DWDM Channel Monitor and DWDM Optical Interrogator Based on the Athermal AWG Demultiplexer and PD Arrays

D‌ec. 03, 2021
POINTek, Inc., a global leader and provider of high-performance high-end athermal AWGs, announced launching of new integrated Athermal AWG Demultiplexer products specifically designed for DWDM channel monitors which could be best used in the Telecom motoring applications and Fiber Braggs Grating (FBG) optical interrogator for various industrial safety monitoring applications. These multiplexers are based on the novel PD arrays, each of which covers 8-channel, 12-channel, and 16-channel PD arrays, resulting in any combinations of PD arrays ranging from 8 to 96 wavelengths.

POINTek research endeavored to integrate Athermal AWG demultiplexer with two types of noble PD arrays as part of a key building block for fiber channel motoring and FBG interrogation: (1) Tap PD arrays which can provide 2% power to the PD arrays for channel monitoring and 98 % power to the designated optical receiver and (2) Terminal PD arrays which terminates as a ribbon fiber pigtail to the PDs for channel monitoring alone.

Athermal AWG Demultiplexer with Tap PD Arrays 

This Tap-PD Array integrated Demultiplexer product (see Figure 1) consists of an athermal AWG demultiplexer and the 
2:98 Tap PD arrays, which tap only 2% power to the PDs and 98% power to pass through.  Thus, the demultiplexed signals with 98% optical power can be delivered to the designated optical receiver while the demultiplexed signals with taped 2% optical power are delivered to the designated PD arrays for channel monitoring.  The Integrated 2:98 power split design allows that no discrete Demultiplexer is required for the channel monitor beyond the trunk line since athermal AWG takes on the role of demultiplexing both the main signals and the monitor signals.

Figure 1.  48CH Athermal AWG Demultiplexer and Channel Monitor with 2:98 Tap PD Arrays

2.   Athermal AWG Demultiplexer with Terminal PD Arrays

This Terminal-PD Array integrated Demultiplexer product (see Figure 2) consists of an athermal AWG demultiplexer and the
Terminal PD arrays. This product differs from the Tap-PD Array Demultiplexer product in the location of the Terminal PD arrays, positioning it after a 2:98 tap coupler in front of the AWG Demultiplxer on the trunk line; thereby this discrete device is used for DWDM channel monitoring only. 

Figure 2.  48CH Athermal AWG with Terminal PD Arrays for DWDM Channel Monitor and Optical Interrogator

This DWDM channel monitor could be used for optical DWDM interrogator in collaboration with FBG sensors. FBG offers the popular way of measuring temperature, and mechanical strain and stress. The fiber optical sensor technology has made significant advances in the measurement of physical parameters for the safety check of physical structures in large transportation industry such as aerospace and railways, and civil, public utilities, and other small industries, utilizing the benefits of optical measurements for early detection of cracks and faults to prevent from any disastrous industrial accidents happening.  Finding a solution for the low-cost FBG interrogator systems has become a challenge where a large number of FBGs are used at various multiple of hundreds and thousands measurement points.
"The Terminal-PD Array Demultiplexer product offers a cost-effective FBG interrogation, which is on the increasing demand for safety monitoring applications such as CBM (Condition-Based Maintenance), HUM (Health & Usage Monitoring), and SHM (Structural Health Management) as tens and hundreds of FBG-based interrogators are used on site, and commercial optical spectrum analyzers for such monitoring applications are too expensive," says Dr. T.H. Rhee, CEO of POINTek.  "We meet customer's unique operational environment optimally by increasing fiber channels via use of a pseudo-TDM capability on the DWDM.  For example, we can integrate a 1x 8 optical switch in a time domain for a 40-CH DWDM AWG to place 40 FBGs on each monitoring for a total of 8 fibers and 320 FBG sensors," Rhee adds.

"We have expanded DWDM channel monitoring options for POINTek's typical Telecom applications with these two types of PD arrays which require low operating voltage.  Also, we are opening new business opportunity in the use of our popular high performance 100GHz athermal AWG demultiplexer for optical interrogation in support of wide varieties of FBG sensor-based structural sensing applications " according to Dr. Donald Yu, CMO of POINTek, operating from Los Angeles, California.

POINTek's low-loss Athermal AWG Multiplexers/Demultiplexers offers an innovated solution for cost-effective DWDM channel monitoring as well as FBG interrogation with a sensible integration with novel PD arrays for FBG interrogation applications.

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