Tunable multi-wavelength fiber lasers based on an Opto-VLSI processor and optical amplifiers

A multi-wavelength tunable fiber laser based on the use of an Opto-VLSI processor in conjunction with different optical amplifiers is proposed and experimentally demonstrated. The Opto-VLSI processor can simultaneously select any part of the gain spectrum from each optical amplifier into its associated fiber ring, leading to a multiport tunable fiber laser source. We experimentally demonstrate a 3-port tunable fiber laser source, where each output wavelength of each port can independently be tuned within the C-band with a wavelength step of about 0.05nm. Experimental results demonstrate a laser linewidth as narrow as 0.05 nm and an optical side-mode-suppression-ratio (SMSR) of about 35 dB. The demonstrated three fiber lasers have excellent stability at room temperature and output power uniformity less than 0.5 dB over the whole C-band

Opto-VLSI-based tunable single-mode fiber laser

A new tunable fiber ring laser structure employing an Opto-VLSI processor and an erbium-doped fiber amplifier (EDFA) is reported. The Opto-VLSI processor is able to dynamically select and couple a waveband from the gain spectrum of the EDFA into a fiber ring, leading to a narrow-linewidth high-quality tunable laser output. Experimental results demonstrate a tunable fiber laser of linewidth 0.05 nm and centre wavelength tuned over the C-band with a 0.05nm step. The measured side mode suppression ratio (SMSR) is greater than 35 dB and the laser output power uniformity is better than 0.25 dB. The laser output is very stable at room temperature

Linear-cavity tunable fibre lasers employing an Opto-VLSI processor and a MEMS-based device

This thesis proposes and demonstrates experimentally two novel linear-cavity tunable fibre lasers employing an erbium-doped fibre (EDF) in conjunction with an Opto- VLSI processor and a MEMS-based device for wavelength selection. The Opto-VLSI processor and the MEMS-based device along with an optical collimator, a Bragg grating plate and an optical lens, enable the realisation of an optical filter for continuous tuning of wavelengths over the amplified spontaneous emission (ASE) range of the EDF. We also propose the use of a section of un-pumped EDF as a saturable absorber (SA), which suppresses noise spikes caused by the high optical pumping power. Experimental results show that by optimising a length of the SA a single wavelength, high power laser signal can be achieved. In addition, we experimentally demonstrate that the performance of the proposed linear-cavity tunable fibre lasers is better than that of ring-cavity tunable laser counterparts. Specifically, we show that linear-cavity based tunable fibre lasers can achieve higher output power, a larger side mode rejection ratio (SMRR) and narrower laser linewidth than ring-cavity tunable fibre lasers

Opto-VLSI-based adaptive optical power splitter/combiner for next generation dynamic optical telecommunication networks

