Semiconductor Laser Module Front Facet Emission
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Solution Overview
Problem
Integrated semiconductor laser modules with MMI optical couplers suffer from high optical loss and reduced output power due to rear facet emission from λ/4 phase-shifted DFB semiconductor lasers, leading to inefficiency and increased power consumption.
Innovation Solution
A semiconductor laser module with distributed reflector (DR) semiconductor laser devices emitting laser light from the front facet, combined with a light selecting unit using a Mach-Zehnder interferometer (MZI) device for selective output, which reduces optical loss and increases output power by directing all emission towards the output facet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a λ/4 phase-shifted DFB semiconductor laser device is used, then the laser device can be integrated on a single substrate, but about half of the optical output is emitted from the rear facet, resulting in degradation of efficiency and increase of power consumption
Solution Approach 1:
The patent inverts the conventional DFB laser design by using a distributed reflector (DR) structure where the reflector is positioned at the front facet rather than the rear facet. This inversion causes the laser to emit light predominantly from the front facet (output side) rather than the rear facet, thereby eliminating the 50% light loss problem while maintaining integrability on a single substrate
2Adaptability or versatility
If an MMI optical coupler is used with n channels, then multiple wavelengths can be handled, but the optical output is decreased to 1/n of its original output power at the MMI optical coupler
Solution Approach 1:
The patent extracts the light selecting function from the MMI coupler system and implements it through individual DR laser devices that inherently provide wavelength selection through their distributed reflector structure. Each DR laser device acts as an independent wavelength source, eliminating the need for MMI coupler-based wavelength multiplexing and its associated 1/n power loss
3Adaptability or versatility
If the number of channels of the MMI optical coupler is increased, then more wavelengths can be transmitted, but the optical loss at the MMI optical coupler is considerably high
Solution Approach 1:
The patent segments the wavelength transmission function into individual DR laser device channels, where each device operates independently at a specific wavelength. This segmentation eliminates the need for a single MMI coupler handling multiple wavelengths, as each DR laser device provides its own wavelength-specific output, thereby eliminating the cumulative optical losses associated with multi-channel MMI couplers
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 solution achieves a significant improvement in optical output efficiency, increasing power output by up to 110% and reducing spectral linewidth to a fifth of that of DFB semiconductor laser devices, while maintaining high efficiency and reducing intensity noise.
Implementation Method 1
Each of the DR semiconductor laser devices is configured to emit a laser light of a different wavelength from an output facet
Implementation Method 2
distributed reflector (DR) semiconductor laser devices
Implementation Method 3
a light selecting unit including a light selecting device substrate and a light selecting device formed on the light selecting device substrate. The light selecting device is configured to selectively output a laser light
Data Source
AI summary
A semiconductor laser module includes a semiconductor laser unit and a light selecting unit. The semiconductor laser unit includes a semiconductor laser substrate and a plurality of distributed reflector semiconductor laser devices formed on the semiconductor laser substrate in an array. Each of the distributed reflector semiconductor laser devices is configured to emit a laser light of a different wavelength from an output facet. The light selecting unit includes a light selecting device substrate and a light selecting device formed on the light selecting device substrate. The light selecting device is configured to selectively output a laser light emitted from a distributed reflector semiconductor laser device. The semiconductor laser unit and the light selecting unit are attached to each other in such a manner that the light selecting device is optically coupled to the distributed reflector semiconductor laser devices.