A Semiconductor Optical Amplifier is essentially a laser diode (LD) with no feedback from its input and output ports and hence is also referred to as a Traveling-Wave Amplifier (TWA). Semiconductor optical amplifiers have proven to be versatile and multifunctional devices that are key building blocks for optical networks.
There are five parameters used to characterize a Semiconductor Optical Amplifier: (1) Gain (Gs); (2) Gain Bandwidth; (3) Saturation Output Power (PSAT); (4) Noise Figure (NF); (5) Polarization Dependent Gain (PDG).
With its wide bandwidth and high saturated power, the semiconductor optical amplifier plays a crucial role in various bands, networks, and applications.
Peak Wavelength(nm) To:From: |
Category |
Typical Gain(dB) From: To |
Typcial Psat(dBm) ToFrom: |
Typical Spectral Width(nm) To:From: |
Max. Noise Figure To(dB) From: |
Typical Current(mA) To: |
Polarization Dependent or Independent |
Package |
Part Number |
|---|---|---|---|---|---|---|---|---|---|
| Peak Wavelength(nm) | Category | Typical Gain(dB) | Typcial Psat(dBm) | Typical Spectral Width(nm) | Max. Noise Figure(dB) | Typical Current(mA) | Polarization Dependent or Independent |
Package | Part Number |
| 880 | In-Line | 20 | 10 | 40 | 8 | 150 | Dependent | Butterfly | IPSAD0801 |
| 1015 | In-Line | 20 | 11 | 80 | 8 | 250 | Dependent | Butterfly | IPSAD1002 |
| 1040 | In-Line | 25 | 10 | 55 | 8 | 250 | Dependent | Butterfly | IPSAD1003 |
| 1050 | In-Line | 25 | 10 | 45 | 10 | 300 | Dependent | Butterfly | IPSAD1001 |
| 1285 | In-Line | 30 | 17 | 60 | 7.5 | 700 | Dependent | Butterfly | IPSAD1201 |
| 1300 | In-Line | 30 | 15 | 60 | 7 | 700 | Dependent | Butterfly | IPSAD1305 |
| 1300 | In-Line | 19 | 7 | 80 | 7.5 | 300 | Dependent | Butterfly | IPSAD1306 |
| 1310 | Booster | 10 | 11 | 40 | 7.5 | 300 | Independent | Butterfly | IPSAD1307 |
| 1310 | Booster | 22 | 10 | 45 | 7.5 | 250 | Independent | Butterfly | IPSAD1301 |
| 1310 | In-Line | 19 | 7 | 50 | 7.5 | 250 | Independent | Butterfly | IPSAD1303 |
| 1310 | In-Line | 29 | 9 | 40 | 7.5 | 200 | Independent | Butterfly | IPSAD1308 |
| 1310 | Pre-amplifier | 16 | 10 | 55 | 7 | 250 | Independent | Butterfly | IPSAD1304 |
| 1310 | Pre-amplifier | 15 | 7 | 45 | 7.5 | 250 | Independent | 8-Pin | IPSAD1309 |
| 1310 | Switch | 18 | 6 | 40 | 9 | 100 | Dependent | Butterfly | IPRAD1301 |
| 1310 | Switch | 10 | 4 | 50 | 7.5 | 100 | Independent | Butterfly | IPSAD1302 |
| 1490 | Pre-amplifier | 16 | 11 | 55 | 8 | 300 | Independent | Butterfly | IPSAD1402 |
| 1490 | Pre-amplifier | 26 | 9 | 40 | 8 | 400 | Independent | Butterfly | IPSAD1401 |
| 1525 | In-Line | 19 | 7 | 50 | 8 | 300 | Dependent | Butterfly | IPSAD1506 |
| 1550 | Booster | 13 | 14 | 55 | 9 | 500 | Independent | Butterfly | IPSAD1505 |
| 1550 | Booster | 20 | 10 | 45 | 9 | 350 | Independent | Butterfly | IPSAD1501 |
| 1550 | Booster | 15 | 10 | 55 | 9 | 350 | Independent | Butterfly | IPSAD1504 |
| 1550 | Booster | 14 | 16 | 60 | 9 | 700 | Dependent | Butterfly | IPSAD1507 |
| 1550 | Booster | 25 | 12 | 60 | 9 | 500 | Dependent | Butterfly | IPSAD1509 |
| 1550 | Booster | 10 | 12 | 40 | 9 | 300 | Independent | Butterfly | IPSAD1510 |
| 1550 | In-Line | 16 | 5 | 50 | 9 | 350 | Independent | Butterfly | IPSAD1503 |
| 1550 | In-Line | 28 | 8 | 45 | 9 | 350 | Dependent | Butterfly | IPSAD1508 |
| 1550 | Switch | 10 | 3 | 50 | 10 | 120 | Independent | Butterfly | IPSAD1502 |
| 1550 | Switch | 18 | 6 | 40 | 9 | 100 | Independent | Butterfly | IPRAD1501 |
| 1550 | Switch | 22 | 8 | 60 | 9.5 | 600 | Dependent | Butterfly | IPSAD1511 |
