wavelengths transmitted through slow and fast axis of polarization maintaining fiber. The Υ-type optical configuration, which consists of a phase modulator and a Faraday rotator mirror combined with an optical circulator, is a simple and compact apparatus to achieve double-pass phase modulation with the same modulation index . In this paper, we show the results of frequency stabilization of two ECLDs using Υ-type configuration, and compare with the results obtained in conventional non-Υ-type configuration. Short-term stability of 200 kHz at an averaging of 10 ms is achieved in the simple Υ-type configuration.

Tunable Optical Clock Pulse Generation from a Phase Modulated CW light Using an SBS-Assisted Optical Filter

We propose tunable optical clock pulse generation from PM light using SBS-assisted optical filtering. With this method, tunable 20-GHz pulses are successfully generated from 10-GHz PM signal by filtering the first-sidebands in PM light.

Polarization Independent Three-Element Solc-Type Birefringent Optical Fiber Loop Filters

Polarization-independent birefringent optical fiber loop filters with narrowband transmission characteristics are studied. Using Jones matrix analysis, a three-element fiber loop filter structure, performing as a Solc-type narrow band filter is designed and fabricated. By selecting proper splice angles between these three elements as well as their birefringence, a narrowband, polarization-independent periodic optical filter with 0.63-nm transmission bandwith and 2.71-nm transmission period is realized

Theoretical Study of Assist Light Effect on XGM and XPM-Based Wavelength-Conversion Using SOAs

For wavelength conversion based on cross-gain modulation (XGM) and cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), a CW assist light is quite effective for acceleration of carrier recovery and reduction of pattern effects. We theoretically study assist light conditions both for XGM- and XPM-based wavelength conversion by numerically simulating eye-diagrams. Taking into account the spatial and temporal variations of carrier density along the SOA length, we successfully clarify the dependences of wavelength, power, and propagation direction of the assist light, and reveal the principal difference of response characteristics between XGM and XPM depending on carrier modulation.

Dynamics in SOA-based wavelength converter using assist light injection

Dynamics in semiconductor optical amplifier (SOA)-based wavelength converter using assist light injection is theoretically studied taking into account the spatial carrier distribution along the SOA length. It is revealed that frequency responses is further improved by counter-propagating assist light for cross-gain modulation, whereas by co-propagating assist light for cross-phase modulation. Full-text article is not available.