The demand for optical power splitters is growing globally, due to the rapid deployment of fibre-to-the-premises, optical metropolitan area network (MAN), and active optical cables for TV/Video signal transport. Optical splitters play an important role in passive optical network (PON) technology by enabling several hundred users to share one optical line terminal. However, current PONs, which use fixed optical power splitters, have limited reconfigurability particularly in adding/dropping users to/from an optical network unit. An adaptive optical power splitter (OPS) can dynamically reallocate the opticalpower in the entire network according to the real-time distribution of users and services, thus providing numerous advantages such as improve an optical network efficiency, scalability, and reliability. An adaptive OPS is also important for realizing self-healing ring-to-ring optical MAN, thus offering automatic communication recovery when line break occurs. In addition, future optical line protection systems will require adaptive optical splitters to switch optical signals from faulty lines to active power lines, avoid the use of optical attenuators and/or amplifiers, and achieve real time line monitoring. An adaptive OPS can also be incorporated in tunable optical dispersion compensators, optical attenuator and optical gain equalizer, and reconfigurable optical switches. This thesis proposes and demonstrates the principle of a novel Opto-VLSI-based adaptive optical splitter/combiner for next generation dynamic optical telecommunication networks. The proposed splitter structure enables an input optical power to be split adaptively into a larger number of output fibre ports, through optimized phase holograms driving the Opto-VLSI processor. The new adaptive optical splitter has additional advantages including lossless operation, adequate inter-port crosstalk, compressed hardware and simple user interface. This thesis demonstrates, in particular, the concept of an adaptive optical power splitter employing an Opto-VLSI processor and a 4-f imaging system experimentally in three stages as follow: (i) a 1×2 adaptive optical power splitter based on an Opto-VLSI processor, a fibre collimator array and 4-f imaging systems (single lens), (ii) a 1×4 adaptive optical power splitter based on an Opto-VLSI processor, a fibre array and 4-f imaging systems (single lens), and (iii) a 1×N lossless adaptive optical power splitter structure integrating an Opto-VLSI processor, optical amplifiers, a fibre array, and an array of 4-f imaging systems (lens array). The thesis also demonstrates the concept of an adaptive optical signal combiner which enables multiple signals to be combined with user-defined weight profiles into a single fibre port. Experimental results demonstrate that an input optical signal can arbitrarily be split into N signals and coupled into optical fibre ports by uploading optimized multicasting phase holograms onto the Opto-VLSI processor. They also demonstrate that N input optical signals can be dynamically combined with arbitrary weights into a single optical fibre port. Excellent agreement between theoretical and experimental results is demonstrated. The total insertion loss of the optical power splitter is only 5 dB. Results also show that the optical amplifiers can compensate for the insertion and splitting losses, thus enabling lossless splitter operation. A crosstalk level around -25 dB and a wavelength spectral range exceeding 40 nm is experimentally realized. In addition, a novel broadband adaptive RF power splitter/combiner based on Opto-VLSI processor is proposed and experimentally demonstrated. By uploading optimized multicasting phase holograms onto the software-driven Opto-VLSI processor, the input RF signal is dynamically split and directed to different output ports, with userdefined splitting ratios. Also, multiple input RF signals can be dynamically combined with arbitrary user-defined weights. As a proof-of-concept demonstration, two input RF signals are dynamically combined with different user-defined weight profiles. We also propose and demonstrate a photonic microwave filter based on the use of an Opto-VLSI-based adaptive optical combiner. The experimental results demonstrate that the developed Opto-VLSI-based adaptive optical combiner can dynamically route multiple input optical signals to a single output, with user-defined weight profiles, thus realising a tunable microwave filter. Overall this Opto-VLSI-based adaptive optical power splitter should allow as many as 32 output ports to be supported while achieving high splitting resolution and dynamic range. This will greatly enhance the efficiency of optical communication networks

A Tunable Multiwavelength Laser Employing a Semiconductor Optical Amplifier and an Opto-VLSI Processor

We propose and experimentally demonstrate a stable tunable multiwavelength laser employing a semiconductor optical amplifier (SOA) in conjunction with an opto-very-large-scale-integration (VLSI) processor. By uploading digital phase holograms onto the opto-VLSI processor, the amplified spontaneous emission of the SOA is arbitrarily sliced and injected back into the SOA to generate multiple lasing wavelengths with a linewidth of 0.5 nm. Experimental results demonstrate a tunable multiwavelength laser with a tuning range from 1528 to 1533 nm with power fluctuations of less than 0.5 dB

Dynamic optical comb filter using opto-VLSI processing

Reconfigurable multi-channel optical filters are presented in this paper. The operation principle of the reconfigurable filter is based on the dynamic beam steering capacity of Opto-VLSI processor in conjunction with a high dispersion free space grating. The dispersion grating separates the input signal spectrum while the Opto-VLSI processor is driven by optimised phase holograms to dynamically select the wavelengths to be coupled into the output port. Experimental results show that up to 8 bands can be synthesised, with a wavelength tuning span of 10 nm and a 3dB bandwidth less than 0.5nm

A 1x4 Adaptive Optical Splitter Based on Opto-VLSI Processor

We propose and experimentally demonstrate a novel high resolution 1×4 adaptive optical power splitter based on the use of an Opto-VLSI processor and a 4-f imaging system with an optimized optical beam waist profile. By uploading optimized multicasting phase holograms onto the software-driven Opto-VLSI processor, an input optical signal is dynamically split into different output fiber ports with user-defined splitting ratios. Experimental results showing dynamic optical splitting over a wavelength range exceeding 50 nm are presented

Advances in Optical Amplifiers

Optical amplifiers play a central role in all categories of fibre communications systems and networks. By compensating for the losses exerted by the transmission medium and the components through which the signals pass, they reduce the need for expensive and slow optical-electrical-optical conversion. The photonic gain media, which are normally based on glass- or semiconductor-based waveguides, can amplify many high speed wavelength division multiplexed channels simultaneously. Recent research has also concentrated on wavelength conversion, switching, demultiplexing in the time domain and other enhanced functions. Advances in Optical Amplifiers presents up to date results on amplifier performance, along with explanations of their relevance, from leading researchers in the field. Its chapters cover amplifiers based on rare earth doped fibres and waveguides, stimulated Raman scattering, nonlinear parametric processes and semiconductor media. Wavelength conversion and other enhanced signal processing functions are also considered in depth. This book is targeted at research, development and design engineers from teams in manufacturing industry, academia and telecommunications service operators