Lens-free in-line optical isolators

Abstract

We constructed a lens-free in-line optical isolator by embedding an isolator chip in a thermally expanded core (TEC) fiber without complicated optical alignment. The chip consists of two pairs of rutile wedges and garnet plates. We fabricated the TEC fibers by heating a single-mode fiber with a 200-mum outer diameter; low loss and a spot diameter as large as 49 mum were successfully obtained. The fabricated isolator has excellent optical properties, an insertion loss of 0.45 dB, and an isolation of more than 50 dB at a 1.55-mum wavelength, which confirms the usefulness of the integration techniques.

All-fiber optical isolator based on Faraday rotation in highly terbium-doped fiber

“…Optical isolators are important components in optical communication networks and laser systems. Traditional optical isolators are based on bulk optics, which require free-space optical coupling for use with fiber-optic systems [1,2]. All-fiber optical isolators are highly desirable, particularly for high-power fiberlaser systems, where fiber termination and small free-space beams place restrictions on how much power can be transported through such components.…”

Polarization proximity effect in isolator crystal pairs

“…Such a study, however, is important in view of recent potential applications involving the integration of several optoelectronic devices on the same chip [2][3][4][5][6]10]. In such devices the overall response of a set of magneto-optical components, including magnetostatic proximity effects [11], plays a significant role and can lead to unexpected and surprising behaviors.…”

“…This substantial reduction of the saturation field is potentially useful for the realization of integrated magneto-optical devices [2][3][4][5][6]10], since a lower saturating field would essentially mean lower power consumption.…”

Magnetic Proximity Effect in Isolator Crystal Pairs

“…They induce nonreciprocal polarization phase shifts originating from the so-called magneto-optical (MO) Faraday rotation [1]. The unidirectional nonreciprocal polarization control is crucial for the reduction of reflection-related instabilities in active electro-optical devices [1][2][3][4][5][6]. A fully functional isolator consists of a magnetically active isolator crystal situated between two crossed polarizers, and a rotation equal to ±45 • of an input linear polarization is required at the wavelength of operation, in the presence of an external magnetic field ±H ext .…”