HP HP-Bench-Briefs-1993-04-12 free download

File name HP-Bench-Briefs-1993-04-12.pdf

HEWLETT PACKARD c SERVICE INFORMATION FROM HEWLETT-PACKARD 2nd, 3rd & 4th Quarters 1993 I R Richard OggIHmlett-Packard the noise floor: what causes it and the name comes from.) The signal is how OSA noise is different from con- then digitized and processed using - ventional microwave spectrum DSP techniques. analyzers. Now, on to the operating modes. Signal Processing These are provided by the transfer switch and the transimpedance I switch. There are a total of five modes First it is necessary to understand the with the first being an OSA. Each of basic block diagram shown in Figure 1. the other four descriptions follow. Optical tuning and resolution is ac- complished in the monochromator. fl Introduction The selected optical signal is coupled Preselector Mode back onto fiber and normally passes In the previous issue of Bench Briefs I through the transfer switch to the The preselector mode uses the mono- explained the difference between the photodetector diode. Here the optical chromator input and the monochro- optical spectrum analyzer and the power is converted to an electrical mator output. The monochromator is lightwave signal analyzer. I covered current. The transimpedance ampli- used as a tunable bandpass filter with modulation and some basic operation fier not only amplifies the signal ac- variable bandwidth. This allows of the OSA. In this issue I will describe cording to variable gain, but changes selection of a single mode from a several different types of measure- the signal from a current to a voltage. Fabry-Perot (FP) laser, or an indi- ment or operatingmodes, and des