A Bragg cell receiver has the potential of being used as an EW receiver. It can cover a wide instantaneous bandwidth of possibly over 1 GHz, and the frequency resolution can be very fine. However, to process short pulses, the frequency resolution is governed by the minimum PW of the input signals rather than by the performance of the Bragg cell. At present, the sensitivity and dynamic range of the Bragg cell receiver is limited by the photodetectors. With present detector technology, the dynamic range is rather low for EW receiver applications. Theoretically, the dynamic range of the Bragg cell receiver can be improved with the interferometric approach. However, further development is required to demonstrate the feasibility. A Bragg cell receiver can be considered a channelized receiver where the channelization is accomplished through optical means. One Bragg cell is equivalent to several hundred filters connected in parallel. In a power Bragg cell receiver, RF amplifiers cannot be added after the frequency channelization to improve the sensitivity, but light amplification may be added in front of the photodetectors to accomplish this. In an interferometric Bragg cell receiver, RF amplifiers can be added after channelization to improve the sensitivity of the receiver. Therefore, the interferometric Bragg cell receiver is very much like the channelized receiver discussed in Chapter 7. A Bragg cell receiver has potential performance characteristics that are very desirable for EW applications. Although the feasibility of the receiver has been demonstrated, extensive research and development, especially in the digitizing circuits, is critically needed to realize its full capability. To take the advantage of the small size of the optical bench, the digitizing circuits must be made small in size using VLSI circuit technology.

Chapter Contents:

• 9.1. Introduction
• 9.2. Optical Fourier Transform
• 9.3. Bragg Diffraction
• 9.4. Bragg Cells
• 9.5. Weighting Effect in a Bragg Cell
• 9.6. General Characteristics of Photodetectors
• 9.7. Types of Photodetectors
• 9.8. Discrete Photodetectors and Fiber Optics
• 9.9. Photodetector Arrays
• 9.10. Laser Sources
• 9.11. Power Bragg Cell Receiver
• 9.12. Interferometric Bragg Cell Receiver
• 9.13. Dynamic Range Improvement by Interferometric Bragg Cell Scheme
• 9.14. Two-Dimensional Optical Processor
• 9.15. Other Parameters Measured by a Bragg Cell Receiver
• 9.16. Integrated Optical Bragg Cell Receivers
• 9.17. Components and Predicted Performance of IOC Bragg Cell Receivers
• 9.18. Summary
• References

Inspec keywords: radio receivers; electronic warfare; VLSI; photodetectors

Other keywords: digitizing circuits; optical processors; Bragg cell receivers; electronic warfare; frequency resolution; channelized receiver; VLSI circuit technology; several hundred filters; optical bench; frequency channelization; interferometric approach; photodetectors; EW receiver

Subjects: Photodetectors; Radio links and equipment; Semiconductor integrated circuits