VCSEL Pumped Fiber Optic Gain Systems

Abstract

Optical pump modules comprising VCSEL and VCSEL array devices provide high optical power for configuring fiber optic gain systems such as fiber laser and fiber amplifier particularly suited for high power operation. Pump modules may be constructed using two reflector or three reflector VCSEL devices optionally integrated with microlens arrays and other optical components, to couple high power pump beams to a fiber output port. The pump module having a fiber output port is particularly suited to couple light to an inner cladding of a double-clad fiber, often used to configure high power fiber laser and fiber amplifier. The pump modules may be operated in CW, QCW and pulse modes to configure fiber lasers and amplifiers using single end, dual end, and regenerative optical pumping modes. Multiple-pumps may be combined to increase pump power in a modular fashion without significant distortion to signal, particularly for short pulse operation.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of Invention[0002]The present invention relates to fiber optic gain systems and in particular to fiber optic lasers and amplifiers including Vertical Cavity Surface Emitting Laser (VCSEL) optical pumps.[0003]2. Background Art[0004]Fiber optic lasers and amplifiers (hereinafter referred as fiber lasers and fiber amplifiers, respectively) are well known in the art for their excellent conversion efficiency, beam quality, small volume, light weight, and low cost. Primarily, fiber lasers and fiber amplifiers have an optical gain medium, typically comprising an optical fiber doped with optically active ions in a core region surrounded by a cladding region. For example, the core may be doped with selective rare-earth ions which upon absorbing optical power from an intense light source such as a high power optical pump, are excited to a higher energy state and when the excited ions return to their ground state they provide optical gain or amplificat...

AI Technical Summary

Benefits of technology

[0016]One important aspect of the high output power module provided in this invention is a three reflector VCSEL device for better wavelength stability of the pump modules in high power fiber gain systems such as, a fiber laser and an amplifier. The optical module together with fiber components are configured to provide a fiber laser and an amplifier. Multi-stage fiber optic systems for example, fiber laser, single or multi-stage amplifiers and other combinations thereof may be configured in a modular fashion for extending the power output requirements for different applications.

[0019]In a variant configuration, the doped silica fiber gain medium is pumped from both ends by providing separate optical pump modules at the two ends of the gain medium. Additional optical components such as an acousto-optic switch may be provided in some applications. The fiber laser may be operated in continuous wave (CW) mode, quasi continuous wave (QCW) mode or pulse (P) mode. Furthermore, fiber laser may be operated for short pulses by operating the pump module using a current source operated in pulse mode. The pulse width of the laser may further be reduced by operating the laser cavity in Q-switching mode.

Problems solved by technology

However this is a very complex arrangement where multiple single mode Er doped fiber amplifiers using Raman pumps, are used as pump source.

However, one disadvantage of this configuration is that the V-groove is designed integral to the cladding layer and works well for a specific pump wavelength.

While pumps using edge emitter lasers are useful for pumping doped core of fiber lasers and amplifiers, edge emitter lasers have a relatively broad linewidth and all the light emitted by the pump laser does not contribute towards exciting the doping ions which absorb only in a narrow wavelength band.

Furthermore, edge emitter laser wavelength varies considerably with operating temperature resulting in misalignment in the pump wavelength and the absorption lines of the doping ions.

One major disadvantage of this approach is that for high optical power application, the wire bonding is prone to failure, thereby imposing a practical limitation on output power that can be obtained from such pumps.

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