Variable Optical Attenuator for Laser Wavelength Tracking

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Solution Overview

Problem

Optical devices in data center and chip-to-chip communication applications require high power due to thermal sensitivity of ring modulators, leading to increased power consumption.

Innovation Solution

Incorporating an uncooled laser, ring resonator modulator, and a variable optical attenuator, with a controller that uses power monitors to adjust heater power and laser current to maintain target output power and track wavelength, reducing overall power usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high heater power is used to control ring modulator wavelength tracking, then wavelength tracking capability is improved, but power consumption increases

Engineering Contradiction:

Improvewavelength tracking capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

A variable optical attenuator is introduced as an intermediary component between the laser and ring modulator. The attenuator dynamically adjusts optical signal intensity, enabling the system to maintain wavelength tracking with reduced heater power by compensating for signal variations through optical attenuation rather than requiring high heater power throughout

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes the attenuation parameter of the variable optical attenuator based on operating conditions. By adjusting the attenuation level, the system can maintain effective wavelength tracking across different temperature and power conditions without requiring maximum heater power continuously

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If high heater power is applied to cover all thermal conditions, then thermal sensitivity compensation is improved, but overall device power requirement increases

Engineering Contradiction:

Improvethermal condition coverageVSAvoiddevice power requirement

Core Design Contradiction:

Adaptability or versatilityVSPower

Solution Approach 1:

The variable optical attenuator provides dynamic adjustment capability, allowing the system to adapt to different thermal conditions in real-time. Instead of applying constant high heater power to cover all possible thermal scenarios, the system dynamically adjusts attenuation to match actual operating conditions, reducing overall power requirements while maintaining adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system applies partial heater power combined with variable optical attenuation to achieve the same effect as excessive heater power alone. By using the attenuator to compensate for reduced heater power, the system covers the full range of thermal conditions with less than maximum heater power, reducing overall device power requirement

Inventive Principle:

Principle #16Partial or excessive action

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 lowers overall operating power by dynamically adjusting heater power and laser current, effectively managing thermal changes and maintaining output power within specified ranges.

Implementation Method 1

the ring heaters are controlled to control a modulation wavelength of the ring modulators to cause the ring modulators to track (e.g. modulate) a laser wavelength over temperature

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a variable optical attenuator which is used, in combination with controlling laser current of the laser, to control an output power of the device

Methodology Applied

Scientific EffectOptical absorption: Absorption (EM radiation)

Data Source

PatentUS11646540B2Variable optical attenuator assisted control of optical devices

Publication Date: 2023.05.09 RANOVUS

AI summary

Variable optical attenuator assisted control of optical devices is provided. A device comprises: an uncooled laser and ring resonator modulator, an optical waveguide configured convey an optical signal of the laser from an input to an output, a heater that heats the ring resonator modulator, a variable optical attenuator that attenuates the optical signal on the optical waveguide, one or more power monitors and a controller. The controller is configured to: in response to determining that one or more of: heater power overhead is unavailable to reduce heater power for laser wavelength tracking; and the heater power is at or below a given lower heater power; and determining that that laser current is increased to assist with ring resonator modulator control for the laser wavelength tracking: control, using the one or more power monitors, attenuation of the VOA to control the output power into a target output power range.