| 1550 | Switch | 13 | 12 | 60 | 9.5 | 400 | Independent | Butterfly | IPSAD1512 |
| 1550 | Switch | 22 | 13 | 60 | 9.5 | 600 | Independent | Butterfly | IPSAD1513 |
| 1550 | Switch | 25 | 13 | 40 | 9.5 | 600 | Dependent | Butterfly | IPSAD1514 |
| 1550 | Booster | 20 | 20 | 40 | 8.0 | 1000 | Dependent | Butterfly | IPSAD1515 |
| 1600 | Booster | 20 | 9 | 50 | 10.0 | 400 | Independent | Butterfly | IPSAD1601 |
| 1650 | Booster | 25 | 13 | 40 | 9.5 | 600 | Dependent | Butterfly | IPSAD1602 |
A Semiconductor Optical Amplifier should have the highest gain appropriate to a given application. A wide optical bandwidth is also desirable so that the Semiconductor Optical Amplifier can amplify a wide range of signal wavelengths. Gain saturation effects introduce undesirable distortion to the output so an ideal Semiconductor Optical Amplifier should have very high saturation output power to achieve good linearity and maximum dynamic range with minimum distortion. An ideal Semiconductor Optical Amplifier should also have a very low noise figure (the physical limit is 3dB) to minimize the amplified spontaneous emission (ASE) power at the output. Finally, an ideal Semiconductor Optical Amplifier should have very low polarization sensitivity to minimize the gain difference between the transverse-electric (TE) and transverse-magnetic (TM) polarization states. However, an ideal Semiconductor Optical Amplifier is impossible to realize because of the physical limitations of the various processes taking place within it.
InPhenix’s 1310nm Semiconductor Optical Amplifier is the ideal O-Band Optical Amplifier. Inphenix also offers Semiconductor Optical Amplifier for E-band, S-band, C-band, L-band, and U-band wavelengths.
O-Band Semiconductor Optical Amplifier
Benefits
- Saturated power > 10dB
- Small signal gain > 10dB over the entire O-band (1270 to 1340nm)
- Ripple < 1 dB
- Compact + Low Cost
Applications
- 100GBASE-LR4 Transceiver test and measurement
- Passive component testing
- Splitting/tap loss compensation
- Reach extension (increase link budget): booster amplifier and per-amplifier
A Semiconductor Optical Amplifier is an optoelectronic device that can amplify an input optical signal under appropriate operating conditions. A schematic diagram of a basic Semiconductor Optical Amplifier is presented in Fig.1 (below).
Fig.1- Semiconductor Optical Amplifier simplified diagram.
An electric current externally applied to the Semiconductor Optical Amplifier excites electrons in the active region of forward biased pn-junction. When photons travel through the active area they can cause these electrons to lose some of their extra energy and generate more photons that match the wavelength of the initial ones, so called stimulated photon emission. The embedded waveguide is used to confine the propagating signal wave to the active area. Therefore, an optical signal passing through the active region is amplified and is said to have experienced optical gain.
Inphenix’s Semiconductor Optical Amplifier come in different form factors starting as small as a 6-pin mini butterfly that can be mounted in a CFP/CFP2 transceiver to a desktop that can be integrated with drivers and custom ordered passive components.
InPhenix offers semiconductor optical amplifier solutions for diverse applications with impressive parameters like gain, bandwidth, and polarization sensitivity.
Inphenix Semiconductor Optical Amplifiers have been tested to meet Telcordia GR-468-CORE for extremely high reliability and comply with RoHS directives.
