Optical Pulse Interleaving for Closely Spaced Burst Shaping
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Solution Overview
Problem
Existing optical pulse burst formation methods are limited by the minimum separation between pulses due to modulator rise time and oscillator repetition rate, restricting higher pulse repetition rates and envelope shaping capabilities.
Innovation Solution
An optical pulse burst formation apparatus using interleaving stages with optical splitters and combiners, along with variable delay and attenuator systems, allows for precise control of pulse spacing and amplitude, enabling closely spaced bursts and adjustable envelope shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical modulators (AOM/EOM) are used to form pulse bursts by pulse picking, then pulse burst formation is achieved, but the minimum separation between pulses is limited by modulator rise and fall time
Solution Approach 1:
The pulse train is divided into multiple sequences using an optical splitter, with each sequence processed through separate optical arms with different delay lines. This segmentation allows independent control of pulse timing in each arm, enabling precise adjustment of pulse separation beyond modulator rise time limitations.
Solution Approach 2:
Delay lines are introduced as intermediary elements between the optical splitter and combiner to precisely control the temporal separation between pulses from different sequences. These delay lines act as mediators that adjust pulse timing without being constrained by modulator rise time.
2Productivity
If interleaving stages are used to achieve higher pulse repetition rates, then pulse repetition rate increases, but the number of required stages increases complexity
Solution Approach 1:
Multiple optical sequences with different delays are merged in the optical combiner to produce the final pulse train. This merging approach achieves high pulse repetition rates by combining lower-rate sequences rather than requiring multiple sequential interleaving stages, thereby reducing system complexity.
3Adaptability or versatility
If whole pulses are selected using conventional modulators, then pulse picking is achieved, but envelope shaping capability is limited by modulator response time
Solution Approach 1:
The system enables dynamic control of pulse parameters by independently adjusting the delay and amplitude of each pulse sequence through variable delay lines and optical attenuators. This dynamic control allows flexible envelope shaping without being constrained by fixed modulator response times.
Solution Approach 2:
The system changes multiple parameters (delay, amplitude, phase) of individual pulse sequences independently to achieve desired envelope shapes. By adjusting delay line lengths and attenuator settings, any envelope configuration can be created without being limited by modulator response time.
4Speed
If modelocked oscillators operate at limited repetition rates (50-100 MHz), then oscillator stability is maintained, but higher pulse repetition rates cannot be achieved
Solution Approach 1:
The oscillator output is segmented into multiple sequences that are processed independently through different optical arms. This allows the use of a stable, lower-repetition-rate oscillator while achieving higher effective pulse repetition rates through the interleaved combination of multiple sequences with different delays.
Data Source
AI summary
An optical pulse generator arranged to generate an initial sequence of optical pulses having an initial inter-pulse period; and an optical pulse burst formation apparatus including: an interleaving stage to receive an initial sequence of optical pulses having an initial inter-pulse period, including: an optical splitter to power split received optical pulses, thereby generating a first and second replica sequences of optical pulses; a first optical arm to receive the first replica sequence, having a first optical path length; and a second optical arm to receive the second replica sequence, having a second optical path length, different to the first optical path length by a path length difference; and an optical combiner arranged to combine the first replica sequence of pulses and the second replica sequence of delayed pulses to form an output sequence of optical pulse bursts.