J-20 is very close to final version

J-20 No.2015 is very close to final condition,
J-20 doesnt use Russian 99M2 as most foreign 'experts' and Russia media claimed
it uses improved third gen turbofan, domestic engine.
phase A wont have WS-15 but domestic improved third gen turbofan, Max 14.3 metric tons thrusts
phase B will be fit with WS-15
J-20 deployment version will have soft laser weapon, not to shoot down a plane or kill a ground target, but to 'kill' infrared guided missiles

Comparable some engine specifications between US/Russia/China :

Here is the different 3D thrust vectoring nozzles between the US/Russia/China.

US

Russia

China

The J-20 "soft kill" laser system will most likely be something like this:

These system tend to inhabit civilian airliners and VIP aircraft such as AF1, but they are also making an appearance on military aircraft, transports being the most common, but they are appearing on combat systems too.

AN/AAQ-24(V) DIRCM (Directional Infrared Countermeasure)

Making missiles toast for 50 years
Northrop Grumman is proud to have been at the forefront of warfighter protection since 1961. That's when our engineers developed the first active onboard IRCM system capable of defeating an air-to-air, heat-seeking missile. Today, our DIRCM laser-based systems protect over 750 aircraft, including large and small fixed-wing, rotary-wing, and tilt-wing platforms.

The AN/AAQ-24(V) Directional Infrared Countermeasure (DIRCM) system is the only DIRCM system in production today that will protect aircraft from today's infrared guided missiles.

Traditional IR countermeasures are not effective against the modern IR missiles that are growing in popularity among terrorist groups and in thirdworld countries. A Directional Infrared Countermeasures (DIRCM) system is required to defeat the latest and future advanced IR threats, and has a lower life cycle cost compared to other IR countermeasure approaches.

Simultaneously tracks and defeats threats in clutter environments
Fast, accurate threat detection and simultaneous jamming in all current IR threat Bands (I, II and IV)
Counters all fielded IR missile threats using a single generic jam waveform
Complete end-to-end self-testing features reduce life-cycle maintenance
Compatible with existing support facilities

Customized installation
The AAQ-24(V) is available in a laser-based configuration. Northrop Grumman then selects from a modular family of transmitters, jammers and missile warning systems to provide a customized installation best able to meet your specific platform, mission and budget requirements. Upgrades to existing systems are easy to install without further airframe modifications.

Other Northrop Grumman IRCM Systems
CIRCM: Common Infrared Countermeasure Systems

Designed specifically to protect rotary wing and medium fixed wing aircraft from IR missiles, our CIRCM offering uses a compact ECLIPSE pointer/tracker, a lightweight COTS processor and advanced Quantum Cascade Laser (QCL) technology for greater reliability and scalability. Learn more about Northrop Grumman CIRCM.

Guardian : Pod-based IRCM

The Guardian™ system provides 360° protection against a wide range of missile threats. The Guardian™ system includes a multiband laser pointer/ tracker and an ultraviolet missile warning sensor. The system is contained almost entirely in a single pod that mounts to the underside of the fuselage. Learn more about Guardian.

Common Infrared Countermeasures program - Wikipedia, the free encyclopedia

Military fighters generate nowhere near the necessary power, at least not without complicated and heavy machinery, to field an effective anti-drone laser. These types of "laser systems" are most commonly IR countermeasures not offensive weapons... even though that has been talked about too.

Considering the OP itself states, "J-20 deployment version will have soft laser weapon, not to shoot down a plane or kill a ground target, but to 'kill' infrared guided missiles" this is a safe guess.