Semiconductor Optical Amplifier Amplification Characteristics
Inphenix’s semiconductor optical amplifiers have proven to be versatile and multifunctional devices that are key building blocks for optical networks. There are five main parameters used to characterize a Semiconductor Optical Amplifier:
- Small Signal Gain (Gs); up to 22 dB at -25dBm input power;
- Gain Bandwidth; up to 80 nm at 3 dB
- Saturation Output Power (Psat) up to 17 dBm;
- Noise Figure (NF) 7.0-8.0 dB;
- Polarization Dependent Gain (PDG) < 1 dB or up to 10 dB
A Semiconductor Optical Amplifier should have the highest gain appropriate to the application. A wide optical bandwidth is also desirable so that the Semiconductor Optical Amplifier can amplify a wide range of signal wavelengths. Gain saturation effects introduce undesirable distortion to the output so an ideal Semiconductor Optical Amplifier should have very high saturation output power to achieve good linearity and to maximize its dynamic range with minimum distortion. An ideal Semiconductor Optical Amplifier should also have a very low noise figure (the physical limit is 3dB) to minimize the amplified spontaneous emission (ASE) power at the output. Finally, an ideal Semiconductor Optical Amplifier should have very low polarization sensitivity to minimize the gain difference between the transverse-electric (TE) and transverse-magnetic (TM) polarization states. However, an ideal Semiconductor Optical Amplifier is impossible to realize because of the physical limitations of the various processes taking place within it.
Fig. 2- Semiconductor Optical Amplifier interrelated parameters.
Semiconductor Optical Amplifier parameters are strongly interrelated, and in order to achieve the best value of one parameter, other specification(s) may have to be compromised and/or the spectral operation area should be controlled, as it is schematically shown on Fig.2.
Types of Semiconductor Optical Amplifiers
Depending on the role a Semiconductor Optical Amplifier will play in the customer’s system, they can be classified into four categories: in-line, booster; switch and preamplifier;
- In-line: higher gain, moderate Psat; lower NF and lower PDG, usually polarization independent Semiconductor Optical Amplifier;
- Booster: higher Psat, lower gain, usually polarization dependent;
- Switch: higher Extinction Ratio and faster rise/fall time;
- Pre-amplifier: good for longer transmission distance, lower NF and higher gain.
In addition, PDG can determine polarity of a Semiconductor Optical Amplifier. For instance, if the PDG is less than 1.5dB, the Semiconductor Optical Amplifier is Polar Independent (P-I) and if the PDG is up to 10 dB, the Semiconductor Optical Amplifier is Polar Dependent (P-D).
Applications of Semiconductor Optical Amplifier
Traditional applications
Amplification is a basic principle application of Semiconductor Optical Amplifiers in optical communication systems. A Semiconductor Optical Amplifier is a highly versatile component that can be used for various amplifications and routing functions in telecommunications. Commercialized Semiconductor Optical Amplifier are now widely available in the market and are fast-becoming a cost-effective solution to optical amplification in advanced optical systems for core, metro, and ultimately access applications. Semiconductor Optical Amplifier can be employed in any optical communication network to regenerate signals at various points in the link by operating either as a booster amplifier (post-amplifier), in-line amplifier.
Telecoms
Semiconductor Optical Amplifiers are in use by a wide variety of industries. One of the most important industries is telecoms, where they are valued for routing and switching. In addition, Semiconductor Optical Amplifier is used to boost or amplify signal output for long-distance fiber-optic communications. In this application, telecom firms employ fiber-optic lines from headquarters to the data centers. These transmission lines can exceed 10km or more, requiring the use of Semiconductor Optical Amplifier to boost/amplify the signal from the usual light sources.
Fig. 3- Semiconductor Optical Amplifier in photonic carriers (top) can be used in Photonic Integrated Circuit (PIC) (bottom-left).
Functional applications
Semiconductor Optical Amplifier can also be used to perform functions that are, and will be, useful in future optically transparent networks. These all-optical functions can help to overcome the so called ‘electronic bottleneck’ which is presently a major limiting factor in the deployment of high-speed optical communication networks, like, for example, optical wavelength converter. Invariably, Semiconductor Optical Amplifier functional applications are based on Semiconductor Optical Amplifier nonlinearities. These nonlinearities are principally caused by carrier density changes induced by the amplifier input signals. The four main types of nonlinearity commonly exploited in Semiconductor Optical Amplifier are cross-gain modulation (XGM), cross-phase modulation (XPM), self-phase modulation (SPM) and four-wave mixing (FWM).
Sensing
Sensing is another important industry utilizing Semiconductor Optical Amplifiers in many applications. One important use of Semiconductor Optical Amplifiers in sensor systems is the Fiber-Bragg Interrogators. In this setup, either an SLD or DFB is used as the input light-source. A Semiconductor Optical Amplifier boosts the optical signal to a fiber-Bragg grating (FBG), often through a circulator to control direction of the optical signals. Changes in temperature or strain change the wavelength or timing of the optical signals to a PD/sensor. This can alert the user to possible malfunctions.
