Tunable DBR Laser With Branched Waveguide For Wide Wavelength Range

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Solution Overview

Problem

Existing DBR lasers require large chip sizes and complex control systems for wide tuning ranges, leading to increased costs and reduced manufacturing yield, and their tuning range is limited by mode competition and optical side modes.

Innovation Solution

A tunable semiconductor laser with a branched optical waveguide, featuring a stem waveguide section optically coupled to multiple branch waveguide sections with tunable DBRs, allowing for different wavelength ranges and lasing cavities, enabling broader tuning through Vernier or digital supermode tuning methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If monolithically integrated arrays of independent DBR lasers are used to achieve wide tuning range, then wavelength coverage is improved, but chip size and device complexity increase

Engineering Contradiction:

Improvewavelength tuning rangeVSAvoidchip size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple DBR laser structures into a single integrated device by sharing common components (waveguide, gain section, phase control section) among multiple tunable DBR reflectors. This allows wide wavelength coverage through multiple DBRs while reducing chip size compared to independent laser arrays.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal laser structure where a single gain section and phase control section can support multiple tunable DBR reflectors with different wavelength ranges. This multi-functional design enables wide tuning range without proportionally increasing chip size.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If monolithically integrated arrays of independent DBR lasers are used to achieve wide tuning range, then wavelength coverage is improved, but manufacturing yield decreases

Engineering Contradiction:

Improvewavelength tuning rangeVSAvoidmanufacturing yield

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

By merging multiple laser functions into a single integrated structure with shared components, the patent reduces the total number of discrete devices that must be manufactured and assembled. This improves manufacturing yield while maintaining wide tuning capability through the integrated multi-DBR design.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If monolithically integrated arrays of independent DBR lasers are used to achieve wide tuning range, then wavelength coverage is improved, but control system complexity and cost increase

Engineering Contradiction:

Improvewavelength tuning rangeVSAvoidcontrol system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the control functions for multiple wavelengths into a single integrated device. A single current source can modulate the refractive index across the entire waveguide structure, simultaneously controlling multiple DBR reflectors. This reduces control system complexity compared to independent control of separate laser devices.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If DBR lasers are designed for broad tuning range, then wavelength coverage is improved, but mode competition and optical side modes increase

Engineering Contradiction:

Improvewavelength tuning rangeVSAvoidlasing mode stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses dynamic control of the refractive index through current modulation to actively select which DBR reflector provides feedback at any given moment. This dynamic switching mechanism enables broad tuning range while maintaining stable single-mode operation by ensuring only one dominant lasing mode exists at a time.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design achieves a broader wavelength tuning range while reducing chip size and complexity, enhancing manufacturing yield and reducing costs by allowing multiple lasing cavities and improved reflectivity, thus overcoming limitations of prior art.

Implementation Method 1

The DBRs comprise diffraction gratings, each grating being formed by a corrugated surface between layers of semiconductor material with different refractive indices

Methodology Applied

Scientific EffectBragg diffraction: Bragg Diffraction

Implementation Method 2

an optical waveguide 106, 108 with a front DBR 110, 112 and rear DBR 114, 116

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS8295315B2Tunable laser

Publication Date: 2012.10.23 LUMENTUM TECHNOLOGY UK LTD

AI summary

The present invention concerns tunable distributed Bragg reflector (DBR) semiconductor lasers, in particular a DBR laser with a branched optical waveguide 5 within which a plurality of differently shaped lasing cavities may be formed, and a method of operation of such a laser. The laser may comprise a phase control section (418), gain section (420, 422), a sampled grating DBR (412) giving a comb-line spectrum and two tunable, chirped DBRs (414, 416) for broadband frequency training and a coupling section (410).