Provided is a double clad fiber device. The double clad fiber device includes a double clad fiber, a pump combiner, at least one first laser diode, and at least one second laser diode. The double clad fiber includes a core and a clad. The pump combiner provides pump light to the core and the clad through one end of the double clad fiber, respectively. The at least one first laser diode provides first pump light to the clad through the pump combiner. The at least one second laser diode provides second pump light to the core through the pump combiner.

Double clad fiber laser device

The invention relates to a system comprising a waveguide laser for exciting laser light at a lasing wavelength λs and a pump for pumping the waveguide laser at a pumping wavelength λp. The invention further relates to a method of providing such a system and its use. The object of the present invention is to provide a system comprising a waveguide laser with a reduced phase noise. The problem is solved in that the pump is a single frequency laser. The invention may e.g. be used in systems where an ultra-low phase noise and/or linewidth is required, e.g. in LIDAR or interferometric systems.

A system comprising a low phase noise waveguide laser, a method of its manufacturing and its use

The present invention relates to an optical module which is capable of amplifying light to be amplified to high power and which has a structure for effectively reducing influences of damage to other optical parts, and heat generation. The optical module includes a fiber unit constituted by an optical coupler, an amplification optical fiber, and an absorption optical fiber. Each of the amplification optical fiber and the absorption optical fiber has a core, a first cladding, a second cladding, and a third cladding. Further, each of the fibers allows the light to be amplified to propagate in a single mode in each of the cores, and allows pumping light to propagate in a multimode in the core, the first cladding, and the second cladding. The core of the amplification optical fiber is doped with an amplification dopant for amplifying the light to be amplified. The second cladding of the absorption optical fiber is doped with an absorption dopant for absorbing the pumping light.

Optical module and processing method

An optical fiber amplifier apparatus and optical signal amplification method are provided. In one example, the amplifier apparatus comprises an optical combiner that is configured to receive an input optical signal to be amplified and a pump light beam. The optical combiner combines for output the input optical signal and the pump light beam. A first cladding pumped optical fiber in which Erbium is the only optically active dopant is coupled to the optical combiner to receive the pump light beam and the input optical signal. The first cladding pumped optical fiber pre-amplifies the input optical signal and passes the pre-amplified input optical signal and power of the pump light beam not absorbed by the first cladding pumped optical fiber. A second cladding pumped optical fiber is provided that is coupled to the first cladding pumped optical fiber. Erbium and Ytterbium are optically active dopants in the second cladding pumped optical fiber. The second cladding pumped optical fiber absorbs power of the pump light beam that was not absorbed by the first cladding pumped optical fiber to further amplify the pre-amplified input optical signal to produce an output amplified optical signal that is a desired amplified version of the input optical signal.

Erbium and erbium/ytterbium cladding pumped hybrid optical amplifier

In this paper, we will review the recent developments of high-power continuous-wave (CW) Er-Yb codoped fi-ber amplifiers (EYDFAs). Several related patents and a couple of methods of improving the performance of high-power EYDFAs are reviewed. Current research results show that the Yb-band amplified spontaneous emission (Yb-ASE) is the main reason that limits the efficiency and stability of an EYDFA at high pump power. Several methods and experimental results dedicated to suppress the Yb-ASE are introduced. Current and potential future developments of high-power EYD-FAs are summarized in the last part of this paper. Keywords: Erbium, fiber amplifiers, fiber lasers, MOPA, ytterbium 1. INTRODUCTION High-power fiber laser sources in the 1.5-μm band have made a great progress in recent years. Due to their many advantages, such as relatively "eye-safe" nature, low atmos-phere transmission loss, light weight, low loss in communi-cation fibers, and readily available reliable and cost-effective fiber communication components, they are of great potential for both military and civilian applications, such as laser in-frared radars (LIDARs), free-space communications, mate-rial processing and so on [1-3]. To flexibly control the linewidth, wavelength, and beam quality of a high-power fiber laser source, a master-oscillator power-amplifier (MOPA) configuration is commonly used. In this configuration, the master-oscillator generates a low-power high beam quality seed, and then the seed is amplified through several stages of power-amplifier until the desired output power is achieved. Apparently, the available power and performance of a MOPA system is largely determined by the performance of the power-amplifier(s). The details of the MOPA configuration will be introduced in the next sec-tion. In the 1.5-μm band high-power MOPAs, double-clad erbium-ytterbium codoped fibers (EYDFs) are usually used as the gain media of the power-amplifier. This fiber has an inner cladding surrounding the core and its refractive index is lower than the core but larger than the outer cladding [4]. The cross-sectional shape of the inner cladding is usually non-circular, which can enhance the mode mixing to pro-mote the pump absorption [5].

A Review of Recent Development of Efficient High-Power Continuous- Wave Er-Yb Codoped Fiber Amplifiers

An optical amplifier having a suitable length of Er/Yb co-doped double clad optical fiber is used to amplify an input optical signal. The inner clad of the double clad optical fiber supports the propagation of a multi mode signal used to excite Er/Yb co-dopants in the double clad optical fiber. Simultaneously, a single mode signal launched from a single mode laser pump co-propagates with the input optical signal in the core of the optical fiber. In this model, single mode light travels in the single mode core region and the multi mode pump light is mainly in the clad region. The interaction between the two laser pumps is negligible.

Vihong Chen

Papers

Simultaneous single mode and multi-mode propagation of signals in a double clad optical fiber