Fig. 4- Fiber-Bragg Grating with Semiconductor Optical Amplifier in-line amplifier
Another important use of Semiconductor Optical Amplifier in sensing is with Light Detection and Ranging (LiDAR). LiDAR devices can be small, for only Doppler-ranging or appear as an array capable for mapping.An example of LiDAR application uses Frequency Modulated Continuous Wave (FMCW) to detect the Doppler effect of movement, such as with autonomous cars and drones. In addition, FMCW can be used for cartography and inspection. Semiconductor Optical Amplifier used in narrowband, usually with DFBs, can have high output power >20mW, for longer range.
Fig. 5- LiDAR chip with integrated Semiconductor Optical Amplifier. An array of these chips gives a wide-area scan.
Fig.6- Frequency Modulated Continuous Wave (FMCW) LiDAR. Semiconductor Optical Amplifier in green.
CWDM
The previously highlighted features of small size, good integration capability and high potential for cost reduction through scaled manufacturing processes will continue to ensure that the Semiconductor Optical Amplifier plays an increasingly important role in future advanced optical networks. Coarse wavelength division multiplexing (CWDM) is an economic route for giving connection flexibility and increased throughput for metro and enterprise network layers. Extending the capacity and distance of CWDM systems (>100 km) requires a low cost optical amplifier operating across the entire optical bandwidth (from 1260 nm to 1620 nm). The Semiconductor Optical Amplifier is the only viable technology available today that can be deployed to meet these expanding applications.
WDM-PON
An expanded role for Semiconductor Optical Amplifier in telecoms is in their use in Wavelength Division Multiplexing-Passive Optical Networks (WDM-PON). Cable companies utilizing fiber-optic lines from the home office to the customer receiving the data, often have nodes, or distribution centers, to assist in switching and routing data. This setup allows the efficient distribution of data to a large customer base. Semiconductor Optical Amplifier are an early application of WDM-PON but may see growth in the future.
There are several other attractive applications of Semiconductor Optical Amplifier, such as intensity and phase modulation, Semiconductor Optical Amplifier logic for the use of optical signal processing, Semiconductor Optical Amplifier add/drop multiplexer for optical time division multiplexed network, Semiconductor Optical Amplifier pulse generator to generate pulse easily at high frequencies (> 10 GHz), Semiconductor Optical Amplifier clock recovery required in optical receivers and 3R generators, Semiconductor Optical Amplifier dispersion compensator to overcome the chromatic dispersion which limits the transmission distance, and Semiconductor Optical Amplifier detector to detect optical signal. Semiconductor Optical Amplifier can also be used for gating optical signals, i.e. signals can be either amplified or absorbed by Semiconductor Optical Amplifier. The blocking properties of Semiconductor Optical Amplifier at low bias currents are extremely useful because they enable channel routing functions, such as reconfigurable add/drop multiplexers (ROADM), to be produced with off channel isolation better than 50dB.
Advantages of Semiconductor Optical Amplifier
- The optical gain provided by Semiconductor Optical Amplifier within a bandwidth is relatively independent of the wavelength of the incident optical signal.
- The injection electric current serves as the pump signal for amplification instead of optical pumping.
- Due to their compact size, Semiconductor Optical Amplifier can be integrated with several waveguide photonic devices on a single planar substrate.
- They use the same technology as diode lasers.
- Semiconductor Optical Amplifier have the ability to operate at communication spectral bands of 1300 nm and 1550 nm with wider bandwidth (up to 100 nm).
- They can be configured and integrated to function as pre-amplifiers at the optical receiver end.
- Semiconductor Optical Amplifier can function as simple logic gates in WDM optical networks.
Limitations of Semiconductor Optical Amplifier
- Semiconductor Optical Amplifier can deliver output optical power up to a few tens of milliwatt (mW) only which is usually sufficient for single channel operation in a fiber–optic communication link. However, a WDM system may require up to a few mWs of power per channel.
- Since the coupling of the input optical fiber into and out of the Semiconductor Optical Amplifier integrated chip tends to induce signal loss, Semiconductor Optical Amplifier must provide additional optical gain in order to minimize the impact of this loss on the input/output facets of the active region.
- Semiconductor Optical Amplifier are highly sensitive to the polarization of the input optical signal.
- They generate higher noise levels in the active medium than optical fiber amplifiers.
- In case multiple optical channels are amplified as required in WDM applications, Semiconductor Optical Amplifier can produce severe crosstalk.
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